ReviewAndean cutaneous leishmaniasis (Andean-CL, uta) in Peru and Ecuador: the causative Leishmania parasites and clinico-epidemiological features
Graphical abstract
Showing 1) landscape of the Andean-CL (uta) endemic areas La Cuesta/Nambuque, Peru; 2) schematic geographical and altitudinal distribution of the Andean-CL; 3) Vertical distribution of L. (V.) peruviana and other Leishmania spp., in Peru; 4) Vertical distribution of L. (L.) mexicana and L. (L.) major-like and other Leishmania spp. in Ecuador; and 5) different clinical forms, severe in Peruvian adults (above) while very mild in Ecuadorian infants (below).
Introduction
Leishmaniasis is one of the parasitic protozoan diseases transmitted by a blood-sucking sand flies belonging to the subfamily Phlebotominae, Phlebotomus spp. transmitting the parasites of the subgenus Leishmania (Leishmania) in the Old World, and Lutzomyia spp. transmitting those of the subgenera L. (Leishmania) and L. (Viannia) in the New World, affecting about 360 million people at risk worldwide (Desjeux, 2001, World Health Organization (WHO), 2010, Alvar et al., 2012). The disease is principally divided into three clinical forms, cutaneous (CL), mucocutaneous (MCL), and visceral (VL) known as kala-azar which is fatal if left untreated. It distributes in tropical and subtropical geographic zones of the world, including highland areas in the Old and New Worlds. In the New World, leishmaniases are prevalent in a wide range of distribution from the southern US to the northern Uruguay; autochthonous VL cases were most recently reported from Uruguay, together with the probable/PCR-proved vector Lutzomyia longipalpis (Satragno et al., 2017).
In the Andean countries, the disease is prevalent from Venezuela to the north of Argentina, through Colombia, Ecuador, Peru, and Bolivia. In Peru, CLs are classically divided into two forms, “uta” and “espundia”, mainly based on the clinico-epidemiological features and the geographical distributions. Clinically, the former (uta) was considered for a long time to be very similar to “Oriental sore” caused by L. (L.) tropica in the Old World and the latter (espundia), American sylvatic tegumentary leishmaniasis such as severe CL, MCL (Weiss, 1943, Herrer, 1951a, Herrer, 1951b). Until the 1970s-1980s, the causative Leishmania species was considered to be L. tropica, or a subspecies of L. mexicana or of L. braziliensis, mainly based on the clinical features and geographical distributions (Lainson et al., 1979, Lainson, 1983, Lainson, 1996, Kreutzer et al., 1983), though it has nowadays been widely recognized as L. (V.) peruviana circulating in the Peruvian Andes (McMahon-Pratt and David, 1981, McMahon-Pratt et al., 1982, Arana et al., 1990, Lucas et al., 1998, Zhang et al., 2006, Arevalo et al., 2007). The disease name ‘uta’ has been used synonymously for the vector and the disease in certain endemic areas of the Peruvian Andes, and the disease was believed to have been present in Peru for a long time, probably long before the discovery of the Americas (Weiss, 1943, Herrer and Christensen, 1975). In Ecuador, on the other hand, autochthonous Andean-CL cases (local disease name: nigua de ratón), very similar to “classical” Peruvian uta were reported for the first time in 1987 from a small town Paute, Azuay Province, located in the country’s mid-southwestern region (Hashiguchi et al., 1987a, Hashiguchi et al., 1987b, Hashiguchi et al., 1991).
From available information and our recent studies, it was assumed that the current status of the Andean-CL (uta) seemed to be changing gradually, especially in the clinico-epidemiological features; the Peruvian form is more severe than the Ecuadorian, affecting higher age groups, and the disease is more rural than before in Ecuador. It is therefore the time to review the past and current status of the disease in both countries, focusing on the causative Leishmania parasites and the patho- and/or clinico-epidemiology. Thus, this article provides useful information for future management of the disease, not only for Andean Leishmania-endemic areas but also for other endemic areas.
Section snippets
Study areas
The Andes, a range of mountains which traverses the South American continent from north to south, divides into diverse natural regions at different areas of the two countries, Peru and Ecuador. The Andes where Andean-CL (uta) exists is totally different in respect to topography, climate, fauna and flora from the lowlands in both (Pacific and Amazon) sides of the Peruvian and Ecuadorian Andes.
Peru is situated in the western regions of the South American continent, bordering neighboring
Geographical and altitudinal distribution of the Andean-CL (uta) in Peru and Ecuador
The geographical and altitudinal distribution of the Andean-CL (uta) in Peru and Ecuador was shown schematically in Fig. 2A. In this study, the altitudinal limitation of the Andean-CL (uta) was basically defined to the areas with 800–900 m a.s.l. or over (Herrer, 1951a, Herrer, 1957, Herrer, 1968). The disease (uta) in Peru exists at altitudes of mainly between 900 m and 3000 m above sea level (m a.s.l.) from 5° to 15° South Latitude in the northern-central and inter-Andean valleys located in the
Comments and conclusions
Since 1986 when CL cases different from the lowland forms in Ecuador was reported for the first time from the Andes regions, it has been considered that the disease would be mostly similar to the Peruvian uta. In this study, the latest available data and information are compiled thoroughly, aiming at comparisons of the disease between the two countries. The results revealed a marked difference of the Andean-CL (uta) in Peru and Ecuador, indicating the different causative Leishmania parasites
Funding
This study was financially supported by the Ministry of Japan (MEXT) (Grant nos. 25257501 and 23256002).
Conflict of interest
The authors have no conflicts of interest to declare.
Acknowledgements
We are indebted to Dr. Masataka Korenaga and Mrs. Kyoko Imamura, Department of Parasitology, Kochi Medical School, Kochi University, Japan, for their invaluable support during leishmaniasis research project, 1986–2015, in Ecuador, supported by the Ministry of Japan (MEXT). We are also indebted to Ecuadorian, Peruvian and Japanese colleagues for their contributions throughout the project, and to Miss Giovana De La Cruz Vásquez, the Executive Office of Scientific Information and Documentation,
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