Domestic and wild felids are frequently parasitized by apicomplexan protozoa in the genus Cytauxzoon. Expanding species diversity has recently been described within this genus, with potential implications for epidemiology and pathogenesis. In light of these findings, this study assessed the genetic diversity of Cytauxzoon spp. in wild felids (n = 66) from different eco-regions of Brazil and Argentina. Of the 66 blood samples analyzed, 53 (80.3%) were 18S rRNA gene PCR-positive for Cytauxzoon spp., including 43 jaguars (Panthera onca) and 10 ocelots (Leopardus pardalis). Panthera onca specimens (100%, 43/43) were most frequently infected, followed by Leopardus pardalis (76.9%; 10/13). Cytauxzoon spp. were not detected in Leopardus braccatus (n = 1) or Puma concolor (n = 9). Phylogenetic analyses of fragments of the 18S rRNA, cytB, and cox-1 gene sequences from jaguars were closely related to Cytauxzoon felis. In contrast, sequences from ocelots were more closely associated with Cytauxzoon brasiliensis. Distance and haplotype analysis further confirmed the circulation of at least two distinct genovariants of C. felis among jaguars, as evidenced by their close positioning and low genetic divergence (0–0.14% for 18S rRNA, 0.37–0.56% for cytB, and 0.08–0.74% for cox-1). Additionally, sequence data from ocelots suggested that multiple genovariants of C. brasiliensis are circulating among these cats in different Brazilian eco-regions. Our study provides evidence of two distinct Cytauxzoon organisms parasitizing free-ranging and captive jaguars and ocelots, respectively, in Brazil and Argentina.

Bovine anaplasmosis and babesiosis are important tick-borne diseases associated with significant economic losses, although fetal infection and abortion are rarely described. This study reports a bovine abortion associated with co-infection by Anaplasma marginale , Babesia bovis and Babesia bigemina. in the Midwestern region of Brazil. Fetal necropsy was performed, followed by cytological, histopathological, immunohistochemical, and molecular analyses. Gross findings included jaundice, splenomegaly, hepatomegaly, and renal discoloration, consistent with severe hemolytic disease. Blood smear evaluation revealed intraerythrocytic inclusions compatible with (A) marginale and Babesia -like merozoites, and PCR confirmed (B) bovis and B. bigemina , and Anaplasma spp. infection was confirmed by sequencing. Histologically, lesions consisted of erythrophagocytosis, hemosiderosis, hemoglobin casts, and marked intravascular leukocytostasis in multiple organs. Immunohistochemistry demonstrated accumulation of macrophages and T lymphocytes, suggesting activation of a fetal inflammatory response. These findings emphasize the importance of including hemoparasitic infections in the differential diagnosis of bovine abortion and support a role for fetal immune responses in lesion development.