The malarial infectivity ofan African village population was tested by selecting a demographically representative sample of individuals for study, regardless of parasitemia or gametocytemia. The infectivity of this population people to laboratory-bred mosquitoes was investigated using membrane feeding techniques. Tests on 322 subjects (greater than

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This report concerns hepatitis B virus (HBV) infections observed in 155 infants from Senegal, studied with a view to determining the factors involved in development of the chronic carrier state. A chronic carrier state was observed in 50.3% of the infants. This study confirms that the risk of chronic carriage is linked to age. This risk declines very rapidly with age, falling from 82% in infants under 6 months old, to 15% in children between the ages of 2 and 3 years. Spontaneous elimination of hepatitis B surface antigen (HBsAg) is uncommon in HBsAg carriers during childhood. The difference observed in chronic carriage between males and females is due to a difference in susceptibility of the two sexes to the development of the chronic carrier state: HBV infections (before 2 years of age) lead to a chronic carriage in 77% of males as against 50% of females. These conclusions are important in view of the immunisation programs being carried out against hepatitis B virus in endemic areas. For a maximum efficacy, vaccination must be carried out at birth, or shortly afterwards.

the term "hygiene practices". Programmes which aim to improve these will have to focus on a small number of behaviours. These targeted behaviours will have to be chosen on the basis of their prevalence in the community, their amenability to change, and the epidemiological evidence of their impact on diarrhoea rates. Some evidence of links between behaviours surrounding stool disposal and childhood diarrhoea is now beginning to emerge, particularly from three studies from Asia."6In an urban setting in West Africa, we carried out a study to identify interventions that might reduce early childhood morbidity from diarrhoea using a wide range of techniques. In this paper we present that component of the study which concerned the association between child defecation behaviour, mothers' stool disposal practices, visible faecal contamination of the environment, and the rate of admission to hospital of young children with symptoms of diarrhoea or dysentery, or both. Other findings from the study, including detailed descriptions of the setting and of mothers' beliefs and practices regarding diarrhoea and stool hygiene, have been presented

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