Background/Objective: Yellow fever (YF) is an acute infectious disease caused by the yellow fever virus which is transmitted by mosquitoes. Neotropical primates are susceptible to infection, which is often presented as epizootic outbreaks. The aim was to evaluate and characterize the immune response against YF in different species of neotropical primates from the Belo Horizonte Zoo. Methods: Vaccine 17DD was administered to 24 neotropical primates, with a single subcutaneous dose. Clinical exams, RNAemia, and detection of IgG and neutralizing antibodies against YFV were performed. In addition, an ethogram was performed to assess clinical changes and animal welfare. Results: At 4 days post-vaccination, RNAemia was detected in nine animals. There was seroconversion and persistence of immune response in Alouatta guariba clamitans, Sapajus xanthosternos, Saguinus imperator and Aotus infulatus. However, the vaccine was not immunogenic for Lagothrix cana. In Pithecia irrorata seroconversion did not persist long term, while the Ateles sp. had a transient immune response. No significant clinical manifestations were observed in any of the vaccinated animals. Conclusions: This study demonstrated a safe, immunogenic and persistent immune response induced by the attenuated 17DD vaccine strain in A. guariba clamitans, S. xanthosternos, S. imperator, and A. infulatus.

Background: Toxoplasmosis and leishmaniosis are zoonotic diseases that affect several species of neotropical primates. Methods: Three black lion tamarins ( Leontopithecus chrysopygus ) kept at a Brazilian zoo died due to a superacute disease. Tissue samples were collected for histopathology, cytology, PCR, and genotyping by PCR‐RFLP and microsatellite (MS) analysis. Results: Toxoplasma gondii was detected by PCR in all tissue samples analyzed. The Brazilian lineage Type BrII (ToxoDB‐PCR‐RFLP #11 genotype) was identified in three animals, and the analysis with MS confirmed the same source of infection. Amastigotes of Leishmania sp. were visualized in cytology and confirmed by IHC in the three animals. Conclusion: This is the first time that this genotype has been confirmed associated with an outbreak of toxoplasmosis affecting neotropical primates in Brazil, or associated with infection by Leishmania sp.