When disease rules the roost

The disease, which has already triggered the mass slaughter of poultry suspected of being the carriers of the deadly H5N1 virus, continues to elude a cure, with researchers still in pursuit of a vaccine. Now that it has crossed over from the avian fraternity into the human conclave, it will perhaps be accorded the priority it deserves. However, the attitude of the officials so far seems a replay of a scene from Albert Camus’ The Plague: “to detect, to see, to register, and then condemn”, the task of doctors “no longer to cure but to diagnose”.

The Hong Kong authorities, fearing a public health disaster similar to the 1968 ‘flu that raged in the territory killing 45, ordered the slaughter of 1.4 million chickens and an unknown number of ducks, geese and other poultry. But despite the decimation of these fowl, the fear of contamination has not subsided. After a relentless fusillade from the Hong Kong media, Chief Executive Tung Chee-Hwa finally admitted on Friday that the administration had “bungled” by leaving thousands of chicken carcasses unattended. And officials revealed that 90,000 more birds remained to be slaughtered. The Government, evidently, had failed to muster the logistical support needed for such a gigantic operation.

The person who has faced the most flak is Health Department director Dr Margaret Chan Fung Fu-chun. She drew criticism last month when she boasted that she ate chicken every day — two weeks later the Government ordered the massacre of all poultry. Likewise, in March 1996, she said a ban on British beef was not necessary during the mad cow disease scare — two days later the Government announced an immediate ban on all imports.

But bureaucratic snafus are only part of the problem. What is even more alarming is that it is not just birds that are being viewed as carriers, but also dogs, cats and rats. A campaign has been launched in Hong Kong to test these animals and see whether they come in contact with poultry. Even horses, which are believed to be among the least vulnerable to attacks of bird ‘flu, are being sought to be protected. Circulars have been issued to jockeys that they must disinfect their hands before touching the animals.

The global dimensions of the crisis are clearly discernible. Although China has denied being the originator of the deadly virus, Hong Kong has banned all imports of chicken from the mainland. And the World Health Organisation has informed Beijing that it is sending a team to investigate the veracity of the charge. Countries like South Korea, the Philippines, the United Arab Emirates and Thailand have also banned chicken imports from China, Hong Kong and even Australia, where another mutation of the virus, known as H5N2, or the `Sydney ‘flu’, surfaced some time ago.

Taiwan, which even while it hopes to make hay from Hong Kong’s travails by projecting itself as a `safer’ poultry exporter, is also nervous about its vulnerability to the virus, which appears to recognise no borders. Even China’s newest ally, South Africa, has imposed a moratorium on poultry imports from Southeast Asia.

Chances are that all this will prove a futile exercise. The H5N1 strain did not originate in Hong Kong. Nor is it new. The first time it was spotted was in terns in South Africa in 1961. And because these birds are a migratory species with a range from Antarctica to the Arctic Circle, the chances are that they have been winging their way round the planet for 40 years. Since that first appearance, it has apparently been identified in geese on the mainland, although authorities there are insisting that they have no cases at present. Nevertheless, if this strain has been in existence for decades, only the mass slaughter of every avian species on earth would guarantee the end of the newly-discovered bird-to-human transmission.

But not everyone subscribes to this theory. There are those who argue that merely slaughtering all avian species does not guarantee the death of the disease, since viruses have an innate capacity to mutate in a million different ways, mimicking the most vulnerable aspects of the human bio-system. Much more research therefore needs to be done before a failsafe elimination procedure can be identified.

Avian ‘flu virus is thought to multiply in flooded paddy fields where infected aquatic birds create a “faecal soup” of disease. When other countries have had outbreaks of avian ‘flu, they have destroyed poultry stocks, but nothing has destroyed the virus, and the prospect of that happening remains remote. To further complicate matters, the so-called “Hong Kong ‘flu” of 1968 was first identified in 1965 and took three years to reach its virulent stage. But this does not mean that the pattern will be repeated on this occasion. Indications are that Hong Kong’s bird ‘flu is weakening as it progresses, and the eradication programme will certainly prove a major obstacle to its spread. But this calls for a concerted public awareness campaign backed by political will. And a holistic approach to the environment in which humanity is not perceived as the predator but protector of all species.

Will the bird ‘flu fly in?

An alert has been sounded in the Indian poultry industry ever since the bird ‘flu virus, H5N1, surfaced in Hong Kong. Dr V.S. Apte, pioneer of poultry vaccine production in India and general manager of the vaccine division of Venkateshwara Hatcheries, told the Indian Express that there is always a possibility of an outbreak of the virus in India. “We have to be alert. If the virus enters the country, the Indian poultry industry could be badly affected,” he points out.

Strict surveillance at entry points into the country was, he felt, the only way to prevent the virus from slipping in. Screening was necessary because many small hatcheries in the country relied on poultry imports from abroad. The virus, Apte said, has existed for the last 100 years and its outbreak was reported in Pakistan as recently as 1995. Although India has never detected its presence, Apte said that was no guarantee against a possible outbreak. He called for an immediate ban on import of poultry and hatchery products from countries affected by this fatal virus.

Scientists too are not ruling out the possibility of the virus spreading to humans. Dr Kalyan Banerjee, former director of the National Institute of Virology (NIV) in Pune, believes that “if the virus lands on Indian soil, the repercussions could be very difficult to predict. People can get infected and, in acute cases, even die.”

But Banerjee said the epidemiological aspect of the virus must be closely studied before making any predictions. Says he: “We do not know from how many infected people in Hong Kong were the four deaths reported.” Explaining the characteristics of the virus, Banerjee said the ‘flu virus is basically a bird virus and moves along with the host. The virus has several antigens in H and N categories with each present in a predominant form in different creatures like pigs, birds and humans. Explains Banerjee, “As the virus has a segmented genome, the segments get mixed and give rise to a new virus. Since its range of hosts is very wide, a new mutant of the virus generally comes up after a gap of few years.”

There is also considerable concern that India lacks the tools to detect the virus. “When there are no tools available to detect the virus, how are we going to detect it through sero surveillance?” remarked an expert from NIV. “There is no other facility in India to isolate and prepare the influenza virus vaccine apart from the NIV laboratory which was in existence until I retired as director last year,” says Banerjee. But the new NIV director, D.A. Gadkari, refused to comment.

The use of avian influenza vaccine itself involves several complexities as it is now widely known that the inactivated vaccines do not prevent infection. Also it is impossible do differentiate between vaccinated and exposed flocks using the agar gel precipitation test, thus making epidemiologic surveillance even more difficult. The virus varies in its pathogenicity with most severe outbreaks in domestic poultry found to be associated with H5 and H7 serotypes. It may be recalled the outbreak of highly pathogenic avian influenza in 1920 and 1930, termed as “fowl plague”, was due to H7N7 serotype.– Davinder Kumar