Serologic and virologic surveillance of avian influenza in Nigeria, 2006-7.

Since January 2006, H5N1 avian influenza has affected Nigeria's poultry population causing enormous loss of resources. The current circulating virus is a potential candidate for pandemic influenza which may severely affect the human and animal population worldwide especially in the resource-poor countries. In this study, we report on our field and laboratory surveillance efforts in Nigeria. A total of 1,821 tissue samples, 8,638 tracheal swabs, 7,976 cloacal swabs and 7,328 avian sera were analysed over a period of two years, with 312 positive results [corrected] We recovered 299 isolates of highly pathogenic avian influenza virus H5N1 mainly from the diagnostic samples of poultry kept in backyard, small scale and free range farms. This finding emphasised the role played by these farming systems in the dissemination of avian influenza in Nigeria and highlights the need for a continued surveillance in humans since human-animal interaction is a key feature in Africa. Furthermore, there is a need for the strengthening of border controls. Since October 2007, there has been no reported and confirmed outbreak of avian influenza in Nigeria.

Serological evidence of chicken anaemia virus infection in Nigerian indigenous chickens.

Serum samples from 20 out of 180 (11.1%) apparently healthy Nigerian indigenous chickens were negative for antibodies against chicken anaemia virus using the enzyme-linked immunosorbent assay (ELISA). Of the 160 positive sera (88.9%), 12 (7.5%) had titres ranging from 1500-3000, 46 (28.8%) had titres from 3000-5000 while 102 (63.8%) had titres between 5000-11000. The overall mean titre value was 5845 +/- 2402. This appears to be evidence of a natural outbreak of the infection since the chickens had no history of vaccination against any poultry disease.