Distribution of Phlebotomine Sandflies in the Cave Area of Satun Province, Thailand.

Suwich Thammapalo,Rawadee Kumlert,Chamnarn Apiwathnasorn,Patcharida Boondej,Aulia Rahmi Pawestri,Rittiporn Benarlee,Kamal Kolaeh

doi:10.3390/tropicalmed5040174

Abstract

Leishmaniasis, a sandfly-transmitted protozoan infection, is a neglected health threat in Thailand and the information on its vector is scarce. This study aimed to identify sandfly distribution, abundance, and environmental conditions of natural breeding sites in the cave areas of Satun Province, where previous cases of leishmaniasis were reported. Sandflies were collected during a six-month period using CDC light traps and modified emergence traps. Species distribution, relative abundance, and environmental conditions of potential breeding sites were determined. Our survey of 12,790 sandflies found the highest female abundance in April–May. We identified six known species, the most prevalent being Sergentomyia anodontis. We also found S. barraudi, a potential Leishmania spp. vector, distributing in this area. Most male sandflies had partially rotated genitalia, indicating the breeding site proximity to our trap locations. Potential resting/breeding sites were discovered outside the cave during February–March, and inside during May–June. The environmental parameters showed warm climate, moderate humidity, moderately alkaline pH, moderate-to-high macronutrients, and low-to-high organic matters. In summary, our study provided the spatiotemporal distribution and environmental condition of sandfly potential breeding sites in the cave areas of Satun Province. This data may contribute to more effective vector surveillance programs in the future.

Highlights

Leishmaniasis is a neglected public health threat in Thailand
Sergentomyia gemmea and S. barraudi, were reported as potential vectors in Thailand [2,8], while Phlebotomus argentipes was identified as a confirmed vector of Leishmania donovani [9]
Through a six-month survey period, our study reported the sandfly species distribution and relative abundance, monthly female abundance, and environmental conditions of potential breeding sites in Satun Province, Thailand, an area with previous reports of leishmaniasis cases

Summary

Introduction

Leishmaniasis is a neglected public health threat in Thailand. The causative agent of this disease is Leishmania spp., an intracellular protozoon of the Family Trypanosomatidae. Until 1999, leishmaniasis was reported sporadically, until it was recognized as autochthonous infection, with most cases present in the southern part of Thailand [1,2]. Leishmaniasis cases had been reported in Thailand since 1960 [3,4,5], this disease did not receive much attention due to its low prevalence. Up to 2016, 26 sandfly species had been reported in Thailand [6]. We performed an extensive literature search by including available data from 1934 to 2019 and discovered that at least 34 sandfly species are circulating in Thailand [7]. Sergentomyia gemmea and S. barraudi, were reported as potential vectors in Thailand [2,8], while Phlebotomus argentipes was identified as a confirmed vector of Leishmania donovani [9]

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Conclusion