Re-infection patterns of ascariasis among school children in Ogun State, Nigeria

Abstract

A study was conducted to determine the direct prevalence, intensity and re-infection pattern of ascariasis among school pupils aged 6-17 years in Ogun State, Nigeria; 2,837 primary school pupils randomly selected from twenty schools in five Local Government Areas (LGAs) namely: Odeda, Obafemi/Owode, Ewekoro, Ado-Odo/Otta, and Ogun Waterside were enlisted for the study. Drug (Levamisole) administration was used to determine the direct prevalence, intensity and the re-infection patterns of infection. The overall direct prevalence for A.lumbricoides was 48.5%. Obafemi/Owode had the highest mean infection rate of 62.6%, followed by Ogun Waterside (59.19%), Odeda (44.8%), Ewekoro (34.2%) and Ado-Odo/Otta (25.6%). Male pupils were slightly more infected (51.9%) than females (48.1%) and also had higher mean intensity (2.2) than females (1.7). Statistical analysis showed no significant difference between the infection rates in both sexes (t=2.60, p=0.234). The cumulative numbers of worms expelled by pupils in the LGAs were Ogun Waterside 778 (39.5%), Obafemi/Owode 768 (39%), Odeda 216 (11%), Ewekoro 152 (7.7%) and Ado-Odo/Otta 55 (2.8%). The morphometric studies revealed that of the 1969 worms voided, adult worms accounted for 92.7% while young worms formed only 7.3%. Re-infection of pupils with ascariasis from different LGAs varied. The calculated monthly re-infection rates (X) were: Ewekoro (1.6%), Odeda (2.3%), Ado-Odo/Otta (2.3%), Ogun Waterside (3.8%), and Obafemi/Owode (4.2%); with a mean value of 2.84% for Ogun State. The re-infection time (N months) are Ado-Odo/Otta (12.7), Ogun Waterside (21.8), Obafemi/Owode (22.92), Odeda (25.45), and Ewekoro (25.9). The mean value for N in Ogun State was 21.75, which implies that it would require 22 months for initial equilibrium of A.lumbricoides infection to be attained in school pupils in Ogun State, Nigeria.

Keywords: Ascaris lumbricoides, reinfection, primary school pupils, Ogun State

Nigerian Journal of Parasitology Vol. 25, 2004: 7-13