Three human deaths from bird flu have been reported in Vietnam, in a second wave of the 2004 outbreak in southeast Asia. They are the first human deaths since the latest outbreak began to sweep its way across the region at the end of June.
Earlier in 2004, 23 people were killed by a highly pathogenic strain of avian influenza, H5N1. This jumped to humans as the disease spread through poultry, and millions of birds were culled.
The three new cases, including two sisters, all died between 30 July and 2 August. They were all from the province of Hau Giang which lies southwest of the Ho Chi Minh City. It is among 11 provinces to be hit by H5N1 avian flu from early July.
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Preliminary tests show the people died of bird flu, although the particular strain is not yet known. 鈥淲e know that these people were infected with influenza type A H5,鈥� says Dick Thompson, a spokesman for the World Health Organization. 鈥淲e don鈥檛 know the end component of that and it will take a few days to sort out.鈥�
Endemic fear
鈥淚t certainly indicates there is a widespread animal outbreak,鈥� he told 快猫短视频. This 鈥渟econd wave鈥� of H5N1 bird flu has hit mainly chickens and ducks in China, Indonesia, Thailand and Vietnam 鈥� triggering fears that it may now be endemic in this region.
鈥淭hese outbreaks, many without apparent epidemiological links to each other, suggest A/H5N1 is now widely prevalent and is very likely to have become endemic,鈥� said the WHO in a statement on 30 July.
Thompson raises the possibility that the disease may have gone undetected between outbreaks. 鈥淚t may have come back or it may be just that it was undetected before. It鈥檚 obvious it鈥檚 going to take a long time to pry out of the environment.鈥�
Vaccine ban
Thailand, which had 65 confirmed outbreaks in 23 provinces as of Monday, has now officially banned the use of a bird flu vaccine. Anyone violating this could face up to five years in prison.
Bird flu vaccines are not 100 per cent effective and although birds given the jab may not fall sick, they may still harbour and shed the virus, making it harder to eradicate.
A second, less pathogenic strain of bird flu, H9N2, was reported on Tuesday by scientists in Hong Kong. They raised concerns that the strain, prevalent in chickens in local markets, could mutate and jump more easily to humans.
Bird flu rarely jumps to humans and efficient human-to-human transmission has not been reported in the current outbreak. However, health agencies are pushing for its eradication because of the risk that bird flu could combine with human influenza in a person. This could give rise to a new virulent form which could spread from person to person, potentially starting a pandemic.
鈥淲e are definitely concerned about the human cases, but it is not unexpected. Every time it jumps into humans it raises the risk of reassortment [of genes] that could lead to the development of a pandemic strain,鈥� says Thompson. The influenza pandemic in 1918 killed 40 to 50 million people over two years.