Capnocytophaga is a bacteria commonly found in the mouths of healthy dogs and cats. It has been around for years but it has recently been in the news because of the infection in two people, one of whom died.

Human infections with the bacteria are not common; only about 200 cases have been reported worldwide since it was first described in 1976, but since reporting is voluntary it is likely more cases have occurred.

The bacteria is found in the mouths of up to 75% of healthy dogs and almost 60% of cats but it rarely causes infections in animals, even if they are bitten by another animal.

Human infections with Capnocytophaga usually occurs through contact of broken skin with animal saliva, often after a bite or scratch or from allowing a pet to lick an open sore.

It is not necessary or recommended to test normal, healthy dogs and cats to see if they are carrying Capnocytophagia. Most pets are expected to be carrying the organism and there is no evidence that antimicrobial therapy would be effective for eliminating the bacteria from the mouth of a healthy animal, or that this would help reduce the risk of transmission to people.

The most important and effective way to prevent infection is to avoid bites and scratches. If a bite or scratch does occur, immediately wash the wound thoroughly with soap and water. Do not allow pets to lick your face or any areas of broken skin, and keep wounds covered with clothing or a bandage. This also applies to any indwelling medical devices such as intravenous or peritoneal catheters. A physician should be consulted about any bite in person with a compromised immune system or who has had their spleen removed.