The Food and Agriculture Organization of the United Nations (FAO) have recently issued a warning about the risk of avian influenza outbreaks reoccuring in Vietnam and China. Last week, the Ministry of Health and the World Health Organization (WHO) held a workshop on planning preparedness for an influenza pandemic.
Influenza A/H5N1 virus has changed
According to the WHO, since the first outbreaks reported in 2003, highly pathogenic avian influenza (HPAI) A (H5N1) infection has caused many deaths. Vietnam has been one of the most severely affected countries in the world for H5N1, reporting 119 confirmed human cases with 59 deaths in 39 provinces/ cities. In early 2011 until now, sporadic outbreaks have occurred in poultry, which fortunately have not resulted in human cases (the last human influenza A/H5N1 case was reported in April, 2010). Although the disease incidence has decreased, an apparently increase in the numbers of influenza A/H5N1 outbreak in wild birds and emergence of new variants of clade 2.3.2.1 in many Asian countries, including Vietnam, are warned by FAO. Genetic characterization of currnet virus strains are similar to A/H5N1 virus clade 2.3.2.1 that were previously recognized (in 2004) in Taiwan, Hong Kong and Southern China.
Disinfection in poultry trading area in Hanoi. (Photo: VNA)
Commenting on the FAO’s warning, Associate Professor, Dr. Nguyen Tran Hien, Director of National Institute of Hygiene and Epidemiology (NIHE) said “new variations of H5N1 virus is not uncommon and surprising. This is only a small variation of the virus that does not represent a new virus strain. According to Dr. Nguyen Tran Hien, even after warnings by FAO, WHO also confirmed that variability of the virus has not increased the risk to humans. The situation of influenza A/H5N1 in humans has not changed. Human influenza A/H5N1 infection occurs in the areas where H5N1 viruses are circulating in poultry, and following contact with infected poultry or a contaminated environment.
According to National Institute of Hygiene and Epidemiology, from 2007 to 2010, there were 5-7 human A/H5N1 cases each year. Human AH5N1 virus infections have occurred sporadically in various provinces, occurring mainly in the winter-spring period, and with most H5N1 cases having had direct contact with infected poultry. There is no evidence of spread from human to human. Characterization of influenza A/H5N1 strains isolated from humans shows they are similar to A/H5N1 virus circulating in poultry in northern Vietnam during the same period. Reassortment between A/H5N1 and seasonal influenza viruses circulating at the same time has not been found. There was no evidence of virulent or mechanisms of virus transmission change.
Indifference to avian influenza A/H5N1 virus
"But it does not mean that we were subjective. The concern is in the process of natural evolution; H5N1 virus can keep small variations, changing gradually into a large variations or can reassortment with other influenza viruses circulating in animals and humans to form a new strain that is able to spread from human to human" - Dr. Nguyen Tran Hien expressed concern. The epidemiology experts recommend that important things to do in the future is to strengthen the monitoring of H5N1 viruses in poultry in order to control and prevent the transmission among poultry and from poultry to humans. However, the biggest challenge now is A/H5N1 virus currently circulating in poultry, especially in duck flocks without symptoms. Meanwhile, the current vaccines used in poultry in Vietnam do not fully protect virus strains clade 2.3.2.1. Besides, the subjective of both residents and managers following a long time with no reported human cases has resulted in poor implementation of preventive measures. In Hanoi, unchecked live poultry have been sold widely in markets despite the provisions of the Hanoi People's Committee for prohibition of live poultry trade in the city.
In 2011, the authorities forecast that, there the risk of reappearance of outbreaks in poultry is still high, especially in the winter-spring period. The sale and trading of unchecked live poultry poses a risk of spreading outbreaks and causing human infections. Therefore, health experts recommend that people should not be subjective, because of the first symptoms of A/H5N1 infection in humans are quite similar to common respiratory infections such as cough, fever, fatigue and admission to hospitals only in the late stages with severe disease. People should be aware of disease prevention, hygiene and regularly disinfect housing with antiseptic; destruction, vaccinating poultry, early detection of the phenomenon of mass bird deaths and immediately notify the local authorities to timely prevent the epidemic from spreading. The slaughter and use of sick/dead poultry should be strictly avoided.