Associations between season and gametocyte dynamics in chronic Plasmodium falciparum infections

Gadalla, A. A.H., Schneider, P., Churcher, T. S., Nassir, E., Abdel-Muhsin, A.-M. A., Ranford-Cartwright, L. C., Reece, S. E. and Babiker, H. A. (2016) Associations between season and gametocyte dynamics in chronic Plasmodium falciparum infections. PLoS ONE, 11(11), e0166699. (doi:10.1371/journal.pone.0166699) (PMID:27870874)

[img]
Preview
Text
132255.pdf - Published Version
Available under License Creative Commons Attribution.

1MB

Abstract

Introduction: In a markedly seasonal malaria setting, the transition from the transmission-free dry season to the transmission season depends on the resurgence of the mosquito population following the start of annual rains. The sudden onset of malaria outbreaks at the start of the transmission season suggests that parasites persist during the dry season and respond to either the reappearance of vectors, or correlated events, by increasing the production of transmission stages. Here, we investigate whether Plasmodium falciparum gametocyte density and the correlation between gametocyte density and parasite density show seasonal variation in chronic (largely asymptomatic) carriers in eastern Sudan. Materials and Methods: We recruited and treated 123 malaria patients in the transmission season 2001. We then followed them monthly during four distinct consecutive epidemiological seasons: transmission season 1, transmission-free season, pre-clinical period, and transmission season 2. In samples collected from 25 participants who fulfilled the selection criteria of the current analysis, we used quantitative PCR (qPCR) and RT-qPCR to quantify parasite and gametocyte densities, respectively. Results and Discussion: We observed a significant increase in gametocyte density and a significantly steeper positive correlation between gametocyte density and total parasite density during the pre-clinical period compared to the preceding transmission-free season. However, there was no corresponding increase in the density or prevalence of total parasites or gametocyte prevalence. The increase in gametocyte production during the pre-clinical period supports the hypothesis that P. falciparum may respond to environmental cues, such as mosquito biting, to modulate its transmission strategy. Thus, seasonal changes may be important to ignite transmission in unstable-malaria settings.

Item Type:Articles
Additional Information:This work was supported by National Environment Research Council (NE/I015329/1) to SER, by Sultan Qaboos University PhD studentship (2010) to AAHG and HB and by The Research Council, Muscat, Oman (RC/MED/BIO/03) to HB.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ranford-Cartwright, Dr Lisa
Authors: Gadalla, A. A.H., Schneider, P., Churcher, T. S., Nassir, E., Abdel-Muhsin, A.-M. A., Ranford-Cartwright, L. C., Reece, S. E., and Babiker, H. A.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:PLoS ONE
Publisher:Public Library of Science
ISSN:1932-6203
ISSN (Online):1932-6203
Copyright Holders:Copyright © 2016 The AuthorsGadalla et al.
First Published:First published in PLoS One 11(11):e0166699
Publisher Policy:Reproduced under a Creative Commons License

University Staff: Request a correction | Enlighten Editors: Update this record