The shape of the iceberg: quantification of submicroscopic Plasmodium falciparum and Plasmodium vivax parasitaemia and gametocytaemia in five low endemic settings in Ethiopia

Malaria Journal

Research

Abraham Aseffa¹  Endalamaw Gadissa¹  Lotus van den Hoogen²  Kevin Tetteh²  Chris Drakeley²  Jodie Schildkraut³  Kjerstin Lanke³  Robert Sauerwein³  Teun Bousema⁴  Fitsum G. Tadesse⁵  Hassen Mamo⁶  Ingrid Felger⁷ 

[1] Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia;Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK;Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands;Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands;Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK;Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands;Medical Biotechnology Unit, Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia;Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia;Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia;Swiss Tropical and Public Health Institute, Basel, Switzerland;University of Basel, Basel, Switzerland;

关键词: Asymptomatic;    Submicroscopic;    Transmission;    PCR;    Serology;    School;    El Ǹino;    Elimination;   

DOI  :  10.1186/s12936-017-1749-4

 received in 2017-01-05, accepted in 2017-02-24,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundThe widespread presence of low-density asymptomatic infections with concurrent gametocytes may be a stumbling block for malaria elimination. This study investigated the asymptomatic reservoir of Plasmodium falciparum and Plasmodium vivax infections in schoolchildren from five settings in northwest Ethiopia.MethodsTwo cross-sectional surveys were conducted in June and November 2015, enrolling 551 students from five schools and 294 students from three schools, respectively. Finger prick whole blood and plasma samples were collected. The prevalence and density of P. falciparum and P. vivax parasitaemia and gametocytaemia were determined by 18S rRNA quantitative PCR (qPCR) and pfs25 and pvs25 reverse transcriptase qPCR. Antibodies against blood stage antigens apical membrane antigen-1 (AMA-1) and merozoite surface protein-1 (MSP-119) were measured for both species.ResultsWhilst only 6 infections were detected by microscopy in 881 slides (0.7%), 107 of 845 blood samples (12.7%) were parasite positive by (DNA-based) qPCR. qPCR parasite prevalence between sites and surveys ranged from 3.8 to 19.0% for P. falciparum and 0.0 to 9.0% for P. vivax. The median density of P. falciparum infections (n = 85) was 24.4 parasites/µL (IQR 18.0–34.0) and the median density of P. vivax infections (n = 28) was 16.4 parasites/µL (IQR 8.8–55.1). Gametocyte densities by (mRNA-based) qRT-PCR were strongly associated with total parasite densities for both P. falciparum (correlation coefficient = 0.83, p = 0.010) and P. vivax (correlation coefficient = 0.58, p = 0.010). Antibody titers against P. falciparum AMA-1 and MSP-119 were higher in individuals who were P. falciparum parasite positive in both surveys (p < 0.001 for both comparisons).DiscussionThis study adds to the available evidence on the wide-scale presence of submicroscopic parasitaemia by quantifying submicroscopic parasite densities and concurrent gametocyte densities. There was considerable heterogeneity in the occurrence of P. falciparum and P. vivax infections and serological markers of parasite exposure between the examined low endemic settings in Ethiopia.

【 授权许可】

CC BY   
© The Author(s) 2017