Human Respiratory Syncytial Virus Subtypes A and B Infection Among Children Attending Primary and Secondary Health Care Facilities in Ibadan, Nigeria.

Human respiratory syncytial virus (HRSV) causes high morbidity and mortality in infants and young children. Although a high prevalence of HRSV has been reported in Nigeria, the subtype of the virus circulating in the country is not known. This crosssectional study was therefore designed to determine the subtypes of HRSV circulating among children in Ibadan. Two hundred and thirty-one nasopharyngeal and oropharyngeal swabs were collected from children presenting with respiratory infections in Secondary Health Facility (SHF) as well as those attending immunization centers in Primary Health Centers (PHCs) in Ibadan, Nigeria. Viral RNA was extracted directly from the clinical specimen and used for HRSV detection with a pair of primers that targets the conserved region of the viral matrix gene. HRSV-positive samples were subtyped using subtype-specific primers targeting the second hypervariable region of the G gene. The prevalence of HRSV infection was 8.7% and 34.6% among children attending the PHCs and SHF respectively. Both subtypes of HRSV were detected (co-circulating) among the study population. None of children was co-infected with of HRSV A and B. Overall, HRSV-A was the predominant subtype detected among children presenting with respiratory infection at the SHF while subtype B was predominant among participants attending PHCs for routine immunization. Higher disease severity scores were associated with HRSV-A infection than infection with HRSV-B. Only HRSV subtype A was detected from those diagnosed of bronchopneumonia and bronchiolitis. In conclusion, subtypes A and B co-circulating among children in Ibadan, with HRSV-A being the predominant subtype. Additional study including samples collected from other parts of the country over a longer period that will cover both wet and dry season will be done to determine the pattern of HRSV circulation in Nigeria.