Bacteria of the genus Bartonella generally causes a wide range of diseases, from harmless to severe. Here in Europe, Bartonella henselae occurs, which causes quite harmless disease in some countries known as "cat scratch disease". As the name shows, the disease is transmitted to humans from cats, either by scratches or bites, or fleas and ticks. The disease is most often found in breeders of cats and small children.

Bartonellosis is rather a mild disease, it is usually dangerous only for immunodeficient patients such as cancer patients, patients without spleen, or HIV positive. A scab-like formation is formed at the site of bacterial intrusion within 1-3 weeks and swelling of the nearby lymph nodes occurs. A typical manifestation is an indeterminate subjective feeling of illness, elevated temperature, loss of appetite and various pains, most often of the head, joints and muscles, back and abdomen. The disease usually disappears spontaneously, whether treated or untreated, within one month of the outbreak. In very rare cases, severe neurological or cardiological disorders such as meningoencephalitis, encephalopathy, seizures, or endocarditis with a very high probability of death may occur. Eye, liver and kidney infections may also occur.

Bartonellosis is best diagnosed by polymerase chain reaction with Bartonella specific primers. Treatment is not necessary in most cases, but if the liver, eyes, spleen, or central nervous system are infected, azithromycin is usually the antibiotic of choice. Doxycycline is preferred for ocular and central nervous system involvement because it permeates well through these tissues. Doxycycline is contraindicated in pregnant women because it is teratogenic.