Awareness the key to decoding bird flu

Sanjay Bhoosreddy

THE recent outbreak of Avian Influenza in ducks at Sukhna Lake in Chandigarh has again raised concerns around animal and human health, a highly technical subject. For the public at large, the issue remains shrouded in myths such as avoiding poultry will keep people safe and the disease is always fatal. Avian influenza (AI), or bird flu as it is commonly called, is a highly contagious viral disease caused by extremely variable viruses which are widespread in several species of food-producing birds (chicken, ducks, turkeys, quails, guinea fowl among others), pet birds, and, particularly, wild waterfowl. 

Spread of viruses

Most of these viruses, which are usually carried without symptoms by wild birds, cause only mild disease in poultry. Others, the highly pathogenic Avian Influenza (HPAI) viruses (detected in Sukhna's ducks) spread rapidly and can kill up to 90-100 per cent of a poultry flock within 48 hours. Spread of these viruses is dynamic and complex and involves multiple host species (where it can reside and may or may not cause infection, or show clinical signs). Commercial poultry farms, wet markets (where live birds and other animals are sold), backyard poultry farms, commercial and family poultry slaughtering facilities, swine (pig) farms, human dietary habits and the global trade in exotic animals may all be responsible in the spread of influenza-A viruses.

Risk to humans

AI viruses are highly species-specific, but have, on occasions, crossed the species barrier to infect humans. AI is caused by Influenza type-A virus and few subtypes are considered highly pathogenic. Wild waterfowl are considered the natural reservoir of all influenza-A viruses. They have probably carried influenza viruses, with no apparent harm, for centuries. Evidence suggests that somehow low pathogenic viruses were introduced in domestic poultry flocks, which then mutated to the highly pathogenic form. Most avian influenza viruses do not cause disease in humans. However, the widespread persistence of highly pathogenic AI virus in poultry populations poses two main risks for human health. 

The first is the risk of direct infection when the virus passes from poultry to humans, resulting in severe zoonotic disease (meaning that they can be contracted from animals to humans and vice-versa). A second risk, of even greater concern, is that the virus may change into a form that is highly infectious for humans and spreads easily from person to person. Such a change could mark the start of a global outbreak (a pandemic).  Similarly, only some swine influenza virus subtypes have caused infections in humans. The primary risk factor, as stated above, for human infection appears to be direct or indirect exposure to infected live or dead animals or contaminated environments.  

Pandemic history

The most widely quoted date for the beginning of the recorded history of avian influenza (AI) is 1878, when researchers first differentiated a disease of poultry (initially known as fowl plague but later renamed HPAI) from other diseases with high death rates. The 20th century witnessed three pandemics which spread worldwide within a year of being detected. The first, “Spanish flu” occurred between 1918 and 1919 and caused the highest known deaths, around 50 million, worldwide.  Most deaths occurred within days of the person being infected and nearly half of those who died were young, healthy adults. It caused more deaths than World War I. The second pandemic, called “Asian flu” occurred 40 years later (1957-1958) and caused around 70,000 deaths in the US. The third and most recent pandemic occurred in 1968 to 1969 known as the “Hong Kong flu” (H3N2). It was detected first in Hong Kong in early 1968 and later that year reached the US, where it claimed thousands of lives. As of December 4, 2014, there are 676 human cases as reported to WHO worldwide due to one subtype (H5N1), out of which 398 were fatal. Though India reported just around 24 episodes in poultry so far, there are no human cases reported.

Chandigarh outbreak

Recently, among some samples of dead ducks from Sukhna Lake tested at the National Institute of High Security Animal Diseases (NIHSAD), Bhopal, one tested positive for HPAI and was confirmed so on November 17. As per AI combat protocol, Avian Influenza control and containment operations by culling (the area is depopulated of infected birds in one square kilometre area), cleaning and disinfection were carried out at the epicentre Sukhna Lake, Chandigarh (one-kilometre zone) and sanitisation certificate issued by UT administration on December 18. Subsequently, Post-Operation Surveillance Plan (POSP) was advised in accordance with the National Action Plan on Preparedness, Control and Containment of Avian Influenza to ensure that no birds are inducted for a month into the culling operation area within one-km radius and regular sampling is done within nine km beyond the operation area, the Lake. The area is now free of AI. The present wave of HPAI emerged in Hong Kong in 1997. India remained free from AI till mid February 2006 and the first outbreak was notified on February 18, 2006. Since then, outbreaks have been reported in Maharashtra, Gujarat, Madhya Pradesh, Manipur, West Bengal, Tripura, Assam, Sikkim, Odisha and Meghalaya, Karnataka, Bihar, Chhattisgarh, Kerala and now at Chandigarh.

