Factors associated with malaria infection in Mudzi District, Mashonaland East Zimbabwe, 2019: a case-control study

Kondo Rural Health Centre recorded 27 malaria patients between the 27th of January 2019 and the 2nd of February 2019 against an epidemic threshold of 19 with the malaria outbreak being confirmed on the 5th of February 2019. Indoor residual spraying as part of integrated vector management control activities had been done in the district before the onset of the rainy season as well as social behaviour change communication but residents were contracting malaria. We, therefore, investigated the risk factors associated with this outbreak to recommend scientifically effective prevention and control measures.

We conducted a 1:1 unmatched case-control study. A case was a resident of Mudzi from the 4th of February 2019 who had a positive rapid diagnostic test for malaria randomly selected from the clinic's line list whilst controls were randomly selected from the neighbourhood of cases. Pretested interviewer-administered questionnaires were used to collect information on demographic characteristics, knowledge and practices of residents in malaria prevention. Data were analysed using Epi info 7.

A total of 567 confirmed malaria cases was recorded with an overall attack rate of 71.7 per 1000 population. Sixty-three case-control pairs were interviewed. The majority of cases 78% (49/63) were from Makaza, Chanetsa and Nyarongo villages which are within 3 km from Vhombodzi dam. A stagnant water body near a house [aOR = 8.0, 95%CI = (2.3-28.6)], engaging in outdoor activities before dawn or after dusk [aOR = 8.3, 95%CI = (1.1-62.7)] and having a house with open eaves [aOR = 5.4, 95%CI = (1.2-23.3)] were independent risk factors associated with contracting malaria. Wearing long-sleeved clothes when outdoors at night [aOR = 0.2, 95%CI = (0.1-0.4)] was protective.

A stagnant water pool close to the homestead and engaging in outdoor activities before dawn and after dusk were modifiable risk factors associated with the malaria outbreak despite the community being knowledgeable on the transmission and prevention of malaria. Community sensitisation and mobilisation in the destruction of stagnant water bodies and cutting of tall grass around homesteads were recommended measures to contain the outbreak.