Control of pyrethroid‐resistant populations of Triatoma infestans, the main vector of Trypanosoma cruzi, by treating dogs with fluralaner in the Argentine Chaco

• Published in: Medical and veterinary entomology Vol. 36; no. 2; pp. 149 - 158
• Main Authors: Laiño, Mariano Alberto, Cardinal, Marta Victoria, Gaspe, María Sol, Enriquez, Gustavo Fabián, Alvedro, Alejandra, Macchiaverna, Natalia Paula, Gürtler, Ricardo E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-2022; Wiley Subscription Services, Inc
• Subjects: Abundance; Animals; Argentina; Chagas Disease - prevention & control; Chagas Disease - veterinary; Dog Diseases - prevention & control; Dogs; fluralaner; Gran Chaco; Infestation; Insect Vectors; Insecticides - pharmacology; integrated vector control management; Isoxazoles; Placebos; Pyrethrins - pharmacology; pyrethroid resistance; Pyrethroids; Triatoma; Triatoma infestans; Trypanosoma cruzi; vector control; Argentina; Chaco; pyrethroid resistance; Gran Chaco; integrated vector control management; vector control; fluralaner
• ISSN: 0269-283X; 1365-2915
• DOI: 10.1111/mve.12561

We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid‐resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo‐controlled before‐and‐after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control‐house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site‐level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner‐treated group, infestation dropped significantly from 100% at baseline to 19% over 6–10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8–0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0−14.7 ‐ triatomines at 0–1 MPT to 4.0–4.2 over 6–10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site‐level infestation and abundance of pyrethroid‐resistant T. infestans and should be tested more widely in Phase III efficacy trials.
Fluralaner kills both pyrethroid‐susceptible and resistant triatomines.
Fluralaner‐treated dogs significantly reduced site infestation and triatomine abundance.
Residual triatomine foci posttreatment were continuously occupied by chickens.