Estimation of the burden of flu-association influenza-like illness visits on total clinic visits through the sentinel influenza monitoring system in Senegal during the 2013-2015 influenza seasons

• Published in: Epidemiology and infection 2018-12, Vol.146 (16), p.2049-2055
• Main Authors: Niang, M N, Barry, M A, Talla, C, Mbengue, A, Sarr, F D, Ba, I O, Hedible, B G, Ndoye, B, Vray, M, Dia, N
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Aged; Aged, 80 and over; Ambulatory Care - statistics & numerical data; Child; Child, Preschool; Children; Cost of Illness; Cough; Epidemiology; Female; Fever; Humans; Immunization; Infant; Infant, Newborn; Influenza; Influenza B; Influenza, Human - epidemiology; Influenza, Human - pathology; Male; Middle Aged; Mortality; Nasopharynx - virology; Original Paper; Orthomyxoviridae - classification; Orthomyxoviridae - genetics; Orthomyxoviridae - isolation & purification; Pandemics; Pharyngitis; Pharynx; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Risk groups; Senegal - epidemiology; Sentinel Surveillance; Vaccination; Vaccines; Viruses; Young Adult
• ISSN: 0950-2688; 1469-4409; 1469-4409
• DOI: 10.1017/S0950268818002418

Knowing the burden of influenza is helpful for policy decisions. Here we estimated the contribution of influenza-like illness (ILI) visits associated with laboratory-confirmed influenza among all clinic visits in a Senegal sentinel network. ILI data from ten sentinel sites were collected from January 2013 to December 2015. ILI was defined as an axillary measured fever of more than 37.5 °C with a cough or a sore throat. Collected nasopharyngeal swabs were tested for influenza viruses by rRT-PCR. Influenza-associated ILI was defined as ILI with laboratory-confirmed influenza. For the influenza disease burden estimation, we used all-case outpatient visits during the study period who sought care at selected sites. Of 4030 ILI outpatients tested, 1022 were influenza positive. The estimated proportional contribution of influenza-associated ILI was, per 100 outpatients, 1.2 (95% CI 1.1-1.3), 0.32 (95% CI 0.28-0.35), 1.11 (95% CI 1.05-1.16) during 2013, 2014, 2015, respectively. The age-specific outpatient visits proportions of influenza-associated ILI were higher among children under 5 years (0.68%, 95% CI: 0.62-0.70). The predominant virus during years 2013 and 2015 was influenza B while A/H3N2 subtype was predominant during 2014. Influenza viruses cause a substantial burden of outpatient visits particularly among children under 5 of age in Senegal and highlight the need of vaccination in risk groups.