Avian influenza

Fact sheet

Key facts

• H5N1 avian influenza virus is a public health concern because of its potential to spark a pandemic. As long as the virus continues to circulate in animals, there will be opportunities for the virus to infect and adapt to humans.
• Three conditions must be met before a pandemic begins:
• a new influenza subtype that has not previously circulated in humans must emerge (itself a rare event);
• this new subtype must be capable of causing disease in humans;
• the virus must be capable of being passed easily among humans. Only this last condition has yet to be fulfilled by H5N1.
• Based on the present evidence, the H5N1 virus does not easily jump the species barrier to infect humans.
• The small number of human cases, despite the tens of millions of poultry infected, over vast geographical areas, since 2003 supports this conclusion.
• The number of human H5N1 cases and deaths in Viet Nam has sharply decreased since 2006
• The highest number of cases has been in the 20-29 age group, the highest number of deaths in the 10-19 year age group.
• Male and female distribution among cases and deaths is approximately equal.
• The number of cases and deaths has been the highest in the northern region and the lowest in the central region.
• The last reported death from H5N1 in Viet Nam was in February 2012.

The situation

• Viet Nam was among the first countries to report cases of Highly Pathogenic Avian Influenza (HPAI). At the peak of the epidemic in Viet Nam in March 2004, 24% of communes and 60% of provinces were affected and 17% of the poultry population died or were culled, amounting to about 45 million birds.
• It is estimated that the direct economic impact of the epidemic affected around 8 million of the 11 million households thought to be engaged in poultry production. This impact has been unevenly distributed, since income from poultry and eggs is more important among the poorest segments of the population.
• From December 2003, when the first human case was detected, up until February 2012, Viet Nam reported the third highest number of human infections (after Indonesia and Egypt) with 123 confirmed cases, including 61 deaths (50% fatality).
• Overall, 36 provinces have reported human infections, with a concentration around the Red River Delta provinces in the north and the Mekong Delta in the south.

WHO's response

WHO, in cooperation with a number of key stakeholders has supported Viet Nam to:

• Strengthen the capacity of preventive medicine staff in early investigation and response to human avian influenza cases in particular, and infectious diseases in general;
• Enhance avian influenza case management and infection control for health care staff;
• Improve laboratory capacity;
• Encourage joint animal health and human health investigation of rumoured cases of H5N1;
• Modify public health legislation to facilitate joint investigations.