EMPRES Transboundary Animal Diseases Bulletin No. 25-2004

FAO has implemented emergency assistance under its Technical Cooperation Programme through a number of projects in affected countries or those at risk of infection for post-avian influenza rehabilitation.

Donors have contributed to the FAO Trust Fund project activities in support of efforts to control the outbreak of avian influenza (AI) in many Asian countries. FAO is collaborating with the World Organisation for Animal Health (OIE) and World Health Organization (WHO) to address the problem of avian influenza as well as other emerging transboundary diseases.

Getting the bigger picture

Highly pathogenic avian influenza (HPAI) type A, subtype H5N1, has been reported in Cambodia, China, Indonesia, Japan, the Lao People’s Democratic Republic, the Republic of Korea, Thailand and Viet Nam - all since December 2003. To obtain a composite picture of the sub-continental scale of the epidemic, FAO is assisting in disease control and surveillance activities.

Controlling the disease

Local cooked poultry market, Lao People’s Democratic Republic

R. WEBB

Stamping out, movement control, surveillance and vaccination have been implemented to control the disease. Vaccination is used in some countries, reducing susceptibility to infection and the amount of virus shed into the environment. It also helps avoid the depopulation of millions of animals.

Biosecurity and basic hygiene practices help to halt disease spread and prevent entry of infection into production units and the food chain. To be successful, biosecurity must be practised by all farmers, cooperatives, abattoirs, etc.

Highly pathogenic avian influenza

(HPAI) is a highly contagious disease of domestic fowl caused by a virus commonly found in waterbirds. The latter are usually not affected by the disease but serve as the entry point of infection into domestic poultry. Many of the strains that circulate in wild birds are either non-pathogenic or low pathogenic for poultry. However, a virulent strain may emerge either by genetic mutation or by reassortment of less virulent strains. Once the virus is introduced into domestic flocks, the presence of wild birds is probably not essential to continue an outbreak, which spreads through other methods including movement of infected poultry, contaminated equipment, vehicles and personnel. Because of the virus’s close relationship with wild birds, HPAI strains can emerge and cause disease in domestic poultry in any country at any time without warning, as has been shown with outbreaks occurring at irregular intervals on all continents. Recent serious epidemics have erupted in Italy (1997), Hong Kong Special Administrative Region of China (1997-98 and 2003), Chile (2002) and the Netherlands (2003). In addition, following the outbreak in China, Hong Kong Special Administrative Region where 18 people were infected and 6 people died of an avian flu strain directly contracted from infected birds, the role of the avian species in the epidemiology of human influenza has had to be reconsidered, as well as the importance of the disease as a public health issue.

Local live poultry market in the Lao People’s Democratic Republic

R. WEBB

The magnitude of the 2004 outbreak in Asia highlights HPAI as a major epidemic transboundary disease with the potential to generate a great deal of concern because of the economic, trade and social repercussions. It has become an international problem that affects animal health, human health, food security, economies and society in general. It has threatened the livelihood of millions of people depending on poultry for their subsistence; the number of poultry lost has been estimated to be more than 100 million. Human infections and deaths caused by a particular strain of the virus, H5N1, have been reported in Viet Nam and Thailand, which has also reported the disease and deaths in other non-avian species, e.g. cats. More than half of the affected countries have experienced HPAI for the first time in their histories.

The seriousness of the problem was initially brought to international attention in December 2003 when high rates of mortality in poultry were reported in Viet Nam. This information emerged from different media sources and was retrieved by FAO and other international organizations through animal disease intelligence systems. However, the situation had probably been dormant for some months or more, underestimated or simply not recognized because of deficient disease surveillance systems.

FAO Animal Production and Health Division