The use of morbidity questionnaires to identify communities with high prevalence of geohelminth infections in Gondar region, Ethiopia.
In this preliminary study, a total of 8006 schoolchildren (aged 9-19 years) from 77 elementary schools was screened for infection with Ascaris lumbriocoides, Trichuris trichiura and hookworms using the Kato-Kata method. A. lumbriocoides was commonly encountered (35.4%) followed by the hookworms (16.3%) and T. trichiura (12.7%). The prevalence of "intestinal worms" (infection by A. lumbricoides, T. tirchiura and/or hookworms) accounted to 50.6%. The children were also asked about their recent experiences of the following: 'diarrhea', 'stomach ache', 'blood in stool', 'distended stomach'. and 'worms' using questionnaires and gave 24.0%, 64.9%, 18.6%. 37.0%, 38.1% 'yes' answers, respectively. At individual level reported 'worms' correlated with the prevalence of A. lumbricoides [OR 7.39 (95% CI: 6.65-8.20)] and 'intestinal worms' [OR 4.72 (95% CI: 4.27-5.22)]. Reported 'diarrhoea' was the best answer for T. trichiura [OR: 4.58 (95% CI: 3.98-5.27)]. Among schools, there were similar associations between prorated 'worms' and the prevalence of A. lumbricoides [OR 0.63 (95% CI: 0.47-0.75)] and 'intestinal worms' [OR 0.55 (95% CI: 0.37-0.69)]. No sign or symptom was significantly associated with hookworm infection. Reported 'worms' had the best though moderate diagnostic performance for 'intestinal worms' (sensitivity: 82.6%, specificity 51.6%, positive predictive value: 66.7%, negative predictive value: 71.7%) and A. lumbrocoides (sensitivity: 91.8%, specificity: 50.0%, positive predictive value: 75.5%, negative predictive value: 64.3%). These results indicate the potential of using reported 'worms' as a means of rapid assessment for identifying communities with a high prevalence of geohelminth infection.