Leishmune® vaccine blocks the transmission of canine visceral leishmaniasis: Absence of Leishmania parasites in blood, skin and lymph nodes of vaccinated exposed dogs

Leishmune® vaccine is the first licensed vaccine against canine visceral leishmaniasis. It contains the Fucose–Mannose-ligand (FML) antigen of Leishmania donovani. The potential Leishmune® vaccine effect on the interruption of the transmission of the disease, was assayed by monitoring, in untreated (n = 40) and vaccinated dogs (n = 32) of a Brazilian epidemic area: the kala-azar clinical signs, the FML-seropositivity and the Leishmania parasite evidence by immunohistochemistry of skin and PCR for Leishmanial DNA of lymph node and blood samples. On month 11 after vaccination, untreated controls showed: 25% of symptomatic cases, 50% of FML-seropositivity, 56.7% of lymph node PCR, 15.7% of blood PCR and 25% of immunohistochemical positive reactions. The Leishmune®-vaccinated dogs showed 100% of seropositivity to FML and a complete absence of clinical signs and of parasites (0%) in skin, lymph node and blood PCR samples (p < 0.01). The positivity in FML-ELISA in untreated dogs significantly correlates with the PCR in lymph node samples (p < 0.001) and with the increase in number of symptoms (p = 0.006) being strong markers of infectiousness. The absence of symptoms and of evidence of Leishmania DNA and parasites in Leishmune®-vaccinated animals indicates the non-infectious condition of the Leishmune®-vaccinated dogs.