Cat-scratch disease (CSD) is a bacterial infection that affects both children and adults. First signs of the ailment occur two weeks after a scratch, bite or licking open wounds. The infected area swells and becomes red with a round raised lesions in 3-7 days after infection. Patients may experience headaches, fever, exhaustion, and poor appetite. Later the lymph nodes swell becoming tender and painful. The disease requires using antibiotics azithromycin and doxycycline for treatment. This research covers the sign and symptoms, cause and transmission, pathogenicity, treatment, and epidemiology of the disease.
Signs & Symptoms
Lymph nodes swelling (lymphadenopathy) occurs between one and three weeks after infection in the jaws, arms, groins, neck, and around (Centers for Disease Control). The patient may have erythematous papule or vesicle at the point of infection experiencing reduced appetite, aches, and malaise. Other symptoms include a backache, chills, joint pains, and abdominal pain (Florin 1419).
In rare cases, CSD can cause cardiac or neurologic conditions, such as endocarditis, meningoencephalitis, and encephalopathy, with a high mortality rate. The disease manifests itself through Parinaud’s oculoglandular syndrome or neuro-retinitis or optic neuritis (Vyas). Furthermore, patients with weak immune systems, including ones affected by HIV, may acquire bacillary peliosis or bacillary angiomatosis that adversely affect their skin. The infection can result in cystic spaces filled with blood in spleen and liver or the loss of sight.
Causes & Transmission
CSD occurs due to infection of Bartonella henselae since cats are its natural reservoir. Kittens serve as the agent of transmission more often than adult cats because they have a tendency to scratch and bite while learning to attack their prey (Centers for Disease Control). The cats get B. henselae infection when feces of the fleas, especially Ctenocephalides felis, get into their wounds. When cats bite and scratches flee, they pick the infected feces between their teeth and nails. Similarly, they acquire the infection through fighting with other infected cats. Once a cat has the infection, it transmits through scratches, bites, and licks on open wounds (Vyas). Besides, other organisms, such as spiders and ticks, act as vectors of transmission of the B. henselae. However, such cases are rare; hence, cat bites, scratches, and licks on open wounds remain the primary means in which the disease reaches the human body.
The bacteria know as B. henselae originates from a cat flea Ctenocephalides felis and causes the cat-scratch disease. The presence of CSD begins to manifest between 3 to 10 days; during this period, a lump starts to form at the infected part of the body (Diana). It takes another 1 to 7 weeks until the lymph node swelling. The initial changes in lymphatic nodes occur due to the proliferation of epithelioid cells. After the spread, the central part of leukocytes undergoes exudation and necrosis. In some cases, the propagation changes result in creating of epithelioid cell tubercles (Diana). Besides, the necrotic centers of the white blood cells undergo homogenization to form tubercles like those in syphilis, tularemia, and tuberculosis.
Cat-Scratch Disease passes without any medication in healthy individuals. However, studies have shown that it may spread and affect the central nervous system, eyes, spleen, and liver in 5% to 14% of patients (Conrad 57). Some medical experts argue that the infection should be left for the body to fight (Florin 1421). However, antimicrobial agents of grade 2B are applicable in treating patients with mild to moderate ailments (Centers for Disease Control and Prevention). Treatment is vital because it helps to prevent the infection from spreading in one’s body. Azithromycin and doxycycline are antibiotics suggested in treatment. In pregnant women, azithromycin is suitable for treatment because it eliminates the side effect caused by doxycycline. Nevertheless, doxycycline is suitable in the treatment of optic neuritis caused by B. henselae because it penetrates the central nervous system and the eye tissues more effective than azithromycin (Florin 1424).
B. henselae has a global presence with major cases reported in the UK, Italy, Israel, Europe, New Zealand, the United States, Australia, and Japan. Only a few cases of CSD were noticed in the UK after 1970 due to the reduced usage of skin antigen test because of safety concerns (Florin 1414). However, research indicates that the population of B. henselae is high in the UK with approximately 20% of all tests. In regions experiencing temperate climates, the condition is common in winter and autumn. Research indicate that the seasonality of the infections results from the temporal breeding of cats, the presence of cat fleas, and kittens acquisition by new owners (Windsor 101).
The examination of factors that influence the distribution of CSD, including climate, season, and geographical location, indicate that in the United States, the disease is common in warm and humid areas compared to other regions. The country experiences seasonal outbreaks of CSD in January and July (Florin 1415). The highest level of patients affected by the disease occurred in 2000 between July and October. Most scholars relate the seasonal distribution of the bacterium to temporal to bleedings, acquisition of cats, and seasonal presence of Ctenocephalides felis in the United States (Florin 1417). Studies have shown that outdoor cats, felines, and cats infested with fleas are most likely to have B. henselae (Florin 1420). Besides, studies indicate that CSD is common in the South America and rare in its western regions (Windsor 101). In America, the rate of infected cats was approximately 28% to 51%. However, infected cats have no clear signs; thus it is hard to distinguish them from the healthy ones.
Most cases of CSD go unreported, so it is impossible to give accurate statistics on the number of cases in most affected regions of the world. In 2000, 0.60 per 10000 of teenagers and 0.86 for children below five years old reported having the CSD in the US (Windsor 101). These cases coincided with the number of cats acquired within the season. Studies indicate that children and teenagers have the infection rate of 54% and 87% (Windsor 101). Recent studies show that CSD is more common in adults with reports indicating the infection rate of 40% (Florin 1417).
Cat-Scratch Disease is an infection caused by B. henselae. Cats acquire the bacteria from bites or scratch of fleas. The disease then moves to humans through cat bites, licks of open wounds or scratches that break the skin. The first signs of the infection occur in 3 to 7 days and the lymph node swelling within 1 to 7 weeks. Patients experience swollen nodes on the neck, armpits, jaws, arms, groins, and around the ear as well as aches, malaise, and reduced appetite. The bacteria causing disease is present in the UK, Italy, Israel, Europe, New Zealand, Australia, America, and Japan. Despite its significant presence, patients can cure taking azithromycin and doxycycline antibiotics.
Centers for Disease Control and Prevention. “Cat-Scratch Disease.” Apr. 30, 2014.
Chen, Diana. “Bartonella henselae” MicrobeWiki. 20 August 2010.
Conrad, Dennis A. “Treatment of cat-scratch disease.” Current Opinion in Pediatrics 13.1 (2001): 56-59.
Florin, Todd A., Theoklis E. Zaoutis, and Lisa B. Zaoutis. “Beyond cat scratch disease: widening the spectrum of Bartonella henselae infection.” Pediatrics 121.5 (2008): e1413-e1425.
Vyas, J. M. “Cat-scratch disease.” MedlinePlus, 9 October 2015.
Windsor, Jeffrey J. “Cat-scratch disease: epidemiology, etiology, and treatment.” British journal of biomedical science 58.2 (2001): 101.