An old friend - bird flu
“What do you say about the chickens, dear professor? - Bronsky shouted... He emphasized with a sharp lacquered finger of incredible size the headline across the entire page of the newspaper: “Chicken pestilence in the republic.” M. Bulgakov “Fatal eggs”
People have been familiar with the disease for a long time, which was named in the 19th century. "flu" (from French. grippe– to grasp). This unwanted companion of humanity not only collects an annual tribute in the form of epidemics, but also causes mass deaths of birds, diseases in pigs and horses, and sometimes even in minks and marine mammals
Influenza is caused by viruses belonging to the orthomyxoviridae family: Influenzavirus A, Influenzavirus B and Influenzavirus C. They are classified based on the so-called antigenic differences in their proteins, nucleoprotein and matrix. Let us recall that antigens are substances that cause the body’s immune response in the form of the formation of specific antibodies.
Types B and C viruses only infect humans. The most pathogenic virus is type A, which will be discussed further. It is he who is capable of infecting a variety of animal species, periodically causing devastating pandemics in the human population. Based on two different glycoproteins located on the surface of the virus - hemagglutinin and neuraminidase - the influenza A virus is divided into so-called subtypes. In total, 16 subtypes of hemagglutinin and 9 subtypes of neuraminidase are known. However, out of 144 possible pairs of combinations, only 86 occur in nature, and 83 of them were found among avian influenza viruses, while viruses of relatively few subtype combinations have been isolated from mammals. However, only viruses of three hemagglutinin subtypes (H1, H2 and H3) and two types of neuraminidase (N1 and N2) circulate widely among people.
Natural reservoir
Influenza A virus, which has now become the “fashionable” avian flu, was first isolated about 100 years ago. In total, since 1961, the virus has been isolated in at least 90 species - representatives of 12 orders of birds - in North America, Europe, India, Japan, South Africa and Australia. At the same time, in the Anseriformes order, the virus was found in more than a quarter of the 149 existing species, and in the Charadriiformes order - in approximately 20 species. Representatives of the latter order (herons, plovers, terns) are widespread throughout the world and are distinguished by their tendency to migrate over long distances.
Thus, the primary reservoir of almost all subtypes of influenza A virus are various birds belonging to the orders Anseriformes and Charadriiformes. Other species, undoubtedly, do not have as much importance in the natural history of influenza viruses as these migratory birds leading an aquatic and semi-aquatic lifestyle.
As a result of studying the genotypes of influenza viruses in various bird species, it turned out that they evolved independently in Eurasia and America. Thus, migration between these two continents (latitudinal migration) appears to play little or no role in the evolution of the influenza virus, while birds migrating along longitudes make a decisive contribution to this process.
Recent history
It is obvious that for centuries and millennia the avian influenza virus “peacefully” circulated in the animal world, being one of the factors of natural selection and population regulation. However, with the development of agriculture and mass poultry farming, “new horizons”, figuratively speaking, opened up for him. This was facilitated by both the inevitable overcrowding of poultry and artificial selection aimed at increasing the productivity of individuals, which also inevitably leads to a decrease in their resistance. However, for a long time, the problem of “bird flu” was a matter of concern only to virologists, veterinarians and livestock specialists.
Everything changed in 1997 with the mass epidemic of “bird flu” in Hong Kong, the culprit of which was the influenza virus type A H5N1 serotype. This event would probably go unnoticed by the world community. However, as it turned out, the same virus became the culprit of the disease in 18 people, leading to death in six infected people. The only effective weapon in the fight against the infection that affected the poultry industry in Hong Kong was the complete destruction of the poultry population. But the genie was already out of the bottle, and in subsequent years the H5N1 influenza virus began to spread throughout Southeast Asia and China, causing enormous economic damage.
Following the routes of bird migrations, from Southeast Asia the virus, together with migratory birds, rushed in the fall of 2005 to the Middle East, North Africa, and southern Europe. Thus, the “bird flu” epizootic began to practically turn into a “panzootic,” causing damage to the poultry industry in many countries around the world and, moreover, beginning to pose a threat to human health. The world community and the media are loudly talking about the coming of a new “plague” of humanity.
The insidious "Spanish flu" and the Hong Kong killer
The story of “bird flu” once again testifies to the truth that if you don’t know something, it doesn’t mean that “something” doesn’t exist.
All of us have repeatedly in our lives encountered a disease that doctors diagnose as influenza. And, as has now been established, most often the primary source of this disease in humans are the descendants of the same “bird flu” viruses that have undergone many years of evolution in the human population, more than once causing epidemics and pandemics.
The first historically recorded pandemic was the infamous “Spanish flu”, whose ancestor was the H1N1 bird flu virus and which caused the death of 20 to 50 million people worldwide. Many people died during the first days of the disease and many more as a result of complications caused by the flu.
1957-1958 “Asian flu”, which claimed about a million lives. First registered in February 1957, it “covered” half the world in just five months, reaching the American continent.
1968-1969 The latest pandemic is the “Hong Kong flu”, and again the death of about a million people around the world. The H3N2 virus serotype that caused it still circulates in the human population.
All of these pandemics had several common features. Thus, the first outbreaks of diseases occurred in Southeast Asia. The emergence of the H2N2 and H3N2 viruses was accompanied by the disappearance from the human population of the influenza viruses that had circulated before them (subtypes H1N1 and H2N2, respectively). The reason for the latter phenomenon remains unclear to this day.
Moving from history to modern times, let us return to the already mentioned outbreak of the disease in poultry in Hong Kong in 1997, which was accompanied by infection of people. The age of the patients ranged from 1 year to 60 years, all of them had high fever, gastrointestinal disorders, and hepatitis. The death of six patients occurred from primary viral pneumonia.
And these were just the “first signs”. Thus, from 2003 to the beginning of February 2006, according to WHO, about 170 cases of bird flu among people were officially registered in the world with a mortality rate of more than 50%. The largest number of cases was recorded in Vietnam (93 people), the highest mortality rate was in Cambodia and Indonesia.
Mass killer job vacancy
The events of recent years could not help but alert influenza specialists. Since it has been established that the periodicity of pandemics in humans is approximately 30-40 years, the end of the last century, as they say, has just come. Who is the contender for the title of the new “mass murderer”?
Previously circulating in wild waterfowl as a natural reservoir, low-pathogenic subspecies of influenza A virus types H5 and H7 have in the last decade significantly increased their pathogenicity both to the natural host and to other species of birds and mammals. Four new variants of the virus have been discovered that have caused death not only in birds, but also in humans: H5N1, H9N2, H7N7 and H7N3. The most common influenza virus in the last ten years is H5N1. It is this highly pathogenic Asian variant of “bird flu” that continues to “master” the planet, spreading widely throughout Eurasia and North Africa. Among its victims, in addition to countless poultry, are the inhabitants of these countries.
The source of the infectious agent, as a rule, is sick or dead poultry from the disease, with which the sick people were in close contact. However, cases have been reported in which infection may have occurred within the family while caring for patients. It should also be borne in mind that long-term circulation of the H5N1 subtype in wild birds can lead to widespread spread of the virus in water bodies, which poses an additional potential risk of infection to humans.
And yet, how likely is another influenza pandemic to occur today? Yes, now the bird flu virus has become more virulent and, in principle, has overcome the bird-human interspecies barrier. Yet it does not yet appear to have the ability to transmit directly from person to person and spread rapidly through a human population, which is a necessary condition for a pandemic to occur. However, the latter only requires a “correct” exchange of genetic material between, say, the H5N1 strain and a human influenza strain, which could well happen if a person or animal were to get human and bird flu at the same time.
