The epidemiology of Schistosoma mansoni in the Lake Tana Basin (Ethiopia): Review with retrospective data analyses

Abstract

Schistosoma mansoni is one of the major waterborne diseases grouped underwater based Neglected Tropical Diseases in Africa. In Ethiopia, the Lake Tana Basin has favorable environment (temperature and water) for S. mansoni transmission. The prevalence of S. mansoni varies among regions based on environmental conditions and human water contact. Therefore, this review was conducted to identify hot spots districts and determine the prevailing S. mansoni prevalence in the Lake Tana Basin. Research articles published in English in the last 65 years were searched from Google scholar, PubMed, and Web of science. In addition, four-year S. mansoni data that were reported in health care facilities were extracted from health management information system in 61 districts of the Lake Tana Basin. In total, 43 research articles on S. mansoni that met the inclusion criteria and were published between 1957 and 2022. Over 98% of the articles were cross-sectional studies, while five articles addressed malacological studies. Among 61 districts, 19 (31%) were identified as hotspot districts for S. mansoni infection in the Lake Tana Basin. S. mansoni prevalence and the abundance of its host snail showed spatial and seasonal variations. On average 2000 school children/year attended health care facilities for S. mansoni infection. Swimming habits [adjusted odds ratio (AOR) = 3.2, p = 0.030], irrigation practice (AOR = 3:09, p ≤ 0.001), fishing (AOR = 2:43, p = 0.005) and being male (AOR = 1.74, p = 0.002) were risk factors for contributing to S. mansoni infection. This study showed the spatial and seasonal variations of S. mansoni prevalence and its endemicity in the hottest lowland areas of the Lake Tana Basin. The research articles on S. mansoni had poor geographical coverage. Malacological studies on water bodies, assessments on knowledge and attitude in the community towards S. mansoni transmission are areas of future studies.

Keywords: Ecology; Ethiopia; Lake Tana Basin; Schistosoma mansoni.

Fig. 1

Maps of the study area. (Left) the Ethiopian map showing the Lake Tana Basin. (Right) the location of the districts in the catchments of the Lake Tana Basin.

Fig. 2

The PRISAM flow diagram for articles included, exclude and a four-year retrospective S. mansoni data from health facilities in the catchments of the Lake Tana Basin.

Fig. 3

Temperature (a) and S. mansoni (b) geo-spatial map of the study area (Lake Tana Basin). The high hotspot districts for S. mansoni infection per1000 risk population are indicated by blue font color (Metema, Takusa, Tach Armacho, Tegede, Adiarikay and Chagni).

Fig. 4

The distribution of S. mansoni infection by gender and age groups.

Fig. 5

The distribution of S. mansoni positive cases by seasons a) and the four trends b).