[4] Symptoms typically include a non-painful bump or blister at the site of injury and painful and swollen lymph nodes.

[2] Cat-scratch disease is caused by the bacterium Bartonella henselae which is believed to be spread by the cat's saliva.

[4] Cat-scratch disease commonly presents as tender, swollen lymph nodes near the site of the inoculating bite or scratch or on the neck, and is usually limited to one side.

In rare situations, CSD can lead to the development of serious neurologic or cardiac sequelae such as meningoencephalitis, encephalopathy, seizures, or endocarditis.

[5] Parinaud's oculoglandular syndrome is the most common ocular manifestation of CSD,[4] and is a granulomatous conjunctivitis with concurrent swelling of the lymph node near the ear.

[4] Bacillary angiomatosis is primarily a vascular skin lesion that may extend to bone or be present in other areas of the body.

[13][14] Cryptic Bartonella infection may be a much larger problem than previously thought, constituting an unrecognized occupational health hazard of veterinarians.

Under the microscope, the skin lesion demonstrates a circumscribed focus of necrosis, surrounded by histiocytes, often accompanied by multinucleated giant cells, lymphocytes, and eosinophils.

[21] However, doxycycline is preferred to treat B. henselae infections with optic neuritis due to its ability to adequately penetrate the tissues of the eye and central nervous system.

[22] Geographical location, present season, and variables associated with cats (such as exposure and degree of flea infestation) all play a factor in the prevalence of CSD within a population.

[23] In warmer climates, the CSD is more prevalent during the fall and winter,[23] which may be attributed to the breeding season for adult cats, which allows for the birth of kittens.

[22] To determine recent incidence of CSD in the United States, the Truven Health MarketScan Commercial Claims and Encounters database was analyzed in a case control study from 2005 to 2013.

The length of the study period was 9 years and was based on 280,522,578 person-years; factors such as year, length of insurance coverage, region, age, and sex were used to calculate the person-years incidence rate to eliminate confounding variables among the entire study population.

[23] Due to the large population of cats residing in the United States, the ability of this disease to continue to infect humans is vast.

Laboratory diagnosis of CSD has improved in recent years, which may support an increase in incidence of the disease in future populations.

[27][5] In 1983, the Warthin-Starry silver stain was used to discover a Gram-negative bacillus which was named Afipia felis in 1991 after it was successfully cultured and isolated.

The causative organism of CSD was originally believed to be Afipia felis, but this was disproved by immunological studies in the 1990s demonstrating that people with cat-scratch fever developed antibodies to two other organisms, B. henselae (originally known as Rochalimea henselae before the genera Bartonella and Rochalimea were combined) and B. clarridgeiae, which is a rod-shaped Gram-negative bacterium.