Identification of the asymptomatic Plasmodium falciparum and Plasmodium vivax gametocyte reservoir under different transmission intensities

Cristian Koepfli, Wang Nguitragool, Anne Cristine Gomes de Almeida, Andrea Kuehn, Andreea Waltmann, Eline Kattenberg, Maria Ome-Kaius, Patricia Rarau, Thomas Obadia, James Kazura, Wuelton Monteiro, Andrew W Darcy, Lyndes Wini, Quique Bassat, Ingrid Felger, Jetsumon Sattabongkot, Leanne J Robinson, Marcus Lacerda, Ivo Mueller

Research output: Contribution to journalA1: Web of Science-article

Abstract

BACKGROUND: Understanding epidemiological variables affecting gametocyte carriage and density is essential to design interventions that most effectively reduce malaria human-to-mosquito transmission.

METHODOLOGY/PRINCIPAL FINDINGS: Plasmodium falciparum and P. vivax parasites and gametocytes were quantified by qPCR and RT-qPCR assays using the same methodologies in 5 cross-sectional surveys involving 16,493 individuals in Brazil, Thailand, Papua New Guinea, and Solomon Islands. The proportion of infections with detectable gametocytes per survey ranged from 44-94% for P. falciparum and from 23-72% for P. vivax. Blood-stage parasite density was the most important predictor of the probability to detect gametocytes. In moderate transmission settings (prevalence by qPCR>5%), parasite density decreased with age and the majority of gametocyte carriers were children. In low transmission settings (prevalence<5%), >65% of gametocyte carriers were adults. Per survey, 37-100% of all individuals positive for gametocytes by RT-qPCR were positive by light microscopy for asexual stages or gametocytes (overall: P. falciparum 178/348, P. vivax 235/398).

CONCLUSIONS/SIGNIFICANCE: Interventions to reduce human-to-mosquito malaria transmission in moderate-high endemicity settings will have the greatest impact when children are targeted. In contrast, all age groups need to be included in control activities in low endemicity settings to achieve elimination. Detection of infections by light microscopy is a valuable tool to identify asymptomatic blood stage infections that likely contribute most to ongoing transmission at the time of sampling.

Original languageEnglish
Article numbere0009672
JournalPLoS Neglected Tropical Diseases
Volume15
Issue number8
Number of pages18
ISSN1935-2727
DOIs
Publication statusPublished - 2021

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