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How Common is Cat Scratch Fever (Cat Scratch Disease)

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By Nicole Cosgrove

cat owner getting scratched by his pet cat
Image Credit: AJR_photo, Shutterstock

Cat scratch fever, or Cat Scratch Disease (abbreviated CSD), is an infection that humans can get from the bite or scratch of a cat. The infection is caused by a specific bacteria that can sometimes progress to severe disease. According to the Cornell Feline Health Website, a study released by the CDC listed the risk of CSD as 0.005%, or 4.5 out of every 100,000 people. While this is a low risk, continue reading to learn more about risk factors and what to monitor for.

What is CSD?

Cat Scratch Disease is caused by a very specific bacteria, Bartonella henselae. This bacteria is spread when a cat has fleas that carry Bartonella. Cats then become carriers of this bacteria, and can pass it on to people or other animals when they bite or scratch.

It can also be spread by a cat’s saliva into a person’s open wound. The damage produced by the cat biting or scratching has to be severe enough to break skin. The bacteria will then affect both the immediately surrounding tissues, and can sometimes get into the bloodstream, causing severe disease.

red domestic cat bites owners hand
Image Credit: Irzhanova Asel, Shutterstock

Incidence and Those at Highest Risk

The CDC released a study evaluating approximately 40 million health insurance claims listing Cat Scratch Disease as the cause of medical treatment. The CDC reported that between the years of 2005 and 2013, there were on average 4.5 cases out of every 100,000 people.

The study found that those who lived in southern states were at highest risk (6.4 cases per 100,000 people), children ages 5-9 years old were at highest risk (9.4 cases per 100,000 people), and 55% of those hospitalized were less than 18 years of age.

It’s estimated that, of those diagnosed with the disease every year, about 12,000 can be treated on an outpatient basis, and only about 500 people will need to be hospitalized and treated.

The study did only evaluate individuals who were younger than 65 years old. Therefore, the numbers above may or may not be reflective of an entire population, especially with immunocompromised elderly individuals.

What To Monitor For

If you have been bitten or scratched by a cat, one of the most obvious abnormalities will be enlargement of the lymph nodes nearest the wound site (referred to as lymphadenopathy). The immediate surrounding tissue will also likely become red, inflamed, and painful. A localized infection at the wound site may also develop.

As the name of the disease states, affected people may then develop a low-grade fever, headache, and body aches. Most people will have mild symptoms. However, some people will develop severe disease requiring aggressive care and hospitalization.

agressive or playful cat bites humans hand
Image Credit: Nau Nau, Shutterstock

Treatment

The cost of treatment is not cheap! Per the study, it’s estimated that the total annual cost of people treated as outpatients is $2,928,000.00. Those treated as inpatients are estimated to have an annual cost of $6,832,000. This equates to approximately $244/patient as an outpatient, and $13,663.00 as an inpatient (includes follow-up care). Therefore in the US, it’s estimated that CSD costs $9,760,000 yearly.

Treatment consists of antibiotics and local wound care. If you get bit or scratched by a cat, you should immediately clean out the wound and contact your doctor. Depending on how bad the wound is, the condition of the cat, and where the injury occurred, your doctor may choose to immediately put you on antibiotics. Other times, they may have you monitor the area for a few days. For instance, if you get bit or scratched near or over a joint or mucous membrane (eyes, nose, mouth, etc.), you should contact your doctor immediately. These areas can be more prone to developing both localized and serious systemic infections.

Some people will develop a severe infection and require hospitalization, IV antibiotics, and aggressive care. Other affected people may do fine with oral antibiotics and pain medications.

Severe Cases

Though rare, some cases of CSD may progress to severe abnormalities. These include neuroretinitis (inflammation of the optic nerve and retina causing blurry vision), Parinaud oculoglandular syndrome (infection of the eye that appears similar to Pink Eye), osteomyelitis (infection within the bone), encephalitis (brain disease that can results in brain damage or death), and endocarditis (infection of the heart which can lead to death).

As with many other types of pathogens, CSD can severely affect those individuals who are already suffering from being immunocompromised. In other words, a person’s immune system is not healthy and working efficiently. We can see this in cancer patients, individuals with AIDS, individuals who have received an organ transplant, etc.

Closing Thoughts

In conclusion, there is a very low risk of contracting and developing Cat Scratch Disease. However, it is not unheard of. While the majority of cases appear to affect children, immunocompromised and elderly people are not without risk. If you get bit or scratched by a cat, it’s best to immediately clean the wound and contact your doctor about recommended next steps.

 

Featured Image Credit: AJR_photo, Shutterstock

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