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International Team to Vietnam to Confirm Phase 6 Pandemic
June 24, 2005
>> A team of international experts is in Vietnam studying whether the H5N1 bird flu virus may be evolving into a form that might trigger a human pandemic, the World Health Organization said on Friday.
The team of virologists and epidemiologists was looking at "the possibility of more widespread H5N1 human transmission, changes in the H5N1 virus and the likelihood of increased human-to-human transmission," it said in a statement.
"What has happened in Vietnam may have public health implications for the entire world and will be crucial in preparing for a possible pandemic," Hans Troedsson, WHO Representative in Vietnam, was quoted as saying in the statement…..
So far, there have been very few cases in which human-to-human transmission is suspected, including a Thai woman killed by the virus after cradling her dying daughter all night.<<
The comments on the international team indicate that the team is going to Vietnam to confirm that pandemic phase 6 has begun. Earlier reports provide more detail on the testing which uses western blot to show that many (probably hundreds or thousands) of serum samples from patients in northern and central Vietnam have antibodies to H5N1 providing evidence for infections this season.
The concluding statement above is simply false. Investigators suspect that the human-to-human transmission is extensive and sustained, signaling phase 6. However, most of the cases in northern and central Vietnam are mild relative to the H5N1 bird flu cases in the south, so the announcement of the large number of positives has been delayed for months as more excuse for not reporting the data are made.
Last year there were several small familial clusters in Vietnam and Thailand, including the one described above. The clusters did not extend beyond family members, but they were bimodal for disease onset dates. Thus, 5-10 after the index case developed symptoms, the relative caring for the index case would develop symptoms and test positive fro H5N1.
This season there were more such clusters, but most were in northern Vietnam. The cluster became larger, extended for longer time periods, and affected a wider age range.
The largest reported outbreak was in Quang Binh in the central highlands. Media reports indicated 195 people had symptoms after one girl died and her brother developed symptoms. Like the other clusters, samples from the index case were not collected, but the younger brother developed symptoms and tested positive for H5N1. However, he survived as did most if not all of the 195 with symptoms. Samples were collected from at least 30 individuals, but the results of the testing by the Institute for Hygiene and Epidemiology in Hanoi was not disclosed.
This outbreak was followed by an outbreak in Haiphong that included a family of five. All five family members were hospitalized on March 22 and all tested positive for H5N1. Neighbors were also hospitalized, but test results were not disclosed.
Another cluster at the Sweden-Vietnam hospital raised the possibility of human-to-human transmission and when a physician at the hospital developed acute respiratory distress on April 1, President Bush signed an executive order making bird flu a quarantinable disease.
Thus in April a large number of serum samples had been collected from suspected clusters of bird flu patients. Instead of announcing test results, the shipment of the samples to the CDC in Atlanta was announced on April 15, with results expected within a week. Instead of announcing the results, an urgent meeting in Manila was called for May 6-7. Instead of announcing the results, WHO put out statements on the evolution of H5N1 and general comments on larger clusters. However, the cases described above were not declared positive.
Now there is an international team going to Vietnam to again look at results. Western blot analysis has confirmed that these patients had been infected, but the data is considered to be "research data" pending confirmation by an HI test. However, the media report indicates Vietnam cannot run the HI test, so the announcement of the positives and the conclusion that phase 6 has begun has not been made.
Media reports have indicated the samples had been sent to the CDC in Atlanta, who has the facilities to do the HI tests. Similarly, Canada has sent scientists to Hanoi and Canada can do the HI tests. Because the number of positive samples are so high, an alternative test is being developed, which would avoid shipment of samples and a rapid confirmation that the mild cases are infected with H5N1. This test will allow WHO to know hwo is infected, but will also allow the patients to remain unconfirmed and off the official list because the test is a "research test".
Thus, WHO can delay the announcement of efficient and sustained human-to-human transmission until the dead bodies increase.
However, there have been 28 confirmed or suspect cases admit to another hospital in Hanoi this month. These patients are from at least 6 provinces in northern and central Vietnam. They have sore throats, a symptoms not commonly reported in H5N1 patients. This new symptom may indicate H5N1 now can more easily cause upper respiratory tract infections, leading to more efficient human-to-human transmission, as H5N1 continues to expand its host range and reach into a human reservoir infected with H5N1 that can be easily transported and transmitted within the human population.
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