Henselae

Henselae refers to Bartonella henselae, a small Gram-negative, facultative intracellular bacterium in the family Bartonellaceae and the causative agent of cat scratch disease (CSD) in humans. It is primarily associated with domestic cats, which serve as the main reservoir; transmission among cats occurs via the cat flea, Ctenocephalides felis. Humans typically acquire infection through scratches or bites contaminated with flea feces containing bacteria, with a papule at the entry site followed by regional lymphadenopathy.

In immunocompromised individuals, infections can be disseminated and include bacillary angiomatosis, peliosis hepatis, and endocarditis; neurologic or ocular involvement may also occur. Diagnosis relies on clinical suspicion supported by laboratory tests such as serology (IFA or ELISA) and PCR on blood or tissue; culture is difficult and requires specialized media and prolonged incubation. Histopathology may show granulomatous inflammation, and special stains like Warthin-Starry can reveal bacilli in tissue.

Treatment: many healthy patients recover without antibiotics, though antibiotics such as azithromycin can shorten illness. Alternatives include doxycycline, rifampin, or trimethoprim-sulfamethoxazole, depending on age and comorbidities. Severe or disseminated disease or disease in the immunocompromised may require longer or combination therapy.

Prevention emphasizes flea control for cats and careful handling to avoid scratches or bites. Henselae infections occur worldwide, with higher detection in settings of close human–cat contact.