The Hidden Dangers of Cat Scratches. How to Protect Yourself

Cat scratch disease (CSD) is a bacterial infection that is transmittable between cats and humans (Source). The disease occurs when an infected cat scratches or bites a person, breaking the skin and transmitting the bacteria called Bartonella henselae into the wound (Source). CSD typically causes a developing red lesion or swelling at the site within 3-10 days after the cat injury. Additional symptoms may include fever, fatigue, headache, and swollen lymph nodes near the wound. While usually self-limiting, CSD can progress to serious complications in immunocompromised individuals, such as encephalitis, endocarditis, and damage to the liver or spleen. Therefore, understanding and preventing CSD in cats, as well as promptly treating scratches and bites, is important for public health.


Cat scratch disease is transmitted to humans through scratches, bites, or saliva from infected cats. The bacteria, Bartonella henselae, can be found in cat claws, teeth, and saliva. When an infected cat scratches or bites a person, the bacteria can get into the wound and cause an infection. The bacteria can also be transmitted if saliva from an infected cat gets into an open wound or the eyes, nose, or mouth of a person. Kittens are more likely to transmit the bacteria than adult cats. Stray and outdoor cats have a higher risk of being infected than indoor cats. Even a minor scratch or bite that does not break the skin can potentially transmit the bacteria if saliva gets into a small cut or the wound. Proper cleaning and disinfection of any cat wound, even superficial scratches, is important to avoid infection. Cats infected with Bartonella henselae may not show any symptoms, so it is difficult to tell if a cat carries the bacteria. For this reason, it is wise to exercise caution with any cat scratch or bite. While cat scratches and bites are the most common method of transmission, Bartonella henselae bacteria have occasionally been found in cat fleas as well, indicating flea bites may also rarely transmit the infection in some cases.


The most common symptoms of cat scratch disease include fever, fatigue, and a rash at the site of the scratch or bite. The rash typically appears 3-10 days after the initial scratch or bite as a small, red bump that can later form a blister or scab. The rash may be accompanied by swelling of the lymph nodes near the affected area, such as under the arm or in the neck if scratched on the hand or face. Lymph node swelling occurs in around 90% of cat scratch disease cases. Other symptoms can include headache, poor appetite, and muscle pains. In rare cases, more serious symptoms may develop if the infection spreads to the liver, spleen, brain, or eyes. However, most people recover fully within 2-4 months without complications.


While cat scratch disease is usually mild, some people can develop serious complications. The most common complications include:1

  • Encephalitis – inflammation of the brain
  • washing cat scratches with soap and water can help prevent infection

  • Arthritis – joint inflammation
  • Hepatitis – liver inflammation
  • Ocular issues like neuroretinitis
  • Splenitis – inflammation of the spleen

These complications tend to occur in less than 1% of cases. However, encephalitis specifically can be very serious and life-threatening if it’s not treated promptly with antibiotics. Encephalitis cases require hospitalization and can cause permanent neurological damage or even death if untreated.2

Those at highest risk for complications include people with weakened immune systems, such as those with HIV/AIDS or those taking immunosuppressant medications. Children under the age of 5 are also at increased risk. Seeking prompt medical treatment is crucial for anyone exhibiting serious symptoms or belonging to a high-risk group.


Cat scratch disease is typically diagnosed through a combination of patient history, physical examination, and lab tests. Doctors will ask if the patient has been scratched or bitten by a cat or kitten recently, which is a major clue in the diagnosis (Johns Hopkins Medicine). Physical examination of the patient may reveal a healing wound from a cat scratch or swollen lymph nodes near the scratch.

To confirm the diagnosis, doctors can order blood tests that look for antibodies to the Bartonella henselae bacteria. These antibodies develop within 2 weeks of infection. Blood cultures can also sometimes isolate the bacteria directly (Cleveland Clinic). In rare cases, doctors may take a sample of fluid from swollen lymph nodes and test it for bacterial DNA (American Academy of Family Physicians). Imaging tests like CT scans or ultrasounds may also be used to examine the lymph nodes.

If the patient’s history, exam, and lab tests all indicate cat scratch disease, then a firm diagnosis can be made without additional testing in most cases.


