PROTECTION OF DOGS FROM BITES OF PHLEBOTOMINE SANDFLIES BY DELTAMETHRIN COLLARS FOR CONTROL OF CANINE LEISHMANIASIS

Dog collars made of PVC plastic impregnated with the pyrethroid insect icide deltamethrin at 30 mg/g were investigated for their protective e fficacy against phlebotomine sandflies. Collared dogs were kept separa tely (two untreated control dogs lived together) in outdoor enclosures , each with a kennel, in the Cevennes, southern France. To measure san dfly mortality and anti-feeding effects due to the deltamethrin-impreg nated collars worn continuously by the dogs for up to 8 months? each d og was periodically sedated and exposed for 2h to 150-200 laboratory-r eared Phlebotomus perniciosus females (plus c. 25 males) inside a net (1.2m square, 1.8m high) indoors. After dogs were removed from the net s, allowed to recover and returned to their kennels, any dead sandflie s were collected from inside the net and counted. Surviving flies were kept overnight, then scored according to whether they were still aliv e or dead, unfed or blood-fed. From tests 2, 3, 4, 13, 20, 26 and 34 w eeks after the dogs began wearing collars, the overall numbers of bloo d-fed female sandflies recaptured were 75 from two dogs with collars, compared with 1911 from two collarless dogs. Thus, for every 100 flies which fed on collarless dogs, only 4 fed on collared dogs, i.e. the c ollars protected dogs from 96% of the bites and this activity was main tained for up to 34 weeks. During the same period, the percentage of r ecaptured female sandflies that had fed on collared dogs was 0-12% com pared to 55-95% on collarless dogs. Immediately after dogs were taken out of the nets, 21-60% of flies confined with the collared dogs were found dead, compared to 0-12% with the controls. It is concluded that, at least in the Mediterranean subregion, this insecticidal collar wou ld protect a dog from the majority of sandfly bites and retain a killi ng effect for a complete sandfly season. Moreover, it seems likely tha t the use of collars on all dogs in a focus of Leishmania infantum wou ld reduce contact between sandfly vectors and canine reservoir hosts s ufficiently to diminish the risk of infection for humans as well as do gs.