Malaria Outbreak –in Hitsats Refugee Camp, Tigray Region, Ethiopia- 2017, A Case-Control Study

Abstract Background: Over 80% of current refugee camps worldwide are located in malaria-endemic areas and malaria accounts for up to 50% of all deaths among refugees. In 2016, 3,152 malaria cases were reported from Hitsats Refugee Camp located in northern Ethiopia. A malaria outbreak was reported from Hitsats Refugee Camp (Population=8498) on June 19 th , 2017. We investigated to describe the epidemiology, identify risk factors, and implement control measures. Methods : We defined a malaria case as any person a resident of Hitsats Refugee camp with fever or fever with headache, rigor, back pain, chills, sweats, myalgia, nausea, and vomiting, or confirmed microscopically or by Rapid Diagnostic Test to have malaria parasites from June 6 th to July 3 rd , 2017 . We identified cases by reviewing the refugee clinic records and conducted a 1:1 case-control study from July 3 rd to 14 th , 2017. Cases were selected randomly using the patient registration book and recruited neighborhood controls who have no signs and symptoms of malaria and tested negative for Plasmodium species during the outbreak period from the same camp. We collected socio-demographic, behavioral, and risk factor information using a pre-tested structured questionnaire. Data were entered and analyzed using Epi-Info version 7.2.2. Multivariable logistic regression analysis was conducted to identify independent factors associated with malaria infection. Result: We identified 4,911 malaria cases with no death. Of those cases, 3,290 (67%) were males, and 4,322 (88%) were aged ≥5years. The overall attack rate (AR) was 58% (4911/8498) and was highest among <5years (84%) and was 55% among people ≥5years. Seventy-eight malaria cases and 78 controls were interviewed. The presence of patient/s with similar signs and symptoms at home (Adjusted Odds Ratio (AOR) =3.5, 95% Confidence Interval (CI) =1.6-7.8) was an independent risk factor associated with malaria. Owning insecticide-treated mosquito nets (ITNs) (AOR=0.17; 95%CI=0.07-0.4) and using personal protective equipment (PPE) to prevent mosquito bites when staying outdoors (AOR=0.18; 95%CI=0.08-0.4) were disease protective factors. Conclusion: The presence of patient/s with similar signs and symptoms at home, lack of ITN ownership and not using PPE were variables associated with malaria infection. Prevention strategies that target ITN distribution and the use of PPE to prevent mosquito bites may mitigate and prevent further outbreaks of malaria in refugee camps.