Cat-Scratch Disease May Lead to Serious Illness

Bartonella henselae, the bacterium that causes Cat-Scratch Disease (CSD), is carried by 40% of cats, according to the Centers for Disease Control and Prevention (CDC). The bacterium is carried in the claws and mouth of infected cats and spreads through bites, scratches, or licks to an open wound by cats.

Annually, CSD occurs in more than 40,000 people worldwide. Patients who have HIV infection are especially vulnerable. Research shows that 80% of cases occur in individuals younger than 21 years of age. Illness occurs approximately 3 to 14 days after infection.

For people, symptoms are marked by fever, headache, and fatigue. There is also a tell-tale bump or swelling in the lymph node under the arm closest to the original scratch or bite. The lymph node could be red with round, raised lesions and can also have pus. In rare cases, there can be severe complications, such as brain, bone, or eye infections, and infections can sometimes be fatal.

Cats can be bacterimic between several weeks and a few years. Clinical diagnosis in cats, according to research from the American Veterinary Medical Association (AVMA), is difficult because cats who are chronically infected appear healthy.

The American Society for the Prevention of Cruelty to Animals (ASPCA) estimates that between 30% and 37% of households in the United States own cats. Considering this estimate, public awareness regarding CSD and prevention is important. For individuals who choose cats as a companion pet, especially if they are immunocompromised, the AVMA recommends that those individuals, “seek a cat raised in a clean, flea-controlled cattery. If possible, the cat should be an adult and obtained from a flea-controlled environment.”

The National Institute of Health’s (NIH) website reported that the CDC will be publishing a new report on CSD in the October issue of the Journal of Infectious Diseases. The report will detail how researchers sought to estimate the extent of the disease and who is most at risk. CSD, they found, is most common in children between the ages of five and nine years old.

Individuals who lived in the southern United States were also susceptible. However, individuals who own cats should not be afraid. Lead researcher, Dr. Christina Nelson, a CDC medical officer, told Medline Plus that, "Cat-scratch disease is preventable and people can reduce their risk.” Owners should keep their cats indoors as B. henselae is transmitted through flea feces and safe flea control products will reduce the chance of both the cat and the owner contracting CSD. If owners plan to allow their cats to roam, they should do so for only very short periods of time. Dr. Nelson said, “Cats that are on the prowl or hunting in the woods get more fleas, so they are more likely to carry the bacteria.”

The CDC says “use of antibiotics to shorten the course of the disease is debated. Most infections resolve themselves without treatment.” However, azithromycin reduces lymph node swelling more quickly than no treatment at all. According to research from the AVMA, antimicrobial treatments that have so far been evaluated in cats potentially reduce the bacteremia but do not eliminate the infection completely.