Controlling Bird Flu in Vietnam Using Reliably Wrong Data
Recombinomics Commentary
March 16, 2005
>> "We are gambling away our chance for an early intervention to control the outbreak at its source and to slow its spread," Klaus Stohr, head of the WHO's flu program, said in a telephone interview, referring to the lack of reliable information coming out of Vietnam.
In the past, the Vietnamese government has had foreign assistance during disease outbreaks, but not recently. <<
The data coming out of Vietnam appears to be reliably false, and therefore can yield useful information. Two independent data sets, one based on retesting H5N1 PCR negative patients, and the second simply looking at the number of PCR positive results in a group of very likely H5N1 positive patients, generates the same figure - the PCR test in Vietnam only detects 20% of the H5N1 positive patients.
This reliably false data can then be used to generate reliably true data. Applying the 1 in 5 rule to the "classic" H5N1 patients indicates that virtually all of the clinically classic patients are H5N1 positive. Then by simply looking at outcomes of these patients, a case fatality rate can be calculated for this group. The PCR test may merely pick up the cases with the highest viral load at the time of collection. This season this subset in the south appears to have a case fatality rate of 100% but the remaining 80% of the H5N1 infected patients in the south likely have a lower fatality rate.
The superiority of the clinical presentation can also be used for determining transmission chains. For the cluster in Thai Binh, it would indicate that both nurses are H5N1 positive, and human-to-human transmission has now been extended to four generations. Additional associated health care workers with bird flu symptoms would extend this chain.
The major concern with the reliably wrong data is its use to lower the number of H5N1 cases, hide familial clusters, or deny human-to-human transmission. It seems that a little common sense and a reliably wrong assay can generate some very reliable data.
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