Soil contamination with geohelminth ova in a tea plantation

To determine the degree of soil pollution in an area of high prevalence and the risk of exposure to geohelminth infection.

A cross-sectional study.

A division of a large tea plantation in Kandy.

All persons resident in one division of the tea plantation, above the age of 1 year.

Prevalence of geohelminth infection measured by microscopic examination of faeces of the study group. Soil samples from 38 specific locations, obtained on 3 different occasions, about 6 months apart, analysed for helminth ova. The average temperature, rainfall and the number of rainy days during the sampling period.

Of the 99 subjects of the study group, 77.7% were positive for at least one geohelminth infection. The prevalence rates for ascariasis, trichuriasis and hookworm infection were 54%, 28%, and 22% respectively. At the first sampling, 10.5% of the soil samples were positive for helminth ova with 7.8% and 2.6% samples showing Ascaris and Necator ova respectively. At the second sampling of the same locations nearly 40% of the samples were positive for helminth ova with 21.6%, 7.8% and 10.5% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively. At the third sampling, 26.2% of the samples were positive with 21%, 2.6% and 2.6% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively. Necator ova were found only once in 2.6% of the samples of the first sampling. The larger number of samples positive for helminth ova were in the second and the third samplings which coincided with high rainfall in the pre-sampling period.

The prevalence of geohelminthiases among the study group was high. Results of soil analysis confirmed continued contamination of soil in and around the home gardens and the work areas with human and dog faeces. With the knowledge of exact locations of soil pollution it was possible to advice the management on remedial measures.