January 5, 2006

Bird flu has affected 12 nations so far. The causative agent, the H5N1 virus, has proved to be especially tenacious and resulted in the death of an estimated 150 million birds, reports Hassan Reyaz Khan

Avian influenza, or ‘bird flu’, is a contagious disease of animals caused by viruses that normally infect only birds and, less commonly, pigs. Avian influenza viruses are highly species-specific, but have infected humans, too.

The current outbreaks of pathogenic avian influenza, which began in South East Asia, are the largest and most severe on record. Never in the history of the disease have so many countries been simultaneously affected, resulting in the loss of so many birds. The causative agent, the H5N1 virus, has proved to be especially tenacious and has resulted in the death of an estimated 150 million birds.

Poultry outbreaks caused by this virus were reported in eight Asian nations: Korea, Vietnam, Japan, Thailand, Cambodia, Indonesia, and China. More recently Malaysia, Russia, Kazakhstan, Mongolia, and Turkey have also reported these cases.

The H5N1 has caused the largest number of cases of severe disease and death in humans. Unlike seasonal influenza, where infection causes only mild respiratory symptoms in most of the people, this disease follows an unusually aggressive clinical course, with rapid deterioration in condition and high fatality rate. Primary viral pneumonia and multi-organ failure are common, too.

The chances of exposure to this disease are during slaughter, de-feathering, butchering, and preparation of poultry for cooking. Most of the cases have been reported in previously healthy children and young adults. More than half of those infected with the virus have died.

The greatest concern is that the virus — if given enough opportunities — will 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.

In the current outbreak, laboratory-confirmed 100 human cases have been reported in Cambodia, Indonesia, Thailand, and Vietnam. In areas experiencing outbreaks, poultry and poultry products can be safely consumed, provided these items are properly cooked and properly handled during food preparation. The H5N1 virus is sensitive to heat, and normal temperatures used for cooking (70ºC) will kill the virus.

Persons involved in food preparation should wash their hands thoroughly and clean and disinfect surfaces in contact with the poultry products. Antibacterial soap and liquids are recommended for this purpose.

Vaccines effective against a pandemic virus are not yet available. Although a vaccine against the H5N1 virus is under development in several countries, no vaccine is ready for commercial production as yet.

The Health Ministry in Pakistan, noting the global outbreak, has also taken precautionary measures to curtail bird flu from spreading in the country. Import of birds from various effected countries, have been banned and a budget of Rs40 million has also been allotted for prevention from this deadly virus.

However, we need to be wary of the fact that the growth of bird flu can result in a major problem, and should use preventive measures, till the vaccines are actually available for the disease.

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