Leishmania (Leishmania) martiniquensis n. sp. (Kinetoplastida: Trypanosomatidae), description of the parasite responsible for cutaneous leishmaniasis in Martinique Island (French West Indies)

The parasite responsible for autochthonous cutaneous leishmaniasis in Martinique island (French West Indies) was first isolated in 1995; its taxonomical position was established only in 2002, but it remained unnamed. In the present paper, the authors name this parasite Leishmania (Leishmania) martiniquensis Desbois, Pratlong & Dedet n. sp. and describe the type strain of this taxon, including its biological characteristics, biochemical and molecular identification, and pathogenicity. This parasite, clearly distinct from all other Euleishmania, and placed at the base of the Leishmania phylogenetic tree, is included in the subgenus Leishmania.


Introduction
Leishmaniasis is a vector-borne parasitic disease caused by Protozoa of the genus Leishmania, of worldwide distribution. In the New World, it is endemic from Mexico in the North to Argentina in the South [13]. Sporadic cases have been reported in the Caribbean area, particularly in Trinidad [12] and the Dominican Republic [1]. In Martinique Island, occasional autochthonous cases of cutaneous leishmaniasis (CL)-like infections were reported in 1917 [11] and 1951 [7]. More recently, two new cases were reported with isolation of the parasites, and identified by isoenzyme electrophoresis as monoxenous trypanosomatids [2,5]. The taxonomical level of the parasites responsible for these two cases (MAR1 and MAR2) was determined by isoenzyme analysis and sequencing of the 18S ribosomal RNA gene, as well as partial sequencing of Nicole Desbois -urn:lsid:zoobank.org:author:BAC8E947-7E42-49ED-B8F0-067DB98A9FFB Francine Pratlong -urn:lsid:zoobank.org:author:64A32660-5357-4057-9B39-6D72FA859DEA Danièle Quist -urn:lsid:zoobank.org:author:73354A1E-BB12-4387-8D5B-88C1C4B498D0 Jean-Pierre Dedet -urn:lsid:zoobank.org:author:7ED189EF-9AFD-4A78-A59E-DF4AB24616E5 *Corresponding author: parasito@univ-montp1.fr Therefore, an endemic focus of CL is present in Martinique, due to a well-established Leishmania parasite, with a divergent taxonomic position, apart from any other existing taxa. Since the name Leishmania americana given by Stevenel in his 1917 paper [11] was lacking a description or a definition, we consider it as a nomen nudum, and therefore propose to name this new Leishmania taxon and describe its main features. Experimental pathogenicity in the murine model: strain infective to BALB/c mice and capable of visceralisation and dissemination in the popliteal and mesenteric lymph nodes, liver, spleen and even brain [8].

Discussion
An endemic focus of cutaneous leishmaniasis has been known in Martinique Island since 1917, but the parasite responsible was clearly identified as a Leishmania by molecular and isoenzymatic techniques only in 2002 [10]; the taxonomic position of this parasite has already been described: it was clearly distinct from all other Euleishmania, placed at the base of the phylogenetic tree, in the subgenus Leishmania. We therefore propose to name this parasite Leishmania (Leishmania) martiniquensis, Desbois, Pratlong & Dedet n. sp.
Since the isolation of the type strain in 1992, the four other strains isolated caused cutaneous lesions, the clinical description of which can be summarised as follows: single lesion of the face, of papulo-nodular type, with or without ulceration, sometimes mimicking a basocellular carcinoma. The lesions were localised to the periorbital area, one to the forehead and the last on the ear lobe. Their evolution was spontaneously favourable over several months.
Apart from the princeps case of 1992, which caused a diffuse CL in an immunocompromised patient, the four other cases corresponded to localised CL in immunocompetent patients. The clinical polymorphism of the localised lesions in immunocompetent patients, and the diffuse lesions in the immunocompromised one are not specific to this new species, but similar to clinical features of CL due to other Leishmania species [4].
From an epidemiological point of view, the L. martiniquensis focus appears to be endemic in Martinique Island, with occurrence of rare human cases. The existence of an animal reservoir is highly likely, the candidate reservoirs being one of the wild rodents or marsupials present in Martinique, such as black rats (found infected in Costa Rica by Zeledon in 1992 [14]) or opossums (reservoir hosts in French Guiana [3]). Recent entomological surveys carried out in Martinique Island confirmed the presence of Lutzomyia atroclavata, isolated for the first time in 1966 in Martinique [6] and reported the presence of a second phlebotomine sandfly species: Lutzomyia cayennensis (Desbois N., unpublished).

Conclusion
At the time of writing, the parasite presently described has never been found outside of Martinique Island. The geographical isolation of this parasite in Martinique might explain its maintenance as an ancestral Leishmania. It remains to determine its vector(s) and reservoir host(s), and to explain why this parasite has not extended to neighbouring countries in the Caribbean area.