Bird Flu

Sheityabati Sagolsem *

Rapid Response Team in their van visiting affected chicken farm after outbreak of deadly Bird flu at Imphal on 26 July 2007 :: Pix - David M Mayum

In India, rearing poultry remained mostly a disorganized sector for a long time. Systemic poultry keeping was introduced in India by the Christian Missionaries in the beginning of the 20th Century. They established first poultry farm in U.P. in 1912. During the second five year plan, an organized effort was introduced by all India Poultry Development Project.

Gradually, poultry production has rapidly developed in the last three decades. Consequently, the production of poultry has been increasing steadily from 8-10% and more than 15% in the last three years. Poultry industry contributes 2% to the national GDP.

But, due to bird flu, more than 100 million birds have died in recent years. Asian Poultry Industry has to face a loss of more than 10 million dollars and overall loss in India is about 4000 crores. Therefore, a little effort has been put forward to understand the causes of bird flu and its preventive measures.

The Bird Flu: [Synonyms - Avian influenza, fowl influenza, fowl plague] Caused by influenza type A virus (H5N1) belonging to family orthomyxoviridae - an RNA virus; can survive for 35 days at 4oC in faecal matter. All avian influenza viruses are maintained naturally in waterfowls and shore birds. The virus can affect domestic and wild bird species including chickens, turkeys, ducks, geese, gulls and shorebirds. The migratory waterfowls do not develop disease when infected with avian influenza.

First H5N1 known from birds to human was in 1997 in Hong Kong where 18 people were infected and 6 died. Since then, it has killed nearly 60% of the people who have been infected. In January 2004, an outbreak occurred in poultry farms in Thailand and within weeks it spreaded to over 10 surrounding countries in Asia. The first report of bird flu in India came from the village of Nawarpur in the Nandurpur district of Maharashtra on 19 February, 2006.

All biotypes of flu viruses are found in birds. They do not usually infect humans. H5N1 virus was originated from birds. Initially, it infected birds but later, involved mammals such as humans, pigs and cats etc.

There are several routes of transmission of the disease viz. air borne transmission if birds are in close proximity, direct contact with contaminated respiratory secretions or faecal material, broken contaminated eggs infecting healthy chicks, movement of infected birds between flocks, movement of contaminated clothing, shoes, equipments, egg plates, feed trucks, contact with infected wild birds and waterfowl, faecal contamination of water and garbage, flies etc.

In low pathogenic form of the disease in birds, there may be ruffled feathers or reduced egg production; and in high pathogenic form, there is respiratory distress and 100% mortality. In human, there may be acute respiratory distress, pneumonia, conjunctivitis, cough, fever, sore throat and muscle aches etc.

The flu can be presented to some extent by adopting the following measures- biosecurity at farm level, use of protective clothing in farm, only essential vehicles should be allowed to access to the site, separate housing depending on age group, deworming should be done, sick birds should be kept away from the farm and use of N-95 respiratory mask.

At market level, improvement of hygiene and proper disposal of wastes, unsold animals should remain at market and not return to the farm and disinfection of materials going back to the farm. Culling is an effective and preferred method of controlling avian influenza. Carcasses should be incinerated or buried deep using lime and soil in the ratio of 1:3, disinfection of the site with 5% formaldehyde or 2% gluteraldehyde after disposal of the carcass, a drug chloralose mixed with feed in concentration of 2-6 % causes loss of consciousness and death can be obtained by suffocation.

Vaccination reduces the susceptibility to infection but care should be taken as poor quality vaccine may accelerate mutation of the virus. In this respect, genetically modified chicken (GMO) may solve the problem of bird flu occurrence. But some researchers have found the danger of consuming GMO chicken as it may carry or be contaminated with other pathogens.

The World Health Organization (WHO) admits that vaccine will not be of any help in treating human being as the virus is able to mutate to another subtype quickly. Antiviral drugs like Tamil Flu, Relenza have effect on some strains but some strains of H5N1 have already become resistant to these drugs.

Herbal antivirals like garlic, green tea, vitamin C can be used to combat the flu. Garlic is a very effective antiviral and best if taken fresh and crushed. Vitamin C boosts the immune system and is an antiviral by blocking the enzyme neuraminidase. Fresh apple juice and green tea are also very effective antiviral.

The avian influenza strain diversity often originates in wild birds but when mixed with viruses of poultry, pig and human, heightens the disease risk in human beings. Moreover, human beings have less ability to develop immunity to different subtypes of flu virus which are evolving continuously.

Therefore, biosecurity system of poultry production should be well protected against known and unknown health threats. Prophylactic vaccination should be carried out to prevent and reduce the outbreak in poultry and finally to get rid of bird flu disease, the traditional backyard poultry rearing may need to be stopped forever in near future.