Evidence for an impact on the incidence of canine leishmaniasis by the mass use of deltamethrin‐impregnated dog collars in southern Italy

Abstract

Dogs are the domestic reservoir of Leishmania infantum Nicolle (Kinetoplastida: Trypanosomatidae), the agent of zoonotic human visceral leishmaniasis. In southern Europe, where canine leishmaniasis (CanL) is widespread due to L. infantum, killing seropositive dogs is considered unacceptable and drug treatment has low efficacy in preventing transmission. We made a field evaluation of the efficacy of deltamethrin dog collars in a CanL focus of southern Italy, Mount Vesuvius area of Campania region, where the vector is Phlebotomus perniciosus Newstead (Diptera: Psychodidae), by assessing their impact on the incidence of CanL in an intervention town, compared to that in dogs of control towns where no collars were fitted. During two consecutive transmission seasons, collars were fitted to 350 (1998) and 354 (1999) dogs from San Sebastiano al Vesuvio (70% of the canine population). Control dogs (371 and 264 in the 2 years, respectively) were from four towns of the same area. Before each transmission season, the CanL seroprevalence in the intervention and control towns was evaluated by cross-sectional surveys and found to be similar (about 15% in 1998 and 10% in 1999, respectively). After each transmission period, incidence rates of seroconversions were determined in adult dogs that were serologically negative before the season under evaluation, and in puppies. After the 1998 season, 2.7% of the dogs in the intervention town seroconverted compared to 5.4% in the control towns (50% protection, P = 0.15). After the 1999 season, 3.5% of collared dogs seroconverted compared to 25.8% of control dogs (86% protection, P < 0.001). The increase in seroconversion rates recorded in control dogs suggests an increase in the Leishmania force of infection in the canine reservoir during the 1999 sandfly season, as supported by the concomitant increase of human cases in control towns and in the whole Campania region. Our results suggest that the impact of mass use of deltamethrin-impregnated dog collars on the incidence of CanL may be negligible during low transmission seasons, or probably in low endemic foci, but can be very strong when the force of transmission is high.

An Epidemic Outbreak of Canine Cutaneous Leishmaniasis in Colombia Caused by Leishmania braziliensis and Leishmania panamensis

“…Up to now, the strategies for control of the canine VL have included: 1) use of collars impregnated with deltamethrin, a strategy that has shown good results in regions such as Italy 29 and Tunis…”

Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review

“…DM treatment of dogs by way of an aqueous bath has been found to be highly effective in protecting the animals against sandfly bites in China (Xiong et al 1994(Xiong et al , 1995. DM impregnated collars have been used in the same country (Chen et al 2001), Italy (Maroli et al 2001), and Brazil (David et al 2001, Reithinger et al 2004. Among the great advantages of DM is its repellant and killing action of long duration No side effects have been detected, and it is considered to offer no human or canine health risk (WHO 1967).…”

Visceral leishmaniasis in Brazil: revisiting paradigms of epidemiology and control

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