What are the other Names for this Condition? (Also known as/Synonyms)

• Bartonellosis
• Benign Inoculation Lymphoreticulosis
• Teeny’s Disease

What is Cat Scratch Disease? (Definition/Background Information)

• Cat Scratch Disease is a bacterial infection caused by Bartonella henselae bacteria, which is found in the saliva and claws of cats and kittens. It is transmitted to humans through contact with infected cats, through bite, lick, or scratch
• After contact with the infected cat or kitten, the contact site may become sore, following which the individual develops fever, body ache, headache, malaise, and enlargement of the lymph nodes
• Healthy individuals with a strong immune system generally overcome the disease and symptomatic treatment may be provided. However, immunocompromised individuals may take longer to recover. The prognosis of Cat Scratch Disease is generally good

Who gets Cat Scratch Disease? (Age and Sex Distribution)

• Individuals of any age are prone to Cat Scratch Disease, though it is common among children and teenagers, especially because they are likely to play more with cats
• The condition is slightly more common in males than in females
• Cat Scratch Disease is seen worldwide, especially in the hot and humid regions. It can affect individuals of any race or ethnicity

What are the Risk Factors for Cat Scratch Disease? (Predisposing Factors)

The risk factors of Cat Scratch Disease include:

• Playing with or petting infected cats or kittens
• Exposure to kittens rather than cats, places an individual at a much greater risk (about 15 times higher risk)
• Areas where the climate is warm and humid, which favor flea population (fleas are carriers or vectors of the bacteria)
• People living in regions where fleas are endemic are at increased risk
• Immunocompromised individuals, such as those with HIV infection, recent surgeries, etc. have a higher chance of being affected by Cat Scratch Disease

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Cat Scratch Disease? (Etiology)

Cat Scratch Disease is a bacterial infection caused by Bartonella henselae, which is found in the saliva of cats and kittens. These bacteria are transmitted to humans through contact with infected cats and kittens.

The transmission of the bacteria to humans may occur in the following ways:

• Cat scratch: The bacteria may be present in its claws
• Cat bite or lick: The bacteria may be present in its oral cavity or saliva
• Petting cats: The bacteria may also be present in the cat’s fur and get transferred to the hands. From the hands, the bacteria can enter into any part of the body through actions such rubbing one’s eyes with the same hand, eating a snack without washing the hands, etc.
• Sometimes, dogs and thorn pricks can also be sources of infection, but these are very uncommon

What are the Signs and Symptoms of Cat Scratch Disease?

The signs and symptoms are different for Typical (Classical) Cat Scratch Disease and Atypical Cat Scratch Disease.

Signs and symptoms for Typical (Classical) Cat Scratch Disease include:

• The symptoms are usually mild
• Individuals with the disease usually have a history of exposure to cats 95% of the times
• A red patch develops in 1 to 3 weeks following exposure to the infected cat. This is called an inoculation lesion. It then becomes a bump, which may develop pus formation, and then break open, finally ending up as a scar
• The other common symptoms seen are:
  • Lymphadenopathy: Swollen lymph nodes in the armpits, head, neck, and groin region
  • Lethargy, malaise
  • Flu-like symptoms such as body aches, headache, and fever

Signs and symptoms for Atypical Cat Scratch Disease (uncommon):

• Usually when individuals present with atypical disease, they may appear to have signs and symptoms of the typical disease. Sometimes, they may present only with symptoms specific to the atypical disease
• Loss of appetite or poor appetite, weight loss
• Backache, joint pain
• Abdominal pain
• Formation of skin rashes
• High fever, sweats, and chills
• Vomiting
• Sore throat
• Fits (seizures)
• Enlargement of the spleen
• Pericarditis (inflammation of the lining outside the heart)
• Pleural effusion (fluid around the lungs)
• Bone lesions: In children, bones lesions (osteolytic) and inflammation of the liver and spleen may also be seen

Some serious and rare, signs and symptoms of Cat Scratch Disease based on the organs affected include:

• Parinaud’s oculoglandular syndrome that is characterized by pink eye, fever, and swelling of the lymph nodes around the ear
• Optic neuritis: Infection of the retina (inner part of the eye)
• Encephalopathy or encephalitis (inflammation of the brain) can occur more commonly in immunocompromised individuals

How is Cat Scratch Disease Diagnosed?

