Field randomized trial to evaluate the efficacy of the Leish - Tec vaccine against canine visceral leishmaniasis in anendemic area of Brazil.

• Autor(a) principal: Silva, Shara Regina
• Data de Publicação: 2016
• Outros Autores: Feres, Ana Maria Leonardi Tibúrcio, Silva, João Carlos França da, Dias, Edelberto Santos, Michalsky, Érika Monteiro, Andrade, Hélida Monteiro de, Coelho, Eduardo Antônio Ferraz, Ribeiro, Gustavo Meirelles, Fernandes, Ana Paula, Coelho, George Luiz Lins Machado
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFOP
• Texto Completo: http://www.repositorio.ufop.br/handle/123456789/6596; https://doi.org/10.1016/j.vaccine.2016.03.019
• topic: Randomized field trial; Canine visceral leishmaniasis; Vaccine; Efficacy

Background: A canine vaccine remains a promising approach for effective control of visceral leishmaniasis(VL), given its complex epidemiology in areas where zoonotic VL is prevalent. Leish-Tec®is a recombi-nant vaccine, based on the Leishmania A2 antigen, against canine VL (CVL). It is, since 2014, the singlecommercial vaccine licensed in Brazil. Here, Leish-Tec®efficacy was estimated through a randomizedfield trial (RFT), in a highly VL endemic area.Methods: The RFT was conducted from 2008 to 2010 in an endemic area of southeastern Brazil, presentinga CVL seroprevalence of 41.9%. Eight hundred forty-seven seronegative dogs were randomly selected toreceive Leish-Tec®(n = 429) or placebo (n = 418). Animals were followed up by clinical, serological, andparasitological exams for 18 months. The CVL incidence in both groups was compared through proportionanalysis.Results: A significant reduction in the number of cases of CVL was observed in the vaccine group, ascompared with the placebo group, whether efficacy was estimated according to parasitological results(71.4%; 95% CI: 34.9–87.3%; p = 0.001; risk ratio = 0.287), by adding results of xenodiagnosis and parasito-logical exams (58.1%; 95% CI: 26.0–76.3%; p = 0.002; risk ratio = 0.419). Among the animals that convertedto a positive anti-A2 serology, efficacy reached 80.8% (95% CI: 37.6–94.1%, p = 0.001; risk ratio = 0.192).Xenodiagnosis has detected a reduction of 46.6% (p = 0.05) in transmission to sand flies from vaccinatedanimals presenting anti-A2 positive serology.Conclusion: The Leish-Tec®vaccine proved significantly effective for prophylaxis of CVL, after naturalchallenge assured by transmission of Leishmania parasites, in a highly endemic area. Noteworthy, thisreport has unveiled the complexity of performing a RFT for anti-CVL vaccines in Brazil, which may behelpful for designing of future studies.