Even as the COVID-19 situation continues for more than a year, another virus has started wreaking havoc in India by causing bird flu. As birds- both domestic and wild- continue to drop dead across the country, states have started large scale culling operations in a bid to control its spread. The disease’s timing and its impact on the poultry sector has made it a very significant issue in the beginning of 2021.
What is Bird Flu?
- It is a highly contagious viral disease that affects birds.
- The disease causes death of the birds in extreme cases- as is being observed in the current outbreak.
- Other symptoms include tremors, diarrhoea, head tilt and paralysis.
- However, not all forms of bird flu are fatal. Some forms causes only mild symptoms or simply a reduction in egg production.
- If it spreads to humans, it causes respiratory illnesses like pneumonia or Acute Respiratory Distress Syndrome in addition to fever, sore throat, cough, abdominal pain and diarrhoea.
- Migratory birds and aquatic birds are a major reservoir of the disease and they spread the disease across international borders.
- Transmission is mainly through contact with the secretions of the infected birds.
- These infected secretions like the saliva, nasal secretions and faeces often enter the water bodies. This then could infect local feral birds and domestic birds.
- The transmission can also be via infected surfaces.
- Highest risk is from home slaughtering and improper handling of dead birds.
- Transmission to humans have been rarely reported.
What causes the disease?
- Bird flu is caused by the influenza viruses.
- There are 4 genera of this virus: alpha/ A type, beta/ B type, gamma/ C type and delta/ D type influenza viruses.
- Alpha viruses infect birds and mammals. The Beta viruses infect humans and seals. The Gamma viruses infect humans, pigs and dogs while the Delta viruses infect livestock like cattle and pig.
- Of these, the first 3 types are of concern for human health. But the Beta and Gamma types are less dangerous due to slow mutation and very rare incidence.
- However, the Alpha viruses are much more dangerous and have been responsible for causing pandemics in the past. Eg: Spanish Flu 1918.
- Also it has multiple subtypes. These subtypes are categorized based on the type of antigens on their surface.
- There are 2 types of surface antigens on influenza A virus: Hemagglutinin (H) and Neuraminidase (N). The H antigen is glycoprotein that helps virus enter cells. The N antigen is an enzyme that helps the virus in exiting a cell.
- There are 18 types of H antigen and 11 types of N antigen.
- Thus the subtypes of the Alpha virus category are just combinations of these 2 antigens i.e. 198 sub-types in total.
- Of these we have identified and sequenced only 30 subtypes. Most of these infect birds and cause bird flu.
- 3 of these subtypes are endemic to human populations:
- H2N2: caused Asian Flu (1957-58) in Singapore and possibly the Russian Flu 1889. This is now thought to be extinct in the wild.
- H3N2: caused the Hong Kong Flu (1968-69) which killed millions of people.
- H1N1: Spanish flu and 2009 swine flu
- The H1N1 and H3N2 are highly transmissible even though they don’t cause a more severe form of the disease. This is the reason behind their pandemic causing ability.
- Some subtypes can spread to other species i.e. change hosts. Eg: H5N1 causes bird flu but can also spreads to cats. H3N8 can spread to dogs and horses. Some subtypes like the H17N10 and H18N11 are found in bats. Other subtypes have been known to move from birds to humans in isolated cases. But these didn’t exhibit human-to-human transmission.
How prevalent is bird flu?
- The disease has been in circulation for centuries.
- Just between August and December of 2020, 561 detections were reported in 15 European countries according to a recent European Food Safety Authority report.
- The 1st outbreak in India was in 2006.
- Migratory birds are the major source of this zoonotic disease in India. These birds arrive in India during 2 periods:
- September to October
- February to March
- Just recently, India declared itself free from avian influenza outbreak.
What are the recent developments?
- The current outbreak in India (reported in some 12 epicentres in January) is the 24th such outbreak since 2006.
- The causative is identified to be either H5N8 subtype or the H5N1
- This outbreak started in 2020, in Saudi Arabia, among wild birds. It then spread to Russia and Kazakhstan where it primarily affected migratory birds. By late 2020, it was reported in European countries especially the western countries. Later it was reported in Japan and other Asian countries.
- Since then the disease has moved to domestic birds and other local birds like crows. Many birds have been falling dead in several states like Himachal Pradesh, Rajasthan and Madhya Pradesh.
- Mass culling is being carried out in several states in a bid to control the virus.
- The disease possibly reached India via the Central Asian Flyway. This flyway stretches between the Arctic in the north and the Maldives in the south and between China in the east and Eastern Europe in the west. The flyway covers almost all of the Indian subcontinent.
How are such outbreaks controlled?
- As soon as the cases are detected in an area, the ‘infected zone’ is declared. This spans an area of 1 km radius from the site of infection.
- All domestic birds in this zone are culled .i.e. slaughtered en masse.
- Culling has been in practice since the advent of big commercial poultry farm in the latter half of 20th These large farms have conditions favourable for massive outbreaks.
- Only domestic birds are culled (not wild birds) as they live in closer proximity with humans.
- The current method of culling is by cervical dislocation or a quick twisting of the neck. This cuts off the blood supply to the brain and stops the breathing.
- Stunning or making the bird unconscious before the cervical dislocation is also recommended.
- To make the process more humane, the OIE (World Organization for Animal Health) requires the administration of oral anaesthesia if the bird is over 3kg.
- The dead birds are incinerated or buried in deep pits which are then covered with lime.
- Other methods of culling include decapitation, electrocution, lethal injection, etc.
- States may ban the transportation, sale and export of poultry products to control the spread.
- The affected states may shut down poultry markets on precautionary grounds.