Such viral progeny could theoretically receive hereditary sets, which are recombinations of RNA segments of both parental viruses, which would ensure its effective transmission in the human population. Ordinary domestic pigs, our closest genetic and physiological relatives, can become a kind of “mixing vessel” for the formation of a new pandemic virus. So far, fortunately, this has not happened, which is why the development and implementation of preventive biosafety measures in poultry farming is the most urgent today. Naturally, along with continued research into the ecology of the virus in its natural environment.
In the Siberian expanses
And yet, why exactly did Siberian scientists, virologists and ornithologists, who do not live and work in Southeast Asia, take the problem of “bird flu” so “close to their hearts”? The thing is that in the south of Western Siberia, migratory flows of birds wintering in various regions of the world converge - Europe, Africa, the Middle East and Central Asia, Hindustan and Southeast Asia. The generously watered Siberian territories are an ideal place for both nesting and stopover for millions of birds.
Mass migrations of birds take place here from the end of March to the first half of June and from the second half of July almost to mid-October, due to which mass concentrations of birds are periodically observed in certain areas of the forest-steppe from spring to autumn. The number of colonies of waterfowl and semi-aquatic birds created during nesting can reach several thousand individuals. All this provides especially favorable conditions for the spread of various viral and other diseases dangerous to humans.
More people die in epidemics. During the Spanish Flu of 1918, the mortality rate was estimated to be 2–3 %. If such a pandemic were to happen again today, about 70 million people would die, and in a relatively short time - in just six months, the virus could take over the entire world and reap its sad harvest. Is humanity ready for such a turn of events? Doctor of Medical Sciences will tell you about the tactics and strategies for combating a possible pandemic in the next issues. V. V. Vlasov, Director of the Russian branch of the Northern European Center of the Cochrane Collaboration (Moscow)
Since 2002, the State Scientific Center for Virology and Biotechnology “Vector”, together with the Institute of Ecology and Systematics of the SB RAS, has been monitoring the bird flu virus in wild migratory birds found in the Novosibirsk region. For laboratory research, samples were taken both from live birds caught in nets (washes from the cloacal area) and from birds shot during spring and autumn hunting - during periods of mass migration.
In 30 of 1,120 samples collected from wild birds from 2002 to May 2005, various strains of influenza virus, including the highly pathogenic H5N1, were detected. As expected, various species of wild ducks turned out to be carriers of the potential infection.
Since the fall of 2003, our scientists began researching the circulation of the influenza virus in wild birds and in the territories adjacent to Russia - in Mongolia. But this is only the beginning of a lot of research work. The gaze of our specialists is fixed on the Siberian North - where tens and hundreds of millions of birds fly to nest in the vast expanses from Taimyr to the Bering Sea every spring from Africa, Europe, Asia, America and Australia, and from where new variants of “bird flu” subsequently spread practically all over the world.
The publication uses photographs by A. Yurlov (IS&EZh SB RAS, Novosibirsk)
The relevance of the problem of acute respiratory diseases (ARIs) is determined by the significant socio-economic damage they cause, which is determined by the widespread distribution of this group of diseases, their high contagiousness, allergization of the body of those who have recovered from the disease with impaired immune status, and the impact of diseases on overall mortality.
Infectious pathology is constantly dominated by influenza and other acute respiratory infections, the proportion of which exceeds 80-90%. In the Russian Federation, 2.3-5 thousand cases of these diseases are registered annually per 100 thousand population. Of the total number of cases of temporary disability, influenza and acute respiratory infections account for 12-14%, and the economic damage they cause is about 90% of the total damage caused by infectious diseases.
Acute respiratory infections are caused by pathogens, the number of species of which reaches 200. These include adeno-, paramyxo-, corona-, rhino-, reo-, enteroviruses, as well as mycoplasmas, chlamydia, streptococci, staphylococci, pneumococci, etc. In this regard the development of effective means of specific prevention of all acute respiratory infections in the foreseeable future seems difficult.
All pathogens of acute respiratory viral diseases are characterized by their low persistence and rapid death in the environment.
From an epidemiological point of view, influenza should be distinguished from the general group of acute respiratory infections due to its potential for pandemic spread.
Flu- anthroponotic viral acute infectious disease with aspiration mechanism of pathogen transmission. It is characterized by an acute onset, fever, general intoxication and damage to the respiratory tract.
Main questions of the topic
1. Characteristics of the pathogen.
2. Source of the infectious agent.
3. Mechanism and routes of transmission of the pathogen.
4. Epidemic process of influenza.
5. Preventive and anti-epidemic measures.
Pathogen influenza is an RNA virus from the family Orthomyxoviridae sort of Influenzavirus. According to the antigenic characteristics, there are 3 serological types of influenza virus - A, B, C.
The surface antigens of the virus include hemagglutinin (H) and neuraminidase (N), on the basis of which subtypes of the influenza A virus are isolated, for example H1N1, H3N2.
Unlike type B and C viruses, which are characterized by a more stable antigenic structure, type A virus has significant variability in surface antigens. It manifests itself either in the form of antigenic drift (partial renewal of antigenic determinants of hemagglutinin or neuraminidase within one subtype, which is accompanied by the emergence of new strains of the virus), or in the form of antigenic shift (complete replacement of a genome fragment encoding the synthesis of only hemagglutinin or hemagglutinin and neuraminidase), leading to to the emergence of a new subtype of influenza A virus.
Influenza viruses have little resistance in the external environment. They tolerate low, negative temperatures better and quickly die when heated and boiled. There is a high sensitivity of influenza viruses to ultraviolet rays and the effects of conventional disinfectants.
The influenza virus can survive at a temperature of 4 °C for 2-3 weeks; heating at a temperature of 50-60 ° C causes inactivation of the virus within a few minutes, the effect of disinfectant solutions is instantaneous.
Source of infectious agent with the flu - a sick person. Its contagiousness appears already at the end of the incubation period, several hours before the onset of the disease. Subsequently, as the disease develops, the patient is most dangerous in the first 2-5 days with intensive release of viruses from the upper respiratory tract. In rare cases, the period of infectiousness can be extended to the 10th day of illness. As a source of infection, the most dangerous are patients with mild forms of influenza who remain in groups of children and adults, use public transport, and attend cinemas and theaters.
The main reservoir of the influenza virus in nature is migratory waterfowl (wild ducks, geese, terns, etc.), which serve as natural sources of infection for poultry. The avian influenza virus can infect mammals: seals, whales, minks, horses and, most importantly, pigs, in whose bodies reassortment of the avian influenza virus with the human influenza virus can occur. Human susceptibility to these viruses is low. The avian influenza virus, unlike the human influenza virus, is more stable in the environment. At a temperature of 36 °C it dies within 3 hours, at 60 °C - after 30 minutes, and during heat treatment of food products (boiling, frying) - instantly. Tolerates freezing well. It survives in bird droppings for up to 3 months, in water at a temperature of 22 °C - 4 days, at 0 °C - more than 1 month. The virus remains active in bird carcasses for up to 1 year.
Transmission mechanism influenza virus - aspiration; transmission route is airborne. During coughing, sneezing and talking, an “infected zone” with a high concentration of the virus is created in the air around the patient, which depends on the frequency of expiratory acts, the intensity of salivation in the patient, the size of aerosol particles, air humidity, ambient temperature and air exchange in the room. Experiments have shown that influenza viruses can remain viable in dried saliva, mucus, sputum, and dust, but the role of airborne dust transmission of the pathogen is insignificant.
