Cat-scratch disease

Cat-scratch disease commonly presents as tender, swollen lymph nodes near the site of the inoculating bite or scratch or on the neck, and is usually limited to one side. This condition is referred to as regional lymphadenopathy and occurs 1–3 weeks after inoculation. arms, neck, or jaw, but may also occur near the groin or around the ear. Optic neuritis or neuroretinitis is one of the atypical presentations. People who are immunocompromised are susceptible to other conditions associated with B. henselae and B. quintana, such as bacillary angiomatosis or bacillary peliosis. ==Cause==

Bartonella henselae is a fastidious, intracellular, Gram-negative bacterium. Transmission The cat was recognized as the natural reservoir of the disease in 1950 by Robert Debré. However, fleas serve as a vector for transmission of B. henselae among cats, Cats could be infected with B. henselae through intradermal inoculation using flea feces containing B. henselae. As a consequence, 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 by cat saliva transmitted in a bite. Cryptic Bartonella infection may be a much larger problem than previously thought, constituting an unrecognized occupational health hazard of veterinarians. ==Diagnosis==

of a lymph node affected by cat scratch disease. H&E stain. of CSD showing a granuloma (pale cells—right of center in the image) and a microabscess with neutrophils (left of image), H&E stain The best diagnostic method available is polymerase chain reaction, which has a sensitivity of 43-76% and a specificity (in one study) of 100%. == Prevention ==

Cat-scratch disease can be primarily prevented by taking effective flea control measures; since cats are mostly exposed to fleas when they are outside, keeping cats inside can help prevent infestation. Strictly indoor cats without exposure to indoor-outdoor animals are generally at negligible risk of infestation. thus thoroughly washing hands after handling a cat or cat feces is an important factor in preventing potential cat-scratch disease transmission from possibly infected cats to humans. == Treatment ==

Most healthy people clear the infection without treatment, but in 5 to 14% of individuals, the organisms disseminate and infect the liver, spleen, eye, or central nervous system. Although some experts recommend not treating typical CSD in immunocompetent people with mild to moderate illness, treatment of all people with antimicrobial agents (Grade 2B) is suggested due to the probability of disseminated disease. The preferred antibiotic for treatment is azithromycin, since this agent is the only one studied in a randomized controlled study. Azithromycin is preferentially used in pregnancy to avoid the teratogenic side effects of doxycycline. However, doxycycline is preferred to treat B. henselae infections with optic neuritis due to doxycycline's ability to adequately penetrate the tissues of the eye and central nervous system. ==Epidemiology==

Cat-scratch disease has a worldwide distribution, but it is a nonreportable disease in humans, so public health data on this disease are inadequate. In warmer climates, the CSD is more prevalent during the fall and winter, To determine the recent incidence of CSD in the United States, the Truven Health MarketScan Commercial Claims and Encounters database was analyzed in a case-control study from 2005 to 2013. The database consisted of healthcare insurance claims for employees, their spouses, and their dependents. All participants were under 65 years of age, from all 50 states. The length of the study period was 9 years and was based on 280,522,578 person-years; factors such as year, length of insurance coverage, region, age, and sex were used to calculate the person-years incidence rate to eliminate confounding variables among the entire study population. which supports higher incidence rates of this disease in women. The risk of contracting CSD increases as the number of cats residing in the home increases. ==History==

Symptoms similar to CSD were first described by Henri Parinaud in 1889, and the clinical syndrome was first described in 1950 by Robert Debré. In 1983, the Warthin-Starry silver stain was used to discover a Gram-negative bacillus which was named Afipia felis in 1991 after it was successfully cultured and isolated. The causative organism of CSD was originally believed to be Afipia felis, but this was disproved by immunological studies in the 1990s demonstrating that people with cat-scratch fever developed antibodies to two other organisms, B. henselae (originally known as Rochalimea henselae before the genera Bartonella and Rochalimea were combined) and B. clarridgeiae, which is a rod-shaped Gram-negative bacterium. ==References==