Molecular detection and genetic diversity of Anaplasma and Ehrlichia species in livestock and dogs in Pakistan

Abstract

Tick-borne pathogens of the genera Anaplasma and Ehrlichia pose notable threat to animal and human health worldwide, contributing to substantial economic and public health losses. These obligate intracellular bacteria, transmitted via tick vectors, infect several mammalian hosts, including ruminants, canines, and humans. In Pakistan, the prevalence and genetic diversity of these pathogens remain insufficiently studied despite the diverse agro-climatic conditions and extensive livestock populations of the country. In this study, molecular characterization of Anaplasma and Ehrlichia species from cattle, goats, and dogs across three major livestock-rearing regions in Pakistan: Faisalabad, Islamabad, and Okara was investigated. During April 2024, a total of 33 cattle, 80 goats, and 150 dogs blood samples were collected and analyzed through 16S rRNA gene amplification. Of the collected samples, 67 samples were PCR positive and were sent for sequencing to conduct molecular analyses. The results showed that Anaplasma ovis (46 isolates), Anaplasma marginale (10 isolates), Anaplasma platys (6 isolates), Candidatus Anaplasma camelli (1 isolate), and Ehrlichia canis (4 isolates) were identified. Phylogenetic analysis confirmed that Pakistani isolates clustered closely with reference strains from Asia, Africa, and Europe, suggesting possible transboundary or intercontinental spread of these pathogens. Genetic diversity analysis indicated moderate haplotype diversity (Hd = 0.602) and low nucleotide diversity (π = 0.01718). Thus, this study highlights the need for continuous molecular surveillance of Anaplasma and Ehrlichia species to assess their genetic variability and zoonotic potential. It also provides crucial data to help understand tick-borne pathogens in Pakistan and informs policy-making for effective disease management in livestock and public health sectors.

Keywords: Anaplasmosis; Genetic diversity; Molecular epidemiology; Tick-borne diseases.