The authors investigated the prevalence of haemagglutination inhibition (HI) antibodies to four strains of influenza viruses among handlers of live pigs in Ibadan, Nigeria. Venous blood specimens were collected from thirty pig handlers (out of a total of forty-eight) at three locations in Ibadan in April and May 2008. The overall prevalence of antibodies to influenza viruses was 100%, while those of influenza A and B viruses were 68.3% and 58.3%, respectively. The prevalence of influenza A/Brisbane/59/2007 (H1N1), A/Brisbane/10/2007 (H3N2), B/Shanghai/361/2002-like and B/Malaysia/2506/2004-like was 46.7%, 90.0%, 76.7% and 40.0%, respectively. A total of 96.7% (n = 30) of pig handlers tested had polytypic influenza antibody reactions. This is the first report to document the prevalence of influenza antibodies among pig handlers in Nigeria and shows that humans who have regular and direct contact with live pigs in Ibadan are exposed to different strains of influenza viruses.
The authors have characterised the genetic diversity of the bluetongue virus (BTV) RNA segments 3 and 10 from Indonesia, Malaysia and Australia. Analysis of RNA segment 3, which codes for the core protein VP3, showed conserved sequences in the previously defined Australasian topotype, but which further divided into four distinct clades or genotypes. Certain genotypes appeared to be geographically restricted while others were distributed widely throughout South-East Asia. Ongoing surveillance programmes in Australia have identified the movement of Indonesian genotypes into northern Australia and possible reassortment among them. Similarly, analysis of RNA segment 10, which codes for the non-structural protein NS3/3A, showed they were also conserved and grouped into five clades or genotypes, three Asian and two North American/South African.
Structured epidemiological studies based on sentinel herds in Indonesia and Malaysia have provided much information regarding the bluetongue (BT) viruses (BTV) and their likely vectors in South-East Asia. Serotypes 1, 2, 3, 7, 9, 12, 16, 21 and 23 have been isolated. Molecular analyses show all group within the Australasian topotype, with four genotypic sub-groupings identified to date. There are relationships to isolates from both India and Australia. Strains of BTV in South-East Asia do not appear to be highly virulent, since BT disease is not seen in local sheep. Known vector species identified include Culicoides fulvus, C. actoni, C. wadai and C. brevitarsis. C. imicola has not been identified in Malaysian or Indonesian studies. Molecular analyses indicate movement of South-East Asian strains of BTV into northern Australia, and the gradation in observations between India and eastern Australia regarding serotype, genotype, virulence and vector species suggests movement along a conceptual gradient through South-East Asia.