Effectiveness of deltamethrin-impregnated dog collars on the incidence of canine infection by Leishmania infantum: A large scale intervention study in an endemic area in Brazil.

Wendel Coura-Vital,Alexandre Barbosa Reis,Luana Araújo Marques,Gleisiane Gomes De Almeida Leal,Aimara Da Costa Pinheiro,Mariângela Carneiro,Knut Stieger

doi:10.1371/journal.pone.0208613

Abstract

To reduce morbidity and mortality caused by visceral leishmaniasis (VL), the Brazilian Visceral Leishmaniasis Control and Surveillance Program promotes the diagnosis and treatment of cases, vector control, euthanasia of seropositive dogs, and health education. Nevertheless, the effectiveness of these measures is questionable as they lead to little reduction in the transmission of the disease. Thus, the effectiveness of strategies such as insecticide-impregnated collars, spot-on insecticides, and immunization of dogs should be assessed. Herein, we evaluated the effectiveness of deltamethrin-impregnated collars on reducing the incidence of Leishmania infantum infection in dogs living in an endemic area of VL. An intervention study was conducted and a total 5,850 dogs were analyzed in baseline. Of these 3,742 seronegative dogs were divided into two groups: collared and uncollared (control). Dogs were followed for 12 months and three interventions were performed. The Cox regression model was used to evaluate the effectiveness of the collar. All analyzes were performed by Intention-to-treat and per-protocol. By intention-to-treat, the incidence rates of L. infantum infection were 7.5 and 7.9 in the collar group, and 6.5 and 13.2 per 1,000 dogs-months in the control group after 6 and 12 months, respectively. In the per-protocol analysis, the incidence rates in the control group were similar to those observed in the intention-to-treat analysis. In the collar group, the incidence rate was 5.1/1,000 dogs-months after 6 and 12 months. The effectiveness by intention-to-treat after adjustment by the multivariate Cox model was 48%. In the analysis per-protocol, the effectiveness increased to 63%. Although collar use was effective when it was evaluated by intention-to-treat, higher effectiveness was found in the per-protocol analysis after one year of follow-up. The data emphasize the importance of the uninterrupted use of deltamethrin-impregnated collars to increase protection against canine VL.

Highlights

Visceral leishmaniasis (VL) is a neglected disease and, despite its worldwide distribution, 90% of global VL cases are concentrated in seven countries: Brazil, Ethiopia, India, Kenya, Somalia, South Sudan, and Sudan [1]
In the Americas, VL is present in 12 countries, with 96% of the cases being reported in Brazil [2]
The treatment of canine visceral leishmaniasis (CVL) with miltefosine has been authorized by the Brazilian Ministries of Health and of Agriculture, Livestock and Supply

Summary

Introduction

Visceral leishmaniasis (VL) is a neglected disease and, despite its worldwide distribution, 90% of global VL cases are concentrated in seven countries: Brazil, Ethiopia, India, Kenya, Somalia, South Sudan, and Sudan [1]. The transmission cycle in Brazil is zoonotic, with domestic dogs being the main urban reservoirs of the parasite [3]. Aiming at reducing morbidity and mortality rates, the Brazilian Ministry of Health has implemented the Visceral Leishmaniasis Control and Surveillance Program (VLCSP) to promote health education, early diagnosis and treatment of human VL cases, vector control with insecticides, and serological screening and euthanasia of infected dogs [5]. The treatment of canine visceral leishmaniasis (CVL) with miltefosine has been authorized by the Brazilian Ministries of Health and of Agriculture, Livestock and Supply. The decision to use this treatment is in the hands of dog owners’ as it has not been adopted as a large-scale preventive strategy in public health [6]

Methods

Results

Conclusion