Abstract
BackgroundPhlebotomus orientalis feeds on a variety of wild and domestic animals and transmits Leishmania donovani from hitherto unknown reservoir hosts to humans in extra-domestic habitats in the Metema - Humera lowlands. The aim of this study was to determine the nocturnal activities of P. orientalis and its preferred blood meal hosts.MethodsCollections of Phlebotomus orientalis were made by using CDC light traps to determine the density as P. orientalis/hour CDC trap and preference to rodents by using Turner’s traps in agricultural fields, animal shelters and thickets of Acacia seyal in Baeker site-1 and Gelanzeraf site-2. The blood meal sources were detected by Reverse Line Blot (RLB) of cytochrome b polymerase chain reaction (PCR) amplification in August, 2012 from collections of sand flies in thickets of A. seyal (March 2011) and dense mixed forest (July 2011) in Baeker site 1. RLB PCR involved first amplification of animal specific sequences of cytochrome b using PCR techniques. Then the amplified sequence was hybridized with 11 species-specific probes for domestic animals adsorbed on nitrocellulose membrane for calorimetric color detection.ResultsA total of 6,083 P. orientalis (2,702 males and 3,381 females) were collected at hourly intervals using 22 CDC traps from January to May 2013. The peak activities of P. orientalis were at 1.00 a.m (134.0 ± 7.21) near animal shelters, 3.00 a.m (66.33 ± 46.40) in agricultural fields and 21:00 pm (40.6 ± 30.06) in thickets of A. seyal. This species was not attracted to the different species of rodents in trials carried out in March and April 2013. RLB PCR identified 7 human (28%), 9 mixed (human and cattle) (36%) and 2 cattle (8%) blood meals while 7 were unknown (28%).ConclusionFemale P. orientalis can bite humans in extra-domestic habitats of Kafta-Humera lowlands at any hour of the night with peak biting after midnight.
Highlights
Phlebotomus orientalis feeds on a variety of wild and domestic animals and transmits Leishmania donovani from hitherto unknown reservoir hosts to humans in extra-domestic habitats in the Metema - Humera lowlands
Species-specific probes This study described a blood meal identification approach based on polymerase chain reaction (PCR) amplification of the mitochondrial cytochrome b gene followed by Reverse Line Blot (RLB) analysis as already described [36,37]
Population dynamics of Phlebotomus orientalis A total of 6,083 P. orientalis (3,381 females and 2,702 males) was collected at one hour interval for 18 nights using a total of 22 CDC traps from agricultural fields near the camps
Summary
Phlebotomus orientalis feeds on a variety of wild and domestic animals and transmits Leishmania donovani from hitherto unknown reservoir hosts to humans in extra-domestic habitats in the Metema - Humera lowlands. In Sudan and northwest Ethiopia, kala-azar is transmitted by P. orientalis [2,3,4] and it claims the lives of thousands of people [5,6,7]. Experimental study on host preferences of P. orientalis and the isolation of L. donovani in east Africa have indicated that Canis familiaris (dogs), Herpeistes ichneumon (mongoose), Genetta genetta (genet cat), Acomys spp. and Arvicanthis spp. as preferred hosts for source of blood meals [2,13,17,18]. Attraction of P. orientalis towards cattle, sheep, goat, mule, donkey and horse has not been defined in east Africa as a whole, even though high Leishmania seroprevalence rate for these domestic animals has been reported in eastern Sudan [22] and northwest Ethiopia [23]
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