Hyper-prevalence of submicroscopic Plasmodium falciparum infections in a rural area of western Kenya with declining malaria cases

Malaria Journal

Sidney O. Ogolla¹  James W. Kazura²  Edwin O. Magomere³  Antony C. A. Otieno⁴  Wolfgang R. Mukabana⁵  Kevin O. Ochwedo⁵  Benyl M. Ondeto⁵  Julius O. Olumeh⁵  Collince J. Omondi⁵  Yan Guiyan⁶  Pauline W. Orondo⁷  John Githure⁷  Harrysone E. Atieli⁷  Shirley A. Onyango⁷  Andrew K. Githeko⁸  Isaiah Debrah⁹ 

[1] Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya;Centre for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA;Department of Biochemistry and Molecular Biology, Egerton University, Njoro, Kenya;Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya;Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya;Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya;Program in Public Health, College of Health Sciences, University of California, Irvine, USA;Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya;Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya;Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya;West Africa Centre for Cell Biology of Infectious Pathogen, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana;

关键词: Submicroscopic;    Plasmodium;    Polymerase chain reaction;    Blood smear;    Western Kenya;    Diagnostic tests;   

DOI  :  10.1186/s12936-021-04012-6

来源: Springer

【 摘 要 】

BackgroundThe gold standard for diagnosing Plasmodium falciparum infection is microscopic examination of Giemsa-stained peripheral blood smears. The effectiveness of this procedure for infection surveillance and malaria control may be limited by a relatively high parasitaemia detection threshold. Persons with microscopically undetectable infections may go untreated, contributing to ongoing transmission to mosquito vectors. The purpose of this study was to determine the magnitude and determinants of undiagnosed submicroscopic P. falciparum infections in a rural area of western Kenya.MethodsA health facility-based survey was conducted, and 367 patients seeking treatment for symptoms consistent with uncomplicated malaria in Homa Bay County were enrolled. The frequency of submicroscopic P. falciparum infection was measured by comparing the prevalence of infection based on light microscopic inspection of thick blood smears versus real-time polymerase chain reaction (RT-PCR) targeting P. falciparum 18S rRNA gene. Long-lasting insecticidal net (LLIN) use, participation in nocturnal outdoor activities, and gender were considered as potential determinants of submicroscopic infections.ResultsMicroscopic inspection of blood smears was positive for asexual P. falciparum parasites in 14.7% (54/367) of cases. All of these samples were confirmed by RT-PCR. 35.8% (112/313) of blood smear negative cases were positive by RT-PCR, i.e., submicroscopic infection, resulting in an overall prevalence by RT-PCR alone of 45.2% compared to 14.7% for blood smear alone. Females had a higher prevalence of submicroscopic infections (35.6% or 72 out of 202 individuals, 95% CI 28.9–42.3) compared to males (24.2%, 40 of 165 individuals, 95% CI 17.6–30.8). The risk of submicroscopic infections in LLIN users was about half that of non-LLIN users (OR = 0.59). There was no difference in the prevalence of submicroscopic infections of study participants who were active in nocturnal outdoor activities versus those who were not active (OR = 0.91). Patients who participated in nocturnal outdoor activities and use LLINs while indoors had a slightly higher risk of submicroscopic infection than those who did not use LLINs (OR = 1.48).ConclusionMicroscopic inspection of blood smears from persons with malaria symptoms for asexual stage P. falciparum should be supplemented by more sensitive diagnostic tests in order to reduce ongoing transmission of P. falciparum parasites to local mosquito vectors.

【 授权许可】

CC BY