Since cat scratch disease usually resolves on its own, treatment focuses on managing symptoms and monitoring for complications. Antibiotics are not routinely prescribed but may be used in certain cases.

antibiotics may be used to treat serious cat scratch disease symptoms

Symptom management involves over-the-counter medications like acetaminophen or ibuprofen for fever and pain relief. Topical antibiotic creams can be applied to the scratch or sore to prevent secondary infections. Warm compresses can help drain enlarged lymph nodes. Rest and fluids are encouraged while ill.

Antibiotics are not normally needed but may be considered for severe, persistent symptoms or if complications develop. The antibiotics azithromycin and rifampin are most commonly used. According to the American Academy of Family Physicians, antibiotics do not seem to alter the course of uncomplicated cat scratch disease. Even without antibiotics, symptoms usually resolve within 2-4 months. Consult a doctor regarding antibiotic treatment (source).

Those with weakened immune systems or more serious complications like encephalitis may require hospitalization and intravenous antibiotics. Abscessed lymph nodes sometimes need to be drained or surgically removed.

Regular follow-up is recommended to monitor symptoms and lymph node swelling. Seek prompt medical attention if symptoms worsen or new concerning symptoms develop.


There are several ways to help prevent cat scratch disease infection:

  • Avoid scratches and bites from cats, especially kittens. Handle cats gently and avoid rough play.
  • Wash any scratches or bites from cats right away with soap and water. Use an antiseptic on the area.
  • Keep cats indoors and away from stray cats to reduce the risk of flea infestation. Fleas can transmit Bartonella bacteria between cats.
  • Control fleas on indoor/outdoor cats with regular flea medication treatments as recommended by your veterinarian. Flea control is important.
  • controlling fleas on cats through medication can reduce disease transmission

  • Do not allow cats to lick open wounds on humans. Licking can potentially transmit Bartonella bacteria.
  • Use caution handling stray cats, especially kittens. Strays are more likely to carry fleas.
  • Wear gloves when handling stray or feral cats. Thick gloves can help prevent bites and scratches.
  • Children should be supervised around cats and taught safe handling to avoid scratches.
  • Getting cats vaccinated may reduce risk of Bartonella infection, but no vaccine is fully protective.
  • cat vaccination may provide some protection against cat scratch infection

While declawing cats is controversial, it is not recommended solely to prevent cat scratch disease, as it does not reduce disease risk. Proper handling and flea control are more effective preventive measures.

If a cat scratch or bite occurs, promptly wash and disinfect the wound to help decrease the chance of infection.

Risk Factors

Certain people are at higher risk of developing cat scratch disease or experiencing more severe symptoms (source 1). Those at higher risk include:

– Children, especially those 5-9 years old, likely due to more frequent and rough play with cats resulting in scratches and bites.

– People with weakened immune systems, such as those with HIV/AIDS, cancer, organ transplants, or taking immunosuppressant medications. They are more prone to developing complications from the infection.

– People with pre-existing illnesses like diabetes and liver or kidney disease. The infection can exacerbate their condition.


The prognosis for most people with cat scratch disease is excellent. Typically, immunocompetent patients recover fully within 2-4 months without any treatment [1]. The enlarged lymph nodes will gradually return to normal size during this time. Most symptoms completely resolve on their own within this timeframe.

However, cat scratch disease can be fatal in immunocompromised patients if untreated. Patients with weakened immune systems are at higher risk for developing more severe disseminated disease or endocarditis, which can be life-threatening. Immunocompromised individuals may require antibiotic treatment to clear the Bartonella henselae infection [2]. With appropriate treatment, the prognosis significantly improves.

Overall, cat scratch disease poses little long-term risk for healthy individuals. But prompt diagnosis and management is essential for immunocompromised patients to prevent dangerous complications.


Cat scratch disease caused by the Bartonella henselae bacteria can lead to serious complications if left untreated. While some cases resolve on their own, it is important to seek medical care if symptoms persist or worsen. Diagnosis involves clinical exam, blood tests, and sometimes lymph node biopsy. Antibiotics are the primary treatment. Avoiding cat scratches and bites, flea control, and proper handwashing can help prevent infection. Though rare, cat scratch disease can lead to damaging effects like neuroretinitis, Parinaud oculoglandular syndrome, encephalitis, and endocarditis. Early diagnosis and appropriate antibiotic treatment is key to reducing the risk of complications. Do not take chances with cat scratch disease; always monitor for symptoms after a cat bite or scratch and follow up with a healthcare provider if concerned.

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