ABSTRACT
To identify the sandfly fauna and analyze ecology of sandfly vector(s) of visceral leishmaniasis in three districts of Somali Regional State, southeast Ethiopia. Methods: Sandflies were collected from four sampling habitats, including indoor, peri-domestic, farm field and mixed forest using light and sticky traps in July 2016, and February and April 2017 in Liben and Dawa zones in the Somali Regional State, southeastern Ethiopia. Results: In total, 4 367 sandfly specimens, belonging to 12 species (three Phlebotomus spp. and nine Sergentomyia spp.) were identified. Phlebotomus (P.) heischi, P. orientalis, and P. martini constituted 45.7%, 31.1%, and 23.1% of the sandfly collection, respectively. There were significant differences in the median number of P. orientalis, and P. martini captured per CDC trap/night between the three sampling districts (P<0.05). In light trap capture, collection habitats had significant effects on the abundance of P. orientalis, and P. martini (P<0.05). More median numbers of P. orientalis, and P. martini species were collected in agricultural fields followed by mixed forest and peri-domestic habitats. P. orientalis and P. martini were caught more in outdoor than indoor habitats, suggesting exophilic behaviour. Conclusions: The study demonstrated that the presence of P. orientalis and P. martini are probable vectors of visceral leishmaniasis in this new focus. The findings of our study will improve the understanding of the dynamics of visceral leishmaniasis transmission and will facilitate the implementation of integrated disease control measures based on ecological knowledge of visceral leishmaniasis vector in Liben and Dawa zones and its surrounding regions.
ABSTRACT
To identify the sandfly fauna and analyze ecology of sandfly vector(s) of visceral leishmaniasis in three districts of Somali Regional State, southeast Ethiopia. Methods: Sandflies were collected from four sampling habitats, including indoor, peri-domestic, farm field and mixed forest using light and sticky traps in July 2016, and February and April 2017 in Liben and Dawa zones in the Somali Regional State, southeastern Ethiopia. Results: In total, 4 367 sandfly specimens, belonging to 12 species (three Phlebotomus spp. and nine Sergentomyia spp.) were identified. Phlebotomus (P.) heischi, P. orientalis, and P. martini constituted 45.7%, 31.1%, and 23.1% of the sandfly collection, respectively. There were significant differences in the median number of P. orientalis, and P. martini captured per CDC trap/night between the three sampling districts (P<0.05). In light trap capture, collection habitats had significant effects on the abundance of P. orientalis, and P. martini (P<0.05). More median numbers of P. orientalis, and P. martini species were collected in agricultural fields followed by mixed forest and peri-domestic habitats. P. orientalis and P. martini were caught more in outdoor than indoor habitats, suggesting exophilic behaviour. Conclusions: The study demonstrated that the presence of P. orientalis and P. martini are probable vectors of visceral leishmaniasis in this new focus. The findings of our study will improve the understanding of the dynamics of visceral leishmaniasis transmission and will facilitate the implementation of integrated disease control measures based on ecological knowledge of visceral leishmaniasis vector in Liben and Dawa zones and its surrounding regions.
ABSTRACT
OBJECTIVE@#To investigate the zoonotic visceral leishmaniasis (ZVL) by identification of the most probable reservoir hosts using parasite isolation and analysis of a possible transmission dynamics of the disease in extra-domestic agricultural fields and rural villages.@*METHODS@#Rodents were collected from selected study sites in kala-azar endemic areas based on information for localities of kala-azar cases for screening of Leishmania infections using parasitological, serological and polymerase chain reaction (PCR) from March, 2013 to January, 2014. Ketamine (Clorketam Veterinary) was used to anaesthesize the rodents according the prescribed dosage (average 2 mg/kg for intra-venous route). The blood obtained using sterile needle was dropped into sterile filter paper and allowed to air dry before sealing in plastic bags. The tissues from liver, spleen and skin were macerated in Locke's solution before transferring them into NNN medium. Blood and touch smears of liver, spleen, skin and bone marrow were prepared for fixing using methanol and staining by Giemsa stain for microscopy. These tissues were also used for DNA extractions and PCR amplification of Leishmania infection.@*RESULTS@#A total of 335 rodents (13 species) were analyzed by sampling internal organs. The infection rate by PCR was 11.1% (6/54) for Arvicanthis nilothicus compared to 17.6% (3/17) and 12.5% (2/16) for Acomys cahirinus and Tarera (G) robustus respectively. Almost all the infections were found from bone marrow samples (8/48 or 16.7%) compared with 1/91 (1.1%) liver, 2/87 (2.2%) spleen and 0/87 (0%) skin. In all study sites with past human VL cases, rodents and proved vectors shared similar habitats.@*CONCLUSIONS@#Leishmania donovani might circulate among different species of rodents in kala-azar endemic lowlands and valleys of Ethiopia by Phlebotomus orientalis and Phlebotomus martini. Detailed studies to substantiate the preliminary data on the possible role of these rodents are urgently needed.
