Infection of alpacas with Anaplasma phagocytophilum in Lithuania

Anaplasma phagocytophilum is an obligate intracellular bacterium and an emerging vectorborne pathogen of zoonotic concern, responsible for granulocytic anaplasmosis in a broad range of mammalian hosts. Its increasing prevalence across Europe is closely linked to the expanding distribution of Ixodes tick vectors and ecological shifts driven by climate change [1, 2]. In 2023–2024, blood samples were collected from 28 alpacas showing clinical signs consistent with blood parasite infections across ten districts in Lithuania (Jonava, Trakai, Anykščiai, Jurbarkas, Širvintos, Vilnius, Kazlų Rūda, Šilalė, Klaipėda, and Ukmergė). Molecular testing confirmed Anaplasma phagocytophilum in 17 animals. Six alpacas died during the study period. In addition to clinical signs, infected animals showed evidence of anaemia, including reduced haemoglobin and red blood cell counts, as well as morphological changes such as anisocytosis, poikilocytosis, and hypochromia. These haematological findings complement clinical presentation and emphasise the significant impact of blood parasite infections on alpaca health. Our results indicate that such an infection is an important health concern in alpacas in Lithuania, associated with severe anaemia and increased mortality.