Sentinel surveillance of influenza-like illness in the Central African Republic, 2010-2015.

Background: Influenza-like illness (ILI) is an important public health problem worldwide. In the Central African Republic, acute infectious diseases are the commonest reason for consultation. The Institut Pasteur of Bangui set up a surveillance network in 2008 to monitor the circulation of influenza viruses. We report the results of use of this surveillance system during the period 2010-2015.
Methods: The first surveillance centre covered Bangui, the capital of the country, and neighbouring areas and epidemiological data on syndromes similar to ILI. Throat and nasopharyngeal swab samples are transmitted weekly to the Institut Pasteur of Bangui, where real-time and multiplex reverse transcription polymerase chain reaction are used to detect and subtype influenza A (H1N1 and H3N2) and B viruses. The demographic characteristics of all patients and of positive cases according to age and the seasonal patterns of influenza virus circulation were analysed.
Results: Between January 2010 and December 2015, 5385 throat swabs were collected; 454 (8.4%) of the samples were positive. Of these, 450 yielded at least one influenza virus and four showed co-infections. Children under the age of 5 years were the most frequently infected (257/450, 57.1%), with irregular peaks of ILI. Influenza B predominated (56.2%; n  = 201), with 39.0% H3N2 and 16.7%H1N1pdm09. Influenza viruses were detected mainly in the rainy season (July-December).
Conclusion: The sentinel surveillance site is yielding important information about the seasonality and age pattern of circulating influenza virus. Nationwide distribution of sentinel sites is warranted.