Cat scratch disease is an acute zoonotic infection caused by the gram-negative bacterium Bartonella henselae, which enters the human body with bites or scratches of cats. A typical form occurs with primary affect in the form of papular-pustular rashes, regional lymphadenitis, fever, hepatosplenomegaly. There may be atypical forms of the disease – ocular, anginal, abdominal, pulmonary, cerebral, etc. The clinical diagnosis is confirmed by microbiological seeding of the separated pustules, histological examination of lymph nodes, ELISA and PCR diagnostics. Etiotropic therapy is carried out with antibacterial agents.
General information
Cat scratch disease (benign lymphoreticulosis, felinosis, granuloma Mollare) is an infectious human disease that develops as a result of the penetration of the pathogen through damaged skin (scratches and cat bites). Felinosis is a widespread and ubiquitous zoonosis; 25 thousand cases of cat scratch disease are registered annually. 80% of the cases are persons under the age of 21; children predominate – boys are more likely to get sick than girls. Usually felinosis occurs in the form of sporadic cases, but outbreaks of infection in families are also possible, when several children and adults successively get sick. The greatest danger in cat scratch disease is atypical forms of the disease, requiring the involvement of not only infectious diseases, but also specialists from the field of neurology, ophthalmology, pulmonology, etc.
Causes
Cat scratch disease in the vast majority of cases (more than 96%) is caused by the gram-negative bacillus Bartonella henselae. In some cases, the etiological role of Alipia felis, Bartonella clarridgeiae, Bartonella quintana was noted. Cats are only asymptomatic carriers of pathogens and rarely have signs of the disease in an erased form. The carriage of bartonella is more often detected in kittens and young individuals up to 2 years old. Between cats, pathogens spread with fleas. Less often, rodents, dogs, and birds act as reservoirs of infection. The mechanism of human infection with disease is associated with the penetration of the pathogen through damaged skin or mucous membranes (usually with bites and scratches) together with the saliva of an infected cat. Disease has a seasonal dependence and occurs more often in autumn and winter. After an infection, a persistent immunity usually develops.
At the site of the introduction of bartonella, an inflammatory reaction develops in the form of a primary affect, from where the pathogens enter the regional lymph nodes in a lymphogenic way, where they multiply intensively, releasing toxins and causing lymphadenitis. Morphological changes in lymphoid tissue are represented by reticulocellular hyperplasia with transformation into granulomas, and then microabsesses. With an atypical course of this disease, hematogenic dissemination of infection involving the liver, spleen, heart, lungs, central nervous system, eyes, bone tissue, etc. is possible.
Cat scratch disease symptoms
Cat scratch disease can occur in typical and atypical forms. In the development of the disease, the incubation period, the initial period, the period of the height of the disease and the period of convalescence are distinguished.
The typical form of cat scratch disease is characterized by a triad of clinical signs: primary affect, regional lymphadenitis, fever. The incubation period for felinosis lasts on average 10-14 days (from 3 days to 2 months). The starting point of the initial period is the appearance of a reddish papule with a diameter of 2-5 mm at the entrance gate of the infection. By this time, cat bites and scratches in most cases are already healing, so patients do not pay attention to a painless nodule. The primary affect is usually localized on the hands, lower extremities, face, neck.
After 2-3 days, during the height of the cat scratch disease, the papule transforms into a pustule, which opens into a small ulcer. After the element dries and the crust disappears, no defects remain on the skin. At the same time, the lymph nodes closest to the lesion become inflamed, thicken and increase in size – regional lymphadenitis develops (usually axillary and cervical areas; less often – submandibular, supraclavicular, inguinal areas). Lymphadenitis is the most permanent sign of a typical form of cat scratch disease and persists for 2 weeks – 2 months. The enlargement of lymph nodes is accompanied by fever and intoxication syndrome: sweating, weakness, muscle and headaches, malaise. Also, during the height of felinosis, there may be an increase in the liver and spleen (hepatosplenomegaly). In most cases, cat scratch disease ends with recovery after 2-4 months. A recurrent, undulating course is possible.
Atypical forms of felinosis include ocular, cerebral, abdominal, pulmonary, etc. The ocular form of cat scratch disease (3-7%) develops when bartonella enters the mucous membrane of the eyes and proceeds according to the type of ulcerative granulomatous conjunctivitis. At the same time, there is swelling of the eyelid, hyperemia of the conjunctiva with the formation of ulcers and granulomas, submandibular and parotid lymphadenitis. In some cases, the lesion of the eyes takes the form of neuroretinitis, clinically manifested by a violation of visual acuity of one eye.
The defeat of the central and peripheral nervous system in the atypical course of cat scratch disease can be expressed by the development of encephalitis, meningitis, encephalopathy, myelitis, polyneuritis. In the abdominal form, hepatosplenomegaly, mesadenitis, and spleen abscesses are noted. In more rare cases, felinosis proceeds with the development of endocarditis, myocarditis, pleurisy, pneumonia, tonsillitis, pharyngeal abscess, erythema nodosum, osteomyelitis, etc. In HIV-infected patients, there is a high risk of a generalized form – bacillary angiomatosis. It is characterized by fever, intoxication, skin angiomatosis, hepatosplenomegaly, endocarditis, lymphadenitis.
Diagnosis
The preliminary diagnosis is based on epidemiological anamnesis data indicating the development of clinical symptoms of felinosis after contact with a cat and violation of the integrity of the skin or mucous membranes. To confirm the clinical diagnosis, laboratory diagnostic methods aimed at detecting Bartonella henselae in tissue samples are used. For this purpose, microbiological seeding of the contents of lymph nodes and abscesses, biopsy and histological examination of altered lymph nodes, PCR, ELISA and RIF can be carried out. A highly sensitive and specific method of diagnosing cat scratch disease is a skin test for felinosis.
The typical form of cat scratch disease during the peak period must be differentiated from infectious mononucleosis, lymphogranulomatosis, lymphoma, tularemia, brucellosis, histoplasmosis, coccidioidosis, toxoplasmosis, cytomegalovirus infection, sarcoidosis and other diseases. With atypical forms of cat scratch disease, patients may need to consult a dermatovenerologist, neurologist, ophthalmologist, pulmonologist, cardiologist and other narrow-profile specialists.
Cat scratch disease treatment
Typical forms of cat scratch disease can be stopped independently, without treatment, however, in diagnosed cases of felinosis, drug therapy is prescribed. The standard treatment regimen for cat scratch disease consists of the use of antibacterial drugs (azithromycin, erythromycin, doxycycline, clindamycin), NSAIDs, antihistamines. The physiotherapeutic effect (diathermy, UHF) on the area of altered lymph nodes is shown. In case of suppuration of the lymph node, puncture aspiration of pus or opening of the abscess is performed; less often – removal of the affected lymph node.
Prevention
Specific prevention of felinosis has not been developed. In order to prevent the disease of cat scratches, it is necessary to take care of removing fleas from cats, observing caution and hygiene rules when contacting pets. Scratches and wounds from cat bites must be treated with antiseptics.