Susceptibility population to new serotypes (subtypes) of influenza virus is high. Post-infectious immunity is type-specific; with influenza A it lasts for at least 3 years, with influenza B it lasts for 3-6 years.
Epidemic process influenza manifests itself in sporadic incidence, epidemic outbreaks and seasonal epidemics (3-6 weeks). Periodically, pandemics occur caused by a new subtype of influenza A virus, to which the vast majority of the population is susceptible. The long-term dynamics of influenza incidence is shown in Fig. 10.1.
Rice. 10.1. Long-term dynamics of influenza incidence in the Russian Federation in 1978-2011.
Seasonal declines in the summer and epidemic rises in the autumn-winter period are associated with common factors that determine the seasonal unevenness of the incidence of acute respiratory infections.
Features of the epidemiology of influenza are largely determined by the unique variability of the surface antigens of its pathogen - the glycoproteins hemagglutinin and neuraminidase.
The degree of antigenic differences determines the breadth and speed of spread of the pathogen, the age composition and the level of morbidity, which is influenced by meteorological factors, hypothermia, the incidence of acute respiratory infections and socio-economic conditions (communication between people, sanitary and hygienic conditions in groups of children and adults). During the twentieth century. Several influenza pandemics have been recorded: the Spanish flu of 1918-1919. - A (HSW1N1); "Asian flu" 1957-1958 - A (H2N2); "Hong Kong flu" 1968-1970 - A (H3N2); "Russian flu" 1977-1978 - A (H1N1), and at the beginning of the 21st century. - “swine flu” 2009-2010. - A (H1N1).
The pandemic spread of influenza in a modern urban environment is mainly associated with typical ways of spreading influenza viruses, depending on the intensity of international transport communications.
In the countries of the northern hemisphere with a temperate climate, influenza epidemics occur in November-March, in the southern hemisphere - in April-October.
The emergence of new antigenic variants of the influenza virus leads to an increase in morbidity in all non-immune age groups, with the greatest impact on children in the first years of life.
The age composition of patients is determined by the level of specific immunity. Children under 6 months of age are less susceptible to influenza due to passive immunity received from the mother. At the age of 6 months to 3 years, the incidence increases.
Influenza B viruses cause epidemic rises in morbidity, which often occur after an epidemic increase in morbidity caused by influenza A, against the background of its decline, which leads to the emergence of two waves of the epidemic. Influenza C virus causes sporadic illness in children.
Preventive and anti-epidemic measures. The main strategic direction in the fight against influenza is vaccine prevention. Healthcare practice currently has a large range of vaccine preparations: live, inactivated, chemical, subunit, split vaccines. To obtain an epidemiological effect from vaccination, it is necessary that the vaccine contains the same types and subtypes of the virus that will cause an epidemic rise in incidence in a particular area, and risk groups must be vaccinated before the seasonal rise in the incidence of influenza.
However, protection only against influenza and the absence of vaccines against other viral acute respiratory infections do not provide the expected effect in the form of a significant reduction in morbidity. At the same time, convincing data have been accumulated indicating that there are real ways to influence the epidemic process of acute respiratory infections. It has been established that the use of nonspecific prophylaxis among risk groups (schoolchildren 7-14 years old, often and for a long time ill) causes a significant reduction in the incidence of acute respiratory infections in the entire population, which leads to a significant reduction in the socio-economic damage caused by these infections.
The stabilization of the epidemiological situation regarding influenza was facilitated by the immunization of the population within the framework of the National Preventive Vaccination Calendar, which began in 2006. For immunization, domestic three-vaccines are used, containing antigenic variants of influenza viruses: types A and B, recommended for the upcoming epidemic season.
Anti-epidemic measures in an epidemic outbreak should begin with isolating the patient. Patients with influenza are hospitalized only for clinical and epidemiological indications: children under 3 years of age, the elderly with concomitant diseases, pregnant women, as well as those living in hostels and boarding schools. In the rooms where the patient is located, there must be ventilation, UV irradiation, regular wet cleaning with the use of disinfectants, and thorough washing of dishes. Regularly replaced gauze masks covering the mouth and nose play a protective role for people around the patient. Work with those in contact with the patient includes monitoring them during the incubation period, which lasts from several hours to 2 days, and, if indicated, using specific and nonspecific protective equipment (Scheme 10.2, 10.3).
Related information.
1.3. EPIDEMIOLOGY
Organization of monitoring of introductions and spread of avian influenza in natural conditions on the territory of the Russian Federation
Date of introduction: from the moment of approval
1. DEVELOPED by the Federal Service for Supervision of Consumer Rights Protection and Human Welfare (G.G. Onishchenko, E.B. Ezhlova, G.F. Lazikova); FGUN SSC VB "Vector" of Rospotrebnadzor (I.G. Drozdov, A.N. Sergeev, A.P. Agafonov, A.M. Shestopalov, E.A. Stavsky, A.Yu. Alekseev, O.K. Demina, E.B. Shemetova, A.A. Sergeev, Yu.V. Tumanov, V.A. Ternovoy); Federal State Institution Central Research Institute of Epidemiology of Rospotrebnadzor (G.A. Shipulin, A.T. Podkolzin, S.B. Yatsyshina); FGUZ RosNIPCHI "Microbe" Rospotrebnadzor (A.V. Toporkov, S.A. Shcherbakova, N.V. Popov, V.P. Toporkov, A.A. Sludsky, I.N. Sharova, M.N. Lyapin, A .N.Matrosov, V.N.Chekashov, T.Yu.Krasovskaya); State Research Institute of Influenza RAMS (O.I. Kiselev, L.M. Tsybalova, T.G. Lobova).
3. APPROVED AND ENTERED INTO EFFECT by the Head of the Federal Service for Supervision of Consumer Rights Protection and Human Welfare, Chief State Sanitary Doctor of the Russian Federation G.G. Onishchenko on December 26, 2008 N 01/15701-8-34
List of abbreviations
Avian influenza virus type A
Biosafety - biological safety
ELISA - enzyme immunoassay
MFA - method of immunofluorescent antibodies
RT-PCR - reverse transcription - polymerase chain reaction method
HRTHA - hemagglutination inhibition reaction
WHO - World Health Organization
1. Scope of application
1. Scope of application
1.2. These guidelines are intended for specialists from bodies and institutions of the Federal Service for Supervision of Consumer Rights Protection and Human Welfare and other organizations, regardless of their legal form of ownership.
2. General provisions
2.1. The purpose of introducing these guidelines is to regulate activities for epizootological monitoring of avian influenza in natural conditions. The set of monitoring measures includes organizing the collection, storage and transportation of material, conducting laboratory research, as well as ensuring the biological safety of the work being carried out. The main objective of monitoring activities for avian influenza is to identify the introduction of the pathogen and the spread of this infection in populations of wild animals of the near-water complex in order to carry out adequate anti-epidemic and preventive measures among people.
2.2. The organization and implementation of activities for epizootological monitoring of avian influenza in natural conditions on the territory of the Russian Federation is carried out by the bodies and institutions of the Federal Service for Surveillance in the Sphere of Consumer Rights Protection and Human Welfare in cooperation with the bodies and institutions of the Ministry of Agriculture and Rosselkhoznadzor.
2.3. The volume, nature and focus of preventive measures among people are determined by the results of an epizootological examination and the forecast of the epizootic and epidemic situation regarding avian influenza in specific regions of the Russian Federation.
