Asymptomatic falciparum and Non-falciparum Malarial Parasitemia in Adult Volunteers with and without HIV-1 Coinfection in a Cohort Study in Western Kenya

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  • 1 Basic Science Laboratory, U.S. Army Medical Research Directorate–Africa/Kenya Medical Research Institute, Kisumu, Kenya;
  • 2 Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland;
  • 3 Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho;
  • 4 Department of Biological Sciences, University of Idaho, Moscow, Idaho

Asymptomatic malarial parasitemia represents the largest reservoir of infection and transmission, and the impact of coinfection with HIV-1 on this reservoir remains incompletely described. Accordingly, we sought to determine the prevalence of asymptomatic malarial parasitemia in Kombewa, Western Kenya, a region that is endemic for both malaria and HIV-1. A total of 1,762 dried blood spots were collected from asymptomatic adults in a cross-sectional study. The presence of parasitemia was first determined by a sensitive Plasmodium genus–specific 18S assay, followed by less sensitive species-specific DNA-based quantitative polymerase chain reaction (PCR) assays. The prevalence of asymptomatic malarial parasitemia by 18S genus-specific PCR assay was 64.4% (1,134/1,762). Of the 1,134 malaria positive samples, Plasmodium falciparum was the most prevalent species (57.4%), followed by Plasmodium malariae (3.8%) and Plasmodium ovale (2.6%) as single or mixed infections. As expected, the majority of infections were below the detection limit of microscopy and rapid diagnostic tests. HIV-1 prevalence was 10.6%, and we observed a significant association with malarial parasitemia by χ2 analysis (P = 0.0475). Seventy-one percent of HIV-1 infected volunteers were positive for Plasmodium 18S (132/186), with only 29% negative (54/186). In HIV-1-negative volunteers, the proportion was lower; 64% were found to be positive for 18S (998/1,569) and 36% were negative (571/1,569). Overall, the prevalence of asymptomatic malarial parasitemia in Western Kenya is high, and knowledge of these associations with HIV-1 infection are critically important for malaria elimination and eradication efforts focused on this important reservoir population.

Author Notes

Address correspondence to Carolyne Kifude, Basic Science Laboratory, U.S. Army Medical Research Directorate–Africa/Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya. E-mail: carolyne.kifude@usamru-k.org

Financial support: This work was supported by National Institutes of Health National Institute of Allergy and Infectious Diseases R01 AI104423 (to V. A. S. and S. L.).

Disclaimer: The contents, views and opinions expressed in this publication are those of the authors and do not necessarily reflect the official policy or position of Uniformed Services University of the Health Sciences. Mention of trade names, commercial products and organizations does not imply endorsement by the U.S. Government. Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and/or publication. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting true views of the Department of the Army or the Department of Defense. The investigators have adhered to the policies for protection of human subjects as prescribed in AR 70–25.

Authors’ addresses: Carolyne Kifude, Stephen Ocholla, John Waitumbi, and Janet Oyieko, Basic Science Laboratory, U.S. Army Medical Research Directorate–Africa/Kenya Medical Research Institute, Kisumu, Kenya, E-mails: carolyne.kifude@usamru-k.org, stephen.ocholla@usamru-k.org, john.waitumbi@usamru-k.org, and janet.oyieko@usamru-k.org. Deborah Stiffler, David Rockabrand, Robin Miller, Emily Parsons, Nathaniel I. Dizon, and V. Ann Stewart, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, E-mails: deborah.stiffler@gmail.com, dmrockabrand@liberty.edu, robinheathermiller@gmail.com, emily.l.parsons2.mil@mail.mil, nadizon93@gmail.com, and ann.stewart@usuhs.edu. Brandi K. Torrevillas, Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID, E-mail: bktorrevillas@uidaho.edu. Shirley Luckhart, Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID, and Department of Biological Sciences, University of Idaho, Moscow, ID, E-mail: sluckhart@uidaho.edu.

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