H5N1 is sensitive to heat. Thus, it is safe to consume poultry as long as it has been cooked properly. Consumers should, however, be aware of the risk of cross-contamination. People involved in the preparation of raw or frozen poultry products should thoroughly wash their hands and disinfect all utensils that come into contact with the poultry

It's been 22 years since the H5N1 avian influenza virus, often called bird flu, was first reported, and it is getting more and more difficult to contain it with each passing year. The virus has killed 377 people, and more than 150 million chickens infected with the virus or suspected of being infected have been killed or culled in more than 60 countries.

The infection is caused by influenza virus type A, which normally infects birds and is highly contagious.

The first case of human infection with highly pathogenic H5N1 avian influenza was reported in Hong Kong in 1997. In 2003, the most devastating and widespread outbreak of H5N1 to date emerged in Asia before spreading to Europe, Africa and North America. The most obvious victim of bird flu is, of course, is the poultry industry.

It is estimated that outbreaks of bird flu cause global losses worth hundreds of billions of dollars.

The biggest threat to the poultry industry stems from the immediate reaction of the customers. Several polls conducted in 2006 found that more than 40 per cent of the people thought they could get bird flu by eating poultry. Poultry sales fell in France and Romania by more than half in 2006. In Italy, sales fell by 70 per cent after wild swans were infected. In 2007, the price of chicken in Indonesia dropped by 50 per cent.

In the same way, every time bird flu is detected in the Kathmandu Valley, the sale of poultry and poultry meat comes down, with many businesses even having to close shop.

But does H5N1 really pose a risk to food safety? Continuing outbreaks of bird flu in poultry in Asia, Europe and Africa have raised concern about the various sources of infection and risks to humans.

Evidence shows that direct contact with infected live or dead poultry is responsible for a majority of infections in humans.

The virus could also spread to humans through contact with contaminated poultry products.

In developed countries, meat is bought, either refrigerated or frozen, from a butcher or supermarket. In Asia, however, it is common practice to buy chicken and other live animals in the market and slaughter them at home. As a result, Asians are exposed to potentially disease-carrying animals, both in their homes or while passing through the markets. Wet markets have been identified as one of the sources of H5N1 infection in humans.

H5N1 is sensitive to heat.

Thus, it is safe to consume poultry as long as it has been cooked properly.

Consumers should, however, be aware of the risk of cross-contamination. People involved in the preparation of raw or frozen poultry products should thoroughly wash their hands and disinfect all utensils that come into contact with the poultry. What is clear is that consumption of raw poultry ingredients poses a high risk and should be discouraged.

The virus can also be present in the tissues of frozen chicken, because low temperatures maintain the viability of the virus. In 2004, Japan and Korea banned imports of both live and frozen poultry meat from China and Thailand after the virus was identified in frozen poultry samples. Thus, whether it is purchased fresh or frozen, the meat should be properly and thoroughly cooked.

The virus can also be found inside egg whites, egg yolks, and on the surfaces of eggs laid by infected birds, but proper cooking inactivates the virus inside the eggs. Uncooked eggs that have not been treated should not be used in food unless it is going to be cooked. There is no epidemiological evidence to suggest that people have been infected by consuming eggs or egg products. To eliminate shell contamination, commercial egg suppliers must wash and disinfect the outsides of eggs with chlorine prior to packaging.

While consumers are mainly concerned about eating poultry and eggs during bird flu outbreaks, some food products are grown using chicken litter as fertiliser. Virus particles in chicken manure tend to be active when used immediately. It is unlikely that litter from an infected poultry farm would be released several weeks after the birds have been killed. Suppliers of poultry manure should, therefore, assure their customers of biosecurity measures on their farms and ensure that poultry litter is composted and dried using heat treatment.

Efforts to contain the virus must include all three stages of the food chain: the poultry farms; the marketplaces; and the tertiary end of the food chain, the food processing industry and consumers.

Other than the farmers who breed and rear birds, many workers are also involved in the food chain, namely, cleaners, packers, cooks, chefs, food handlers and other kitchen workers who come into contact with birds. People responsible for slaughtering birds must wear protective clothing.

Workers cleaning and decontaminating poultry houses must also take special precautions as they are likely to have come into contact with contaminated manure.

Poultry growers and processors have to ensure that no dead birds are delivered to slaughterhouses.

They must also adopt zero tolerance of faecal contamination of carcasses and must dispose of tissues, such as the lungs, trachea, head and intestines, where the virus is most likely to reside.

Improved farming practices are needed to contain the spread of bird flu. They include improved biosecurity measures, quarantine for sick birds, disinfection of transport vehicles and cages, and protective clothing for farm workers.

Outbreaks of bird flu have been occurring sporadically for the last 10 years, causing grave losses on the poultry industry.

Early detection and diagnosis of primary bird flu infection should be of utmost concern, as this will allow the authorities to take swift measures, such as biosecurity, quarantine and culling, as well as other control measures to safeguard the poultry industry. Rapid, accurate and easy-to-use testing methods are needed to prevent the spread of the disease.

A version of this article appears in the print on February 17, 2022, of The Himalayan Times.