Cytauxzoon spp. are tick-borne haemoprotozoans that infect domestic and wild felids and are of increasing relevance in veterinary medicine and epidemiology of vector-borne pathogens. In Brazil, the genetic diversity of these agents in wild felids has been progressively expanded, culminating in the description of Cytauxzoon brasiliensis. However, the occurrence of this species in domestic cats is unknown. Therefore, the present study aimed to detect and molecularly characterize C. brasiliensis in domestic cats from the state of Rio de Janeiro, Brazil, and to describe the main hematological findings observed in positive animals. A total of 404 blood samples from domestic cats were analyzed using nested PCR targeting the 18S rRNA gene, followed by molecular characterization using the mitochondrial cytB gene. Positive samples were subjected to similarity, phylogenetic, and haplotype diversity analyses. Hematological data from positive animals were also evaluated, along with differential molecular diagnoses for other hemoparasites and infectious agents. Four samples (~ 1%) were positive for Cytauxzoon sp. in the 18S rRNA-based assay, and three showed intraerythrocytic inclusions suggestive of piroplasms in blood smears. The sequences obtained clustered phylogenetically with isolates previously identified as C. brasiliensis in Brazilian wild felids, confirming the presence of this agent in domestic cats. Hematological analyses revealed thrombocytopenia in all four positive animals, anemia in two animals, and variable leukocyte abnormalities. No molecular detection of Bartonella spp., hemoplasmas, members of the family Anaplasmataceae, or Leishmania infantum chagasi, was observed. These results demonstrate, for the first time, the infection of domestic cats by C. brasiliensis in the state of Rio de Janeiro and reinforce the need to include this agent in the differential diagnosis of feline hemoparasitoses. In addition, the findings suggest that infection may be associated with relevant hematological alterations, although studies including a larger number of animals and a more robust clinical-epidemiological design are still needed to clarify its actual pathogenic impact on the host.
Brandão et al. (Tue,) studied this question.