May 31, 2006 (CIDRAP News) – Experts who investigated two clusters of human cases of H5N1 avian influenza in Azerbaijan in March concluded that one cluster marked the first time humans probably contracted the disease from wild birds—in this case, dead swans.
"Close contact with and de-feathering of infected wild swans were the most plausible exposures to influenza A/H5N1 virus in the Daikyand cluster," which included seven confirmed cases and four deaths, says the investigators' report, published this week in the monthly issue of Eurosurveillance.
"The . . . cluster in Daikyand settlement is the first event where wild birds were the most likely source of influenza A/H5N1 infection in humans," states the report by a team of 20 authors from several countries and the World Health Organization (WHO).
The WHO reported in March that wild swans were suspected as the source of infection in the cases. The Eurosurveillance article is the first detailed published presentation of the evidence for that view.
Two clusters of H5N1 cases were investigated in Azerbaijan in March. Azeri authorities reported a cluster of nine possible cases in Daikyand, a town in southeastern Azerbaijan, Mar 6. Three days later, two more suspected cases were reported in Bayim-Sarov, Tarter district, in the east-central part of the country. The human cases had been preceded by outbreaks in wild and domestic birds in February.
A WHO-led international team of 11 experts investigated the cases with the help of a field laboratory from the US Naval Medical Research Unit 3 from Cairo, Egypt. Influenza A/H5 was confirmed in seven of the patients from Daikyand, including six from the same family and another from a neighboring family. Four cases were fatal, and five patients were females between the ages of 15 and 20.
Family members initially denied any contact with sick or dead wild birds or domestic poultry, but others reported that many wild swans had died in the area in February and that the family might have had contact with dead swans, the report says. Relatives of the patents eventually revealed that the affected family had been involved in de-feathering dead swans. Swan feathers are used in pillows and bring a good price in the area, the article says.
In the Tarter district, 1 of the 2 suspected cases was confirmed and the other was classified as probable, according to the report. The investigators said the two patients, a 24-year-old man and his 18-year-old sister, had bought and eaten a turkey that was thought to have been ill.
While affirming that the Daikyand victims probably caught the virus by handling wild swans, the report says that limited human-to-human transmission can't be ruled out, given the incomplete information available.
In other observations, the report says the Azeri cases point up the importance of oxygen therapy in H5N1 infections.
"Severe hypoxia, caused by the prolonged course of viral pneumonia, appeared to be underrecognised and treated late in children," the report sates. "The early establishment of oxygen saturation monitoring and provision of continuous oxygen therapy is therefore crucial to prevent decompensation and multi-organ failure already observed" in H5N1 cases elsewhere.
Gilsdorf A, Boxall N, Gasimov V, et al. Two clusters of human infection with influenza A/H5N1 virus in the Republic of Azerbaijan, February-March 2006. Eurosurveillance Monthly 2006 May;11:5 [Full text]
Mar 21 CIDRAP News story "WHO confirms seven human bird flu cases in Azerbaijan"