Entomological and Anthropological Factors Contributing to Persistent Malaria Transmission in Kenya, Ethiopia, and Cameroon

Abstract

Introduction In order to improve our understanding of the fundamental limits of core interventions and guide efforts based on prioritization and identification of effective/novel interventions with great potentials to interrupt persistent malaria transmission in the context of high vector control coverage, the drivers of persistent disease transmission were investigated in three eco-epidemiological settings; forested areas in Cameroon, coastal area in Kenya and highland areas in Ethiopia. Methods Mosquitoes were sampled in three eco-epidemiological settings using different entomological sampling techniques and analysed for Plasmodium infection status and blood meal origin in blood-fed specimens. Human behavioural surveys were conducted to assess the knowledge and attitude of the population on malaria and preventive measures, their night activities, and sleeping pattern. The parasitological analysis was conducted to determine the prevalence of Plasmodium infection in the population using rapid diagnostic tests. Results Despite the diversity in the mosquito fauna, their biting behaviour was found to be closely associated to human behaviour in the three settings. People in Kenya and Ethiopia were found to be more exposed to mosquito bites during the early hours of the evening (18-21h) while it was in the early morning (4-6 am) in Cameroon. Malaria transmission was high in Cameroon compared to Kenya and Ethiopia with over 50% of the infected bites recorded outdoors. The non-users of LLINs were 2.5 to 3 times more likely to be exposed to the risk of acquiring malaria compared to LLINs users. Malaria prevalence was high (42%) in Cameroon, and more than half of the households visited had at least one individual infected with Plasmodium parasites. Conclusions The study suggests high outdoor malaria transmission occurring in the three sites with however different determinants driving residual malaria transmission in these areas.

Outdoor malaria vector species profile in dryland ecosystems of Kenya

“…Thus, the contribution of outdoor biting to malaria persistence could be much higher as universal coverage of ITNs and IRS has not been achieved. A multicountry study in Cameroon, Kenya and Ethiopia found high malaria transmission outdoors compared to indoors 5 . While this phenomenon is not new 9 – 11 , the profile of vectors implicated in outdoor transmission could differ in different eco-epidemiologic settings 5 .…”

“…A multicountry study in Cameroon, Kenya and Ethiopia found high malaria transmission outdoors compared to indoors 5 . While this phenomenon is not new 9 – 11 , the profile of vectors implicated in outdoor transmission could differ in different eco-epidemiologic settings 5 .…”

“…Despite this progress, the disease still exerts a huge health burden accounting for an estimated 19% of all outpatient consultations in Kenya 4 . This trend is potentially indicative of the disease persistence and facilitated by several factors including house characteristics, use of bednets or other control measures, human activities and behavior, and vector-related factors 5 . However, entomologic determinants remain critical.…”

Composition of mosquito fauna and insecticide resistance status of Anopheles gambiae sensu lato in Itang special district, Gambella, Southwestern Ethiopia

“…Very recently, An. coustani , was found being infected with Plasmodium species [ 56 ] showing evidence of possible malaria transmission by An. coustani in the country.…”

Evaluating recurrent episodes of malaria incidence in Timika, Indonesia, through a Markovian multiple-state model

“…The Ministry of Health of the Republic of Indonesia reports that 97% of malaria cases in Indonesia occur in Papua, where malaria is endemic and common, as evidenced by an API value (Annual Parasite Index) greater than 5/1000 population ( Kemenkes, 2018 ). Geographic conditions, population characteristics, the presence of vectors, and inadequate health services also contribute to malaria transmission ( Hasyim, Dale, Groneberg, Kuch, & Müller, 2019 ; Bamou et al., 2021 ; Meireles, De Souza Sampaio, Monteiro, & Goncalves, 2020 ). Consequently, malaria cases occur throughout the year ( Lawpoolsri et al., 2019 ) and people living in endemic areas can potentially suffer from recurrent malaria.…”