A tick bite rash can appear on a person's skin after he has been bitten by a tick. Several types of ticks carry bacteria that can cause disease in humans. In many cases, a tick bite rash is the first sign of the disease, though in a few cases, a person may get sick without getting a rash. Diseases that may have a rash include Lyme disease, ehrlichiosis, and southern tick-associated rash illness (STARI).
The rash that usually appears when a person has been bit by a deer tick is typically round and red. In some people, the rash may look more like a bruise. It commonly looks like a bulls-eye or target, as the middle of the rash fades, leaving a dot surrounded by a ring. The rash usually appears within 30 days of the bite. Not all people with Lyme disease develop a rash at the bite sight, though.
People who have been bitten by the lone star tick can develop a tick bite rash that is similar in appearance to the Lyme disease rash. This rash is known as STARI and is often accompanied by flu-like symptoms. STARI doesn't seem to be as severe as Lyme disease, as it doesn't cause neurological symptoms. The cause of the condition is unknown, though patients seem to recover with antibiotics.
The lone star tick can spread another disease, ehrlichiosis, which is caused by Ehrlichia chaffeensis bacteria. Some people with ehrlichiosis develop a red, flat rash on their skin. People may also experience a petechial rash or areas of bleeding beneath the skin. The petechial rash commonly looks like a collection of small red dots. A tick bite rash appears only in about half the cases of ehrlichiosis.
Rocky Mountain spotted fever is another disease spread by deer ticks and dog ticks that can result in a rash and flu-like symptoms. The symptoms of Rocky Mountain spotted fever are often similar to ehrlichiosis, and the two diseases can be mistaken for each other. Rashes caused by the disease typically appear after a patient has displayed other symptoms of the disease.
The rash is usually a collection of small red or pink spots on the skin. Usually, the rash appears on the wrists, palms, and the soles of the feet first and then works it way up a person's limbs. As the rash ages, it can begin to look like a bruise. The disease is treatable with antibiotics.