scholarly journals Variation in relapse frequency and the transmission potential of Plasmodium vivax malaria

2016 ◽  
Vol 283 (1827) ◽  
pp. 20160048 ◽  
Author(s):  
Michael T. White ◽  
George Shirreff ◽  
Stephan Karl ◽  
Azra C. Ghani ◽  
Ivo Mueller
Keyword(s):  
Plasmodium Vivax ◽  
Reproduction Number ◽  
Phenotypic Diversity ◽  
Substantial Variation ◽  
Seasonal Transmission ◽  
Transmission Potential ◽  
Plasmodium Vivax Malaria ◽  
Tropical Areas ◽  
First Relapse ◽  
Selection Of

There is substantial variation in the relapse frequency of Plasmodium vivax malaria, with fast-relapsing strains in tropical areas, and slow-relapsing strains in temperate areas with seasonal transmission. We hypothesize that much of the phenotypic diversity in P. vivax relapses arises from selection of relapse frequency to optimize transmission potential in a given environment, in a process similar to the virulence trade-off hypothesis. We develop mathematical models of P. vivax transmission and calculate the basic reproduction number R 0 to investigate how transmission potential varies with relapse frequency and seasonality. In tropical zones with year-round transmission, transmission potential is optimized at intermediate relapse frequencies of two to three months: slower-relapsing strains increase the opportunity for onward transmission to mosquitoes, but also increase the risk of being outcompeted by faster-relapsing strains. Seasonality is an important driver of relapse frequency for temperate strains, with the time to first relapse predicted to be six to nine months, coinciding with the duration between seasonal transmission peaks. We predict that there is a threshold degree of seasonality, below which fast-relapsing tropical strains are selected for, and above which slow-relapsing temperate strains dominate, providing an explanation for the observed global distribution of relapse phenotypes.

scholarly journals Platelet disturbances correlate with endothelial cell activation in uncomplicated Plasmodium vivax malaria

2020 ◽  
Vol 14 (7) ◽  
pp. e0007656
Author(s):  
João Conrado Khouri Dos-Santos ◽  
João Luiz Silva-Filho ◽  
Carla C. Judice ◽  
Ana Carolina Andrade Vitor Kayano ◽  
Júlio Aliberti ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Plasmodium Vivax ◽  
Vivax Malaria ◽  
Cell Activation ◽  
Endothelial Cell Activation ◽  
Plasmodium Vivax Malaria

scholarly journals Short-Time Recurrences of Plasmodium vivax Malaria as a Public Health Proxy for Chloroquine-Resistance Surveillance: A Spatio-Temporal Study in the Brazilian Amazon

2021 ◽  
Vol 18 (10) ◽  
pp. 5061
Author(s):  
Antonio A. S. Balieiro ◽  
Andre M. Siqueira ◽  
Gisely C. Melo ◽  
Wuelton M. Monteiro ◽  
Vanderson S. Sampaio ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Multilevel Models ◽  
Malaria Incidence ◽  
Chloroquine Resistance ◽  
Spatial Clusters ◽  
Temporal Study ◽  
Plasmodium Vivax Malaria ◽  
Spatio Temporal ◽  
Spatially Varying ◽  
Short Time

In Brazil, malaria caused by Plasmodium vivax presents control challenges due to several reasons, among them the increasing possibility of failure of P. vivax treatment due to chloroquine-resistance (CQR). Despite limited reports of CQR, more extensive studies on the actual magnitude of resistance are still needed. Short-time recurrences of malaria cases were analyzed in different transmission scenarios over three years (2005, 2010, and 2015), selected according to malaria incidence. Multilevel models (binomial) were used to evaluate association of short-time recurrences with variables such as age. The zero-inflated Poisson scan model (scanZIP) was used to detect spatial clusters of recurrences up to 28 days. Recurrences compose less than 5% of overall infection, being more frequent in the age group under four years. Recurrences slightly increased incidence. No fixed clusters were detected throughout the period, although there are clustering sites, spatially varying over the years. This is the most extensive analysis of short-time recurrences worldwide which addresses the occurrence of P. vivax CQR. As an important step forward in malaria elimination, policymakers should focus their efforts on young children, with an eventual shift in the first line of malaria treatment to P. vivax.

scholarly journals PvMSP8 as a Novel Plasmodium vivax Malaria Sero-Marker for the Peruvian Amazon

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 282
Author(s):  
Elizabeth Villasis ◽  
Katherine Garro ◽  
Angel Rosas-Aguirre ◽  
Pamela Rodriguez ◽  
Jason Rosado ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Area Under The Curve ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Population Based ◽  
Peruvian Amazon ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Malaria Exposure ◽  
Plasmodium Vivax Malaria

The measurement of recent malaria exposure can support malaria control efforts. This study evaluated serological responses to an in-house Plasmodium vivax Merozoite Surface Protein 8 (PvMSP8) expressed in a Baculovirus system as sero-marker of recent exposure to P. vivax (Pv) in the Peruvian Amazon. In a first evaluation, IgGs against PvMSP8 and PvMSP10 proteins were measured by Luminex in a cohort of 422 Amazonian individuals with known history of Pv exposure (monthly data of infection status by qPCR and/or microscopy over five months). Both serological responses were able to discriminate between exposed and non-exposed individuals in a good manner, with slightly higher performance of anti-PvMSP10 IgGs (area under the curve AUC = 0.78 [95% CI = 0.72–0.83]) than anti-PvMSP8 IgGs (AUC = 0.72 [95% CI = 0.67–0.78]) (p = 0.01). In a second evaluation, the analysis by ELISA of 1251 plasma samples, collected during a population-based cross-sectional survey, confirmed the good performance of anti-PvMSP8 IgGs for discriminating between individuals with Pv infection at the time of survey and/or with antecedent of Pv in the past month (AUC = 0.79 [95% CI = 0.74–0.83]). Anti-PvMSP8 IgG antibodies can be considered as a good biomarker of recent Pv exposure in low-moderate transmission settings of the Peruvian Amazon.

scholarly journals Plasmodium vivax from Duffy-Negative and Duffy-Positive Individuals Shares Similar Gene Pool in East Africa

2021 ◽  
Author(s):  
Daniel Kepple ◽  
Alfred Hubbard ◽  
Musab M Ali ◽  
Beka R Abargero ◽  
Karen Lopez ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
East Africa ◽  
Sub Saharan Africa ◽  
Road Density ◽  
Genetic Characteristics ◽  
Plasmodium Vivax Malaria ◽  
Genetic Clusters ◽  
Sub Saharan ◽  
The Impact ◽  
Duffy Negative

Abstract Plasmodium vivax malaria was thought to be rare in Africa, but an increasing number of P. vivax cases reported across Africa and in Duffy-negative individuals challenges this conventional dogma. The genetic characteristics of P. vivax in Duffy-negative infections, the transmission of P. vivax in East Africa, and the impact of environments on transmission remain largely unknown. This study examined genetic and transmission features of P. vivax from 107 Duffy-negative and 305 Duffy-positive individuals in Ethiopia and Sudan. No clear genetic differentiation was found in P. vivax between the two Duffy groups, indicating between-host transmission. P. vivax from Ethiopia and Sudan showed similar genetic clusters, except samples from Khartoum, possibly due to distance and road density that inhibited parasite gene flow. This study is the first to show that P. vivax can transmit to and from Duffy-negative individuals and provides critical insights into the spread of P. vivax in sub-Saharan Africa.

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