Risk factors associated with a gastroenteritis outbreak, Firestone District, Margibi County, Liberia, February 2018

Abstract

Introduction: Gastroenteritis is an inflammation of the intestines that leads to diarrhoea and vomiting. It is one of the commonly reportable diseases in humans and primarily affects children under five years. Globally, gastroenteritis is estimated to result in 1.45 million deaths annually. The burden of gastroenteritis remains exceptionally high in developing counties, especially in areas characterized by poverty. On February 5, 2018, the Margibi County Surveillance Officer received a call from the District Surveillance Officer regarding an outbreak of severe acute diarrhoea from Division 15 and 17 communities of Firestone District. We investigated to confirm the existence of an outbreak, verify the diagnosis, identify risk factors, and institute appropriate control measures. Methods: In this study, we defined gastroenteritis as the acute passage of watery or bloody diarrhoea (AWD) of three or more loose or liquid stools within 24 hours (or more frequent passage than is normal for the individual) with or without blood We visited affected and surrounding communities and conducted active case search. The team conducted a 1:1 unmatched case-control study to identify risk factors for developing the illness. We inspected drinking water sources and household water storage facilities. We collected two swabs of freshly passed (< 1 hr) stool samples to identify the causative agent. We established a temporary mobile treatment site in affected communities to treat uncomplicated cases and referred severe cases to Du-side Hospital. We temporarily restrained community dwellers from consuming water from the creek and hand pump. Results: We identified and line listed 66 cases, 62 presented with diarrhea and vomiting, but no deaths. Males accounted for 63%, median age of 16 years (range: 2 - 64 years) while 65.1% were age-group over 20 years. Division 15 accounted for 60% of the total number of cases, and 34.8% were admitted at Du-side Hospital. Rubber tappers and students accounted for 36.4% and 31.8% respectively. Drinking water from the creek was 56.0% hand pump 37.9%, while pipe-borne water 6.1%. The overall attack rate was 68 per 1,000 inhabitants. All cases were seen within 24 hours. Community health volunteers identified 35% of the cases while conducting an active case. Drinking water sources, from creek (OR: 6.5 (2.0-21.7), p = 0.00) and hand pump (OR: 6.5 (2.0-21.7), p = 0.00), were significantly associated with being ill and having gastroenteritis. Other significant associated risk factors were working as rubber tapper (OR: 4.0 (1.4-11.7), p = 0.02) and having no formal education (OR: 3.1 (1.10-8.84), p = 0.08). Laboratory analysis isolated E. coli and Shigella sp in the creek water. Six jerry cans of safe drinking water, water guards, hand sanitizers and laundry soap were provided to each household. Conclusion: Our findings revealed that the outbreak was due to E.coli infection and Shigella. It was established that the consumption of unsafe drinking water from the creek and hand pumps led to the outbreak. Rubber tappers and no formal education were the possible drivers for the outbreak. However, the daily provision of safe drinking water, rapid case detection and management helped to contain the outbreak quickly without any mortality.