Visceral Leishmaniasis in Traveler to Guyana Caused by Leishmania siamensis, London, UK.

To the Editor: Polley et al. reported a case of Leishmania siamensis infection outside Thailand (). In Thailand, 2 Leishmania species, L. siamensis (MON-324, World Health Organization code MHOM/TH/2010/TR) and L. martiniquensis (MON-229, World Health Organization codes MHOM/TH/2011/PG and MHOM/MQ/92/MAR1), are sporadically reported in immunocompetent and immunocompromised patients and cause cutaneous and visceral leishmaniasis (). Cases of asymptomatic visceral leishmaniasis caused by both species were also detected in HIV-infected patients in Thailand ().

Before 2017, L. siamensis was described as having 2 lineages: PG and TR. Additional information from zymodeme and genetic analysis indicated that these 2 lineages are different species (i.e., lineage PG is L. martiniquensis and lineage TR is L. siamensis) (). A review of leishmaniasis cases in Thailand during 1999–2016 () summarized the biological characteristics of L. martiniquensis and L. siamensis and clarified Leishmania species reported in humans (Thailand and Myanmar), animals (Thailand, Germany, Switzerland, and the United States), and sand flies (Thailand).

Polley et al. () reported phylogenetic analysis of internal transcribed spacer 1 sequences of 8 isolates of L. siamensis (GenBank accession nos. EF200012, JX195637, GQ281279, GQ226034, JQ866907, JQ617283, JQ001751, and GQ293226) against reference sequences of other Leishmania species. Their results confirmed that these sequences clustered with L. siamensis sequences as a monophyletic group, supported by bootstrap values of 100%.

However, 7 of these sequences (GenBank accession nos. EF200012, JX195637, GQ281279, GQ226034, JQ866907, JQ001751, and JQ617283) are L. martiniquensis sequences (MON-229), as reported in our article (). Thus, we have revised and updated our sequences submitted to GenBank regarding the species of L. martiniquensis (MON-229) and L. siamensis (MON-324) for future analysis.

The patient had a history of traveling to Caribbean Grenada, which is in the same geographic area where L. martiniquensis was first reported (). Thus, we believe that the correct diagnosis for the 65-year-old woman in the study by Polley et al. () was visceral leishmaniasis caused by infection with L. martiniquensis.