Recent Molecular Assessment of Plasmodium vivax and Plasmodium falciparum Asymptomatic Infections in Botswana

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  • 1 University of Botswana, Department of Biological Science, Gaborone, Botswana;
  • 2 University of Namibia School of Medicine, Windhoek, Namibia;
  • 3 Regent University College of Science and Technology, Department of Engineering, Computing and Allied Health Sciences, Accra, Ghana;
  • 4 Biomedical and Public Health Research Unit, Council for Scientific and Industrial Research–Water Research Institute, Council Close, Accra, Ghana;
  • 5 University of Lund, Department Clinical Sciences, Lund, Sweden;
  • 6 National Malaria Program Ministry of Health and Wellness, Gaborone, Botswana;
  • 7 Department of Microbiology and Immunology, Immunology Translational Research Program, Yong Loo Lin School of Medicine, Immunology Program, Life Sciences Institute, National University of Singapore, Singapore;
  • 8 Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore;
  • 9 A*STAR Infectious Diseases Laboratories, Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore;
  • 10 Botswana–University of Pennsylvania Partnership, University of Botswana, Gaborone, Botswana;
  • 11 Division of Infectious Diseases, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
  • 12 Department of Biomedical Sciences, Faculty of Medicine, University of Botswana, Gaborone, Botswana

In 2016, we reported the presence of Plasmodium vivax in Botswana through active case detection. A real-time PCR was used during a similar study in 10 districts to assess changes in the P. vivax prevalence. We assessed 1,614 children (2–13 years of age) for hemoglobin (Hb; g/dL) and Plasmodium parasites. The median age of all participants was 5.0 years (25th percentile, 3 years; 75th percentile, 8 years). The median Hb (g/dL) level was 12.1, but 18.3% of the participants had anemia (Hb < 11.0 g/dL); these participants were clustered in the younger than 5 years age group in all districts (P < 0.001). The risk of anemia decreased with age 5 years or older (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.197–0.34; P < 0.001). The prevalence rates of Plasmodium parasites were as follows: P. vivax, 12.7%; P. falciparum, 12.7%; P. malariae, 0.74%; and P. ovale (P. ovale curtisi), 0.68%. Mixed infection rates were as follows: P. falciparum and P. vivax, 2.35%; P. falciparum and P. ovale curtisi, 0.56%; P. vivax and P. malariae, 0.06%; and P. falciparum and P. malariae, 0.68%. The infections were largely asymptomatic (99.6%). Using logistic regression, the risk of infection with P. vivax was highest in Kweneng East (OR, 6.2; 95% CI, 2.9–13.1), followed by South East (OR, 5.6; 95% CI, 2.5–12.3) and Ngami (OR, 5.1; 95% CI, 2.2–12.0). Compared to the risk of infection for children younger than 5 years, the risk of infection decreased for children 5 years or older in regions with high rates of P. vivax and P. falciparum infections. P. vivax and P. falciparum have expanded within the asymptomatic population in Botswana; therefore, careful attention is required for their elimination.

Author Notes

Address correspondence to Isaac K. Quaye, Department of Engineering, Computing and Applied Health Sciences, Regent University College of Science and Technology, Box DS 1636, Dansoman, Accra, Ghana. E-mail: isaac.quaye@regent.edu.gh

Financial support: This work was supported by the Global Health Institute, Merck KGaA, Darmstadt, Germany.

Authors’ addresses: Thato Motshoge and Laurent Rénia, University of Botswana, Gaborone, Botswana, E-mails: motshogethato@yahoo.com and renia_laurent@immunol.a-star.edu.sg. Daniel Hosea Haiyambo, University of Namibia, School of Medicine, Windhoek, Namibia, E-mail: dhaiyambo@unam.na. Ruth Ayanful-Torgby, Biomedical and Public Health Research Unit, Council for Scientific and Industrial Research–Water Research Institute, Council Close, Accra, Ghana, E-mail: ruthmine2@gmail.com. Larysa Aleksenko, University of Lund, Lund, Sweden, E-mail: larysa.aleksenko@med.lu.se. Davies Ntebela, National Malaria Program, Ministry of Health and Wellness, Gaborone, Botswana, E-mail: dntebela834@gmail.com. Benoit Malleret, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, E-mail: benoit_malleret@nus.edu.sg. Elias Peloewetse, University of Botswana, Gaborone, Botswana, E-mail: pelowee@mopipi.ub.bw. Giacomo Maria Paganotti, Botswana–University of Pennsylvania Partnership, Gaborone, Botswana, Division of Infectious Diseases, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, and Department of Biomedical Sciences, Faculty of Medicine, University of Botswana, Gaborone, Botswana, E-mail: paganottig@bup.org.bw. Isaac K. Quaye, Regent University College of Science and Technology, Dansoman, Accra, Ghana, E-mail: isaac.quaye@regent.edu.gh.

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