ABSTRACT
Objective To investigate the zoonotic visceral leishmaniasis (ZVL) by identification of the most probable reservoir hosts using parasite isolation and analysis of a possible transmission dynamics of the disease in extra-domestic agricultural fields and rural villages. Methods Rodents were collected from selected study sites in kala-azar endemic areas based on information for localities of kala-azar cases for screening of Leishmania infections using parasitological, serological and polymerase chain reaction (PCR) from March, 2013 to January, 2014. Ketamine (Clorketam Veterinary) was used to anaesthesize the rodents according the prescribed dosage (average 2 mg/kg for intra-venous route). The blood obtained using sterile needle was dropped into sterile filter paper and allowed to air dry before sealing in plastic bags. The tissues from liver, spleen and skin were macerated in Locke's solution before transferring them into NNN medium. Blood and touch smears of liver, spleen, skin and bone marrow were prepared for fixing using methanol and staining by Giemsa stain for microscopy. These tissues were also used for DNA extractions and PCR amplification of Leishmania infection. Results A total of 335 rodents (13 species) were analyzed by sampling internal organs. The infection rate by PCR was 11.1% (6/54) for Arvicanthis nilothicus compared to 17.6% (3/17) and 12.5% (2/16) for Acomys cahirinus and Tarera (G) robustus respectively. Almost all the infections were found from bone marrow samples (8/48 or 16.7%) compared with 1/91 (1.1%) liver, 2/87 (2.2%) spleen and 0/87 (0%) skin. In all study sites with past human VL cases, rodents and proved vectors shared similar habitats. Conclusions Leishmania donovani might circulate among different species of rodents in kala-azar endemic lowlands and valleys of Ethiopia by Phlebotomus orientalis and Phlebotomus martini. Detailed studies to substantiate the preliminary data on the possible role of these rodents are urgently needed.
ABSTRACT
Visceral leishmaniasis (VL) has been known to occur since the 1980s on the western bank of the White Nile River (Central Sudan), 150 km south of Khartoum, and has resulted in high mortality. The most recent outbreak of the disease in this area began in 2006. Entomological surveys were carried out during May 2008, June 2010 and May and July 2011 in the White Nile area. Sandflies were collected using Centers for Disease Control light traps and sticky oil traps in the village of Kadaba and the nearby woodland. Phlebotomus females were dissected for the presence of Leishmania promastigotes. A total of 17,387 sandflies, including six species of Phlebotomus and 10 species of Sergentomyia, were identified. The Phlebotomus species recorded were Phlebotomus orientalis, Phlebotomus papatasi, Phlebotomus bergeroti, Phlebotomus duboscqi, Phlebotomus rodhaini and Phlebotomus saevus. P. orientalis was collected in both habitats. The relative abundance of P. orientalis in the woodland habitat was higher than that recorded in the village habitat. In the woodland habitat, there was a notable increase in the relative abundance of P. orientalis during the surveys conducted in 2008 and 2010 compared to 2011. None of the 311 P. orientalis females dissected were infected with Leishmania promastigotes, although relatively high parous rates were recorded in both habitats. Based on the distribution of P. orientalis recorded in this study, this species is the most likely vector of VL in the endemic focus in the White Nile area. Further investigation is required to elucidate the seasonal abundance and distribution of the vector, as well as the transmission season of VL in both habitats so that appropriate control strategies for the vector can be designed.