Identification of the asymptomatic Plasmodium falciparum and Plasmodium vivax gametocyte reservoir under different transmission intensities.
Adolescent
Asymptomatic Diseases
Brazil
/ epidemiology
Child
Child, Preschool
Cross-Sectional Studies
Female
Humans
Infant
Malaria, Falciparum
/ epidemiology
Malaria, Vivax
/ epidemiology
Male
Papua New Guinea
/ epidemiology
Plasmodium falciparum
/ genetics
Plasmodium vivax
/ genetics
Thailand
/ epidemiology
Young Adult
Journal
PLoS neglected tropical diseases
ISSN: 1935-2735
Titre abrégé: PLoS Negl Trop Dis
Pays: United States
ID NLM: 101291488
Informations de publication
Date de publication:
08 2021
08 2021
Historique:
received:
02
11
2020
accepted:
21
07
2021
revised:
09
09
2021
pubmed:
28
8
2021
medline:
26
11
2021
entrez:
27
8
2021
Statut:
epublish
Résumé
Understanding epidemiological variables affecting gametocyte carriage and density is essential to design interventions that most effectively reduce malaria human-to-mosquito transmission. 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). 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.
Sections du résumé
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.
Identifiants
pubmed: 34449764
doi: 10.1371/journal.pntd.0009672
pii: PNTD-D-20-01927
pmc: PMC8428688
doi:
Types de publication
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
e0009672Subventions
Organisme : NIAID NIH HHS
ID : U19 AI089686
Pays : United States
Organisme : NIAID NIH HHS
ID : U19 AI129392
Pays : United States
Déclaration de conflit d'intérêts
The authors have declared that no competing interests exist.
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