New tools for Chagas disease vector control

CARBAJAL DE LA FUENTE AL; LENCINA, P.; SPILLMANN, C.; GURTLER RICARDO E

México, DF

Congreso; 13 th INTERNATIONAL CONGRESS OF PARASITOLOGY; 2014

BACKGROUND: The Mendoza Chagas disease control program introduced the use of a vehicle-mounted automatic sprayer (AS) (Malanca) for house spraying with pyrethroid insecticides. The AS appears to be more efficient than the traditional manual compression sprayers (MS) used by vector control programs, especially in rural houses with large peridomestic structures, but the comparative performance of both treatments has not been investigated. METHODS: To evaluate the effectiveness and efficiency of insecticide spraying operations using AS versus MS we conducted a randomized intervention trial in Lavalle Department (Mendoza, Argentina) between May 2013?2014. Experienced vector control personnel assessed house infestation at site level using timed manual collections with a dislodjant aerosol at 0, 1, 4 and 12 months postintervention. All houses positive for T. infestans at baseline were randomly allocated to AS or MS and sprayed with SC deltamethrin (Bayer) at an intended dose of 25 mg/m2. For each house we quantified total sprayed area, insecticide applied, water required, and time to complete the house insecticide spray. Houses found infested after initial interventions were re-sprayed with the same treatment. RESULTS: T. infestans was found in 41 (55%) of 76 houses in domestic (4%), peridomestic (41%) or both habitats (9%) at baseline. The interventions reduced house infestation from 100% to 16%, 0% and 11% at 1, 4 and 12 months postintervention, respectively, and did not differ significantly between treatments. Endpoint infestations were restricted to peridomestic habitats. Although the insecticide applied per m2 and water required were similar between treatments, AS was faster than MS. CONCLUSIONS: Both treatments had similar effectiveness and efficiency, but did not completely suppress infestations. The main advantage of AS was reduced physical effort under harsh field conditions. These encouraging results justify the execution of larger field trials in different settings before issuing a final recommendation.