University of Khartoum

Spatio-Temporal Distribution and Behaviour of Phlebotomine Sandflies (Diptera: Psychodidae) In Ten Sentinel Sites In Sennar State, Sudan, 2015-2016

Spatio-Temporal Distribution and Behaviour of Phlebotomine Sandflies (Diptera: Psychodidae) In Ten Sentinel Sites In Sennar State, Sudan, 2015-2016

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Title: Spatio-Temporal Distribution and Behaviour of Phlebotomine Sandflies (Diptera: Psychodidae) In Ten Sentinel Sites In Sennar State, Sudan, 2015-2016
Author: Ahmed, Khalid Sarour Mustafa Mohamed
Abstract: Human visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) represent major public health problems in Sudan. Both spectrum of leishmaniasis are widespread in Sudan, particularly in the savannah region for VL and most of the arid region for CL. Both VL and CL exist in Sennar State which located at the southeast part of Sudan. The current study was conducted as longitudinal entomological surveys between February 2015 and January 2016 to determine the fauna, abundance, distribution and seasonal dynamics of phlebotomine sand flies with emphasis on leishmaniasis vectors in ten sentinel sites in Sennar State. Collections of sand flies were done using CDC light traps (LTs), sticky paper traps (STs), and pyrethrum spray catches (PSCs) inside residential rooms/huts. A total of 58860 sand flies, including three Phlebotomus spp. and six Sergentomyia spp. were collected and identified. Sergentomyia clydei (258916; 44.0%) was the most abundant species followed by S. antennata (23115; 39.3%). The mean density of P. orientalis and P. papatasi collected by LTs and STs were significantly varied between the sentinel sites (P= 0.00 for both species in each trap collections). For LT collections, the highest density/trap for P. orientalis and P. papatasi were in Azazadamuos (0.8±0.14) and Sennar (5.6±1.7), and the lowest were in Elsoki (0.01±0.01) and Abuhojar (0.84±0.2) respectively. In contrast, on ST collections, the highest density/trap for P. orientalis and P. papatasi were in Dinder (1.6±0.31) and Mazmoum (4.4±0.4), and the lowest were in Abuhojar (0.2±0.1) and Wadalabas (1.2±0.3) respectively. The outdoor to indoor ratio for P. orientalis and P. papatasi were 3.2:1 and 1.1:1 in LTs, which indicate relatively high exophilic behavior for the VL vector. Habitat preference experiment revealed that forest habitat was more productive for the most sand fly species collected in the area than animal sheds and in-village habitats. Phlebotomus orientalis and P. papatasi were recorded at indoor sites in PSCs collections indicating that these two species exhibit some degree of endophilic behavior. All sand fly species recorded in the area showed marked fluctuation in their seasonal abundance. Phlebotomus orientalis was found to occur during the dry months of the season (October – May) and completely disappear during the rainy season (July – September) (i.e. seasonal species). Phlebotomus orientalis had two major peaks of 5 abundance the first in March (0.7±0.1 flies/LT/night and 1.6±0.3 flies/ST/night) and April (0.6±0.1 flies/LT/night and 1.6±0.3 flies/ST/night). In contrast, P. papatasi was collected in all months during this study (i.e. non-seasonal species). Phlebotomus papatasi showed one major peak of abundance in LT collection and two on ST collections. The peak month for P. papatasi in LT collection was April (6.5±1.9 flies/trap/night), and on ST collections were March and April (5.1±0.6 and 5.6±0.6 flies/trap/night respectively). The mean densities of both P. orientalis and P. papatasi showed significant positive and negative correlation with mean monthly temperatures and relative humidities respectively (P< 0.05) for LT, ST and PSC collections. The maps generate from the distribution of sand flies in Sennar State showed that P. orientalis and P. papatasi exist in all sentinel sites investigated. Finally, the current study might indicate that P. orientalis and P. papatasi are the only vectors of VL and CL in Sennar State where the transmission can occur during months with relatively high temperature and low RH%. In addition, the species exhibits predominant endophilic and exophilic feeding behavior which indicate possibility of disease transmission at outdoor as well as indoor sites.
URI: http://khartoumspace.uofk.edu/123456789/25913


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