High Genetic Diversity of Ehrlichia canis in Rio de Janeiro, Brazil

Strategic Insights -

Research presented by a team from the Federal Rural University in Rio de Janeiro, Brazil, has shed light on the genetic variability of Ehrlichia canis, a bacterium that causes canine monocytic ehrlichiosis, a disease that affects dogs and is often associated with thrombocytopenia. The study analyzed 404 blood samples from dogs with thrombocytopenia, with the positivity rate for the dsb and p28 genes being 21.04% and the trp36 gene having a detection rate of 34.1% in the positive samples. The analysis revealed high genetic diversity among the circulating E. canis strains in the mesoregions studied, with the identification of distinct genogroups, including the American and Brazilian genogroups.

Key Takeaways:

  • The study analyzed 404 blood samples from dogs with thrombocytopenia in two mesoregions in the state of Rio de Janeiro, Brazil.
  • The positivity rate for the dsb and p28 genes was 21.04% (85/404), while the trp36 gene had a detection rate of 34.1% (29/85) in the positive samples.
  • Phylogenetic analysis revealed high genetic diversity among the circulating E. canis strains in the mesoregions studied, with the identification of distinct genogroups, including the American and Brazilian genogroups.
  • The haplotype network mirrored the trp36-defined genogroups, suggesting genetic structuring associated with the American and Brazilian variants.
  • The study highlights the importance of molecular surveillance to better understand the epidemiology of canine ehrlichiosis and the strains involved in the infection.
  • The research was conducted by a team from the Federal Rural University, including Diogo Santos Maia, Jonathan David Ribas Chagas, Matheus Dias Cordeiro, Zbigniew Zajac, Angelique Foucault-Simonin, Alejandro Cabezas-Cruz, Huarrisson Azevedo Santos, Douglas McIntosh, Claudia Bezerra da Silva, and Bruna de Azevedo Baeta.

Statistics:

  • 404 blood samples from dogs with thrombocytopenia were analyzed in the study.
  • The positivity rate for the dsb and p28 genes was 21.04% (85/404).
  • The trp36 gene had a detection rate of 34.1% (29/85) in the positive samples.
  • 23 samples positive for the p28 gene and 29 samples based on trp36 results were sequenced.
  • Phylogenetic analysis revealed 17 distinct haplotypes (Hd = 0.9872) with region-specific clustering.

Sources:

  • NewsRx. Reports from Federal Rural University Describe Recent Advances in Ehrlichia canis (High genetic diversity of Ehrlichia canis trp36 and p28 genes in dogs from Rio de Janeiro, Brazil). Life Science Weekly. October 21, 2025; p 4556.
  • High genetic diversity of Ehrlichia canis trp36 and p28 genes in dogs from Rio de Janeiro, Brazil. Veterinary Research Communications, 2025;49(6):350.
  • Springer. Veterinary Research Communications. www.springerlink.com/content/0165-7380/
  • Springer. www.springer.com