An epidemiological study of rotavirus diarrhoea in a cohort of Nigerian infants: I. Methodology and experiences in the recruitment and follow-up of patients.

A community-based prospective study was carried out in the city of Ibadan, Nigeria, to determine the epidemiology of rotavirus infection and diarrhoea among children in the first two years of life. Implementation of the proposed study methods was hindered by a number of factors common to large urban areas in developing Africa. These factors included difficulties in recruiting the study sample because of maternal fears, cultural beliefs, and lack of paternal consent. Following recruitment, longitudinal surveillance was made difficult by inefficient telecommunications, a haphazard house numbering system, transportation difficulties, mobility of the population, and lack of incentive for continued participation. Despite these difficulties, 73% of the recruited newborns remained in the study until they reached the age of 12 months. The drop-out rate in the second year of study was higher, largely because fewer incentives could be provided during the second year. This paper reviews the operational considerations of implementing a longitudinal study protocol under these conditions, and discusses the potential impact of these problems and the measures taken to overcome them on the results of this study.