Socio-economic and behavioural factors affecting the prevalence of Ascaris infection in a low-country tea plantation in Sri Lanka

The identification of the factors that affect the prevalences of geohelminthiases should help to maximize the effectiveness of programmes for the control of these diseases. In the present study, the relationships between the prevalence and intensity of human infection with Ascaris and the availability of sanitary facilities, socio-economic status and personal health habits have been explored in Sri Lanka. The 176 subjects, who lived on a low-country tea plantation, were aged 2-50 years (median = 13 years) and were investigated between the July and December of 2000. When the prevalence and intensity of Ascaris infection were determined, using Kato-Katz smears, 50.0% of the subjects were found to be secreting the eggs of the parasite. Almost all (96.6%) of the subjects lived in terraces of one-room houses built by the plantation owners, and only 30.7% had access to a latrine. Most (90.3%) obtained their drinking water from common taps, and 48.8% boiled their drinking water. The subjects who only drank water that had been boiled and those who washed their hands before meals were relatively unlikely to be infected (P< 0.05 for each). In congested living conditions with poor sanitary facilities, the level of faecal contamination of the environment is invariably high. Even under these conditions, however, good hygiene and the boiling of all drinking water can reduce the risks of Ascaris infection. In the study setting and in similar environments, regular anthelmintic therapy, improvements in housing conditions and sanitary facilities, and health education, to promote risk-reducing patterns of behaviour, would all be beneficial.