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Cat-scratch disease (CSD), also known as cat's claw fever, is a benign, self-limiting lymphatic disorder caused by Hansai Bartonella infection, which in most cases resolves spontaneously within 2 to 4 weeks, but more severe disseminated disease may occur. This article introduces the clinical manifestations, evaluation and treatment of cat scratch disease to facilitate further understanding.
Clinical manifestations of CSD
CSD is a zoonotic disease in which the main pathogen is Hansey Baltonella, and cats, dogs, and rats are the main hosts of Baltonella. Cat scratches or bites (especially kittens) are the main route of transmission from cats to humans, and can also be transmitted through the bite of fleas.
The disease is more common in young patients, the incidence of the disease is mostly by the cat bite or close contact with the cat history, the clinical manifestations are generally 3 to 7 days after the cat scratch biting local one to several erythematous papules, pain is not significant, a small number of papules turn into blisters or pustules, occasionally puncture to form small ulcers, after 1 to 3 weeks to leave a short period of pigmentation or scab and heal. 1 to 2 weeks after the scratch infection, the lymph nodes in the drainage area appear enlarged, common in the head and neck, armpits, groin, etc. Enlarged lymph nodes generally resolve spontaneously within 2 to 4 months, and a few can last for several months. Systemic manifestations include low-grade fever, headache, chills, fatigue, anorexia, nausea, or vomiting.
Patients with disseminated disease can have a range of complications, especially in older people or immunocompromised people. Extranodal metastases can occur, causing systemic lesions. Skin, lymph, and internal organs can be affected, and ocular and nervous system involvement is rare.
Organ involvement may involve the liver, spleen, and kidneys, and be accompanied by fever, weight loss, and abdominal pain. In adults, only a minority of patients with immunocompetent CSD develop hepatosplenic involvement. Eye lesions are mainly manifested in optic nerve retinitis, conjunctivitis or inflammation of retinal vasculature. Neurological complications of CSD include ataxia, cranial nerve palsy, or alzheimer's-like symptoms, while children present with encephalitis or aseptic meningitis.
Diagnosis and evaluation of CSD
The diagnostic criteria for CSD include at least three aspects: (1) a history of cat contact or cat scratches; (2) a positive skin test at the site of a cat scratch; (3) localized lymphangitis and exclusion of other causes of lymphangitis, lymph node biopsy with typical histopathological damage. Typical pathology is granulomatous inflammation with a small central abscess.
It is important to note that the differential diagnosis of fever of unknown origin (FUO) requires consideration of CSD when there is a correlation. A suspected diagnosis can be made by history and typical clinical presentation. Serological tests such as enzyme immunoassays and indirect fluorescence analysis are helpful in confirming the diagnosis, and a negative serological test does not exclude highly suspect cases of CSD.
Imaging is necessary for visceral involvement in CSD, and ultrasound, CT, and MRI can be used to assess liver, spleen, and renal involvement, as well as to follow up and assess response to treatment.
Differential diagnosis of CSD
The differential diagnosis of CSD includes causes of acute, subacute, and chronic lymphadenopathy. Skin papules similar to lesions at the site of scratch bite may occur in fungal infections, leishmaniasis, and nocardiosis. Multiple sources of infection should be considered in immunocompromised patients.
Treatment of CSD
CSD is self-limiting, with mild cases requiring no treatment. Supportive measures include antipyretic and anti-inflammatory drugs, as well as debridement and disinfection of scratching and biting sites. In mild-moderate patients with normal immune function, a course of treatment with azithromycin may be required. For severe diseases such as high fever, concomitant encephalitis and immunodeficiency patients (HIV infection, etc.), it is advisable to use a combination of antibiotics in a timely manner, and the time should be more than 2 weeks. Antibiotic options include rifampicin, trimethoprim-sulfaisoxazole, and ciprofloxacin.
Noteworthy issues
CSD is a common cause of lymphadenopathy, especially in children. A thorough history and physical examination, as well as a high index of suspicion, are helpful in the diagnosis. In the evaluation and treatment of patients, it is necessary to combine the age and comorbidities of the patient. In 90% to 95% of pediatric patients, CSD is completely relieved by controlling symptoms only through supportive measures. Cutting off the spread of Hansai Baltona through fleas between different cats can reduce human infection.
Resources:
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2.SUN He. Lu Guangzhong. LI Qiang. One example of cat's claw fever. Chinese Journal of Infectious Diseases.2018.36(4):248-249.
3.Klotz SA,Ianas V,Elliott SP: Cat-scratch disease. Am Fam Physician. 2011, 83:152-5.
4.Nakamura C, Inaba Y, Tsukahara K, et al. A pediatric case with peripheral facial nerve palsy caused by a granulomatous lesion associated with cat scratch disease. Brain Dev, 2018, 40(2):159-162.