Diversity patterns, Leishmania DNA detection, and bloodmeal identification of Phlebotominae sand flies in villages in northern Colombia

Abstract

Leishmaniases are neglected tropical diseases exhibiting complex transmission cycles due to the number of parasite species circulating, sand fly species acting as vectors and infected mammals, including humans, which are defined in the New World as accidental hosts. However, current transmission scenarios are changing, and the disease is no longer exclusively related to forested areas but urban transmission foci occur, involving some species of domestic animals as suspected reservoirs. The aim of this study was to determine the transmission cycles in urban environments by evaluating sand fly diversity, detection of Leishmania DNA, and bloodmeal sources through intra and peridomestic collections. The study was carried out in Colombia, in 13 municipalities of Cordoba department, implementing a methodology that could be further used for the evaluation of vector-borne diseases in villages or towns. Our sampling design included 24 houses randomly selected in each of 15 villages distributed in 13 municipalities, which were sampled in two seasons in 2015 and 2016. Sand flies were collected using CDC light traps placed in intra and peridomestic habitats. In addition to the morphological identification, molecular identification through DNA barcodes was also performed. A total of 19,743 sand flies were collected and 13,848 of them (10,268 females and 3,580 males) were used in molecular procedures. Circulation of two known parasite species–Leishmania infantum and Leishmania panamensis was confirmed. Blood source analyses showed that sand flies fed on humans, particularly in the case of the known L. infantum vector, P. evansi; further analyses are advised to evaluate the reservoirs involved in parasite transmission. Our sampling design allowed us to evaluate potential transmission cycles on a department scale, by defining suspected vector species, parasite species present in different municipalities and feeding habits.

Behavioral Aspects of Phlebotomine Sand Flies Associated with a Case of Cutaneous Leishmaniasis in Atlántico, Northern Colombia

“…The high abundance of Lu. evansi coincides with the findings of previous studies on leishmaniasis foci in the departments of Sucre, [8][9][10] Bolívar, 7,11 and Córdoba, 12 where the relative abundance of this species fluctuated between 70% and 90% and where Lu. evansi was considered the most likely vector in each focus.…”

“…evansi with L. infantum has been reported in different localities of the Caribbean region of Colombia. 12,16 In addition, studies conducted particularly in the Montes de María region suggest that Lu. evansi could be involved in transmitting the etiological agent of CL because this sand fly species was found naturally infected with flagellates of Leishmania braziliensis and because nucleotide sequence analysis allowed this parasite to be grouped with isolates of L. braziliensis from patients with CL residing in the same area.…”

“…In each dwelling, sampling was conducted for two consecutive nights. are anthropophilic and have been implicated as suspected vectors in the CL transmission cycle in several foci in the Caribbean region of Colombia, particularly in the departments of Córdoba, 12,18 Sucre, 8 and Bolívar. 11 They have also been associated with the transmission of Leishmania panamensis and L. braziliensis in different CL foci in Central and South America.…”

Studies of host preferences of wild-caught Phlebotomus orientalis and Ph. papatasi vectors of leishmaniasis in Sudan

“…However, many factors limit the use of this approach; sand flies are minute insects compared to mosquitoes and ingest less blood volume (0.3–0.6 μl per blood meal) and (2–6 μl per blood meal) respectively [ 13 , 18 , 19 ], and this reduces the active time period which to determine the blood meal source (24–48 hours) post blood meal ingestion [ 11 , 19 – 22 ]. These difficulties impose critical challenges from disease ecology perspective and epidemiological assessment of disease transmission [ 23 ].…”

“…Several PCR-based methods have been used to identify blood meal sources of sand flies including one that targets the prepronociceptin (PNOC) gene [ 29 – 31 ], FTA-based technology [ 11 ], PCR-RFLP [ 32 , 33 ]. Besides, real time PCR assays [ 34 ], multiplex PCR [ 35 ], barcoding PCR [ 23 , 36 , 37 ], PCR reverse-line blotting (RLB) and ELISA assays [ 17 , 27 , 28 , 38 – 40 ].…”