Risk factors for severe respiratory syncytial virus infection leading to hospital admission in children in the western region of The Gambia

Background Acute lower respiratory tract infections (ALRI) are the major ca use of mortality and morbidity in young children worldwide. Respiratory syn cytial virus (RSV) infection is the most important viral cause of severe AL RI but only a small proportion of children infected with this virus develop severe disease. To identify possible risk factors for severe RSV infection leading to hospital admission we have carried out a case-control study of Gambian children with RSV infection admitted to hospital. Methods In all, 277 children admitted to three hospitals in the Western Reg ion of The Gambia with lower respiratory tract infection due to RSV were co mpared with 364 control children matched for age and location of residence who had not been admitted to hospital with an ALRI during the RSV season. A detailed questionnaire covering a wide range of potential social, environm ental and nutritional risk factors was administered to the child's guardian . Results Cases came from larger or more crowded compounds than controls; inc reased risk was particularly associated with greater numbers of children in the age group 3-5 years living in the compound (odds ratio [OR] for greate r than or equal to 2 children in the age group 3-5 years = 9.1, 95% CT: 3.7 -28). Cases were more likely to have a sibling who had died (OR = 3.4, 95% 6 CI : 1.7-7). Controls were more likely to have been exposed to smoke from cooking fires (OR for the mother of cases cooking at least once daily = 0. 31, 95% CI: 0.14-0.7). Other protective factors were father's nationality a nd some professions. Vegetables were included in the diet of controls more frequently than in that of cases (OR = 0.16, 95% CT:0.06-0.46). Mothers of cases complained of asthma more frequently than mothers of controls, bur th e number of asthmatic mothers was small (4.2 versus 0.5%, P = 0.05). Conclusions Risk factors for severe RSV infection identified in this study are not amenable to public health interventions. Prevention of severe infec tion is likely to require the development of an effective vaccine.