2.4. The Rospotrebnadzor departments for the constituent entities of the Russian Federation, in whose territory epizootics of avian influenza have been detected, together with the executive authorities of the constituent entities, Rosselkhoznadzor authorities, the Ministry of Emergency Situations and other interested services and departments are planning activities aimed at preventing the spread of the virus among poultry, in poultry farms and among people , as well as aimed at minimizing the consequences of possible outbreaks, if they have already occurred, and their suppression. A comprehensive plan of preventive measures for avian influenza is drawn up by the departments of Rospotrebnadzor together with the health authorities of the constituent entities of the Russian Federation, Rosselkhoznadzor and other interested services and departments for a period of at least 2 years with annual adjustments.
2.5. The forecast of the epidemiological and epizootological situation regarding avian influenza on the territory of the Russian Federation is compiled by the scientific and methodological center for reference diagnostics and study of highly pathogenic strains of influenza virus - NMCH (Federal State Institution State Research Center for Virus and Virus "Vector" of Rospotrebnadzor). The forecast is compiled on the basis of reports provided to the NMCG on the epidemiological and epizootological situation regarding avian influenza in Russia (1-2 times a year), prepared by the Center for Ecology and Epidemiology of Influenza - CEEG (State Research Institute of Virology named after D.I. Ivanovsky RAMS) and the Federal Influenza Center - FCG (State Research Institute of Influenza, Russian Academy of Medical Sciences). These conclusions are formed on the basis of information provided to CEEG and FTG from the relevant institutions supervised by them (anti-plague stations and support bases, determined by Order of Rospotrebnadzor dated March 31, 2005 N 373). The formulated generalized forecast and conclusions about the epidemiological and epizootological situation in Russia are sent to the Federal Service for Surveillance in the Sphere of Consumer Rights Protection and Human Welfare. Data on the forecast of the epidemiological and epizootological situation regarding avian influenza on the territory of the Russian Federation are transmitted to WHO, to the information website of the NMTC, to the National Influenza Centers of the CIS countries and developing institutions (CEEG and FTG) after agreement with the Federal Service for Surveillance in the Sphere of Consumer Rights Protection and human well-being.
2.6. Advisory, methodological and practical assistance to the departments of Rospotrebnadzor in the constituent entities of the Russian Federation on the issues of prevention and implementation of anti-epidemic measures among people in territories affected by the avian influenza epizootic is provided by the NMTC, CEEG and FTG, the Anti-plague Center, regional centers for monitoring pathogens of infectious diseases I-II pathogenicity groups and Centers for the Indication and Diagnostics of Causative Agents of Dangerous Infectious Diseases, created on the basis of anti-plague institutions.
3. Rationale for the need to monitor avian influenza
The need to monitor avian influenza is determined by the real danger of the introduction of the causative agent of this disease by migratory birds and the formation of foci of infection in many regions of the Russian Federation, as well as the occurrence of epizootics among poultry and the potential ability of the avian influenza virus to cause human infection.
Since 1997, epizootics have been observed among wild and domestic birds caused by highly pathogenic influenza A viruses of the H5N1 subtype, which can also cause severe illness among people with high mortality. In recent years there has been an expansion influenza virus range birds, increasing the species spectrum of carriers, increasing the virulence of circulating strains. The ability to survive in the environment for a long time, especially at low temperatures, determines the expansion of the virus's distribution area and the need for monitoring activities across vast territories of the Russian Federation.
Cases of transmission of the influenza A virus subtype H5N1 from person to person have not been recorded, although familial outbreaks of disease have been noted repeatedly. However, the joint circulation of human and avian influenza virus strains increases the likelihood of a reassortment event and the emergence of a pandemic variant of the influenza virus.
The Federal Service for Veterinary and Phytosanitary Surveillance (Rosselkhoznadzor) monitors the situation regarding avian influenza, primarily solving the problems of preventing epizootic outbreaks among domestic animals. However, epidemiological monitoring of avian influenza in natural habitats is currently carried out insufficiently.
4. Organization of epizootological monitoring of avian influenza in natural conditions
4.1. Epizootological and epidemiological features of avian influenza
4.2. The purpose and objectives of epizootological monitoring of avian influenza in natural conditions
The main goal of epizootological monitoring of avian influenza is the timely detection of cases of introduction of the avian influenza virus into natural biotopes and tracking the characteristics of the spread of this infection among wild animals of the near-water complex.
To achieve the goal, it is necessary to solve the following tasks:
select geographic points for monitoring with compilation of an inventory of water bodies where a large number of birds of the limnophilic complex accumulate for rest, nesting and feeding;
organize mobile mobile teams to collect samples of material for research;
establish the species composition, abundance, and distribution features of potential AIV carriers in the biotopes of the semi-aquatic complex;
collect samples of field material for laboratory testing for the presence of avian influenza virus, process and promptly analyze the results obtained;
study the epizootological status of individual species and groups of birds and other animals of near-water biocenoses;
study the parameters of the epizootic process in foci of avian influenza (seasonal characteristics, epizootic areas, species spectrum of infected animals, etc.);
assess the degree of risk of infection of various types of reservoirs located in close proximity to rural settlements and large poultry farms;
compile a list of settlements where domestic animals can be infected with avian influenza from wild water birds;
develop measures to prevent epizootic outbreaks and human diseases;
carry out sanitary education and outreach work among the local population;
make forecasts for the development of the situation;
organize notification of health authorities and local executive authorities about the results of an epizootological survey of territories for the presence of foci of the avian influenza virus and the forecast for the development of the epidemic situation.
4.3. Tactics and methods of epizootological monitoring of avian influenza in natural conditions
The basis of epizootological monitoring of avian influenza in natural conditions is the examination of aquatic and near-aquatic biocenotic complexes, which is carried out in a planned manner. The search for the causative agent of avian influenza should be carried out, first of all, in near-water biotopes located both in places of concentration and nesting, and along and inside the intercontinental routes of seasonal flights or migrations of birds belonging primarily to the orders Anseriformes, Charadariformes, Grebes, copepods, ankle-footed, crane-like, pigeon-like, gallinaceous, passerine. In this case, areas for collecting material are selected near and (or) on the territory of populated areas and recreational areas, as well as in areas where deaths of birds from influenza and cases of human illness were noted. Key areas (long-term monitoring points - LTM) are also selected here, where research will be carried out over several seasons. Each site is examined at least 3 times a year (during the spring migrations, during the nesting and post-breeding periods). According to epidemiological indications, emergency additional epidemiological examinations are carried out.
A prerequisite for starting an epizootological survey of semi-aquatic biotopes is the beginning of the spring migration of birds of the semi-aquatic complex, information about mortality cases among marsh, lake, and river birds.
The epizootic situation is assessed on the basis of an epizootological survey, which records the population status of background animal species in near-water biotopes, and based on the results of laboratory studies confirming the presence of the avian influenza pathogen in various objects. Based on these data, a reasoned conclusion is given about the danger of the epizootic.
When conducting an epidemiological examination for avian influenza in natural biocenoses, it is necessary to pay attention to bodies of water where solitary, flocking and colonial birds accumulate. Especially in stagnant fresh or low-mineralized reservoirs with an abundance of coastal aquatic and shrub vegetation, where there are optimal conditions for shelter, rest, feeding and nesting of birds. When choosing survey sites and determining the composition and number of samples, they are guided by the features of the hydrographic network of the area being surveyed: the location of reservoirs, their sizes. First of all, lakes, swampy lowlands, ponds, bays, estuaries, eriks, floodplains, etc., located in close proximity to rural settlements, are monitored.
