Confirmation of the absence of local transmission and geographic assignment of imported falciparum malaria cases to China using microsatellite panel

Abstract

Background Current methods to classify local and imported malaria infections depends primarily on patients travel history, which can have limited accuracy. Genotyping has been investigated as a complementary approach to track the spread of malaria and identify the origin of imported infections.Methods An extended panel of 26 microsatellites (16 new microsatellites) for Plasmodium falciparum was evaluated in 602 imported infections from 26 sub-Saharan African countries to the Jiangsu province of People's Republic of China. The potential of the 26 microsatellite markers to assign imported parasites to their geographic origin was assessed using a Bayesian method with MCMC (Markov Chain Monte Carlo) as implemented in the program Smoothed and Continuous Assignments (SCAT) with a modification to incorporate haploid genotype data.Results The newly designed microsatellites were polymorphic and are not in linkage disequilibrium with the existing microsatellites, supporting previous findings of high rate of recombination in sub-Saharan Africa. Consistent with epidemiology inferred from patients travel history, we found no evidence for local transmission; nearly all genetically related infections were identified in people who traveled to the same country near the same time. The smoothing assignment method assigned imported cases to their likely geographic origin with an accuracy (Angola: 59%; Nigeria: 51%; Equatorial Guinea: 40%) higher than would be achieved at random, reaching statistical significance for Angola and Equatorial Guinea.Conclusions Routine genotyping is valuable for malaria case classification and program evaluation in an elimination setting. Method for assigning geographic origin of mammals based on genetic data were adapted for malaria and showed potential for identification of the origin of imported infections.

Plasmodium falciparum genetic diversity in malaria endemic areas of Pakistan using merozoite surface protein 2 (msp-2)

“…and Honduras [26]. In zones with decreasing local transmission, it is expected that lower level of parasite diversity (heterogeneity) will be existing [27]. Decreasing level of transmission and diversity has been linked with enhanced interventions of controlling malaria control disease [28].…”

Within-Household Clustering of Genetically Related Plasmodium Falciparum Infections In A Moderate Transmission Area of Uganda

“…(16) Samples with parasite density > 5 parasites/ µL of blood were then genotyped using 26 microsatellite loci. (17) Two rounds of PCR were conducted for all loci, and PCR products were diluted and sized by capillary electrophoresis using an Applied Biosystems 3730xl DNA Analyzer. Alleles were sized from electropherograms using microSPAT software, which includes a probabilistic algorithm to lter artifacts.…”

Parasite Genetic Diversity Reflects Continued Residual Malaria Transmission in Vhembe District, A Hotspot in the Limpopo Province of South Africa

“…A total of samples were genotyped using a previously described 26 microsatellite marker panel protocol (26,27,32). Brie y, the 26 microsatellite loci were ampli ed using a semi-nested PCR protocol.…”