# Molecular Characterization and Epidemiology of Anaplasmataceae in Ticks and Domestic Animals in the Colombian Caribbean

## TL;DR

This study identifies various Anaplasmataceae bacteria in ticks and domestic animals in the Colombian Caribbean, revealing high infection rates and potentially new variants.

## Contribution

The study reports the presence of novel and diverse Anaplasmataceae species in ticks and domestic animals in the Colombian Caribbean region.

## Key findings

- Over 60% of blood samples from cattle and equids tested positive for Anaplasmataceae.
- Multiple Anaplasmataceae variants, including Ehrlichia ruminantium and E. muris, were identified in ticks.
- Some Anaplasmataceae variants found may be novel to the region.

## Abstract

Tick-borne diseases represent a significant threat to both animal and public health, especially in tropical regions. Little is known about the epidemiology of these diseases in domestic animals and ticks in the Colombian Caribbean. To investigate infections caused by Anaplasmataceae bacteria, this study examined 1156 ticks and blood samples collected from 56 cattle and 17 equids in northern Colombia. Four tick species were identified, with Dermacentor nitens and Rhipicephalus microplus being the most prevalent. Around 9% of pooled tick samples and more than 60% of blood samples tested positive for Anaplasmataceae. Genetic analyses confirmed the presence of Anaplasma marginale in cattle and revealed several variants of Anaplasma and Ehrlichia, including Anaplasma sp. closely related to A. platys-like, Ehrlichia ruminantium, and E. muris. Some of these findings represent potentially novel variants in Colombia and highlight the complexity of transmission cycles between ticks and their animal hosts.

Tick-borne diseases (TBD) pose a significant threat to both animal and public health, particularly in tropical regions. In the Colombian Caribbean region, there is limited knowledge of the epidemiology of TBD in domestic animals and their vectors. In this study, conducted in northern Colombia from 2021 to 2022, we analyzed the molecular diversity of Anaplasmataceae in a total of 1156 ticks and blood samples collected from their infested hosts: 56 cattle and 17 equids (horses and mules). Polymerase chain reaction (PCR) assays were performed, using primers to amplify the mitochondrial 16S rRNA gene for tick identification and bacterial 16S and 23S rRNA to detect Anaplasmataceae. The amplified products were sequenced and analyzed for molecular characterization of species. Four tick species were identified: Dermacentor nitens (55.6%), Rhipicephalus microplus (43.0%), Rhipicephalus sanguineus sensu lato (0.7%), and Amblyomma patinoi (0.7%). Overall, 9.4% of the pooled tick samples were identified as R. microplus, and 64.4% of the blood samples tested positive for Anaplasmataceae. Molecular analyses identified Anaplasma marginale in cattle and several species in ticks, including an Anaplasma sp. closely related to A. platys-like, Ehrlichia ruminantium, and E. muris and Ehrlichia variants closely related to Candidatus E. rustica, E. canis, and E. minasensis. The results indicate high infection rates and the circulation of both well-known and potentially novel Anaplasmataceae species, suggesting complex transmission dynamics among ticks and hosts.