Effects of fipronil on dogs over Triatoma infestans, the main vector of Trypanosoma cruzi, causative agent of Chagas disease

AMELOTTI I; CATALÁ SS; GORLA DE

ZEITSCHRIFT FUR PARASITENKUNDE (PARASITOLOGY RESEARCH)

Springer

Año: 2012

0044-3255

Chagas disease is the most important endemic disease in LatinAmerica, mainly transmitted by Triatoma infestans in the SouthernCone countries of South America. Dogs are one of the maindomestic reservoirs of Trypanosoma cruzi, the etiological agent ofChagas disease. The presence of dogs in rural households ofendemic areas significantly increases the likelihood of the vectorialtransmission of the parasite. We studied the mortality and bloodintake of T. infestans exposed to dogs treated with different dosesand formulations of fipronil. Two doses, two formulations, anddifferent distances to the application point of fipronil werecompared. Third instar nymphs of T. infestans were fed at differenttime intervals after the insecticide application up to 45 dayspost-application. No significant difference was found between theblood intake of nymphs fed on control and treated dogs withdifferent doses and formulations (p > 0 .05). The spray formulationshowed lower effect and persistence than the spot-on formulation.The mortality rate caused by the spot-on formulation in the26.8-mg active ingredient (a.i.)/kg dose was higher (48 %) than withthe13.4-mg a.i./kg dose (25 %), 24 h after the insecticideapplication. The effect was highly heterogeneous among replicatesof the same treatment. The mortality rate of nymphs fed over thepoint of the insecticide application was higher than the mortality ofnymphs fed over places 12 cm apart from the fipronil applicationpoint, suggesting that the distribution of fipronil over the dog bodyis lower than the needed one to obtain a persistent triatomicideeffect.