Experimental Infection of Ferrets with Bartonella henselae: In Search of a Novel Animal Model for Zoonotic Bartonellosis

<i>Bartonella henselae</i> is an important zoonotic pathogen with a wide range of clinical manifestations in humans. Despite advances in understanding its pathogenesis, there is no broadly applicable laboratory animal model for bartonellosis. This study aimed to assess the potential utility of an experimental model of chronic <i>B. henselae</i> infection using ferrets, a species previously utilized in various human pathogen studies. Six ferrets (n = 6) were divided into three groups: a control group (n = 2), a low-dose infection group (n = 2), and a high-dose infection group (n = 2). The two infection groups were inoculated intradermally with 10⁵ (low dose) and 10⁹ (high dose) CFU/mL <i>B. henselae</i>, respectively. Clinical signs, serological responses, and bacteriological findings were monitored over seven weeks; ferrets were then euthanized and tissues were examined histologically. Only minimal or transient systemic clinical signs and laboratory abnormalities developed in <i>B. henselae</i> inoculated ferrets. The high-dose group seroconverted to <i>B. henselae</i> antigen within two weeks, maintaining elevated titers throughout the study. Histopathological examination revealed that four <i>B. henselae</i>-infected ferrets had notable microscopic inflammatory lesions in the liver parenchyma (3/4), heart (1/4), and brain (1/4); similar lesions were not observed in the tissues of the two control ferrets. Despite the presence of microscopic lesions and seroconversion in the high-dose group, bacteremia was not documented and <i>B. henselae</i> DNA was not successfully amplified by quantitative PCR from lesional organs. This pilot study demonstrated that ferrets may serve as a promising model for investigating <i>B. henselae</i> pathogenesis, diagnosis, treatment, and prevention.