A profile of influenza virus infection in acute respiratory illness in Ghana

Introduction: Influenza surveillance was initiated by routine monitoring of acute respiratory illness in selected health institutions in Ghana as part of national preparedness efforts to the threat of pandemic influenza. Methodology: Under the Ghana Health Service, 8 health facilities in three regions have, since September 2007, served as sentinel sites. Adult patients with abrupt onset of fever >38ºC and at least cough, sore throat, coryza, myalgia and headache were recruited as study subjects and throat swabs/nasopharyngeal aspirates were collected. Children, 5 years and below, presenting with body temperature >38OC, cough and coryza, at 2 hospitals in the Greater Accra Region were also studied. Virus isolation and identification by cell culture and haemagglutination assays were done. Additionally, polymerase chain reaction (PCR) assays, antiviral susceptibility testing and genetic characterization by sequencing was done. Results: As at 6th May 2009, 410 adults and 358 children under 5 yrs of age (768 patients in total) have been studied with 57 influenza virus isolates. Thirty-nine patients were also positive by PCR for influenza A infection with 15 H1N1 and 5 H3N2 subtypes identified. Amongst the virus isolates, 30 H1N1 and 1 H3N2 influenza A subtypes with 26 influenza type B (Yamagata lineage) strains have been characterized. Two clades of the H1 viruses are apparent and Oseltamivir resistance has averaged 59% amongst influenza A H1N1 isolates. No evidence of H5N1 infection was found with 3 influenza A infections requiring further characterization. Conclusion: Overall, influenza virus infection averaged 12.5% and the profile of influenza viruses contributing to acute respiratory illness in Ghana has been discerned providing a clear snapshot of recent locally circulating influenza viruses. In light of “avian and swine” flu outbreaks worldwide, this is an important contribution to the World Health Organization’s global influenza surveillance network. With the Noguchi Memorial Institute for Medical Research established as the ‘National Influenza Centre’, Ghana’s Health Service has enhanced capacity to detect influenza outbreaks, assess the impact of this virus on health and formulate appropriate public health policies.