Influenza is circulating in Africa, but virtually no information or attention is evident, says a new essay in this week's PLoS Medicine. Maria Yazdanbakhsh and Peter Kremsner argue that the lack of adequate surveillance means that the burden of influenza in Africa is incorrectly believed to be negligible. But sporadic reports from various regions in Africa indicate that influenza is circulating and may be regularly causing epidemics.
Whereas in temperate areas influenza activity displays a seasonal pattern with marked peaks in the winter, influenza is present all year round throughout the tropics.
The authors say that the well-established surveillance network WHO Flu Net in place in Europe and North America, provides continuous data on influenza burden and the spread of viral types and subtypes. Recent threats of pandemic influenza have prompted similar active monitoring in parts of Southeast Asia and Latin America. But the prevalence and incidence of influenza in most tropical countries especially in Africa are largely unknown, say the authors, and improved surveillance is needed.
For example, the authors state, the WHO H1N1 swine flu update of May 2009 contained reports of infected patients in many countries, but none in Africa, whereas two reports in October 2009 confirmed swine flu cases from South Africa and Kenya. This indicates that "that the virus was circulating in Africa, but because of the lack of a rigorous surveillance system, it was not reported as readily."
Yazdanbakhsh M, Kremsner PG (2009) Influenza in Africa. PLoS Med 6(12): e1000182. doi:10.1371/journal.pmed.1000182