First molecular detection Anaplasma phagocytophilum in sheep in Brazil.

Anaplasma phagocytophilum is an obligate intracellular Gram-negative bacterium and the etiological agent of granulocytic anaplasmosis in humans and several animal species, characterized by a broad geographic distribution and notable genetic variability. In Brazil, the pathogen has been reported in domestic dogs, cats, horses, and wildlife; however, this is the first description of its occurrence in sheep. An Ideal-breed lamb underwent coprological examination after presenting weakness, stunted growth, pale mucous membranes and poor body condition, which revealed a high parasitic burden, particularly of strongylids. Hematological analysis indicated a packed cell volume below the reference range (20%). Although no hemoparasite were observed, molecular detection was conducted by PCR targeting the msp4 and 16 S rRNA genes, followed by sequencing and phylogenetic analysis. The results confirmed the presence of A. phagocytophilum, showing 83.78-99.35% identity with sequences of the same species deposited in GenBank. The animal was treated for gastrointestinal nematodes but did not receive specific therapy against the hemoparasite. This report highlights the potential role of sheep as reservoirs of the agent and underscores the importance of considering this pathogen in the differential diagnosis of animals from tick-endemic regions. Anaplasma phagocytophilum represents an emerging public health concern, with outbreaks linked to interactions among humans, animals, and vectors. Given its zoonotic relevance and the paucity of studies in Brazil, this finding reinforces the need for epidemiological surveillance, accurate diagnostic tools, and integrated control strategies to mitigate pathogen dissemination.