Epidemiology of severe respiratory syncytial virus infection in Ethiopian infants : A prospective study

Background: Respiratory Syncytial Virus (RSV) is the commonest cause of lower respiratory tract infection (LRTI) in infants. However, the role of RSV in LRTI is unknown in Ethiopia. Objective: We aimed to determine the prevalence, seasonality and associated factors of RSV infection in previously healthy young infants with LRTI in Ethiopia. Methods: RSV antigen test was performed from nasopharyngeal swab of 117 young infants with symptoms of severe LRTIs. The first 10 eligible infants in each month from June 2018 to May 2019 were included in the study. Clinical, laboratory and imaging data were collected using a semi–structured questionnaire and data were analyzed using descriptive and analytical methods, chi-square test and logistic regression were applied as appropriate. Results: Majority of study subjects was male (65%) with median age of 3 months. Bronchiolitis was the commonest diagnosis (57%) followed by pneumonia and bronchitis. RSV was isolated from 26 (22.2%) of all infants and 37 % of those with bronchiolitis and 11 % of those with pneumonia. While RSV was observed to occur year round, the typical RSV season extended from June to November and only rainy season (Adjusted Odds Ratio 10.46 [95%.C.I. 1.95, 56.18]) was an independent predictor of RSV infection. Conclusion: RSV was isolated approximately in a fifth of infants, mostly in the rainy season. Lack of clinical, laboratory and imaging predictors of RSV infection emphasize the need of specific diagnostic tests for identification of the virus. As RSV is less common in our setting compared to other area, the other causes of LRTI should be investigated in future studies.