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Western Blots on 2005 H5N1 in Vietnam Lack Transparency
July 4, 2005
>> PC: All that happened last week was that WHO said that they were given reasons to believe that there has been a serious worsening of the situation. The indicators were from lab work and observation. We sent an international team into Vietnam to do some tests and to see if this theory could be supported. It could NOT be supported and all the lab tests we did, did not support the fear that the situation had gotten a lot worse so basically, we're back where we were which is a steadily worsening situation in Vietnam and across the region and quite clearly, there's an enormous cause for concern and absolutely no reason to let our guard down.
And that was Peter Cordingley, World Health Organization's spokesmen for the Western Pacific, speaking to Howie Lim. <<
The above comments by Peter Cordingley do not contain enough detail to allay fears that appear to be linked to western blot analysis of 1000 serum samples collected in northern Vietnam in March. These samples were reportedly sent to CDC in Atlanta in April after an urgent meeting was called. After the CDC reportedly tested the samples a second urgent meeting was called in Manila on May 6-7.
Concerns that H5N1 was transmitting more efficiently in northern Vietnam were raised, but the epidemiological data cited was similar to the data from H5N1 confirmed cases in the WHO "official list" and did not reflect the data in the 1000 unreported tests.
The Manila meeting was followed by a team of experts who traveled to Vietnam and found no additional evidence to "support" the western blot data. However, it would seem that the supporting data would involved HI tests and the track record on HI tests by WHO expert consultants is less than ideal. Thus, WHO is discounting positive data with negative data, which is cause for concern.
The HI is not always straight forward because H5N1 is evolving and use of the wrong H5N1 as a target in the assay can lead to false negatives.
Well publicized examples of this have happened in Japan and South Korea, which happen to be the two countries other than China where the ARG deletion in the HA cleavage site has been detected. However, sequences of the 2003 and 2004 isolates were deposited at GenBank long after the associated infections in South Korea and Japan and there have been HI issues in both countries.
In Japan, there was evidence that workers cleaning up an H5N1 infected farm developed antibodies to H5N1. These data were presented long after the outbreak was over, and the titers (measured by HI) were exceedingly low. WHO explained that the delay in releasing the data and low titers were due to a requirement of developing a new HI assay to measure the antibodies. Thus, it took months to develop an assay against the 2004 H5N1 version isolated in Japan, but WHO has managed to generate negatives against the 2005 northern Vietnam isolate and declared the western blot positives as being false, or at least unsupported by additional evidence as a justification for issuing a press release indicating that the concerns about increased human to human transmission of H5N1 in northern Vietnam were unfounded.
Similarly, there have been HI issues in South Korea where human WSN/33 sequences have been detected in swine isolates. The sequences at GenBank include WSN/33 and H9N2 sequences. WHO dismissed the WSN/33 sequences as lab error, but consultants failed to use appropriate primers for WSN/33 and instead relied on universal primers, which detected H1N2 isolates (which had been identified previously in Korean swine). FAO in South Korea also failed to detected WSN/33 antibodies using an HI assay, although such antibodies were detected by the lab identifying the sequences and the 2004 WSN/33 sequences were supported by evolving 2005 WSN/33 sequences from fatal swine infections. Moreover, South Korea was uable to detected H9N2 antibodies although the H9N2 sequences at GenBank showed that the swine isolates were clearly from South Korea and had evolved from H9N2 2003 sequences from isolates from live markets in South Korea. The 2003 sequences have been published.
The WHO statements on the western blot data require more detail. A failure to find supporting evidence is not very convincing. It is somewhat like the denials by China on human H5N1 cases in Qinghai. China initially stated that there were no "reported" cases. However, the report on the site visit by WHO indicated only 2 patients had been tested. They had classical bird flu symptoms and the specificity of the primers used are being investigated. China indicated that the other 600 people who had been exposed to the birds had not been tested because they had been "dispersed" In the SARS outbreak, many patients were dispersed to military hospitals where they were tested but the results were not reported. Boxun reports of payoits of over 700 death benefits to families of bird flu victims suggests that many of the contacts with H5N1 in Qinghai were dispersed 6 feet under ground.
WHO and China both need to be more transparent.
The negative HI data can be very questionable, and use of negative HI data to discount positive western blots can be dangerous to the world's health.