- Surveillance among poultry farms, zoos and near water bodies is stepped up.
- A control room is set up at the centre to check for cases of any transmission to humans.
- Kerala state government has declared the outbreak to be a state disaster.
- The Gujarat government has issued revised standard operating procedures for its annual bird conservation program, Karuna Abhiyan. Extra precautions are to be taken by the volunteers participating in the program.
- According to WHO, it is safe to consume poultry products as long as they are properly prepared and cooked.
- The virus can be killed by normal cooking temperatures (70 degree Celsius in all parts of the product).
How prepared are we for an influenza pandemic?
- World has been more prepared for an influenza pandemic than for a coronavirus pandemic.
- There are several vaccines already available for treating the disease and many countries have stockpiled them in preparation for a possible outbreak. Eg: the US FDA approved a vaccine against H5N1 in 2007.
- There have been several scientific progresses in the fight against influenza virus in the last decade: in 2011, the FI6 antibody was discovered. This antibody targets the H proteins on the viral surfaces. It can bind to all types of H antigen and neutralize it. This could be developed to potentially fight off all subtypes of the virus.
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- An action plan has been formulated by the Department of Animal Husbandry and Dairying in 2005 and it has been revised several times since then, the latest in 2021. This provides guidance to the states with regards to prevention, control and containment of outbreaks.
- As these outbreaks tend to occur during the winters, periodic advisories are issued to the states at the beginning of each winter. Enhancing surveillance, ensuring strategic reserve of PPE supplies, undertaking IECs for increasing public awareness, etc. are part of the advisories.
- The department also provides other support to the states:
- Financial support for undertaking culling operations and paying compensations.
- Training camps for veterinary work force
- Technical support– lab services etc.
- ASCAD Scheme: Assistance to States for Control of Animal Diseases Scheme is a component of the centrally sponsored ‘Livestock Health and Disease Control’ scheme. This was introduced by the agriculture ministry. Strengthening of existing surveillance and control measures are the key focus areas of this scheme.
- Prevention and Control of Infectious and Contagious Diseases in Animals Act, 2009 provides legislative basis for prevention, control and eradication of infectious diseases affecting animals. It is also aimed at meeting India’s international obligation in facilitating import and export of animals and their products.
- Bhopal-based National Institute for High Security Animal Diseasesplays a key role in providing technical assistance.
What are the concerns?
- Animal husbandry sector has been affected due to sale and export ban in some regions. There is a possible loss of 1,500 crore INR as there is reluctance among the public to consume poultry. The sector has already been affected by last year’s lockdown and was expecting to recover during the winter months.
- The drop in demand has led to a 40-60% drop in prices. This is set to have a severe impact on poultry farmers.
- A lot of the commercial farms have poor sanitary conditions. This would make them very vulnerable to outbreaks.
- Many of the poultry farms are merely backyard farms that are distributed across many settlements. Monitoring of disease outbreaks in such farms is very challenging.
- Given the migratory nature of the viruses’ reservoir, complete elimination of the disease is difficult.
- In addition to this, the health authorities and healthcare infrastructure are already being stretched to the limits by the ongoing COVID-19 situation. If the virus were to jump to humans, the ensuing public health crisis could prove too much for the management system.
- The influenza viruses are much faster at mutation (compared to coronaviruses) and hence require regular updation of the vaccines.
- Possibility of the virus mutating to acquire the ability to infect multiple species and the eventual implication for human population. Several subtypes are just a few mutations away from being able to infect humans (eg: H5N1 could potentially evolve to cause pandemic) and such incidents have been reported earlier. Eg: H7N9 caused the 2013-16 Chinese epidemic.
- Scientists have identified that the next pandemic would be because of influenza virus, given their role in many of the recent pandemic.
- The situation could negatively impact the efforts to conserve migratory birds.
What is the way forward?
- Quick reporting and timely action are key to preventing an all-out outbreak.
- Training of poultry farmers and bird handlers on identify symptoms and biosecurity measures.
- Strengthening the biosecurity of the poultry industry.
- Compliance with protocol for disinfection and proper disposal of birds that die from the disease.
- Prevent transmission to healthy birds and even more importantly to humans.
- Indian dietary habit generally involves proper cooking of meat. However, proper precautions must be taken when preparing and handling fresh meat or poultry products.
- Properly following international guidelines for vaccinating poultry birds.
- Regular and more frequent sample checks at wintering sites in India.
- Genome sequencing of virus samples to track evolution. This would help raise flag if a more dangerous form emerges.
- Increasing research into the virus-carrying capacity of migratory birds– especially those using the central Asian flyway. This will aid preventive measures.
- International bodies like the UN, WHO and OIE could work with the countries in the CAF region to improve coordination for disease surveillance. For instance, the first reported case of the current outbreak in Asia was in Chinese breeding sites in October– coordination could have helped warn the countries down the flyway.
- Health aspects of migratory birds must be covered by the Convention for Conservation of Migratory Species of Animals which currently only covers their conservation and the conservation of their nesting sites.
Bird flu is not a new issue. Scientists have been studying it for years and have even come up with possible vaccines. However, it poses a great danger due to its mode of transmission via migratory birds and its capacity for mutation. Though the current outbreak poses no immediate threat to human lives, it has major economic implications for the poultry sector. This is a major concern given the current attempts to diversify the source of farm income. What is required now is efficient surveillance and prompt action followed by renewed attempts at improving sanitary conditions and general disease surveillance.
Practice question for mains
Critically assess the causes and consequences of bird flu. Despite repeated incidence, why haven’t we been able to prevent the disease? (250 words)