Anthropophilic phlebotomine sand fly Lutzomyia species and search for the natural Leishmania infections in an area endemic for cutaneous leishmaniasis in Ecuador
Graphical abstract
Map of study area and a CL patient house. Sandfly collection was performed in and around the house from which an infantile case was reported.
Introduction
Leishmaniasis is one of the neglected vector-borne diseases caused by protozoans belonging to the genus Leishmania, and it is associated with poverty, affecting at least 12 million people in 98 countries and regions in the world; 350 million people at risk of contracting the disease, among them some 2 million new cases occur yearly. The three main clinical forms of the disease, cutaneous (CL), mucocutaneous (MCL) and visceral (VL) are transmitted by the bite of a tiny female sand fly infected with the parasites (Alvar et al., 2012).
In Ecuador, the disease is one of the major public health concerns, and prevalent in 22 of the country's 24 provinces, in Pacific coast subtropical, Amazonian tropical and Andean highland areas (Hashiguchi et al., 2017). In the country, the disease is mandatory notification since 2005. From 2001 to 2014, a total of 21,305 cases were notified to the Ministry of Public Health (Ministerio de Salud Publica: MSP-Epi2, 2001–2014 elaborado: Eduardo Aguilar, 2001–2010; Lenin Velez, 2011–2014); most of them were CL and very infrequently MCL (Hashiguchi and Gomez, 1991; Hashiguchi et al., 2017), but not VL cases. In the MSP-Epi2 data, for example, a total of 6608 cases were registered in the Ministry during 2010 and 2014, ranging yearly from 899 to 1629 (average 1321.6). Among them, relatively few cases were reported from Manabi province (1–101 cases, av. 46.4); only one case in 2013 and 16 in 2014, probably because of political or logistic reasons (MSP-Epi2).
In 2016–2017, an outbreak of CLs was reported from Manabi and Santo Domingo provinces in the country (Molares, 2017). Little information, however, is available on the epidemiology and transmission of the disease in the areas. In the current study, therefore, we conducted a preliminary study on anthropophilic phlebotomine sand flies and their natural Leishmania infections in an area from which L. (V.) guyanensis was reported as a CL-causative agent (Kato et al., 2019). The results revealed that a considerable number of anthropophilic sand fly species of the genus Lutzomyia was observed as possible vectors of the Leishmania parasite in the area, though no positive sand flies for the Leishmania were detected by both microscopic- and/or PCR-tests. These findings however provide basic information useful for the future control and management of the disease in the areas.
Section snippets
The study area
Manabí province is situated in the Pacific coastal region of northwestern Ecuador, between 0°0′N latitude, 80°03′ W longitudes and 01° 45′S latitude, 80°10′ W longitudes (Fig. 1). It is divided into two geographical regions, i.e., the Pacific coastal dry area (Fig. 1, solid color areas: elevation, less than 300 m above sea level; a.s.l.) and the cordilleran wet area (Fig. 1, dark gray color areas: elevation, 300–700 m a.s.l.). Meteorological and ecological features such as temperature, relative
Results and discussion
Because of the principal aim of the present study was to have information on the blood-sucking females of human-biting sand fly Lutzomyia spp., as probable vectors of the Leishmania parasite causing CL, here only the females were considered and mentioned throughout. Besides, almost all of the sand flies caught were females especially in case of human landing collections except a small number of males, while considerable numbers of males were also captured by light traps. These males, however,
Conclusion
In the current study area where L. (V.) guyanensis is circulating, eight human-biting species of sand flies were observed, none of them however tested positive for natural Leishmania infections by microscopic- and/or PCR-tests. Among the eight species observed, Lu. robusta and Lu. trapidoi were most dominant having highly anthropophilic behavior. These species were therefore assumed to be probable vectors of the Leishmania parasite prevailing in the area. Our findings provide basic information
Funding
This study was financially supported by the Ministry of Japan (MEXT) (Grant nos. 25257501 and 17H01685), and by the Sistema de Desarrollo e Investigacion, Universidad Catolica de Santiago de Guayaquil, Ecuador (Grant no. SINDE-SIU #415–214).
CRediT authorship contribution statement
Yoshihisa Hashiguchi: Conceptualization, Formal analysis, Funding acquisition, Investigation, Project administration, Resources, Writing - original draft, Writing - review & editing. Eduardo A. Gomez: Investigation, Resources. Lenin N. Velez: Investigation, Resources. Nancy V. Villegas: Investigation, Resources. Makoto Kubo: Investigation, Resources. Tatsuyuki Mimori: Investigation, Resources. Kazue Hashiguchi: Formal analysis, Investigation, Resources. Hirotomo Kato: Conceptualization, Funding
Declaration of Competing Interest
The authors have no conflict of interest to declare.
Acknowledgement
We are indebted to Zambrano F.C., Parraga, F.D., Martillo, V.P. (Ministerio de Salud Publica, Ecuador) for their technical support during the field phase of the present study.
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