During the epizootological survey, observations of weather conditions, phenological phenomena are carried out, bird counts are carried out, the nature of their distribution, numbers and activity. It is necessary to identify and track the timing, duration and routes of their mass seasonal flights and feeding migrations. When searching for foci of avian influenza, attention is paid to the external signs of epizootics in wild birds, especially noting a sharp decrease in the number and activity of birds, changes in their behavior in water bodies, the appearance of lethargic individuals, ruffled feathers, inactivity, etc. Given the high sensitivity of chicks to the influenza virus, sick individuals are most likely to be identified during the brood period.
The main objects when collecting samples for laboratory analysis are waterfowl and semi-aquatic birds: geese, swans, ducks, waders, gulls and terns, herons and rails. To obtain complete information, other birds living in water bodies, including diurnal raptors (falconiformes) and passerines, should also be hunted. It is necessary to study synanthropic birds: pigeons, magpies, crows and sparrows. All dead birds found on a pond or in a coastal zone must be subject to collection and laboratory analysis. It is also necessary to catch small mammals that live along the banks of water bodies: water vole, muskrat, mice, shrews, etc.
The timing and duration of expeditionary field work are determined by weather conditions, phenological phenomena of the year, and the characteristics of bird ecology. The optimal periods for collecting material when studying avian influenza should be considered periods of mass seasonal migrations of migratory birds in spring and autumn (April, September), as well as nesting and brood periods from the appearance of chicks to their rise to the wing (May-July).
At the preliminary stage, before going to the field, cartographic materials are studied, topographic, hydrographic, geobotanical or landscape maps and diagrams of scales 1:25000-1:200000 are purchased. Based on these documents, calendar and territorial plans and work schedules are drawn up, parking areas and routes for zoological groups are outlined.
Epizootological examination is carried out by sequential radial detour of the territory. Routes, sequence of transfers, places, number and duration of stops are determined depending on the situation, nature of the area, working conditions, convenience of access and transportation of collected samples to the laboratory.
The responsibilities of the expedition group are also responsible for monitoring the population: its numbers, economic activities and the nature of its presence on water bodies. Particular attention is paid to the movement of agricultural workers, hunters, fishermen, tourists and vacationers during the period of possible deterioration of the avian influenza situation. It is necessary to carry out active explanatory and sanitary educational work among the local and temporary population, in close contact with representatives of local health authorities, authorities, police, and representatives of the veterinary service.
The minimum composition of the field team: ornithologist, theriologist, virologist, epidemiologist, laboratory assistant, driver, cook. Bird shooting can be carried out on a contractual basis by a special team of hunters.
During epizootological examination, generally accepted zoological and environmental methods are used, regulated by current regulatory documents (for example, MU 3.1.1029-01).
4.4. Rules for collecting, storing and transporting material for laboratory research
All work on the collection, storage and transportation of field material suspected of containing avian influenza virus type A (subtypes H5 and H7) is carried out in accordance with the current SP 1.2.036-95 and MU 3.1.1027-01. Work on collecting field material is carried out in seasonal protective clothing, supplemented with a respirator, safety glasses and rubber gloves (Appendix 6 SP 1.3.1285-03).
For laboratory research, the following is taken from natural biotopes:
birds, chicks;
bird eggs;
bird feces and/or swabs from the cloaca and trachea;
small mammals of near-aquatic biotopes;
water and silt in nesting areas.
Hunted chicks, small birds and mammals(living and dying individuals are first killed using a forceps) are placed in bags made of thick white fabric (each animal in a separate bag), the edges of the bags are folded twice and tied tightly. The bags are used with the scar facing out. They are provided with labels indicating the date, exact address, station, type of animal, and the name of the collector. For transportation, fabric bags with animal carcasses are placed in an oilcloth bag.
In large birds They take a swab from the cloaca and cut off the head and part of the neck. The head is placed in a separate oilskin bag, which is provided with a label.
Storage conditions. At temperatures from 2 to 8 °C - within 24 hours; if long-term storage is necessary, animals are opened, organs and tissues are frozen at temperatures below minus 40 °C.
Transportation conditions. Animal carcasses and heads - during the day at a temperature of 2 to 8 ° C. Organs are frozen in a Dewar flask or thermal container with dry ice.
Cloaca swabs taken with dry sterile probes with cotton swabs. After collecting the material, the swab (the working part of the probe) is placed in a sterile disposable microtube with 500 μl of a sterile 0.9% sodium chloride solution or phosphate buffer. The end of the probe is broken off or cut off so that it allows the lid of the test tube to be closed. The test tube with the solution and the working part of the probe is closed and placed in a stand, which is then placed in a thermal container with cooling elements.
Storage conditions. At temperatures from 2 to 8 °C - for 3 days. If long-term storage is necessary, freeze the material at a temperature below minus 40 °C.
Transportation conditions. At temperatures from 2 to 8 °C - for 3 days. Frozen - in a Dewar flask or thermal container with dry ice.
If the bird must be kept alive ( representatives of rare species), after capture, swabs are taken from her cloaca.
Bird eggs taken from the nest (no more than 50% of the clutch), marked and placed in plastic containers with recesses for eggs, lined with cotton wool. The containers are placed in a metal container and delivered to the laboratory.
Storage conditions. Store for 3 days at a temperature of 2 to 8 °C. If long-term storage is necessary, the contents of the eggs are transferred to sterile plastic bottles with screw caps and frozen at temperatures below minus 40 ° C.
Transportation conditions. Within a few hours after collection - at ambient temperature. For 3 days - at a temperature of 2 to 8 °C. The contents of the eggs are frozen at a temperature below minus 40 °C in a thermal container with dry ice.
Bird feces(4-5 g) are collected with disposable spatulas (spatulas) into sterile plastic containers (plastic bottles with screw caps).
Storage conditions. At temperatures from 2 to 8 °C - for 3 days, at temperatures of minus 40 °C - 30 days.
Transportation conditions. At temperatures from 2 to 8 °C - for 3 days. Frozen material is placed in a thermal container with cooling elements at a temperature of minus 70 °C.
Water and silt collected from nesting sites in the coastal zone. Sludge (5-10 g) is collected with scoops and transferred to sterile plastic bottles with screw caps. Water in a volume of 1 liter is collected in sterile plastic bottles with screw caps. Containers and bottles are marked and placed in a metal container with absorbent material, the amount of which must be sufficient to adsorb the contents in the event of a violation of the integrity of the transport container.
Storage conditions. At temperatures from 2 to 8 °C.
Transportation conditions
When collecting organ samples, sterile surgical instruments (scissors, scalpels, tweezers) and sterile containers are used.
Internal organs(fragments of the trachea, lungs, spleen, brain, sinuses, air sacs, intestines) from slaughtered or dead birds, chicks, and small mammals are obtained by autopsy of animals. Before opening, the carcass is immersed in a disinfectant solution (5% chloramine B) for 20-30 s. When taking samples of animal organs, the site of the future incision is treated with a 5% iodine solution or a 70% ethyl alcohol solution, and the skin, abdominal muscles or skull bones are cut with sterile instruments. An incision in the wall of the abdominal cavity is made with an “apron”, bringing the lateral incision lines along the ribs above the level of the heart, and the resulting flap is folded back to expose the internal organs. Before taking the brain, the entire occipital part of the skull is cut off. Using a second set of instruments, pieces of internal organs ranging in size from a small pea to a hazelnut are cut off, the samples are placed over the burner flame in sterile disposable plastic tubes or containers, and sealed tightly.
