The Centers for Disease Control and Prevention recently published the results of a retrospective study investigating the incidence of Cat Scratch Disease (CSD), a bacterial infection that can be caused by the scratches or bites of cats infected with the bacteria Bartonella henselae. The vast majority of CSD cases in people are readily treated and result in no long term health consequences, but in very rare cases, more serious infections of the brain, eyes, and heart may occur. While it has been known for some time that cats can carry Bartonella (they’re infected primarily by fleas that can carry the bacteria and infect cats when they bite them) and that it can cause infections of scratches or bites, this study was carried out to better define how common CSD is in the United States, and who is at greatest risk for this relatively rare condition.
Researchers reviewed the insurance databases of approximately 40 million health insurance enrollees per year between 2005 and 2013 and searched for a coded diagnosis of CSD. They found that the average annual incidence of CSD was approximately 4.5 cases per 100,000 population, or approximately 0.005%. They found that the highest incidence was in southern states and that children between the ages of 5 and 9 years are at increased risk for CSD. Among adults, women between the ages of 60 and 64 years were at highest risk. Immunocompromised individuals are at a higher risk for serious complications of CSD.
The study also reports on the seasonality and geographic distribution of CSD in the US and hypothesizes about the potential causes of documented trends in CSD. It stresses that CSD is a relatively rare condition and that cat owners can take a number of precautions, including keeping cats inside, following strict flea control practices, monitoring young children’s interactions with cats (particularly with kittens, who are at greater risk of being infected with Bartonella and who may bite more readily during play), washing any cat bites/scratches with soap and running water, and washing hands after even casual contact with cats.