Impact of Community-Based Mass Testing and Treatment on Malaria Infection Prevalence in a High-Transmission Area of Western Kenya: A Cluster Randomized Controlled Trial

Abstract

Background: Global gains toward malaria elimination have been heterogeneous and have recently stalled. Interventions targeting afebrile malaria infections may be needed to address residual transmission. We studied the efficacy of repeated rounds of community-based mass testing and treatment (MTaT) on malaria infection prevalence in western Kenya.

Methods: Twenty clusters were randomly assigned to 3 rounds of MTaT per year for 2 years or control (standard of care for testing and treatment at public health facilities along with government-sponsored mass long-lasting insecticidal net [LLIN] distributions). During rounds, community health volunteers visited all households in intervention clusters and tested all consenting individuals with a rapid diagnostic test. Those positive were treated with dihydroartemisinin-piperaquine. Cross-sectional community infection prevalence surveys were performed in both study arms at baseline and each year after 3 rounds of MTaT. The primary outcome was the effect size of MTaT on parasite prevalence by microscopy between arms by year, adjusted for age, reported LLIN use, enhanced vegetative index, and socioeconomic status.

Results: Demographic and behavioral characteristics, including LLIN usage, were similar between arms at each survey. MTaT coverage across the 3 annual rounds ranged between 75.0% and 77.5% in year 1, and between 81.9% and 94.3% in year 2. The adjusted effect size of MTaT on the prevalence of parasitemia between arms was 0.93 (95% confidence interval [CI], .79-1.08) and 0.92 (95% CI, .76-1.10) after year 1 and year 2, respectively.

Conclusions: MTaT performed 3 times per year over 2 years did not reduce malaria parasite prevalence in this high-transmission area.

Clinical trials registration: NCT02987270.

Keywords: asymptomatic malaria infections; malaria in Kenya; malaria transmission reduction; mass drug administration; mass testing and treatment.

Figure 1.

Study site and clusters, including core areas. A, Study site in relation to Kenya. B, Health and Demographic Surveillance System (HDSS) in relation to western Kenya. C, Clusters within HDSS, core areas within clusters, and study health facility location. Figure reprinted from Samuels et al [9] (open access; https://creativecommons.org/licenses/by/4.0/); no changes were made. Abbreviations: CDC, Centers for Disease Control and Prevention; HDSS, Health and Demographic Surveillance System; KEMRI, Kenya Medical Research Institute.

Figure 2.

Compound and individual study enrollment by survey and arm.

Figure 3.

Effect size of mass testing and treatment on blood smear prevalence, clinical malaria, and clinical malaria as a proportion of malaria. *Sample size insufficient for < 5-year age category. Abbreviations: CI, 95% confidence interval; MTaT, mass testing and treatment; Yr, year.