What is Cat Scratch Disease?
Cat scratch disease is an infectious disease that occurs after a bite and scratches of cats and occurs with the formation of a primary affect in the form of suppurative papules with subsequent development of regional lymphadenitis. (Synonyms: Mollare granuloma, felenosis, cat scratch fever, benign lymphoreticulosis).
Causes of Cat Scratch Disease
Cat scratch disease pathogen – Rochalimaea henselae. Polymorphic stationary gram-negative bacteria; morphologically similar to members of the genus Rickettsia and exhibits similar properties of Afipia felis. A motile non-fermentative gram-negative rod-shaped bacterium. It is capricious for cultivation in vitro, more preferably grown on HeLa cells.
A reservoir and source of infection are considered to be various mammals (cats, dogs, monkeys, etc.). The disease is recorded everywhere. In regions with a temperate climate, the rise in incidence is noted from September to March. Given the nature of the infection, the main contingent is persons under 21; 90% of the history indicate bites or scratches caused by kittens. Studies conducted on animals have shown that the microorganism does not cause them to develop any pathology and they do not respond to the development of hypersensitivity reactions upon intradermal administration of the pathogen antigen. The incidence is 10: 100,000 of the population (25,000 cases annually).
Pathogenesis During Cat Scratch Disease
Risk factors for developing the disease:
- Violations of cellular immune reactions
- HIV infection, especially when the content of CD4 + lymphocytes below 100 in 1 μl
- Long-term use of HA, azathioprine, cyclophosphamide, cyclosporine, alcohol abuse
The penetration of the pathogen through the damaged skin or, more rarely, through the mucous membrane of the eye leads further to the development of an inflammatory reaction in the form of a primary affect. Then, along the lymphatic pathways, the microbe enters the regional lymph nodes, which is accompanied by the occurrence of lymphadenitis. Morphological changes in the lymph nodes are characterized by reticulocellular hyperplasia, the formation of granulomas, and later microabscesses. The disease is usually accompanied by hematogenous dissemination involving other lymph nodes, liver, central nervous system, myocardium in the pathological process. Severe and long, and often atypical course of the disease is observed in patients with HIV infection.
Symptoms Illnesses of Cat Scratches
The incubation period lasts from 3 to 20 days (usually 7-14 days). According to clinical manifestations, it is possible to distinguish typical forms (about 90%), manifested in the appearance of primary affect and regional lymphadenitis, and atypical forms, which include:
- eye forms;
- damage to the central nervous system;
- damage to other organs;
- cat scratch disease in HIV-infected.
The disease can occur both in acute and in chronic. It also differs in the severity of the disease.
A typical disease begins, as a rule, gradually with the appearance of a primary affect. In place of a scratch or cat bite that had already healed by that time, a small papule with a rim of skin flushing appears, then it turns into a vesicle or pustula, later on into a small sore. Sometimes the abscess dries out without the formation of an ulcer. Primary affect is more often localized on the hands, less often on the face, neck, lower limbs. The general condition remains satisfactory. 15-30 days after infection, regional lymphadenitis is noted – the most constant and characteristic symptom of the disease. Sometimes it is almost the only symptom. An increase in body temperature (from 38.3 to 41 ° C) is observed in only 30% of patients. Fever is accompanied by other signs of intoxication (general weakness, headache, anorexia, etc.). The average duration of fever is about a week, although in some patients it may take up to a month or more. Weakness and other signs of intoxication last an average of 1-2 weeks.
Often affects the elbow, axillary, cervical lymph nodes. Some patients (about 5%) develop generalized lymphadenopathy. The size of the enlarged lymph nodes more often in the range from 3 to 5 cm, although in some patients they get 8-10, painful on palpation, not soldered to the surrounding tissues. In half of the patients, the affected lymph nodes suppurate with the formation of thick yellowish-greenish pus, which is not possible to isolate during normal sowing on the normal nutrient media of the bacterial microflora. The duration of adenopathy from 2 weeks to one year (on average about 3 months). In many patients, there is an increase in the liver and spleen, which persists for about 2 weeks. In some patients (5%), an exanthema appears (rubella-like, papular, like erythema nodosum), which disappears after 1-2 weeks. A typical clinical form accounts for about 90% of all cases of illness.