Storage conditions. Freeze at temperatures below minus 40 °C.
Transportation conditions. Frozen - in a Dewar flask or thermal container with dry ice.
Strokes-imprints, obtained from the mucous membrane of the upper respiratory tract (better) and internal organs, are prepared on clean glass slides, defatted with ether, to which mucous or fresh sections of organs are pressed. The preparations are dried in air and fixed for 20 minutes in chemically pure acetone cooled from 2 to 8 °C. Place in slide racks (on edge). Make a note that the strokes are fixed.
Storage conditions. At a temperature of 2 to 8 °C for a week, at a temperature of minus 20 °C - up to 6 months.
Transportation conditions. At temperatures from 2 to 8 °C.
Temperatures below minus 40 °C are ensured in a Dewar flask filled with liquid nitrogen (minus 196 °C) or in a thermal container with dry ice (minus 70 °C).
Transportation of samples is carried out in accordance with SP 1.2.036-95. The thermal container and Dewar flask are wrapped in paper (lined with material), laced, sealed and transported to the laboratory by express. A covering letter and a packaging certificate are attached to the delivered material. The thermal container and Dewar flask must have a special sign (label with a mark) “Danger! Do not open during transportation.” If the material is to be stored and transported in a Dewar flask or in a thermal container with dry ice, sealed plastic containers resistant to low temperatures or cryovials are used to collect the material. Dewar flasks and dry ice containers must not be hermetically sealed to prevent the release of slowly evaporating nitrogen or carbon dioxide.
Before leaving for field conditions, Dewar vessels must be checked in the laboratory for compliance with passport data and suitability for operation and transportation. When filling, loading, unloading and carrying Dewar flasks, it is necessary to have ordinary overalls, shoes and canvas gloves to prevent the possibility of nitrogen getting on exposed parts of the body in the event of a spill or splashing of nitrogen. During transportation, Dewar flasks must be carefully secured to prevent tipping, splashing, or spilling of nitrogen.
Only one-time freezing and thawing of any material is allowed.
5. Laboratory research methods
Laboratory studies are carried out in accordance with the current sanitary and epidemiological rules SP 1.3.1285-03, regulating work with microorganisms of I-II groups of pathogenicity (hazard), MUK 4.2.2136-06 "Organization and conduct of laboratory diagnostics of diseases caused by highly virulent strains of the influenza virus type A birds (VGPA).
Fluorescent antibody method (FAM)
For MFA, fixed smears-imprints of animal organs and mucous membranes are used. The reaction is carried out in accordance with the instructions for the diagnostic drug "Fluorescent immunoglobulins for early differential diagnosis of influenza A (H5)", produced by LLC "Enterprise for the production of diagnostic drugs" of the State Research Institute of Influenza RAMS (St. Petersburg).
In each smear, at least 20-25 fields of view are examined.
The brightness of viral antigens stained with luminescent immunoglobulins is assessed using a generally accepted scale:
++++ (4+) - bright fluorescence inside tissue cells;
+++ (3+) - moderate fluorescence inside tissue cells;
++ and + (2+ and 1+) - weak fluorescence inside (or outside) tissue cells.
A positive result of an immunofluorescence study is the detection in the preparation of at least 5-8 organ tissue cells that have characteristic inclusions with specific fluorescence of three and four pluses.
Polymerase chain reaction (PCR)
Molecular genetic studies are carried out in accordance with current regulatory documents: MU 1.3.1794-03 “Organization of work during PCR studies of material infected with microorganisms of pathogenicity groups I-II”; WHO recommendations for the detection of avian influenza virus subtype H5N1 in samples from people suspected of having the disease (WHO, Geneva, August 2007); Instructions for using a test system for detecting influenza A virus RNA and identifying subtypes H5 and H7 using reverse transcription and polymerase chain reaction (for example, AmpliSens kits Influenza virus A H5N1-FL" or "FLU", produced by the Central Research Institute of Epidemiology of Rospotrebnadzor).
The "FLU" kit allows you to detect RNA of the influenza A virus and identify subtypes H5 and H7 in material from dead and sick animals and environmental objects. The material for the study is: droppings, smears from the cloaca and trachea, internal organs (fragments of the trachea and lungs, spleen, brain), water, swabs from eggs and egg whites. The test system includes reagent kits: for RNA extraction, for obtaining cDNA on an RNA template, for amplification of cDNA sections (PCR) and detection of amplification fragments in the formats of electrophoretic analysis and hybridization-fluorescence detection (FEP and FRT), and also contains control samples .
AmpliSense set Influenza virus A H5N1-FL" allows you to detect the RNA of the influenza A virus and identify the H5N1 subtype in material from dead and sick animals and environmental objects. The material for the study is: droppings, smears from the cloaca and trachea, internal organs (fragments of the trachea and lungs, spleen, brain), water, egg washes and egg whites. The test system includes reagent kits: for RNA extraction, for obtaining cDNA on an RNA template, for amplification of cDNA sections (PCR) and detection of amplification fragments in hybridization-fluorescence detection formats (FEP). and FRT), and also contains control samples.
Enzyme-linked immunosorbent assay (ELISA)
For the study, individual bird blood sera without signs of hemolysis and bacterial contamination with a volume of 0.3-0.5 ml are used. The reaction is carried out in accordance with the temporary instructions for the use of a kit for detecting antibodies to the avian influenza virus (AIV) by enzyme-linked immunosorbent assay (for example, “Kit for detecting antibodies to the avian influenza virus by ELISA”, produced by SPE “AVIVAC”).
The results are taken into account on a spectrophotometer at a wavelength of 492 nm (when using OPD) or 450 nm (when using TMB).
All stages of incubation are carried out for 30 minutes at a temperature of 20-30 °C.
Hemagglutination inhibition reaction (HAI)
Detection of specific antibodies to the avian influenza virus in the blood serum of birds is carried out using a micromethod in accordance with the instructions for use of the “Set of antigens and serums for the diagnosis of avian influenza in the hemagglutination inhibition reaction (HAI)”.
The reaction is recorded visually after complete sedimentation of erythrocytes in the control wells (in the form of a “button”). The antibody titer in serum is considered to be its highest dilution, in which there is completely no agglutination of red blood cells by the influenza virus antigen.
Positive samples identified during laboratory testing are sent for virus isolation and identification to the Federal State Budgetary Institution State Research Center for Virus Virus "Vector" of Rospotrebnadzor.
