Epidemiological and Entomological Characteristics of Plasmodium falciparum Malaria in Dire Dawa City, Ethiopia

Abstract

Malaria is caused by parasites of the genus Plasmodium, which is transmitted to humans by a bite of an infected female Anopheles mosquito. The South Asian malaria vector, Anopheles stephensi, was first confirmed in Djibouti in 2012, and distributed and established widely in the eastern part of urban settings of Ethiopia located on the main transportation corridor from Djibouti to Addis Ababa. The objective of this study was to assess epidemiological and entomological characteristics of imported and locally-acquired Plasmodium falciparum malaria in patients visiting Goro health center and Dire Dawa University student clinic, Dire Dawa city, Ethiopia. For this purpose a facility-based case-control study was conducted from March 01 to May 30, 2022where a total of 55 index cases and 150 controls were recruited. An index case and controls identified at the health center were followed to their homes and their family members were tested to find other malaria parasites in family members. Malaria infection using 18S based quantitative polymerase chain reaction (qPCR) among family members of index cases (n=163) were compared with that of febrile controls (n=366). Adult and immature stages of mosquitoes were collected by prokopack aspirator and standard dipper, respectively, from the participants’ homes and surrounding to identify the vector responsible for malaria transmission. A pretested structured questionnaire was used to assess socio-demographic, entomological and clinical data collection. Collected data were exported to Stata Software version 17.0 for analysis. Odds ratio with 95% CI was used as a measure of association, and variables with a p-value of ≤0.05 were considered as statistically significant. The prevalence of malaria among study participants by RDT, microscopy and qPCR is 13.4%, 12.4% and 19.3%, respectively. Members of the index cases were more likely to be qPCR positive (22.7%, 37/163) than members of the control household (HH) (14.8%, 54/366; odds ratio [OR]; 6.2, 95%CI, 4.2-9.2; P<0.001). Being a family member of index case, spending evenings away from home, using anti-mosquito spray in home, malaria history in the past two weeks, being male and proximity to mosquito breeding sites were significantly associated with positive test result for malaria (P value < 0.00). The finding of this study showed that the principal malaria vector found was Anopheles stephensi and is contributed to current malaria transmission in Dire Dawa city. Interventions and strategies which focus on breeding sites are needed to reduce malaria infections in the area.