Environmental management for the control of Triatoma infestans in the southern area of the Gran Chaco (Argentina)

ABRAHAN L, HERNÁNDEZ L, HRELLAC H, CATALÁ S, GORLA D.

Isla de Margarita, Venezuela

Congreso; XVIII Congreso Latinoamericano de Parasitología (FLAP); 2007

Peridomestic populations of Triatoma infestans, the main vector species of Chagas disease, are highly resilient in the region of the Gran Chaco. This study compared the efficiency of a new structure of goat corrals as a method to eliminate/reduce the infestation by T. infestans in rural communities and to improve the economic profit of the goat producers. The study was carried out in rural houses of La Rioja (Argentina) where a house infestation by T. infestans of 62.3% was reported by 2006. The study included an experimental group,  (25 houses where new corrals were built) and a control group (50 houses) with traditional goat corrals.The new corral replaces all the wooden walls of the traditional corral by a wire fence and a cement block wall with a metal roof. Base line data on T. infestans abundance  was estimated by  manual timed collection in September 2006, previous to the official vector control intervention. Two post intervention evaluation was carried out in January and April 2007. In order to verify the hypothesis of higher productivity of the goat herd, measurements on calves mortality, development rate, body size and calves per goat, were collected. By April 07 goat corrals of the control group showed an infestation rate of 80% whereas 64% of the experimental corrals were infested. Density estimate in the last evaluation showed that the experimental corrals were infested basically by younger nymphs and very few older nymphs and adults, contrasting with the findings in the control corrals. The growth rate of calves’ body weight was similar in experimental and control corrals. A small significant difference between experimental and control groups was detected in goat fecundity (1.8 vs 1.5) and calf mortality (0.049 vs 0.061) respectively. The number of marketed calves/ number of births showed the highest difference between experimental and control group (0.079 vs 0.043). This field experiment needs a longer observation period and results informed here are preliminary. Building features of the new corrals do not guarantee the lack of colonization by T. infestans. The new corrals were built near infested traditional corrals and the quality of the construction was generally low. However, the simpler structure of the new corral would increase the detection efficiency of a low infestation by active search and it is possible that a vector control intervention using insecticide would be much more efficient on the new corral than on a traditional corral.