Characterization of Leishmania (Leishmania) waltoni n.sp. (Kinetoplastida: Trypanosomatidae), the Parasite Responsible for Diffuse Cutaneous Leishmaniasis in the Dominican Republic

Abstract

Abstract. Leishmania parasites isolated, between 1979 and 1988 by the late Bryce Walton, from Dominican Republic (DR) patients with diffuse cutaneous leishmaniasis, were characterized using a panel of 12 isoenzymes, 23 monoclonal antibodies, small subunit ribosomal DNA (SSu rDNA), and multilocus sequence analysis (MLSA). The isoenzyme and monoclonal antibody profiles and the MLSA results showed that the Dominican Republic parasites were distinct from other described Leishmania species. This new species belongs to the mexicana complex, which is distributed in central and parts of northern South America. It is suggested that the parasites uniqueness from other members of the mexicana complex is related to it being isolated on an island for millions of years. If Leishmania (Leishmania) waltoni fails to adapt to some imported mammal, such as the house rat, it will be the only Leishmania to be classified as an endangered species. The excessive destruction of habitats on Hispaniola threatens the survival of its vectors and presumed natural reservoirs, such as the rodent hutias and the small insectivorous mammal solenodon. The concept of Leishmania species is discussed in the light of recent evaluations on criteria for defining bacterial species.

Comparison of Leishmania typing results obtained from 16 European clinical laboratories in 2014

“…Such occasional dubious results are unavoidable when dealing with closely related species, in particular L. guyanensis-L. panamensis ; L. braziliensis-L. peruviana ; L. mexicana-L. amazonensis ; and L. donovani-L. infantum [ 9 ]. Also newly documented parasite species such as L. martiniquensis [ 32 ] and L. waltoni [ 33 ], and variants as the L. braziliensis outlier [ 9 , 12 , 15 , 18 ] further complicate the interpretation of typing results. It is therefore of utmost importance that species identification is performed with a well-documented standard operating procedure (SOP), clearly describing not only experimental procedures, but also in detail how results should be analysed, interpreted, and reported.…”

The history of leishmaniasis

“…In accordance with the first hypothesis it was postulated that the New World species L. mexicana , which belongs to the subgenus Leishmania and shares many characteristics with L. major [ 18 ], dispersed into the Nearctic together with its rodent hosts during the Eocene. After entering South America, climatic and ecological factors probably caused further speciation giving rise to L. venezuelensis , L. amazonensis and L. waltoni [ 5 , 23 ]. Leishmania chagasi , another New World species that belongs to the subgenus Leishmania , is meanwhile considered to be synonymous with L. infantum which was brought to South America in historical times (about 500 years ago by European settlers or their dogs) [ 26 , 27 ].…”

“…He based his decision on apparent morphological differences [ 41 ] and named the new species by a lapsus calami Leishmania brazilienses [ 63 ], which was corrected to Leishmania braziliensis by Vianna’s colleague Alfredo Augusto da Matta (1870–1954) in 1916 [ 64 ]. Although L. peruvianna was already described in 1913, all other New World Leishmania species causing LCL and MCL were characterised much later: L. mexicana in 1953, L. guyanensis in 1954, L. amazonensis and L. panamensis in 1972, L. venezuelensis in 1980, L. lainsoni in 1987, L. naffi and L. shawi in 1989, L. lindenbergi in 2002 and L. waltoni in 2015 [ 5 , 41 ]. Another species that previously was associated with leishmaniasis in humans and animals in Colombia and Panama, L. colombiensis [ 65 ], has been recently reclassified as Endotrypanum colombiensis [ 6 ].…”

An annotated checklist of the eukaryotic parasites of humans, exclusive of fungi and algae

“…Mammalian hosts unknown, rats may serve as reservoir hosts; presumed zoonotic in humans. Arthropod vectors are sand flies in the genus Lutzomyia (Shaw et al 2015).…”