Malaria Transmission Dynamics in a High-Transmission Setting of Western Kenya and the Inadequate Treatment Response to Artemether-Lumefantrine in an Asymptomatic Population. (29th June 2022)

• Record Type: Journal Article
• Authors: Andagalu, Ben; Watson, Oliver J; Onyango, Irene; Opot, Benjamin; Okoth, Raphael; Chemwor, Gladys; Sifuna, Peter; Juma, Dennis; Cheruiyot, Agnes; Yeda, Redemptah; Okudo, Charles; Wafubwa, Jackline; Yalwala, Santos; Abuom, David; Ogutu, Bernhards; Cowden, Jessica; Akala, Hoseah M; Kamau, Edwin
• Is Part Of: Clinical infectious diseases. Volume 76:Number 4(2023)
• Page Start: 704
• Page End: 712
• Publication Date: 2022-06-29
• Subjects: Plasmodium falciparum -- malaria surveillance and transmission dynnamics -- malaria control and elimination -- artemether/lumefantrine -- drug resistance; Communicable diseases -- Periodicals; 616.905
• DOI: 10.1093/cid/ciac527
• Languages: English
• ISSNs: 1058-4838

Abstract

Abstract: Background: Assessing the infectious reservoir is critical in malaria control and elimination strategies. We conducted a longitudinal epidemiological study in a high-malaria-burden region in Kenya to characterize transmission in an asymptomatic population. Methods: 488 study participants encompassing all ages in 120 households within 30 clusters were followed for 1 year with monthly sampling. Malaria was diagnosed by microscopy and molecular methods. Transmission potential in gametocytemic participants was assessed using direct skin and/or membrane mosquito feeding assays, then treated with artemether-lumefantrine. Study variables were assessed using mixed-effects generalized linear models. Results: Asexual and sexual parasite data were collected from 3792 participant visits, with 903 linked with feeding assays. Univariate analysis revealed that the 6–11-year-old age group was at higher risk of harboring asexual and sexual infections than those <6 years old (odds ratio [OR] 1.68, P < .001; and OR 1.81, P < .001), respectively. Participants with submicroscopic parasitemia were at a lower risk of gametocytemia compared with microscopic parasitemia (OR 0.04, P < .001), but they transmitted at a significantly higher rate (OR 2.00, P = .002). A large proportion of the study population who were infected at least once remained infected (despite treatment) with asexual (71.7%, 291/406) or sexual (37.4%, 152/406) parasites. 88.6% (365/412) of feeding assays conducted in individuals who failed treatment the previous month resulted in transmissions. Conclusions: Individuals with asymptomatic infection sustain the transmission cycle, with the 6–11-year age group serving as an important reservoir. The high rates of artemether-lumefantrine treatment failures suggest surveillance programs using molecular methods need to be expanded for accurate monitoring and evaluation of treatment outcomes. Abstract : Primary school children are the most important infectious reservoir for transmission of malaria. Asymptomatic participants with submicroscopic parasitemia transmit malaria at a significantly higher rate compared with microscopic parasitemia. One-third of the study population failed treatment with artemether-lumefantrine.