[Results of two-year surveillance of flu in Abidjan, Côte d’Ivoire]

Influenza (flu) is a seasonal viral disease that may have a favorable outcome or be associated with a high morbidity and mortality rate during epidemics. In view of the lack of epidemiological and virological data about flu in Côte d’Ivoire, a surveillance network was set up in Abidjan to monitor the spread of flu and characterize isolated viruses. Over the 24-month period from January 2003 to December 2004, nasal secretions were collected in patients presenting with flu syndrome at various heath care centers in Abidjan. Laboratory identification of viruses was performed by the ELISA technique using anti-A and anti-B monoclonal antibodies (immunocapture) and by isolation on MDCK cells. A fraction of the original samples and isolates was sent for confirmation to the Pasteur Institute in Paris, France and to the National Institute for Communicable Diseases (NICD) in Johannesburg, South Africa. Amongst the 211 samples analyzed, 30 (12.8%) proved positive for flu virus. Twenty-two isolates were positive for influenza virus A including 21 for A (H3N2) type and one for A (H1N1) type. The remaining 8 isolates were positive for influenza virus B. Most of these strains were isolated from patients in two age ranges, i.e. 0 to 5 years (34%) and 15 to 59 years (47%). More than 60% of the strains were isolated in June and October but the study duration was too short to define a flu season. Further surveillance data will allow better determination of flu season and definition of clinical and biological characteristics as a prerequisite for a preventive immunization program.