Nocturnal periodicity of Phlebotomus (Larroussius) orientalis (Diptera: Psychodidae) in an endemic focus of visceral leishmaniasis in Northern Ethiopia.

Araya Gebresilassie,Solomon Yared,Alon Warburg,Essayas Aklilu,Habte Tekie,Asrat Hailu,Teshome Gebre-Michael,Aviad Moncaz,Oscar David Kirstein,Meshesha Balkew

doi:10.1186/s13071-015-0804-7

Araya Gebresilassie, Solomon Yared + Show 8 more

Open Access

https://doi.org/10.1186/s13071-015-0804-7

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Journal: Parasites & vectors	Publication Date: Mar 28, 2015
Citations: 28	License type: CC BY 2.0

Affiliation: Jigjiga University, Addis Ababa University

Abstract

BackgroundPhlebotomus orientalis is the major vector of the intramacrophage protozoa, Leishmania donovani, the etiological agent of visceral leishmaniasis (VL) in northern Ethiopia and Sudan. The objective of this study was to determine the nocturnal periodicity of P. orientalis in the VL endemic focus of Tahtay Adiyabo district, northern Ethiopia.MethodsSandflies were collected using CDC light traps by changing collecting bags at an hourly interval from dusk to dawn for six months (January-June 2013) from outdoors (i.e. peri-domestic and agricultural fields). Sandfly specimens collected in the study were identified to species level and counted.ResultsIn total, 21,716 nocturnally active sandfly specimens, which belong to two genera (i.e., Phlebotomus and Sergentomyia) were collected and identified. In the collection, P. orientalis, the dominant species in the genus Phlebotomus, constituted 33.79% while Sergentomyia spp. comprised 65.44%. Analysis of data showed that activity of P. orientalis females increased from 18:00 to 24:00 hours, with a peak after midnight (24:00–03:00 hrs). Likewise, activity of parous P. orientalis females was found to be unimodal, peaking at 24–01:00 hrs.ConclusionP. orientalis females had marked nocturnal activity, which peak after midnight. Similarly, the epidemiologically dangerous parous females generally were more active after midnight. Therefore, humans are at risk of L. donovani infections through the bite of P. orientalis possibly between midnight and dawn.

Highlights

Phlebotomus orientalis is the major vector of the intramacrophage protozoa, Leishmania donovani, the etiological agent of visceral leishmaniasis (VL) in northern Ethiopia and Sudan
Nocturnal activity rhythms A total of 21,716 (65.20% male) nocturnally active sandfly specimens, which belong to two genera were collected and identified
The overall hourly activity patterns of P. orientalis was significantly different among collection intervals (ANOVA, F(df=12) =8.04; P = 0.000, Figure 1) with a peak nocturnal activity (21.5 flies/trap/hr) before midnight (22:00– 23:00 hrs)

Summary

Introduction

Phlebotomus orientalis is the major vector of the intramacrophage protozoa, Leishmania donovani, the etiological agent of visceral leishmaniasis (VL) in northern Ethiopia and Sudan. Phlebotomine sandflies have considerable public health importance in the tropics and subtropics attributed mainly to their role as potent vectors of the various forms of leishmaniasis (visceral and dermal), bartonellosis and 3-day fever (Pappataci fever). These diseases are transmitted by the bite of infected female sandflies of the genus Phlebotomus in the Old World and Lutzomyia in the New World when taking repetitive bloodmeals [1,2,3,4]. Most phlebotomine sandflies from the Old World are active during the night [2,5,6,7]. Why the time of nocturnal activity of most sandflies varies with season and time

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