Confirmation of H5N1 Transmission in Pakistan
Recombinomics Commentary 19:24
December 27, 2007
The outbreak followed a culling of infected chickens in the Peshawar region, in which a veterinary doctor was involved. Subsequently he and three of his brothers developed proven or suspected pneumonia.
The brothers cared for one another and had close personal contact both at home and in the hospital, a WHO spokesman in Geneva said. One of them, who was not involved in the culling, died on November 23.
His was the human-to-human transmission case confirmed by the WHO. The others all recovered.
"All the evidence suggests that the outbreak within this family does not pose a broader risk," the WHO spokesman told Reuters. "But there is already heightened surveillance and there is a need for ongoing vigilance."
The above comments provide additional data supporting human-to-human (H2H) transmission of H5N1 in Pakistan. The brothers of the index cases had bird flu symptoms, including pneumonia, and had not participated in the cull. However, they did care of each other, providing exposures that could transmit bird flu from one family member to another (H2H).
Confirmation of one of the fatal cases is described above. The other fatal case was said to have not been tested, although media reports indicate samples were collected from both fatal cases. Moreover, recent media reports describe initial confirmation failures at the labs in London.
These reports sound strikingly familiar to reports from the outbreaks in Turkey, two years ago. Although 21 cases were lab confirmed in Turkey, the WHO reference lab could only confirm 12 of the cases and sequences have only been released from four of the cases. In Turkey, almost all positives were from clusters, indicating they were true positives. Two years ago the false negatives in London were attributed to samples degradation.
Media reports suggest more false negatives have been generated in London. These false negatives by WHO regional reference labs again raise serious questions about negatives in human and bird tests. In Turkey, the first four siblings all tested negative initially, and the sole survivor remains unconfirmed.
False negatives by WHO reference labs remain causes of concerns.
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