Trends and seasonal patterns in intestinal parasites diagnosed in primary health facilities in Northwest Ethiopia.

Introduction: Intestinal parasites have an insidious impact on human health. In response to high parasite frequencies in Northwest Ethiopia, mass drug administration (MDA) is provided for school children using albendazole/mebendazole (since 2007) and praziquantel (since 2015). The study objective was to assess trends and seasonal patterns of intestinal parasite infections in a context of MDA.

Methodology: This was a descriptive study collecting routine data from laboratory registers in two health centres in Denbia district, Amhara region. Stool test results (wet-mount direct microscopy) from patients attending these centres between 2013 and 2018 were included. Frequencies of different parasite species were evaluated within and across the years and stratified by age and gender.

Results: From a total of 8002 stool test results, the overall parasite frequency was 53.3%; this proportion remained constant. The most frequently diagnosed soil-transmitted helminths (STH) were Ascaris lumbricoides (16.9%) and hookworm (3.9%). STH frequency varied over the years, but was similar at the beginning (20.0%) and the end (22.0%) of the six-year period. STH infections were more frequent in winter (December-February; 20.4%) than in other seasons (16.0%). The most frequently diagnosed protozoa were Entamoeba histolytica/dispar (18.5%) and Giardia lamblia (12.2%). The frequency of Giardia steadily increased from 9.6% in 2013 to 15.3% in 2018. E. histolytica/dispar peaked in summer and G. lamblia in autumn.

Conclusions: Trends in routine laboratories may be a proxy for a status quo in the community. These findings suggest that higher MDA coverages and/or interventions beyond MDA are needed to reduce intestinal parasite-related morbidity.