qRT-PCR versus IFA-based Quantification of Male and Female Gametocytes in Low-Density Plasmodium falciparum Infections and Their Relevance for Transmission.
Biomarkers
/ chemistry
Cross-Sectional Studies
Female
Fluorescent Antibody Technique, Indirect
/ methods
Humans
Malaria, Falciparum
/ epidemiology
Male
Oocytes
/ chemistry
Papua New Guinea
/ epidemiology
Plasmodium falciparum
/ chemistry
Protozoan Proteins
/ genetics
RNA, Protozoan
/ blood
Reverse Transcriptase Polymerase Chain Reaction
/ methods
Sensitivity and Specificity
Spermatocytes
/ chemistry
Plasmodium falciparum
low density
male gametocytes
sex ratio
transmission reservoir
ultrasensitive diagnostics
Journal
The Journal of infectious diseases
ISSN: 1537-6613
Titre abrégé: J Infect Dis
Pays: United States
ID NLM: 0413675
Informations de publication
Date de publication:
03 02 2020
03 02 2020
Historique:
received:
09
04
2019
accepted:
14
08
2019
pubmed:
23
8
2019
medline:
22
9
2020
entrez:
23
8
2019
Statut:
ppublish
Résumé
Accurate quantification of female and male gametocytes and sex ratios in asymptomatic low-density malaria infections are important for assessing their transmission potential. Gametocytes often escape detection even by molecular methods, therefore ultralow gametocyte densities were quantified in large blood volumes. Female and male gametocytes were quantified in 161 PCR-positive Plasmodium falciparum infections from a cross-sectional survey in Papua New Guinea. Ten-fold concentrated RNA from 800 µL blood was analyzed using female-specific pfs25 and male-specific pfmget or mssp qRT-PCR. Gametocyte sex ratios from qRT-PCR were compared with those from immunofluorescence assays (IFA). Gametocytes were identified in 58% (93/161) P. falciparum-positive individuals. Mean gametocyte densities were frequently below 1 female and 1 male gametocyte/µL by qRT-PCR. The mean proportion of males was 0.39 (95% confidence interval, 0.33-0.44) by pfs25/pfmget qRT-PCR; this correlated well with IFA results (Pearsons r2 = 0.91; P < .001). A Poisson model fitted to our data predicted 16% P. falciparum-positive individuals that are likely to transmit, assuming at least 1 female and 1 male gametocyte per 2.5 µL mosquito bloodmeal. Based on model estimates of female and male gametocytes per 2.5 µL blood, P. falciparum-positive individuals detected exclusively by ultrasensitive diagnostics are negligible for human-to-mosquito transmission.Estimating the transmission potential of ultralow-density malaria infections informs interventions. Almost all infections with ≥1 female and male gametocyte per 2.5 µL mosquito bloodmeal, and thus with highest likelihood of contributing to human-to-mosquito transmission, were detectable by standard molecular diagnostics.
Sections du résumé
BACKGROUND
Accurate quantification of female and male gametocytes and sex ratios in asymptomatic low-density malaria infections are important for assessing their transmission potential. Gametocytes often escape detection even by molecular methods, therefore ultralow gametocyte densities were quantified in large blood volumes.
METHODS
Female and male gametocytes were quantified in 161 PCR-positive Plasmodium falciparum infections from a cross-sectional survey in Papua New Guinea. Ten-fold concentrated RNA from 800 µL blood was analyzed using female-specific pfs25 and male-specific pfmget or mssp qRT-PCR. Gametocyte sex ratios from qRT-PCR were compared with those from immunofluorescence assays (IFA).
RESULTS
Gametocytes were identified in 58% (93/161) P. falciparum-positive individuals. Mean gametocyte densities were frequently below 1 female and 1 male gametocyte/µL by qRT-PCR. The mean proportion of males was 0.39 (95% confidence interval, 0.33-0.44) by pfs25/pfmget qRT-PCR; this correlated well with IFA results (Pearsons r2 = 0.91; P < .001). A Poisson model fitted to our data predicted 16% P. falciparum-positive individuals that are likely to transmit, assuming at least 1 female and 1 male gametocyte per 2.5 µL mosquito bloodmeal.
CONCLUSIONS
Based on model estimates of female and male gametocytes per 2.5 µL blood, P. falciparum-positive individuals detected exclusively by ultrasensitive diagnostics are negligible for human-to-mosquito transmission.Estimating the transmission potential of ultralow-density malaria infections informs interventions. Almost all infections with ≥1 female and male gametocyte per 2.5 µL mosquito bloodmeal, and thus with highest likelihood of contributing to human-to-mosquito transmission, were detectable by standard molecular diagnostics.
Identifiants
pubmed: 31437280
pii: 5553499
doi: 10.1093/infdis/jiz420
pmc: PMC7325619
doi:
Substances chimiques
Biomarkers
0
Pfs25 protein, Plasmodium falciparum
0
Protozoan Proteins
0
RNA, Protozoan
0
Types de publication
Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
598-607Subventions
Organisme : NIAID NIH HHS
ID : U19 AI129392
Pays : United States
Informations de copyright
© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America.
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