Suspect Qinghai H5N1 Cluster in Lagos Nigeria
Recombinomics Commentary
January 24, 2007
A mother and daughter, who recently died in mysterious circumstances in Lagos, have been suspected to have died of the deadly bird flu disease, thus, giving rise to speculations of a possible human-to-human infection of the disease in the country.
The two were said to have died within two weeks after they allegedly ate a chicken the mother bought for the family during the Christmas and New Year celebrations at a popular chicken market along Ikorodu Road, Lagos.
While the mother died on the January 4, the daughter also lost her life January 17.
The above comments describe a suspect cluster in Lagos, Nigeria. Such a cluster is not unexpected. Last season the H5N1 Qinghai strain migrated into the Middle East and Africa, resulting in human cases in Turkey, Iraq, Azerbaijan, Egypt and Djibouti. Surprisingly, there were no reported human cases in western Africa, although H5N1 in birds was reported in Nigeria, Niger, Cameroon, Ivory Coast, and Burkino Faso. The largest number of poultry outbreaks was in Nigeria.
Sequence analysis indicated there were multiple independent introductions into Nigeria, including geographically close farms in Lagos. Many of the sequences in Nigeria are closely related to the sequences in Egypt.
Recently Egypt has had outbreaks in poultry and people, including a three member cluster in Gharbiya, The sequences from Gharbiya have a Tamiflu resistance marker, N294S, which likely was present in bird H5N1 since the samples from the cluster were collected two days after the start of Tamiflu treatment, and the sequences had no evidence of a wild type sequence. Additional sequencing of earlier samples should resolve the role of Tamiflu in the generation of N294S in the sequences from two of the cluster members. In addition to the Tamiflu resistance, the cluster also had an altered receptor binding domain, V223I, which may have contributed to the largest cluster reported to date in Egypt.
The suspect cluster in Nigeria is cause for concern, because of the linkage to Egypt as well as the large number of poultry outbreaks last season and this season. It is also likely that H5N1 is present in countries neighboring Nigeria.
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