The diagnosis of Cat Scratch Disease may include:

• Thorough evaluation of the individual’s medical history and a complete physical examination, including examination of the skin
• During history taking, the physician may want to know the following:
  • When the symptoms began and whether they are becoming worse
  • Any history of exposure to cats, kittens, or dogs (including if the individual walked barefoot outdoors recently)
• A physical examination may reveal a cat scratch or bite on the skin, swollen lymph nodes, and an enlarged spleen. History and physical exam may suggest a diagnosis of Cat Scratch Disease
• Sometimes, the diagnosis may be difficult with only a history and physical exam, especially when there is no history of exposure to cats or kittens
• Indirect fluorescent antibody test (IFA) for Bartonella henselae is a screening (blood) test for Cat Scratch Disease. However, the test cannot differentiate between an active infection or a previous one
• Blood culture followed by polymerase chain reaction (PCR) for detection of Bartonella henselae is the most definitive test for Cat Scratch Disease
• Lymph node biopsy may be done to rule-out other causes of swollen glands. It is not used as the primary test for Cat Scratch Disease

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Cat Scratch Disease?

Generally, Cat Scratch Disease does not lead to any complications. However, an immune compromised individual may be more susceptible to complications.

• Encephalopathy: Inflammation of the brain
• Endocarditis: Inflammation and infection of the inner lining of the heart chambers and valves
• Osteomyelitis: Infection of the bone
• Optic neuroretinitis: Inflammation and or infection of the optic nerve and retina
• Hepatitis: Inflammation of the liver that may cause abdominal pain
• Parinaud’s oculoglandular syndrome that is characterized by pink eye, fever, and swelling of the lymph nodes around the ear

How is Cat Scratch Disease Treated?

Cat Scratch Disease is usually a mild disease and symptomatic treatment may suffice for most individuals. A spontaneous resolution of the condition may also take place in individuals with a healthy immune system. The treatment options may include:

• For mild and moderate Cat Scratch Disease, local heat application to reduce the swelling of the lymph nodes and medications for fever and pain are sufficient
• Lymph node aspiration with needle is sometimes performed to relieve pain in the lymph nodes. Incision and drainage of lymph nodes is generally not recommended, because it may result in scarring and fistulae formation (abnormal opening to the skin from deeper parts), which may lead to secondary infections
• For severe cases of Cat Scratch Disease and for immune-compromised individuals, antibiotics such as azithromycin, rifampin, ciprofloxocin, gentamicin, or trimethoprim-sulfamethoxazole may be prescribed

The healthcare provider will recommend the best treatment options based upon each person’s individual circumstances.

How can Cat Scratch Disease be Prevented?

There is no vaccine to prevent Cat Scratch Disease. The preventative measures for Cat Scratch Disease includes reducing the risk of Bartonella henselae transmission from cats. This can be achieved by:

• Avoiding petting methods that may make the cats and kittens aggressive to the extent that they end up scratching or biting
• Play cautiously with cats and kittens while ensuring that they do not lick the face, areas around the eyes, or any skin wound
• Ensuring that the cats are free from fleas
• Immediately washing any scratch, licks, or bites of cats and kittens with running water and soap

What is the Prognosis of Cat Scratch Disease? (Outcomes/Resolutions)

• The prognosis of Cat Scratch Disease is generally good for both healthy and immunocompromised individuals. Complications are also very rare in normal healthy individuals
• Immune-compromised individuals usually recover fully with proper antibiotic treatment, though it may take them longer

Additional and Relevant Useful Information for Cat Scratch Disease:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/infection-center/