Cat Scratch Disease
Cat-scratch disease is an infection caused by the bacteria Bartonella henselae.
What is going on in the body?
The bacteria causes a local infection at the site where it entered the body. Lymph nodes near the area become swollen 1 to 7 weeks after exposure to the bacteria. Sometimes, a small, solid skin lesion will develop at the site.
Most cases of cat- scratch disease are self-limited, which means they go away on their own. In rare cases, cat-scratch disease can cause infections in other body areas, such as:
- conjunctivitis and other eye problems
- encephalitis, injury with confusion and occasionally seizures
- osteomyelitis, a bone infection
- pneumonia, persistent fever, liver, and heart problems, among others
People with impaired immune systems are more likely to suffer severe and complicated infections. This includes people with immunodeficiency disorders, such as HIV. People who are being treated with chemotherapy or radiation therapy for cancer are also at higher risk.
What are the causes and risks of the infection?
Bacteria causes cat-scratch disease. They are transmitted by contact with the saliva of a cat. An individual can become infected from a cat bite or scratch, or from flea bites.
The saliva is found on the cat's fur and paws after the cat grooms itself. The cat itself is usually healthy. Young cats are the most common source of infection for humans.Cat-scratch disease is most common in children and adolescents. It is seen most often in late summer, fall, and early winter.
How is the infection diagnosed?
Diagnosis of cat-scratch disease begins with a medical history and physical exam. Library tests may be ordered to see if the person is producing antibodies to the bacteria. A polymerase chain reaction (PCR) test may also be ordered. Using special techniques, the bacteria can sometimes be seen in a biopsy specimen from the affected body part.
Long Term Effects
What are the long-term effects of the infection?
Most healthy people recover without long-term effects. People with impaired immune systems can have permanent organ damage. Antibiotics may be recommended for both groups.
What are the risks to others?
Cat-scratch disease is not passed from person to person.
What are the treatments for the infection?
In healthy people, the infection usually goes away in 2 to 4 months without treatment. In complicated cases, antibiotics, such as azithromycin (i.e., Zithromax, Zmax) or doxycycline (i.e., Adoxa, Doryx, Oracea, Periostat, Vibramycin) can be used. Other antiobiotics may be prescribed for specific indications.
What are the side effects of the treatments?
Antibiotics may cause rash, stomach upset, or allergic reactions.
What happens after treatment for the infection?
Most people recover from cat-scratch disease and need no further treatment. If the person has an impaired immune system or permanent organ damage, further treatment may be required.
How is the infection monitored?
Any new or worsening symptoms should be reported to the healthcare professional.