From the Guidelines
Cat scratch disease should be treated with azithromycin 500mg on day 1, followed by 250mg daily for 4 additional days for patients weighing ≥45.5 kg, as it has been shown to reduce lymph node size by 80% at 30 days in a double-blind placebo-controlled study 1. The disease is caused by Bartonella henselae and typically presents as a papule or pustule at the scratch site, followed by regional lymphadenopathy within 1-3 weeks. Some key points to consider in the management of cat scratch disease include:
- The disease course varies, but lymphadenopathy generally resolves within 1–6 months without treatment 1.
- Extranodal disease, such as central nervous system, liver, spleen, bone, and lung involvement, develops in ≤2% of cases 1.
- Diagnosis may be difficult due to the fastidious nature of the organism, but serological testing, PCR, and Warthin-Starry silver stain of infected lymph node tissue can support the diagnosis 1.
- Treatment with antimicrobial agents has had variable results, but azithromycin has been shown to be effective in reducing lymph node size 1.
- Prevention involves avoiding rough play with cats, washing scratches promptly with soap and water, and keeping cats free of fleas which can transmit the bacteria between cats. In immunocompromised patients, more severe complications can occur, and treatment should be tailored to the individual patient's needs, with consideration of more aggressive treatment options 1.
From the FDA Drug Label
Doxycycline is indicated for the treatment of the following infections: ... Bartonellosis caused by Bartonella bacilliformis. The answer is yes, doxycycline is indicated for the treatment of Bartonellosis, which is the infection that causes cat scratch disease, as Bartonella henselae is the primary causative agent of cat scratch disease, and it is a species of the Bartonella genus. 2
From the Research
Causes and Transmission of Cat Scratch Disease
- Cat scratch disease is caused by the bacterium Bartonella henselae, which is transmitted to humans through a bite or scratch from an infected cat or kitten 3, 4, 5.
- Cat fleas are responsible for horizontal transmission of the disease from cat to cat, and on occasion, arthropod vectors (fleas or ticks) may transmit the disease to humans 4.
Symptoms and Diagnosis of Cat Scratch Disease
- The most common manifestation of human disease is lymphadenitis, with atypical forms of infection including Parinaud oculoglandular syndrome, stellate neuroretinitis, and hepatosplenic infection 3.
- Diagnosis is most often arrived at by obtaining a history of exposure to cats and a serologic test with high titers of immunoglobulin G antibody to B. henselae 4.
- Cat scratch disease should be included in the differential diagnosis of fever of unknown origin, lymphadenopathy syndrome, and serious neurologic disease 4, 6.
Treatment and Prevention of Cat Scratch Disease
- Most cases of cat scratch disease are self-limited and do not require antibiotic treatment, but antibiotics such as azithromycin, erythromycin, and doxycycline may be effective in severe or persistent cases 3, 4, 6.
- Treatment of uncomplicated central nervous system disease is generally supportive, with antibiotic therapy reserved for patients with atypical or severe involvement 6.
- Counseling patients to treat their cats for fleas and avoid rough play with their cats is a recommended prevention strategy, particularly for immunosuppressed patients 7.
Epidemiology and Clinical Burden of Cat Scratch Disease
- Approximately 24,000 people are infected with cat scratch disease every year, with an estimated 12,000 outpatients and 500 inpatients diagnosed annually in the United States 5, 7.
- A substantial proportion of U.S. clinicians have diagnosed cat scratch disease within the past year, but knowledge gaps remain regarding treatment and prevention 7.