Avian influenza A(H5) in rural areas in Asia: food safety considerations
12 February 2004 - In several countries in Asia, most rural families keep small free-range poultry* flocks, and up to 80% of poultry are raised at small-household village level. This poses a challenge for controlling outbreaks of highly pathogenic avian influenza A(H5) (HPAI) in poultry and raises concerns about handling poultry in countries currently experiencing outbreaks.
In animals, HPAI is most commonly transmitted through direct contact with wild birds, especially asymptomatic waterfowl, and contacts with infected poultry and poultry products. There are also common indirect routes, e.g. through contaminated clothing, footwear, vehicles and equipment, as well as contaminated feed, water, manure and litter. Insects, rodents, cats and dogs can also act as vectors and transmit the disease.
Previous outbreaks of HPAI, notably in Hong Kong Special Administrative Region of China in 1997 and in the Netherlands in 2003, have occurred in areas characterized by industrial production conditions that allowed rapid and effective implementation of recommended animal control measures (including systematic culling of infected flocks, quarantine, bans on the movement of animals, and compensation schemes for affected farmers and smaller-scale poultry owners).
While efficient control measures could be rapidly implemented for the industrial production of poultry in the affected countries in Asia, the current outbreaks are happening in areas where poultry and humans often share the same environment. Poultry are present in almost all villages and are generally marketed as live animals – the “farm-to-fork” chain may be as short as a few metres. In these conditions, the disease can spread quickly between the many small flocks. The practice of home slaughtering means that human exposure to the virus can easily occur in infected areas. Applying the recommended control measures to curb the outbreaks in the animal population would be extremely difficult and would take time, thus increasing the risk of human exposure to the virus.
Current guidance on the food safety aspects of the disease in poultry is valid for areas where efficient animal control measures are in place and ensure that infected animals or eggs would not enter the food-chain or be marketed. In the present outbreaks, however, until the animal control measures put in place become effective, there is a risk that infected eggs or live birds excreting viruses will be marketed or enter the food-chain, particularly in rural settings. Additional guidance is therefore needed.
Investigation of previous outbreaks has established that close contact with live infected poultry has been the principal means of transmission to humans. The practice of marketing live poultry directly to consumers should therefore be discouraged in areas currently experiencing influenza outbreaks among poultry.
Appropriate messages should be developed to inform the rural population about the need to restrain or stop the movement of animals, as well as the measures to be taken if a family identifies a sick or dead bird within its small flock. The importance of hygiene in reducing the mechanical spread of the disease on vehicles, equipment, footwear and clothing should be re-emphasized.
It is expected that the practice of home slaughtering will not be halted completely, and advice on how to slaughter as safely as possible should be given. Sick birds, or birds from flocks in which one or more birds are sick, should never be slaughtered for consumption and their eggs should not be marketed for human or animal consumption. The slaughter should be carried out by one designated person wearing protective personal equipment. Where this is not possible, strict hygiene should be observed by the person who slaughtered the animals. The slaughter should preferably take place in a confined area away from the kitchen; children and animals should be kept away. It is important to use hot water for scalding. After slaughter, cleaning and disinfection of the area, including safe disposal of the feathers and animal remains, are equally important.
Until the disease in animals is effectively contained, there is a risk of infected animals being handled for human consumption, thus increasing the risk of exposure for anyone taking part in these activities.
WHO reiterates that, once poultry has entered the food-chain as a processed product (whole refrigerated or frozen carcasses and products derived from these), cooking so that the centre of the product reaches a minimum temperature of 70 °C would render it safe for human consumption. The same applies to eggs. Eggs from infected birds can harbour the virus both outside and within the shell and should therefore be cooked before consumption.
* Poultry are birds that are commonly reared for their flesh, eggs, or feathers, and include chickens, ducks, geese, turkeys and guinea-fowl.