Ocular forms of the disease are observed in 4-7% of patients. In their manifestations, these forms resemble Parino oculoglandular syndrome (Parino conjunctivitis). It develops, probably, as a result of falling on the conjunctiva of the infected cat’s saliva. One eye is usually affected. The conjunctiva is sharply hyperemic, edematous, against this background one or several nodules appear that can ulcerate. Significantly enlarged lymph node, located in front of the ear lobe (reaching the size of 5 cm or more), the lymph node often suppurate, the duration of lymphadenopathy reaches 3-4 months. After festering and fistula formation, cicatricial skin changes remain. Sometimes not only the parotid, but also the submandibular lymph nodes are enlarged. Severe fever and signs of general intoxication are characteristic of the acute period of the disease. Inflammatory changes in the conjunctiva persist for 1-2 weeks, and the total duration of the eye of the claw scratch cathoglandular disease ranges from 1 to 28 weeks.
Changes in the nervous system occur in 1-3% of patients. They manifest as encephalopathy, meningitis, sciatica, polyneuritis, myelitis with paraplegia. Neurological symptoms are accompanied by high fever. They appear 1-6 weeks after the onset of lymphadenopathy. Neurological examination reveals diffuse and focal changes. There may be a transient disorder of consciousness. Coma cases are described. Thus, lesions of the nervous system develop against the background of the classic clinical manifestations of cat scratch disease (in severe cases of this disease). They can also be considered complications of this disease.
Other complications can be observed: thrombocytopenic purpura, primary atypical pneumonia, spleen abscess, myocarditis.
In persons with immunodeficiency disease takes a generalized character. For HIV-infected people characterized by gradual onset, increased fatigue, general malaise, weight loss, recurrent fever, headaches; local lesions are rarely observed. Possible neurological manifestations: impaired cognitive functions, behavior. They can be mistaken for mental disorders caused by HIV. In AIDS patients, disseminated skin lesions resembling Kaposi’s sarcoma are typical; note damage to the bones and various organs. Patients with impaired immune status are characterized by the development of bacterial angiomatosis and peliosis, accompanied by excessive proliferation of the capillary network. Damage to regional lymph nodes, internal organs (including endocarditis-like heart, liver, spleen), and skin (on the latter in the form of nodules and / or papules of a bodily or bluish-purple color; discharge and the formation of crusts).
Current and forecast. In typical cases, the disease is self-limited after 2–4 months. With the right treatment comes full recovery. When the process recurs, a second course of antibiotics is prescribed.
Diagnosing Cat Scratch Diseases
Diagnosing the classic form of cat scratch disease is not a big deal. Important contact with the cat (95% of patients), the presence of primary affect and the appearance of regional lymphadenitis (usually after 2 weeks) in the absence of the reaction of other lymph nodes. The diagnosis can be supported by microbiological examination of blood by sowing on blood agar, histological examination of papule biopsy or lymph node with staining of sections using silver and microscopic search for bacteria aggregations, as well as molecular genetic testing of the causative agent from the patient’s biopsy.
Differentiate from the skin-bubonic form of tularemia, tuberculosis of lymph nodes, lymphogranulomatosis, bacterial lymphadenitis.
In some patients in the hemogram eosinophilia and increased ESR are noted. Skin test with a specific antigen (positive in 90% of patients 3-4 weeks after the onset of the disease).
Treatment Cat Scratch Diseases
The disease ends in a spontaneous cure. With suppuration of the lymph node – puncture with suction of pus. The use of the new antibiotic ketolide from the macrolide group is promising.
Drugs of choice:
- In uncomplicated cases – erythromycin 500 mg 4 r / day or doxycycline 100 mg 2 r / day orally, or ciprofloxacin 500 mg 2 r / day orally for 10–14 days with a normal immune system or 8–12 weeks in case of immunodeficiency (rifampicin may be additionally prescribed)
- With endocarditis, lesions of internal organs or bones – erythromycin 500 mg 4 r / day or doxycycline 100 mg 2 r / day parenterally for 2–4 weeks and then inside for 8–12 weeks
- Alternative drugs – tetracyclines, azithromycin, clarithromycin, chloramphenicol, ofloxacin, ciprofloxacin.
Prevention of Cat Scratch Disease
Specific prevention is not developed. Scratches and cat bites should be disinfected.