Asymptomatic malaria remains high among seasonal migrant workers depart to home from malarious areas and may cause a resurgence of malaria transmission at high lands of northwest Ethiopia: a cross-sectional study

Abstract

Background In Ethiopia, thousands of seasonal migrant workers used to travel from non-malaria or mild malaria transmission areas to malaria endemic areas for the purposes of seasonal farm activities. Most of these migrants are staying in the farm areas for land preparation, ploughing, planting, weeding and harvesting for specific period of time and back to their living areas. However, there is limited evidence how the seasonal migrant workers contribute in the transmission of malaria to new or less malaria transmission areas. Methods A cross sectional study was conducted at departure phase of seasonal migrant workers in Metema district from September 2018 to October 2019. A total of 1208 seasonal migrant workers were interviewed during their departure to home. Interviewed face to face interview was done using a pretested structured questionnaire. Moreover, blood samples were collected from each study participant for microscopic malaria parasite examination. The data was fitted with the logistic regression model to estimate the predictors’ of malaria transmissions. Results At the departure to home, the prevalence of malaria among seasonal migrant workers was 17.5% (15.6-19.45%). About 71.80 % (177/212) of the cases were Plasmodium falciparum, and 28.20% (35/212) Plasmodium vivax. The majority of seasonal migrant workers (77.4%) were from rural residence and highlanders (55%). Most (55.4%) of the migrants were visited two and more farm sites during their stay at development corridors for harvesting activities. About 116 (54.7%) asymptomatic malaria cases were returning to Dembiya(21.7%), Chilaga(19.8%) and Metema(13.2%) districts. Conclusion This study focuses on the prevalence of asymptomatic malaria among seasonal migrant workers during the departure phase to home. The role of seasonal migrant workers in carrying and spreading malaria parasites, as well as challenging the country's malaria prevention and elimination efforts, could be enormous. Age, occupation, origin, the number of farm sites visited, and the frequency with which LLINs used were all associated with an increased asymptomatic malaria prevalence in the study area. Tailored interventions for seasonal migrant workers could be in place by programers, partners and implementers to enhance malaria control and elimination.