Author:
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Koepfli, Cristian; Rodrigues, Priscilla T.; Antao, Tiago; Orjuela-Sanchez, Pamela; Van den Eede, Peter; Gamboa, Dionicia; Hong, Nguyen van; Bendezu, Jorge; Erhart, Annette; Barnadas, Céline; Ratsimbason, Arsène; Menard, Didier; Severini, Carlo; Menegon, Michela; Nour, Bakri Y. M.; Karunaweera, Nadira; Mueller, Ivo; Ferreira, Marcello U.; Felger, Ingrid
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Abstract:
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Plasmodium vivax is the geographically most widespread human
malaria parasite. To analyze patterns of microsatellite
diversity and population structure across countries of different
transmission intensity, genotyping data from 11 microsatellite
markers was either generated or compiled from 841 isolates from
four continents collected in 1999-2008. Diversity was highest in
South-East Asia (mean allelic richness 10.0-12.8), intermediate
in the South Pacific (8.1-9.9) Madagascar and Sudan (7.9-8.4),
and lowest in South America and Central Asia (5.5-7.2). A
reduced panel of only 3 markers was sufficient to identify
approx. 90% of all haplotypes in South Pacific, African and
SE-Asian populations, but only 60-80% in Latin American
populations, suggesting that typing of 2-6 markers, depending on
the level of endemicity, is sufficient for epidemiological
studies. Clustering analysis showed distinct clusters in Peru
and Brazil, but little sub-structuring was observed within
Africa, SE-Asia or the South Pacific. Isolates from Uzbekistan
were exceptional, as a near-clonal parasite population was
observed that was clearly separated from all other populations
(FST>0.2). Outside Central Asia FST values were highest
(0.11-0.16) between South American and all other populations,
and lowest (0.04-0.07) between populations from South-East Asia
and the South Pacific. These comparisons between P. vivax
populations from four continents indicated that not only
transmission intensity, but also geographical isolation affect
diversity and population structure. However, the high effective
population size results in slow changes of these parameters.
This persistency must be taken into account when assessing the
impact of control programs on the genetic structure of parasite
populations. |