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A serosurvey was carried out to assess the prevalence of HIV infection in The Gambia and the importance of possible risk factors. The overall prevalence of HIV-2 infection among the 4228 adults studied was 1.7% while that of HIV-1 was 0.1%. The prevalence of HIV-2 was similar in both sexes but higher among those greater than 25 years of age and those who lived in two small towns along a main transport route. Among men, multivariate analysis showed prevalence of HIV-2 infection was significantly greater among those in the more affluent occupations, those without a secondary education and those with a history of urethral discharge. Among women, infection was more frequent in divorcees and widows and those who had been married several times. The prevalence was also higher in individuals born in Guinea-Bissau and in an ethnic group which originated there.

The vaccination status of 251 children aged 12-18 months in two peri-urban Gambian communities was determined from their health cards. Two subgroups were identified: children who were fully vaccinated, and those who had received less than half their vaccinations. The social and environmental circumstances of these children were investigated to detect factors which were associated with poor vaccination compliance. Mothers of well vaccinated children were more inclined to bring them for non-curative services. Mothers of poorly vaccinated children had a poorer knowledge of the diseases against which their children should be vaccinated and they also had a more superstitious view of disease causation. Those children who showed poor compliance came from larger families. In the poorly vaccinated group both parents were less well educated and there was a trend towards poorer literacy.

Mortality and morbidity from malaria were measured among 3000 children under the age of 7 years in a rural area of The Gambia, West Africa. Using a post-mortem questionnaire technique, malaria was identified as the probable cause of 4% of infant deaths and of 25% of deaths in children aged 1 to 4 years. The malaria mortality rate was 6.3 per 1000 per year in infants and 10.7 per 1000 per year in children aged 1 to 4 years. Morbidity surveys suggested that children under the age of 7 years experienced about one clinical episode of malaria per year. Calculation of attributable fractions showed that malaria may be responsible for about 40% of episodes of fever in children. Although the overall level of parasitaemia showed little seasonal variation, the clinical impact of malaria was highly seasonal; all malaria deaths and a high proportion of febrile episodes were recorded during a limited period at the end of the rainy season.

Significant variations in the prevalence of splenomegaly were found among members of the three main ethnic groups resident in North Bank Division, The Gambia. Among young children splenomegaly and malaria were less prevalent in Mandinkas than in Wollofs or Fulas, suggesting that some genetic or environmental factors protect Mandinka children from this infection. Among older children and adults splenomegaly was found most frequently in Fulas. Six of 22 adults with very large spleens had a high serum IgM level and probably had the hyperreactive malarial splenomegaly (tropical splenomegaly) syndrome. Four of these six subjects were Fulas. This finding, together with the results of a previous study in Nigeria, suggest that Fulas have a predisposition to this condition.

A study was undertaken in the Farafenni area of The Gambia to determine the relation between morbidity from malaria in children and the use of bed-nets (mosquito-nets). From comparisons of parasite and spleen rates in bed-net users and in non-users it seemed that bed-nets had a strong protective effect. However, the prevalence of malaria in the study population was also influenced by ethnic group and place of residence, and the association of bed-net use with these two confounding factors accounted for some of the differences observed between bed-net users and non-users. Nevertheless, a significant inverse correlation between splenomegaly and the use of bed-nets remained. This suggests that bed-nets give Gambian children some protection against malaria and that the use of bed-nets, either untreated or treated with an insecticide such as permethrin, should be investigated further as a means of malaria control in Africa.

A randomised, controlled trial of bovine rotavirus vaccine was undertaken in Gambian infants. Three doses were administered, from the age of ten weeks, concurrently with oral or killed polio vaccine. Prevaccination rotavirus neutralising antibody levels were high. 84/185 infants (45%) showed an increase in neutralising antibody titre after receiving rotavirus vaccine, compared with 20/91 (22%) unvaccinated infants. Clinical rotavirus infection was detected in 24/78 (31%) children in the rotavirus/oral polio group, 34/83 (41%) children in the placebo/oral polio group, and 23/92 (25%) children in the rotavirus/killed polio group, giving an overall vaccine efficacy of 33% (95% CI 4-53%). RIT 4237 did not appear to reduce the severity of clinical infections. Most cases (92%) were caused by rotaviruses with short RNA electropherotypes. Serological responses to rotavirus vaccination appeared unaffected by the concurrent administration of oral polio vaccine. Lower types 1 and 3 polio antibody levels were found in children who received oral polio and rotavirus vaccines but the differences were not statistically significant.

A survey of deaths in children under the age of 7 years was made over a 1-year period in a rural area of The Gambia with few facilities for curative medicine but with a good record of infant immunizations. One hundred and eighty-four deaths were investigated. Only 12% of deaths occurred in a hospital or health centre but an attempt was made to establish a cause of death by interviewing the family of each dead child and by examining any health records that were available. The infant mortality rate was 142 per 1000 live births and the child mortality rate (death in children aged 1-4 years) 43 per 1000 per year. Acute respiratory infections, malaria and chronic diarrhoea with marasmus were the most frequent causes of death after the 1st month of life. Few children died of diseases that could have been prevented by routine immunizations. An effective immunization programme has probably had some effect on deaths in infancy and early childhood but it will be necessary to find ways of preventing deaths from malaria, acute respiratory infections and chronic diarrhoea/marasmus at the primary health care level if infant and childhood mortality are to be reduced further in rural areas of The Gambia.