Studies On The Transmission Dynamics Of Leishmania Donovani In Gadarif State Eastern Sudan

Abstract

This study was carried out in eastern Sudan by introducing dogs from non endemic area to VL endemic area to elucidate the natural L. donovani infection in dogs(Canis familiaris, Linnaeus, 1758) and then to determine their role in transmission of visceral leishmaniasis as reservoir hosts. This study comprised 3 groups of dogs, the first one was the natural L. donovani , infection test group, consisted of 35 dogs selected with the age of less than 6 months, from non endemic area of V.L. ( Khartoum) transferred to the VL. endemic area (17 dogs in Tabarak Alla and 18 in Barber el fugara). The second group was healthy controls consisted of five dogs kept at Khartoum State, in the Police Dogs Directorate. The third group consisted of 25 local dogs sampled randomly during a survey done in December 2008 – Feb. 2009. All dogs from group 1&2 were checked free from Leishmania donovani . They were vaccinated with routine vaccines (Distemper, canine adenovirus type 2, canine parvovirus and rabies). The field study was continued for more than 2 years (32 months) (June 2006 – February 2009). Trips for sampling and data collection were regulated every (1-2) months. Dogs were tested for the development of symptoms and signs of CVL on monthly basis. Venous blood and lymph node, bone marrow aspirates were collected for the detection of infection using the PCR, DAT, microscopy and culture. The results showed that, the transferred dogs group (1) had developed typical clinical signs of CVL like, lymphadenomegaly, long nails, weight loss, & different skin lesions. Parasitological examination showed the presence of the distinctive promastgote forms in cultures of BM& LN in (18.2%) of transferred dogs, which also showed (55.6%) and (100%) of PCR & DAT positive results respectively. In the other hand, the local dogs, although they showed no clinical symptoms, they were (84%) & (96%) positive by PCR& DAT respectively. In addition to these results, questionnaires designed to know the relation of keeping domestic animals including dogs & the VL infections in human. Showed a positive contribution of them to VL risk factors. It was concluded that dogs can acquire natural infection with Leishmania donovani, and thus may be considered as a potential reservoir of leishmaniasis that can play a significant role in VL transmission in that endemic area.