Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Jul 6;17(7):e0270968.
doi: 10.1371/journal.pone.0270968. eCollection 2022.

Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocols

Frank Baiden  1 , Suzanne Fleck  1 , Bailah Leigh  2 , Philip Ayieko  1   3 , Daniel Tindanbil  1 , Tuda Otieno  1 , Bolarinde Lawal  1 , Mattu Tehtor  2 , Maariam Rogers  2 , Lazarus Odeny  4 , Mary H Hodges  5 , Mustapha Sonnie  5 , Mohamed Samai  2 , David Ishola  1 , Brett Lowe  1 , Deborah Watson-Jones  1   3 , Brian Greenwood  1
Affiliations

Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocols

Frank Baiden et al. PLoS One. .

Abstract

Introduction: Recurrent parasitic infections may influence the immune response to vaccines. In the Partnership for Research on Ebola VACcinations extended follow-UP and clinical research capacity build-UP (PREVAC-UP) study being undertaken in Mambolo, northern Sierra Leone, participants are being followed up to assess the potential impact of exposure to malaria and/or helminth infections on long-term immune response to two Ebola vaccines. To support the development of the assays that will be used in this evaluation, a parasitological survey was conducted in Mambolo between November 2019 and February 2020.

Methods: Healthy individuals aged ≥1 year who were resident in Mambolo Chiefdom were selected using a stratified sampling approach and questionnaires were administered to explore their sociodemographic characteristics. Microscopy was used to detect malaria parasites, intestinal helminths and urinary schistosome infections. Rapid blood tests were used to detect infections with Onchocerca volvulus and Wuchereria bancrofti. We estimated the overall prevalence of these infections and used adjusted logistic regression models to explore risk factors for malaria and hookworm infection.

Results: Eight hundred and fifteen (815) residents, 50.9% of whom were female were surveyed. Overall, 309 (39.1%) of 791 persons tested for malaria had a positive blood slide; Plasmodium falciparum was the dominant species. Helminth infection was detected in 122 (15.0%) of 815 stool samples including three mixed infections. The helminth infections comprised 102 (12.5%) cases of hookworm, 11 (1.3%) cases of Trichuris trichiura, 10 (1.2%) cases of Schistosoma mansoni and two (0.2%) cases of Ascaris lumbricoides. Being male (OR = 2.01, 95% CI 1.15-3.50) and residing in a non-riverine community (OR = 4.02, 95%CI 2.32-6.98) were the factors associated with hookworm infection. Onchocerca volvulus and Wuchereria bancrofti infections were found in 3.3% and 0.4% of participants respectively.

Conclusion: Malaria and hookworm are the most prevalent parasite infections and those most likely to influence long-term immune response to Ebola vaccines among the trial participants.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

References

    1. Statistics Sierra Leone. Demographic and Health Survey 2019. Freetown, Sierra Leone: Statistics Sierra Leone; 2020.
    1. World Health Organisation. Situation Report Ebola Virus Disease. Geneva, Switzerland: World Health Organisation; 2016.
    1. Badio M, Lhomme E, Kieh M, Beavogui AH, Kennedy SB, Doumbia S, et al.. Partnership for Research on Ebola VACcination (PREVAC): protocol of a randomized, double-blind, placebo-controlled phase 2 clinical trial evaluating three vaccine strategies against Ebola in healthy volunteers in four West African countries. Trials. 2021;22(1):86. doi: 10.1186/s13063-021-05035-9 - DOI - PMC - PubMed
    1. Levy Y, Lane C, Piot P, Beavogui AH, Kieh M, Leigh B, et al.. Prevention of Ebola virus disease through vaccination: where we are in 2018. Lancet. 2018;392(10149):787–90. doi: 10.1016/S0140-6736(18)31710-0 - DOI - PMC - PubMed
    1. Samai M, Seward JF, Goldstein ST, Mahon BE, Lisk DR, Widdowson MA, et al.. The Sierra Leone Trial to Introduce a Vaccine Against Ebola: An Evaluation of rVSVG-ZEBOV-GP Vaccine Tolerability and Safety During the West Africa Ebola Outbreak. J Infect Dis. 2018;217(suppl_1):S6–S15. doi: 10.1093/infdis/jiy020 - DOI - PMC - PubMed

Publication types