Molecular characterization of Hepatozoon spp. in cats living in Germany and other European countries

Hepatozoon spp. are increasingly reported in cats from Mediterranean countries, but data for Central and Northern Europe remain limited. This study investigated the occurrence and molecular diversity of Hepatozoon spp. in 1357 blood samples from cats living in Germany and other European countries using real-time PCR targeting the 18S rRNA gene. Hepatozoon spp. DNA was detected in 58 cats (4.3 %; 95 %-CI: 3.3-5.5 %). Thirty-seven positive samples were further analyzed by conventional PCR and sequencing. Four sequence types (A-D) were detected. Hepatozoon felis sequences classified within the genogroup I (types A and B) were identified in 33 cats; Hepatozoon silvestris haplotype I (type C) in one cat; and sequences showing 98.5 % identity to H. silvestris (type D) in three cats. Younger cats had a significantly higher infection risk (p = 0.026), while no association with sex was found. Samples submitted for targeted Hepatozoon testing and travel disease screening showed higher positivity rates. Among the 37 molecularly characterized cases, 31 had a known import origin, primarily from Greece, Spain, Cyprus, Italy, Bulgaria, the United Arab Emirates, Jordan, and Turkey. Notably, the H. silvestris-positive cat from Austria had no travel history, representing the first autochthonous case in a domestic cat in Austria. This study highlights the emergence of feline Hepatozoon infections in Europe, involving genetically diverse species. Infections should be considered mainly in cats with Mediterranean origin, travel history, outdoor access, or tick exposure. Identifying vectors responsible for transmission is crucial for implementing effective prevention strategies.