In view of a threat of global outbreak of AI and apprehensions of a human pandemic, the Department of Animal Husbandry, Dairying & Fisheries (DADF), Government of India, had prepared an action plan to deal with eventuality, if any.  The present action plan has been prepared taking into account the new experiences, the lessons learnt from the past and the contemporary scientific information and it aims at routine and targeted surveillance and instant stamping out of birds in a defined radius from epicentre, destruction of contaminated material, restriction on movement of poultry and Post-Operation Surveillance Plan (POSP).

Surveillance of the disease and monitoring of preparedness for prevention and control of Avian Influenza are constantly emphasised with state governments.  Samples have been tested by NIHSAD, Bhopal and various Regional Disease Diagnostic Laboratories (RDDLs) are carrying out surveillance on the disease to enable early detection. In the event of Avian Influenza outbreak, the concerned state and the adjoining states are alerted immediately.  Almost entire veterinary workforces in the country have been trained to handle control-and-containment operations. To enable an immediate response, community members are trained for providing information on HPAI / suspected HPAI to the nearest veterinary institution. Sensitisation of general public on Avian Influenza through information, education and communication campaigns are carried out. The Government compensates the farmers for the forced culling of poultry and the destruction of eggs and poultry feed.

Import of poultry and poultry products  from HPAI positive countries are banned and a sanitary import permit is required for imports of animal products. 

Myths and precautions

There is a myth that eating poultry or eggs may transmit AI. There is no evidence to suggest that the consumption of properly cooked poultry or eggs could transmit the AI virus to humans. 

Cooking and boiling destroys the virus. However, preparation of chicken/eggs etc. requires handling of dressed chicken or sometimes contaminated eggs where virus may be present. One should not eat the birds/eggs in the declared affected zone.  All of these should be destroyed. In areas free of the disease, poultry and poultry products can be prepared and consumed as usual (following good hygienic practices and proper cooking), with no fear of acquiring AI infection. In areas experiencing outbreaks, poultry and poultry products can also be safely consumed provided these items are properly cooked and properly handled during food preparation. 

The AI virus is sensitive to heat. Normal temperatures used for cooking (70· C in all parts of the food) will kill the virus. All parts of the poultry must be fully cooked (no “pink” parts). Eggs, too,  must be properly cooked (no “runny” yolks). Consumers should also be aware of the risk of cross-contamination. Juices from raw poultry and poultry products should never be allowed, during food preparation, to touch or mix with items eaten raw. When handling raw poultry or raw poultry products, persons involved in preparation should wash their hands thoroughly and clean and disinfect surfaces in contact with the poultry products. Soap and hot water are sufficient. In areas experiencing outbreaks in poultry, raw eggs should not be used in foods that will not be further heat-treated as, for example by cooking or baking. 

The economic cost of Avian Influenza

Epidemics of HPAI can spread rapidly, devastate the poultry industry and cause severe trade restrictions. Poultry being an important source of food and livelihood in our country, it is important that we approach the problem from both the social and the economic angle. There are many direct losses like culling and mortality of bird, disposal cost of culled birds, job losses due to closure of farms, actual export loss due to cancelled consignment etc., loss from reduction in consumption, loss from ban on sale, loss from ban on movement of poultry to affected areas, cost of re-stocking, control and containment etc. Further, there are many indirect and notional losses like lost feed, ingredients, veterinary medicine, chick breeder sales, loss from proposed supply to other states, nutrition loss in rural households, lower economic activity in rural areas, indebtedness of farmers, traders and other players, etc. There will be other consequential losses like risk in poultry business and investment, price and demand effects, environmental pollution, losses due to trade restrictions business and tourism interruptions. With the growth of global trade and travel, a localised epidemic can transform into a pandemic rapidly, with little time to prepare a public health response.

The writer, an I AS officer, is Joint Secretary, Department of Animal Husbandry, Dairying and Fisheries, Ministry of Agriculture. The views expressed are personal