Publication
Title
The ongoing risk of Leishmania donovani transmission in eastern Nepal : an entomological investigation during the elimination era
Author
Abstract
Background Visceral leishmaniasis (VL), a life-threatening neglected tropical disease, is targeted for elimination from Nepal by the year 2026. The national VL elimination program is still confronted with many challenges including the increasingly widespread distribution of the disease over the country, local resurgence and the questionable efficacy of the key vector control activities. In this study, we assessed the status and risk of Leishmania donovani transmission based on entomological indicators including seasonality, natural Leishmania infection rate and feeding behavior of vector sand flies, Phlebotomus argentipes, in three districts that had received disease control interventions in the past several years in the context of the disease elimination effort. Methods We selected two epidemiologically contrasting settings in each survey district, one village with and one without reported VL cases in recent years. Adult sand flies were collected using CDC light traps and mouth aspirators in each village for 12 consecutive months from July 2017 to June 2018. Leishmania infection was assessed in gravid sand flies targeting the small-subunit ribosomal RNA gene of the parasite (SSU-rRNA) and further sequenced for species identification. A segment (similar to 350 bp) of the vertebrate cytochrome b (cytb) gene was amplified from blood-fed P. argentipes from dwellings shared by both humans and cattle and sequenced to identify the preferred host. Results Vector abundance varied among districts and village types and peaks were observed in June, July and September to November. The estimated Leishmania infection rate in vector sand flies was 2.2% (1.1%-3.7% at 95% credible interval) and 0.6% (0.2%-1.3% at 95% credible interval) in VL and non-VL villages respectively. The common source of blood meal was humans in both VL (52.7%) and non-VL (74.2%) villages followed by cattle. Conclusions Our findings highlight the risk of ongoing L. donovani transmission not only in villages with VL cases but also in villages not reporting the presence of the disease over the past several years within the districts having disease elimination efforts, emphasize the remaining threats of VL re-emergence and inform the national program for critical evaluation of disease elimination strategies in Nepal.
Language
English
Source (journal)
Parasites and vectors
Publication
2023
ISSN
1756-3305
DOI
10.1186/S13071-023-05986-9
Volume/pages
16 :1 (2023) , p. 1-11
Article Reference
404
ISI
001099043700003
Pubmed ID
37932813
Medium
E-only publicatie
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Faculty/Department
Research group
Project info
Towards new concepts in anti-Leishmania treatment by modifying the interplay between sand fly transmitted parasites and the host innate immune system
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identifier
Creation 04.12.2023
Last edited 25.04.2024
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