Geohelminth infection is highly prevalent in tropical and subtropical countries where poor conditions frequently prevail and insufficient water supply, inadequate sanitation, and low health awareness are present. Children and mothers of childbearing age are at greatest risk due to these infections. To define the determinants of the intensity of infection, a study of the prevalence, intensity and risk factors for geohelminth infection was undertaken among school children aged 5 to 9 years attending a primary school in the fishing village in Peda Jalaripet, Visakhapatnam, South India.
One hundred and eighty nine (92.6%) of 204 children were infected with one or more of the geohelminth parasites. The predominant parasite was Ascaris lumbricoides (prevalence 91 %), followed by Trichuris trichiura (72%), then hookworm (54%). Study of age-specific prevalence of infection revealed that the prevalence of A. lumbricoides infection was higher among younger children than older children. While aggregation of parasite infection was observed, hookworm infection was more highly aggregated than A. lumbricoides or T. trichiura. Multivariate analysis identified parents' occupation, child's age and mother's education as risk factors contributing to the intensities of A. lumbricoides infection. Children from fishing families whose mother had low education levels had the highest intensity of A. lumbricoides infection.
To determine the role of environmental contamination at specific sites in the transmission of geohelminth intensity, a study of soil contamination was undertaken in the village. Three hundred and fifty soil samples were collected from five defined household sites (entrance of the house, wash areas, eating places, rubbish disposal areas and yard) within each of 70 households. A further 70 soil samples from commonly used community sites (playgrounds, school premises, market areas and public places) were also collected. These 630 soil samples were analysed for the presence of geohelminth eggs and larvae.
Soil samples from the household sites were heavily contaminated with Ascaris species eggs (87% prevalence), and with Toxocara species eggs (81 %). Similar results were obtained from environmental soil samples, with a prevalence of 83% observed for Ascaris sp., and 71% for Toxocara species. To define the relative contribution of different environmental sites in terms of transmission, factor analysis was undertaken. Kitchen and rubbish areas of household samples were identified as the major sources of contamination for Ascaris sp. infection, whereas house entrance and yard were more important for hookworm infection.
The present study indicates a high prevalence but low intensity of geohelminth infection among school children. In addition, the study also demonstrates a high level of soil contamination with geohelminth infection including To xocara sp. in the school premises and domestic environments. Thus, school health education is likely to be an important consideration for any geohelminth control programmes among school children.
The following are considered as the implications of the study: Firstly, school health education programmes should include sessions on the geohelminths transmission and should highlight the importance of soil. School children should be encouraged to avoid soil-contact behaviours including walking barefoot. Secondly, construction of latrines should focus on child-friendly toilets to avoid open and uncontrolled-defecation. Even though toilets did not appear to influence on intensity of infection in this study, promiscuous defecation clearly increases the level of infection. Finally, community health education including geohelminth infection should be introduced to promote parasite-free environment.
Key Words: Geohelminths, prevalence, intensity, risk factors, soil contamination.