Risk factors for contracting watery diarrhoea in Mzilikazi, Bulawayo City, Zimbabwe, 2020: a case control study

Abstract

Introduction: Mzilikazi clinic had an upsurge of diarrhoea cases with 41 cases from the 28^th to the 30^th of September 2020, against a threshold of 11. We therefore, investigated the risk factors associated with this outbreak to recommend prevention and control measures.

Methods: we conducted a 1:1 unmatched case-control study. A case was any person who suffered from diarrhoea, and was resident in the clinic´s catchment since the 21^st of September 2020. Demographic data, knowledge and practices related to diarrhoea were collected using a standard questionnaire for both cases and controls. Environmental assessment, water quality and stool testing was also done. We conducted univariate and multivariate analysis at 95% confidence interval, to determine factors independently associated with contracting diarrhoea.

Results: the median age was 30 years (Q1=12, Q3=46) for cases and 30 years (Q1=22, Q3=48) for controls. The dominant gender was female for cases and male for controls. The independent risk factors were: drinking borehole water [adjusted Odds Ratio (aOR)=2.66; 95%CI=(1.41-5.00)], storing water in open container [aOR=2.76; 95%CI=(1.38-5.53)] and being under-five years old [aOR=5.73; 95%CI=(2.06-15.89)]. Boiling drinking water [aOR=0.39; 95%CI=(0.20-0.75)] was protective. Coliforms were detected from boreholes and stored water samples, and Shigella flexneri was isolated from 2 of the 13 stool specimens collected. Residents accessed water from decommissioned boreholes due to severe municipal water rationing.

Conclusion: being under-five years old, drinking borehole water and storing water in open containers were independent risk factors. Health education on home water treatment, distribution of water storage containers, and Aquatabs was done.