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Fatal H5N1 Bird Flu Familial Cluster in Azerbaijan Confirmed
March 21, 2006
Samples from 11 patients under investigation in Azerbaijan for possible H5N1 infection have now been tested at a WHO collaborating laboratory in the United Kingdom. Positive H5N1 results were obtained for seven of these patients. Five cases were fatal.
Six of the cases occurred in Salyan Rayon in the south-eastern part of the country. All six cases resided in the small Daikyand settlement of around 800 homes.
A 17-year-old girl died on 23 February. Her first cousin, a 20-year-old woman, died on 3 March. The 16-year-old brother of this woman died on 10 March. A 17-year-old girl, a close friend of the family, died on 8 March. All four of these cases lived together or near each other. The source of their infection is presently under investigation.
The additional two cases in Salyan involve a 10-year-old boy, who has recovered, and a 15-year-old girl, who is hospitalized in critical condition.
The seventh case occurred in a 21-year-old woman from the western rayon of Tarter. She died on 9 March.
Two additional patients, from Salyan and the adjacent rayon of Neftchela, have been hospitalized with symptoms of bilateral pneumonia. Testing of these patients is presently under way.
The above comments from the WHO update confirm media reports and commentaries on the relationship of the Azerbaijan familial cluster. It is reassuring that such relationships are again appearing in WHO updates. The initial familial clusters in Turkey did not include the relationship between three familial clusters of cousins.
Like Turkey, in addition to the familial cluster there is a geographical cluster suggesting the transmission of H5N1 to people has become more efficient. The proximity of the Azerbaijan cases to the Dogubeyazit cluster in eastern Turkey raises the possibility that S227N may be involved. Donor sequences were identified in H9N2 isolates that are endemic to the region, so new recombinants could be generated. However, the S227N change only reduces affinity for avian receptors, so S227N detected in the index case in Turkey could have also been transmitted to the index case in Azerbaijan via infected birds.
Alternatively, the close proximity of Azerbaijan to Dogubeyazit may indicate more efficient human-to-human transmission via less intimate contact. The dates of death of family members and a close friend suggest human-to-human transmission may be more efficient.
Isolation of the H5N1 and release of the sequences from this cluster would be useful. Although one H5N1 sequences from the bird flu infection in western Turkey last October has been released, none of the sequences from human cases in Turkey have been made public. This delay appears to be linked directly to Weybridge, since they have already released the turkey H5N1 sequence from Turkey. Moreover, they have held a large number of H5N1 sequences from isolates throughout Europe. Other countries, such as Russia, Italy, France, Nigeria, Iraq, Iran, and Denmark have released sequences as soon as the accuracy of the sequence has been verified.
The growing cluster in Azerbaijan highlights the need for immediate release of the sequestered sequences as well as rapid release of the H5N1 in this new geographic and familial cluster.