6. Ensuring biological safety requirements when conducting epizootological monitoring of avian influenza in natural conditions
To ensure the biological safety of work when conducting epidemiological monitoring in potential natural foci of avian influenza, the following must be taken into account:
Employees of anti-plague institutions participate in the examination, and employees of other medical and biological organizations and institutes that have access to work with pathogenic pathogens of groups I-II of pathogenicity may also be involved. Support personnel (drivers, shooters, etc.) are allowed to work after instruction;
the entire squad or expedition must be familiar with the biological safety requirements when working with pathogens of natural focal infections circulating in the given territory. The leader (chief) of the epidemiological team (expedition) is responsible for compliance with these requirements when capturing wild animals and collecting field material;
any material is considered potentially dangerous in relation to the possible content of pathogens of natural focal diseases characteristic of the landscape zone within which it is collected;
reconnaissance survey of the area, installation of fishing gear is carried out in special clothing (overalls or anti-encephalitis suit, boots);
inspection of exposed fishing gear and collection of field material is carried out in work clothes, supplemented with aprons and oversleeves made of waterproof fabric (film), rubber gloves (2 pairs) [at the end of work, aprons, oversleeves and gloves are disinfected];
To protect the respiratory system, use disposable cotton-gauze bandages or dust respirators (preference is given to Lepestok respirators or respirators of at least FFP2 class);
protection of the organs of vision is carried out with tight-fitting glasses;
Disinfection of fishing gear and other tools is carried out daily at the end of work by heating in the sun (in summer), boiling, treatment with disinfectant solutions, followed by airing; boxes and depositors are treated with disinfectant solutions;
analysis of field material and autopsies of animals are carried out in a type I anti-plague suit (respiratory protection is similar to paragraph 6 of this section, the specifics of collecting material and preparing samples for transportation to the laboratory are set out in section 4.4 “Collection of field material for laboratory research”);
upon completion of the work given in paragraph 9, instruments and protective clothing are disinfected (see Appendix 4), used tips, pipettes are disinfected by immersion in a 6% solution of hydrogen peroxide for 60 minutes, dispensers are disinfected by wiping twice with an interval of 15 minutes 6 % hydrogen peroxide solution (exposure 120 min);
the remains of field material that is not subject to laboratory research are burned or disinfected by autoclaving, the resulting waste is placed in specially dug holes, which are then buried;
transportation of the material to the diagnostic laboratory is carried out by expedition transport;
expedition participants are subjected to daily thermometry; upon completion of work, observation is established for a period of 7 days;
The emergency first aid kit must be equipped in accordance with SP 1.3.1285-03
7. Ensuring biological safety when conducting laboratory diagnostic tests
7.1. Carrying out work not related to the accumulation of the virus, the formation of aerosols of infected material (coloring smears, performing serological reactions with non-disinfected diagnostic material, serological studies with non-disinfected material, RNA isolation) is carried out in a type IV anti-plague suit, supplemented with a cotton-gauze bandage (respirator) and two pairs of rubber gloves. The work is carried out in a class II biological safety cabinet*.
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7.2. Work on infecting cell cultures or chicken embryos, as well as work related to the possibility of aerosol formation, is carried out in class III safety boxes. Work is carried out in a type IV anti-plague suit, a cotton-gauze bandage (respirator) and rubber gloves (two pairs)*.
________________
* In the absence of biological safety boxes, work is carried out in a type I anti-plague suit, supplemented with a waterproof apron and a second pair of gloves.
7.3. Working with inactivated material, carrying out reverse transcription and PCR reactions, and electrophoretic detection of research results are carried out in a type IV anti-plague suit, supplemented with rubber gloves (two pairs).
7.4. Before starting work, personnel should be instructed on the procedure to follow in the event of an emergency, including the following scenarios: an accident in a biological safety cabinet; accident outside the biological safety cabinet; aerosol-generating accident.
7.5. Disinfection regimes for various objects during laboratory diagnosis of avian influenza virus are carried out in accordance with SP 1.3.1285-03:
7.5.1. Disinfection of room surfaces (floors, walls, doors), equipment, work tables and others by wiping twice at an interval of 15 minutes with a 6% solution of hydrogen peroxide or a 3% solution of chloramine (exposure 120 minutes) followed by UV treatment for 30 minutes .
7.5.2. Disinfection of protective clothing is carried out:
a) boiling in a 2% soda solution for 30 minutes from the moment of boiling;
b) soaking for 30 minutes at 50 °C in a 3% solution of hydrogen peroxide with the addition of 0.5% detergent.
7.5.3. Disinfection of gloves - by soaking for 60 minutes in a 6% solution of hydrogen peroxide with the addition of 0.5% detergent or in a 3% solution of chloramine.
7.5.4. Disinfection of laboratory glassware, autoclaved dispensers, tips, virus-containing liquids, agarose gel, and metal instruments is carried out using the autoclaving method - pressure 2.0 kgf/cm (0.2 MPa), temperature (132±2) °C, time 45 minutes.
7.5.5. Disinfection of dispensers - wiping twice with an interval of 15 minutes with a 6% solution of hydrogen peroxide (exposure 120 minutes), followed by UV treatment for 30 minutes.
7.6. The emergency prevention first aid kit must be equipped in accordance with SP 1.3.1285-03 and supplemented with two of the following antiviral drugs: arbidol, rimantadine, algirem, oseltamivir, zanamivir.
8. Normative references
1. Fundamentals of the legislation of the Russian Federation on protecting the health of citizens. M., 1993.. - Note from the database manufacturer.
6. SP 1.2.036-95 "Procedure for recording, storage, transfer and transportation of microorganisms of pathogenicity groups I-IV."
7. The procedure for the development, examination, approval, publication and distribution of normative and methodological documents of the system of sanitary and epidemiological regulation: Collection R 1.1.001-1.1.005-96. M., 1998.
8. SP 3.1.097-96 "Prevention and control of infectious diseases common to humans and animals: Collection of sanitary and veterinary rules."
9. MU 3.1.1029-01 "Guidelines for capturing, recording and forecasting the number of small mammals and birds in natural foci of zoonoses."
10. MU 1.3.1794-03 "Organization of work during PCR studies of material infected with microorganisms of pathogenicity groups I-II."
11. MU 4.2.2039-05 "Technique for collecting and transporting biomaterials to microbiological laboratories."
12. MUK 4.2.2136-06 "Organization and conduct of laboratory diagnostics of diseases caused by highly virulent strains of avian influenza virus type A (AVAI) in humans."
16. Methodological recommendations "Rapid diagnosis of influenza and other acute respiratory viral infections using the immunofluorescence method." St. Petersburg, 2006, approved. Head of the Federal Service for Supervision of Consumer Rights Protection and Human Welfare G.G. Onishchenko April 25, 2006
17. Methodological recommendations "Isolation of influenza viruses in cell cultures and their identification." St. Petersburg, 2006, approved. Head of the Federal Service for Supervision of Consumer Rights Protection and Human Welfare G.G. Onishchenko April 25, 2006
18. SP 1.2.1318-03 “Procedure for issuing a sanitary and epidemiological report on the possibility of working with pathogens of human infectious diseases of I-IV pathogenicity (hazard) groups, genetically engineered modified microorganisms, poisons of biological origin and helminths.”
19. Interstate standard GOST 25581-91 "Agricultural, synanthropic, wild, exotic poultry." Date of introduction: 01/01/93. Methods for laboratory diagnosis of influenza.
20. Order of the Ministry of Health and Social Development of Russia dated May 31, 2005 N 376 “On the provision of extraordinary reports on emergency situations of a sanitary and epidemiological nature.”
21. Order of the Federal Service for Surveillance in the Sphere of Consumer Rights Protection and Human Welfare dated March 31, 2005 N 373 “On improving the system of epidemiological surveillance and control of influenza and acute respiratory viral infections.”
22. Order of the Federal Service for Surveillance in the Sphere of Consumer Rights Protection and Human Welfare dated May 10, 2007 N 144 “On the creation of a scientific and methodological center for reference diagnostics and the study of highly pathogenic strains of the influenza virus.”
23. Order of the Ministry of Agriculture of Russia dated March 27, 2006 N 90 (registration number 7756) “On approval of the Rules for the fight against avian influenza.”
24. Recommendations for the protection of people in contact with infected birds and participating in the mass slaughter of animals potentially infected with avian influenza viruses, approved. Chief State Sanitary Doctor of the Russian Federation 05.08.05 N 0100/6198-0523.
