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 cause of mortality and morbidity in young children worldwide. Respiratory syncytial virus (RSV) infection is the most important viral cause of severe ALRI 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 Region of The Gambia with lower respiratory tract infection due to RSV were compared 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, environmental and nutritional risk factors was administered to the child's guardian.

RESULTS: Cases came from larger or more crowded compounds than controls; increased risk was particularly associated with greater numbers of children in the age group 3-5 years living in the compound (odds ratio [OR] for > or =2 children in the age group 3-5 years = 9.1, 95% CI: 3.7-28). Cases were more likely to have a sibling who had died (OR = 3.4, 95% 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 and some professions. Vegetables were included in the diet of controls more frequently than in that of cases (OR = 0.16, 95% CI: 0.06-0.46). Mothers of cases complained of asthma more frequently than mothers of controls, but the 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 infection is likely to require the development of an effective vaccine.