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How should we prepare ourselves against avian flu?

A Shenzhen man was reported to be critically ill with H5N1 flu last week...

(Posted on 22 June 2006)

How should we prepare ourselves against avian flu?

A Shenzhen man was reported to be critically ill with H5N1 flu last week and mainland chicken imports was banned as a result. Along with this new case, 19 cases of human bird-flu have been recorded on the mainland. In addition, outbreaks of avian flu have continued to be reported around the world during the past half year. How should we prepare ourselves against such an imminent pandemic?

Avoid in touch with birds to minimize the risks of transmission

Avian flu is an infectious disease which affects birds including poultry like chickens, ducks and geese. Humans can contract the disease only if they have close contact with the infected poultry.

To date, no cases of infection have been found in poultry farms, or wholesale and retail markets in Hong Kong. However, as previous tests have confirmed that some wild birds carry the H5N1 virus, the risk that poultry may become infected with the disease still exists. If an outbreak of avian flu occurs in a poultry farm, the risk of human infection resulting will surely increase. It will be even more dangerous if human-to-human transmission takes place, but fortunately no such cases have been reported so far.

At present, the drugs used in treating human influenza are adamantanes (including amantadine and rimantadine) and neuraminidase inhibitors, such as oseltamivir and zanamivir. According to laboratory study results, these drugs may be effective against certain avian flu viruses, but the clinical effects remain unconfirmed because some avian flu viruses have shown resistance to adamantanes. As for neuraminidase inhibitors, only individual laboratory studies show that these drugs can inhibit the growth of the H5N1 virus, but there has been no clinical study to prove their effectiveness in the treatment and prevention of the disease or to decide on the appropriate dosage.

In recent years, it has been found that some drugs under study, such as viramidine, may act as inhibitors on the H5N1 virus in a laboratory environment. In addition, it may be more effective in combatting the disease if existing drugs are used in combination e.g. if adamantanes are used in combination with neuraminidase inhibitors, or if dosages are increased, e.g. oseltamivir. More clinical studies are required to prove actual effectiveness.

Antiviral drugs may be used for prevention under special circumstances

Currently there is no avian flu vaccine for large-scale use among humans. However, there are currently many vaccine studies aimed at finding an effective means of preventing human infection, and some limited human clinical trials are in progress to further prove the effectiveness of vaccine. Therefore, at this stage, observing good hygiene on a daily basis should be effective in preventing avian flu infection.

No outbreaks of infection have been found in any poultry farm in Hong Kong so far, and thus the risk of infection in Hong Kong is not high. But the level of risk among poultry trade workers and laboratory researchers should be monitored. Although it has not been confirmed that human influenza vaccine is effective in preventing avian flu, it can in theory help reduce the risk of infection by another virus or by a mutant avian flu virus for high risk persons. Under special circumstances, antiviral drugs may be used for preventing transmission of the disease between high risk persons.

As far as the public is concerned, avoiding contact with wild birds and live poultry is the most effective means of prevention. If it is inevitable to be in contact with live poultry due to work requirements or for other reasons, wear proper protective clothing like apron, gloves and face mask, and wash your hands thoroughly after any contact with live poultry. It is also important to maintain a hygienic environment. Consult your doctor and tell him of your travel history if you have been to any place with avian influenza outbreak reports or have had contact with live poultry or birds.

Source: The University of Hong Kong Li Ka Shing Faculty of Medicine