25. WHO guidelines for the diagnosis and control of animal influenza (WHO/CDC/CSR/NSC/2002.5).
26. WHO recommendations for the detection of avian influenza virus subtype H5N1 in samples from people with suspected disease. WHO, Geneva, August 2007. (Recommendations for laboratory procedures to detect avian influenza A H5N1 virus in specimens from suspected human cases. WHO Geneva, August 2007).
27. Onishchenko G.G., Kiselev O.I., Sominina A.A. Strengthening influenza surveillance and control as a critical element of preparing for seasonal epidemics and the next pandemic (guidance). Moscow-St. Petersburg, 2004.
28. Bird flu. Clinical features, standardized principles of diagnosis, treatment and prevention, approved. Head of the Federal Service for Supervision of Consumer Rights Protection and Human Welfare G.G. Onishchenko 09/02/05.
29. Neklyudova L.I., Gumennik A.E., Fedorova Yu.B. and others. Practical virology (Part III). M., 1981.
30. Detection of arbovirus circulation. Methods of virological and serological studies. Clinical and epidemiological characteristics of little-studied arboviral infections. Approaches to monitoring natural foci of arboviruses / Ed. acad. RAMS D.K. Lvova // Results of science and technology. Ser. Virology. T.25. M., 1991.
31. Syurin V.N., Famuylenko A.Ya., Solovyov B.V. and others. Viral diseases of animals. M.: VNITIBL, 1998.
Appendix 1. List of documentation permitting the collection of field biological material as part of monitoring avian influenza within the borders of the Russian Federation
Appendix 1
1. Permission to shoot birds.
A) The permit is issued by the regional hunting inspectorate. An organization planning to shoot birds in order to detect individuals infected with the avian influenza virus writes a letter of justification addressed to the head of the regional game inspection. The letter is written on company letterhead in the prescribed form.
B) Shooting of birds can only be carried out by a member of the regional hunting society, endowed with the appropriate documents. It is advisable to involve persons who have the right to conduct hunting from among the employees of the organization conducting the epizootological survey. Purchase consumables (cartridges) in sufficient quantities from the travel expenses item.
2. Permission to conduct epizootological research in near-water stations with the right to set up a temporary camp in the water protection area.
The permit is issued by the regional fisheries inspection. It is necessary to provide explanations about the purpose and objectives of the planned research in the areas controlled by the fisheries inspection, which are written on letterhead in the prescribed form.
3. Coordination with regional environmental authorities.
A clear explanation of the planned activities is necessary in connection with the real threat of complicating the epidemiological situation. An explanatory letter is written to the head of the regional environmental committee on letterhead in the prescribed form.
4. Coordination with the border service of the Russian Federation.
Coordination is carried out only in cases of conducting epidemiological studies in border zones. A request for permission to work in the border zone is written to the head of the border service of a given region on letterhead in the prescribed form.
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Avian influenza is a highly contagious viral infection that can affect all species of birds. The most sensitive domestic species are turkeys and chickens. Wild bird species can serve as vectors of infection. Due to natural resistance, they themselves, as a rule, do not get sick and can cover considerable distances during the migration process. The natural reservoir for avian influenza viruses (AIVs) are waterfowl, which are most often responsible for introducing infection into households.
Avian influenza viruses belong to the influenza A viruses of the ORTHOMYXOVIRIDAE family. There are several subtypes of the pathogen, which are determined depending on the characteristics of the antigenic structure of hemagglutinin (H) and neuraminidase (N). Currently, 15 H subtypes (H1 - H15) and 9 neuraminidase subtypes (N 1 - N 9) are known, which can reassort in various combinations. Among the most pathogenic for poultry are viruses with the antigenic formula H 7N 7 (chicken plague virus) and H 5N 1, which can cause complete death of chickens.
Over the past 7 years, the avian influenza viruses H 5N 1 and H 7N 7, as a result of mutations, have sharply changed their biological properties and acquired the ability not only to overcome the host barrier with direct infection of people (bypassing the intermediate host), but also to cause extremely severe clinical forms of the disease, significant some of which end in death.
Isolated viruses of the H 5N 1 subtype actively reassort and, overcoming the interspecies barrier, are “directed” from the reservoir of waterfowl to domestic birds, and, more recently, to wild birds living on land and to humans. This dictates the need for broader infection surveillance and control, especially since the influenza virus (unlike other respiratory agents) spreads unusually quickly and cannot be controlled by traditional isolation, quarantine, or travel advice. This makes it urgent to strengthen influenza surveillance to determine the factors that allow avian virus to be transmitted to humans and to subsequently develop effective vaccines against the H5 virus for both humans and animals.
Currently, the virus is more widespread in nature due to its adaptation to other mammals (cats, dogs, pigs).
Clinical picture of the disease in humans
The duration of the incubation period for influenza A (H 5N 1) is usually 2-3 days, varying from 1 to 7 days. The disease begins acutely with chills, myalgia, possible sore throat, and rhinorrhea. In Southeast Asian countries, more than half of the patients had watery diarrhea in the absence of mucus and blood in the feces, and repeated vomiting in a quarter of cases. An increase in body temperature is one of the early and persistent symptoms. Already in the first hours of illness, the temperature exceeds 38C and often reaches high and hyperpyretic values. At the height of the disease (on the 2-3rd day of illness), damage to the lower respiratory tract (lower respiratory syndrome) is characteristic with the possible development of primary viral pneumonia: cough, shortness of breath and dysphonia. The cough is usually wet, and there is often an admixture of blood in the sputum. Auscultation - hard breathing, wheezing. On a chest x-ray in the early stages, nonspecific changes in the lungs are found - diffuse, multifocal or individual infiltrates, which are capable of rapid spread and fusion. In some cases, segmental or lobar compactions may be detected. The progression of the disease is accompanied by the development of respiratory failure and acute respiratory distress syndrome.
Manifestations of pantropism of the virus and developing during the process of intoxication can be damage to the liver and kidneys; more than 30% of patients develop acute renal failure.
Young children experience severe disease. Encephalitis may be added to the main syndromes. In this case, the symptoms are supplemented by severe headache, vomiting, impaired consciousness and nausea.
The prognosis is usually unfavorable. Mortality reaches 50-80%. Death is usually observed in the second week of illness.
Chemoprophylaxis
Chemoprophylaxis of avian influenza is carried out by taking interferon inducers (cycloferon and amixin), Remantadine, Algirem, Arbidol and Oseltamivir (Tamiflu) as antiviral drugs. Chemoprophylaxis is most effective in risk groups, among contact persons and in foci of infection. The duration of administration is equivalent to the period of onset of the convalescence stage.
The use of symptomatic agents is indicated. For hyperthermia, antipyretic drugs (paracetamol, ibuprofen or Nise) are indicated.
Drugs that are not used in the treatment of influenza A (H 5N 1): salicylates (aspirin), analgin. Analgin and anti-grippins are strictly contraindicated for the treatment of bird flu.
Antibiotics are prescribed only if mixed pneumonia is suspected.
Conclusion
An alarming aspect is the possibility of simultaneous co-infection of people with human and avian viruses with the resulting emergence of reassortants carrying surface genes from avian viruses, and internal genes from epidemic human viruses, which can give the pathogen the ability to transmit in the human population and give rise to a new pandemic virus. In addition, the possibility of direct transmission of the avian virus from person to person is of concern.
Research Institute of Influenza RAMS
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