Effects of fipronil on dogs over Triatoma infestans, the main vector of Trypanosoma cruzi, causative agent of Chagas disease.
Chagas disease is the most important endemic disease in Latin America, mainly transmitted by Triatoma infestans in the Southern Cone countries of South America. Dogs are one of the main domestic reservoirs of Trypanosoma cruzi, the etiological agent of Chagas disease. The presence of dogs in rural households of endemic areas significantly increases the likelihood of the vectorial transmission of the parasite. We studied the mortality and blood intake of T. infestans exposed to dogs treated with different doses and formulations of fipronil. Two doses, two formulations, and different distances to the application point of fipronil were compared. Third instar nymphs of T. infestans were fed at different time intervals after the insecticide application up to 45 days post-application. No significant difference was found between the blood intake of nymphs fed on control and treated dogs with different doses and formulations (p > 0.05). The spray formulation showed lower effect and persistence than the spot-on formulation. The mortality rate caused by the spot-on formulation in the 26.8-mg active ingredient (a.i.)/kg dose was higher (48%) than with the 13.4-mg a.i./kg dose (25%), 24 h after the insecticide application. The effect was highly heterogeneous among replicates of the same treatment. The mortality rate of nymphs fed over the point of the insecticide application was higher than the mortality of nymphs fed over places 12 cm apart from the fipronil application point, suggesting that the distribution of fipronil over the dog body is lower than the needed one to obtain a persistent triatomicide effect.
Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR- CONICET), Entre Ríos y Mendoza s/n (5301) Anillaco, La Rioja, Argentina. iamelotti@crilar-conicet.gob.ar
Ivana
I
Amelotti
Silvia S
SS
Catalá
David E
DE
Gorla
D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage*; D004283:Dog Diseases / Q000517:prevention & control*; D004285:Dogs; D004478:Ectoparasitic Infestations / Q000517:prevention & control / Q000662:veterinary*; D005247:Feeding Behavior / Q000187:drug effects; D009758:Nymph / Q000187:drug effects; D011720:Pyrazoles / Q000008:administration & dosage*; D016019:Survival Analysis; D016896:Treatment Outcome; D014224:Triatoma / Q000187:drug effects* / Q000254:growth & development
D000977:Antiparasitic Agents; D011720:Pyrazoles; C082360:fipronil