From the Guidelines
Cat scratch fever is not common, affecting a relatively small number of people, with approximately 12,000 cases reported annually in the United States. The disease, officially called cat scratch disease (CSD), is caused by the bacterium Bartonella henselae, which is transmitted through scratches, bites, or contact with the saliva of infected cats, particularly kittens 1. Most cases are mild and resolve without specific treatment within 2-4 weeks. Typical symptoms include a bump or blister at the scratch site, followed by swollen lymph nodes, fever, headache, and fatigue.
Key Considerations
- The disease is more likely to affect children and those with weakened immune systems.
- For severe cases, antibiotics like azithromycin may be prescribed, with a recommended dose of 500mg on day one, then 250mg daily for 4 days for patients weighing ≥45.5 kg, and 10 mg/kg on day 1, then 5 mg/kg on days 2–5 for those weighing <45.5 kg 1.
- To prevent infection, it is essential to promptly wash cat scratches with soap and water, avoid rough play with cats, and maintain good hand hygiene after handling pets.
- Diagnosis of Bartonella infections may be difficult due to the fastidious nature of the organism, but serological testing, PCR, and a positive Warthin-Starry silver stain of infected lymph node tissue can support the diagnosis 1.
From the Research
Prevalence of Cat Scratch Fever
- Cat scratch disease is a common infection that usually presents as tender lymphadenopathy, and it should be included in the differential diagnosis of fever of unknown origin and any lymphadenopathy syndrome 2.
- The disease is commonly diagnosed in children, but adults can also present with it 2, 3.
- An estimated 12,000 outpatients and 500 inpatients are diagnosed with cat scratch disease annually in the United States 4.
Diagnosis and Treatment
- 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 2.
- Most cases of cat-scratch disease are self-limited and do not require antibiotic treatment 2, 3.
- In complicated cases, treatment with trimethoprim-sulphamethoxazole, ciprofloxacin, or azithromycin is recommended 3, 5.
- A survey of clinicians found that only 12.5% chose the recommended treatment option of analgesics and monitoring for uncomplicated cat scratch disease, while 71.4% selected antibiotics 4.
Epidemiology
- Cat scratch disease has a worldwide distribution, with higher rates reported in temperate climates during the autumn and winter 3.
- The disease is caused by the bacterium Bartonella henselae, which is transmitted to humans through cat scratches or bites 2, 3.
- Cat fleas play a role in amplifying the reservoir of B. henselae, but it is unlikely that they are directly involved in human infection 3.