Confirmation of New H5N1 Cases in Pakistan
Recombinomics Commentary
December 21, 2007
The World Health Organisation (WHO) suspects there has been only limited human-to-human transmission of the H5N1 virus in Pakistan, but international test results are still pending, a top official said on Friday.
David Heymann, WHO assistant director-general for health security and environment, also said that no new suspect human bird flu cases had emerged in Pakistan since December 6, signaling there had been no further spread.
The above comments from WHO raise additional concerns about the human to human (H2H) transmission in Pakistan. Although media reports have described two H5N1 fatalities in a large familial cluster, the number of additional reported cases continues to grow. The above statement indicates new cases have been confirmed this month by NAMRU-3, which contradicts statements made yesterday by the Pakistan Ministry of Health that the last case was November 23.
Many of the cases appear to be mild, which limits detection and contact tracing. Testing of patients after they have been given prophylactic oseltamivir (Tamiflu) also limits detection. However, even with these limitations, new cases are being identified. It remains unclear if these new cases extend the transmission change, which would appear to be the longest and most sustained reported to date for H5N1.
The index case for the longest chain developed symptoms October 25, and two brothers died November 19 and November 29. New cases this month may extend this chain further. Earlier reports described a female health care worker who had tested positive. A male doctor was also hospitalized with symptoms at the same hospital that treated the index case as well as the two fatal cases. It remains unclear if the positive patients this month included the two previously mentioned health care workers, but if they are confirmed, it seems likely that the transmission chain has been sustained for at least six weeks.
Media reports indicated the initial lab positives were confirmed last Saturday in Pakistan.
The absence of a WHO situation update, detailing age, gender, disease onset dates, hospital admission dates, dates of death, and the relationship between confirmed cases remains a cause for concern.
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