Rapid assessment of prevalence of Trypanosoma brucei qambiense trypanosomiasis in Terego, Arua district, Uganda, May, 1996

Abstract

Introduction: Sleeping sickness due to Trypanosoma brucei gamhiense is found m Arua district, northwestern Uganda. Between 1992 and 1993 the number of sleeping sickness cases diagnosed in Yumbe Hospital, Arua, quadrupled from 57 to 220 per year. The majority of cases came from Terego county, which has 24 pttrishes, 99,794 people and an area of 7,830 kilometers. The objective was to identify parishes in Terego with high prevalence of trypanosomiasis so that the sleeping sickness program can target intervention and reduce transmission. Methodology: Lot Quality Assurance Sampling ( LQAS) methodology was used to identify parishes with sleeping sickness prevalence of’ 10%. The upper and lower thresholds were 10% and 2’Y o, respectively. With lot size of 5000, critical number cd 2, alpha error of 5% and hem error of 20%, a sample size per parish of 59 was calculated. Parishes with more than 2 cases were identified as unacceptable. The comhined sample size for the whole county was 1,416. The 59 h oult o s per parish were selected by simple xh Id. random technique. One individual from each household was selected rand~rmly. The individual underwent card agglutination test for trypanosomes (CATT), microhaematocrit (MHCT) and qualitative huffy coat (QBC) tests for evidence of trypanosomrs in blood. Lymph nodes and cerehrospinal fluid (CSF) were also tested for evidence of trypanosomes. Results: The study was done in only 14 parishes because of civil unrest. There were 21 cases in the 14 parishes giving a prevalence of 3% (95% confidence interval: l-4%,). Tl lere was no association between gender and trypanosomiasis hut there were more male cases. Two parishes which had more than 2 cases were identified as hot spots. Only 38% of CATT posttives were cases. Conclusions: Overall prevalence m Terego was 3%. Two parishes had prevalence ahove 10% and should he targets for health education and treatment.