Seven Vietnamese patients found infected with bird flu after samples retested
AP | March 8, 2005
The World Health Organization says seven Vietnamese patients who initially tested negative for bird flu have been found to be carrying the virus after their samples were retested _ suggesting that avian influenza may be more widespread than originally believed.
All seven, who were first tested in January, have since recovered, WHO regional spokesman Peter Cordingley said Tuesday.
"There's no doubt. The WHO accepts that we are missing cases. It's quite possible that some people are falling sick and their symptoms are very light and they don't end up in hospital," he said.
"It's also possible that they have a very light viral load and Vietnamese tests may not be sensitive enough to pick it up," he said.
The WHO will wait to receive more details on the seven cases before adding them to the overall tally for Vietnam, Cordingley said.
Vietnam has suffered the worst of any country hit by the bird flu, with 33 deaths since the deadly virus first emerged across the region in December 2003, killing millions of poultry before jumping to humans. A total of 46 people have died from the avian influenza, the others in Thailand and Cambodia.
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In the most recent wave of outbreaks which began last December, 14 people have died in Vietnam.
The seven cases were part of a batch of nearly 90 specimens that had tested negative at Ho Chi Minh City's Pasteur Institute, said an official there on condition of anonymity.
The samples were sent to a laboratory in Japan as part of a move earlier in the year by the WHO, Japan's National Institute of Infectious Diseases and the U.S. Centers for Disease Control and Prevention, to work with health authorities in Vietnam to improve the reliability of diagnostic tests.
The seven people, all from southern Vietnam, did not have clinical or epidemiological factors typical of previous bird flu cases, the institute official said. One patient had tuberculosis.
Last month, the New England Journal of Medicine reported on one case dating back to February 2004 where the victim exhibited none of the classic respiratory symptoms associated with bird flu.
Instead, Oxford University researchers said the 4-year-old boy had suffered from encephalitis, or inflammation of the brain, before slipping into a coma. His case was only discovered months later after researchers found his samples among encephalitis victims.
Those findings suggested that the total number of infections may have been underestimated.