Cat scratch fever

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2] Fizza Zulfiqar, MD[3]

Cat scratch fever is a usually benign infectious disease caused by the intracellular parasite Bartonella. It is most commonly found in children 1-2 weeks following a cat scratch. The cats serve as the natural reservoir for B.henselae.

It was first described in 1889 by Henri Parinaud. The cat was recognized as the vector of the disease in 1931 by Dr. Robert Debré.

The causative organism was first thought to be Afipia felis, but this was disproved by immunological studies demonstrating that cat scratch fever patients developed antibodies to two other organisms, Bartonella henselae and Bartonella clarridgeiae, which are rod-shaped Gram negative bacteria.

Cat scratch disease can be transmitted from a scratch or bite from an infected cat, as well as from exposure to cat fleas. The breach in the skin or mucosal surfaces (eg, mouth and eyes) if comes in contact with infected cat saliva can lead to the spread of the disease. B. henselae causes an acute inflammatory reaction associated with activation of a proinflammatory cascade following invasion of endothelial cells.

Ticks are also a major transmitter of this disease. It is often transmitted at the same time a human may get Lyme disease. It is often missed when people are tested and diagnosed for Lyme disease as the symptoms can be similar, such as fatigue, and headaches.

People having cats as pet at are higher risk of getting the disease. Immunosuppression leads to the disseminated form of the disease.

Most cases of Cat scratch disease are clinically diagnosed.

To confirm the clinical impression serologic testing including enzyme immunoassay (EIA) or indirect fluorescence assay (IFA) are performed.

High titers (greater than 1:256) of immunoglobulin G antibody to Bartonella are diagnostic.

Lymph node or tissue biopsy is rarely done.

Polymerase chain reaction (PCR) tests for Bartonella on tissue or blood are also available.

Cat scratch fever is a usually benign infectious disease caused by the intracellular parasite Bartonella. It is most commonly found in children 1-2 weeks following a cat scratch. The most common manifestation is tender lymphadenopathy ^[1]

The most commonly involved lymph nodes are the axillary, epitrochlear, submandibular, cervical, and supraclavicular lymph nodes.

Visceral involvement is more commonly seen in children infected with the symptoms of fever and abdominal pain manifesting as hepatomegaly, splenomegaly.

Ocular symptoms include optic neuritis and parinaud oculoglandular syndrome( tender regional lymphadenopathy of the preauricular or cervical lymph nodes associated with conjunctivitis or eyelid infection )

Neuroretinitis seen rarely in pateints.

A simple blood test can test for the presence of antibodies for Bartonella. It can be quite common for someone to have Lyme disease, Babesia and Bartonella from a single tick bite.

Most healthy people will clear the infection without treatment, and antimicrobial therapy is not recommended for immunocompetent patients with mild to moderate Bartonella henselae disease due to the risk of side-effects from antibiotics. Azithromycin, ciprofloxacin, doxycycline, and multiple other antibiotics have been used but with unclear benefit.^[2]

Azithromycin is preferentially used in pregnancy to avoid the side-effects of doxycycline.

Corticosteroids are given for a persistent disease.

Needle aspiration of suppurative lymph nodes can also be performed.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]

The disease was first described in 1889 by Henri Parinaud. The cat was recognized as the natural reservoir of the disease in 1931 by Dr. Robert Debré.^[1][2] Judy Dolan was the first person to be diagnosed with the disease in the United States of America.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]

The causative organism was first thought to be Afipia felis, but this was disproved by immunological studies demonstrating that cat scratch fever patients developed antibodies to two other organisms, Bartonella henselae (B. henselae) and Bartonella clarridgeiae, which are rod-shaped Gram-negative bacteria.

Kittens are more likely to carry the bacteria in their blood, and may therefore be more likely to transmit the disease rather than adult cats. However, the results of experimental studies showed that fleas serve as a vector for transmission of B. henselae among cats,^[1] and that viable B. henselae are excreted in the feces of Ctenocephalides felis, the cat flea.^[2] Another study showed that cats could be infected with B. henselae through intradermal inoculation using flea feces containing B. henselae.^[3] As a consequence, it is believed that a likely means of transmission of B. henselae from cats to humans may be inoculation with flea feces containing B. henselae through a contaminated cat scratch wound or across a mucosal surface. Although Bartonella DNA has been reported in ticks, there is no evidence that CSD can be transmitted by tick bites.^[4]

The primary cutaneous lesion consists of a red papule at site of inoculation, 1–2 weeks after contact, which may become pustular or crusted, which is accompanied by enlargement of regional – usually the cervical and axiallary – lymph nodes. Under the microscope, the skin lesion demonstrates a circumscribed focus of necrosis, surround by histiocytes, often accompanied by multinucleated giant cells, lymphocytes, and eosinophils. The regional lymph nodes demonstrate follicular hyperplasia with central stellate necrosis with neutrophils, surrounded by palisading histiocytes (suppurative granulomas) and sinuses packed with monocytoid B cells, usually without perifollicular and intrafollicular epithelioid cells

The Warthin–Starry stain is used to confirm the presence of B. henselæ.

Atypical cat scratch disease takes several different forms depending on organ systems involved. Atypical forms of disease are becoming increasingly recognized in clinical practice.

Parinaud’s oculoglandular syndrome is a granulomatous conjunctivitis with concurrent swelling of the lymph node near the ear.

Optic neuritis, involvement of the retina, and neuropathy can also occur.

Bacillary angiomatosis is caused by Bartonella henselae, the causative organism of cat scratch disease. It is primarily a vascular skin lesion that may extend to bone or be present in other areas of the body. In the typical scenario, the patient has HIV or another cause of severe immune dysfunction.

Bacillary peliosis is a condition that most-often affects patients with HIV and other conditions causing severe immune compromise. The liver and spleen are primarily affected, with findings of blood-filled cystic spaces on pathology ^[5]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]

Cat scratch disease should be differentiated from the following diseases:

• HIV / AIDS
• Cytomegalo virus infection
• Epstein-Barr virus infection
• Mycobacterial infections
• Coccidioidomycosis
• Leishmaniasis
• Lyme Disease
• Lymphogranuloma Venereum (LGV)
• Sarcoidosis
• Syphilis
• Toxoplasmosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]

The prevalence of Cat scratch fever ranges from a low of 1.8 per 100,000 patients, to a high of 9.3 per 100,000 patients with an average prevalence of 6.6 per 100,000 patients.

The peak incidence seems to be situated between 30 and 50 years, 75 % of cases being reported during the cold period of the year, between September and April.

The male-to-female ratio is 3:2.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

People having cats as pet at are higher risk of getting the disease.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]

It may take 7 to 14 days, or as long as two months, before symptoms appear. Most cases are benign and self-limiting, but lymphadenopathy may persist for several months after other symptoms disappear. In temperate climates, most cases occur in fall and winter. The disease usually resolves spontaneously, with or without treatment, in one month. In immunocompromised patients more severe complications sometimes occur.

Possible complications of Cat scratch fever include:

• Uveitis
• Endocarditis
• Aseptic meningitis
• Osteomyelitis
• Acute encephalopathy

The prognosis is generally favorable. Patients with normal immune system recover without treatment and those who are immunocompromised will recover with antibiotic use.

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