The effects of surface soil exchangeable cations on the prevalence of Ascaris lumbricoides in Ogun State, Nigeria

Abstract

The study examined the association between surface soil physico-chemical properties and the prevalence of Ascaris lumbricoides in Ogun State. A school-based prevalence survey was carried out among 1,800 school pupils randomly selected from five Local Government Areas (LGAs) representing the major soil-geological zones in relation to their parent rocks namely: Odeda LGA (undifferentiated Basement Complex), Obafemi/Owode LGA (Sandstone-Abeokuta Formation), Ewekoro LGA (Upper Coal Measure Ewekoro formation), Ado-Odo/Otta LGA (Coastal Plain Sands I-Alfisols), and Ogun Waterside LGA (Coastal Plain Sands II-Utisols). Kato smear method was used to determine the indirect prevalence and intensity of infection while drug (Levamisole) administration was used to determine the direct prevalence and intensity of infection, in addition to analysis of the physico-chemical characteristics of the surface soil samples from the LGAs. The overall indirect prevalence of infection was Ascaris lumbricoides (72.5%), Hookworm (8.5%) and Trichuris trichiura (6.0%). The direct prevalence for A.lumbricoides was 48.5%. The physico-chemical studies of surface soils (5cm depth) from the LGAs showed that sand/silt content and pH varied significantly among the soils. The total nitrogen and exchangeable cations (Mg⁺⁺, Ca⁺⁺, K⁺, and Na⁺) also vary significantly (P<0.05). High prevalence of ascariasis was more correlated with decreasing amount of manganese in soils.

Keywords: Ascaris lumbricoides, soil-transmitted helminths, physico-chemical properti

Nigerian Journal of Parasitology Vol. 25, 2004: 25-31