Comparative Microsatellite Typing of New World Leishmania infantum Reveals Low Heterogeneity among Populations and Its Recent Old World Origin

Katrin Kuhls,Thierry Wirth,Mohammad Zahangir Alam,Elisa Cupolillo,Gabriele Schönian,Michael A Miles,Isabel L Mauricio,Gabriel Eduardo M Ferreira,M Dora Feliciangeli,Rolando Oddone,Shaden Kamhawi

doi:10.1371/journal.pntd.0001155

Abstract

Leishmania infantum (syn. L. chagasi) is the causative agent of visceral leishmaniasis (VL) in the New World (NW) with endemic regions extending from southern USA to northern Argentina. The two hypotheses about the origin of VL in the NW suggest (1) recent importation of L. infantum from the Old World (OW), or (2) an indigenous origin and a distinct taxonomic rank for the NW parasite. Multilocus microsatellite typing was applied in a survey of 98 L. infantum isolates from different NW foci. The microsatellite profiles obtained were compared to those of 308 L. infantum and 20 L. donovani strains from OW countries previously assigned to well-defined populations. Two main populations were identified for both NW and OW L. infantum. Most of the NW strains belonged to population 1, which corresponded to the OW MON-1 population. However, the NW population was much more homogeneous. A second, more heterogeneous, population comprised most Caribbean strains and corresponded to the OW non-MON-1 population. All Brazilian L. infantum strains belonged to population 1, although they represented 61% of the sample and originated from 9 states. Population analysis including the OW L. infantum populations indicated that the NW strains were more similar to MON-1 and non-MON-1 sub-populations of L. infantum from southwest Europe, than to any other OW sub-population. Moreover, similarity between NW and Southwest European L. infantum was higher than between OW L. infantum from distinct parts of the Mediterranean region, Middle East and Central Asia. No correlation was found between NW L. infantum genotypes and clinical picture or host background. This study represents the first continent-wide analysis of NW L. infantum population structure. It confirmed that the agent of VL in the NW is L. infantum and that the parasite has been recently imported multiple times to the NW from southwest Europe.

Highlights

In 1937 the causative agent of visceral leishmaniasis (VL) in the New World was designated as a distinct species, Leishmania (L.) chagasi Cunha & Chagas [1]
It is caused by parasites belonging to the Leishmania donovani complex, which includes L. infantum and L. donovani in the Old World (OW) and L. infantum
Different scientific approaches led to different conclusions, either favouring the hypothesis of indigenous origin of this parasite and its status as distinct species, or a recent importation of L. infantum by European colonists and synonymy of L. infantum and L. chagasi

Summary

Introduction

In 1937 the causative agent of visceral leishmaniasis (VL) in the New World ( referred to as American visceral leishmaniasis – AVL) was designated as a distinct species, Leishmania (L.) chagasi Cunha & Chagas [1]. Visceral leishmaniasis in the New World extends from the southern parts of the USA [5,6] and Mexico to the North of Argentina, including countries such as Brazil, Paraguay, Bolivia, Venezuela, Suriname, Guyana, Colombia, Honduras, Panama, Costa Rica, El Salvador, Guadeloupe, Guatemala, and Nicaragua [7,8,9,10,11]. The principal foci are located in drier, poorly forested areas, there are several foci in the densely forested Amazon region and the Guianan Ecoregion Complex (GEC), which covers some States of Venezuela and all of Guyana, Suriname and French Guiana and the upper parts of the Brazilian states Amazonas, Roraima, Para, and Amapa. There are few cases reported from Suriname and no cases from French Guiana except a recently imported canine case [14,15,16,17]

Methods

Results

Discussion

Conclusion