Cat Scratch Disease

Cat Scratch Disease

What is Cat Scratch Disease?

Cat Scratch Disease (CSD) or Bartonellosis is a bacterial infection that occurs world wide.

What causes Cat Scratch Disease?

It may develop after a scratch or bite that breaks the skin caused by a cat infected with the bacterium – Bartonella henselae (B. henselae). Sometimes if an infected animal licks an open wound the infection can develop in the child or young adult.  The cat is usually young but does appear ill.  Cat fleas spread infection between cats. It is unlikely that the cat flea can directly cause infection in humans.  Cat scratch disease occurs most frequently in children and young adults aged less than 20 years.  If the infected individual has a normal immune system then the disease is usually mild and gets better without any treatment.

What does CSD look like?

At the inoculation site one or more small inflamed lumps may develop that sometimes become ulcerated. The lymph nodes in the area may enlarge and become a little tender.  In a child who has normal immunity, general sympoms such as fever and feeling unwell, or tiredness are uncommon and usually mild, but may occasionally be more severe. The upper limbs are the most common site of the cat scratch or bite involved and the enlargement of the lymph nodes enlargement mostly occurs in the armpits, neck and along the jawline on the same side as the bite.  These children do not usually require treatment. The lymph node enlargement usually resolves in 3-4 months.

Rarely eye or mucous membrane infections may develop

What is the likely outcome of CSD?

In an individual with a normal immune system CSD is usually a self-limiting disease, with the primary inoculation site resolving after 3 weeks, and localised lymphadenopathy resolving in 1-3 months.

What other problems can occur with CSD?

In children with HIV infection or who are being treated with chemotherapy interfering with their systems ability to deal with the infection may make them become quite sick, particularly if the infection spreads to involve other organ systems. These children require antibiotics such as azithromycin, or erythromycin and a multidisciplinary approach to therapy is often required  In more widespread disease inpatients who are sick require a search for underlying problems with the immune system.  A condition known as Bacillary Angiomatosis  where the infection leads to the development of proliferation of blood vessels may develop in the skin and deeper tissues of these patients. These are seen vlinically as red lumps.  The risks of cat ownership should  be discussed in these patients

This information has been written by Dr Rudy Yeh, Dr Glenda Wood (FACD)

This page was updated February 2019

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