Ehrlichiosis

Ehrlichiosis is a disease of humans and animals caused by bacteria named Ehrlichia. The bacteria, which are transmitted by ticks, can infect certain types of white blood cells.

Cases of ehrlichiosis have been confirmed in many states in this country, including Illinois.

The bacteria are transmitted to humans by the bite of an infected tick. The lone star tick, the American dog tick (or wood tick) and the deer tick (or black-legged tick) have been associated with ehrlichiosis.

Anyone is susceptible to the disease, but persons who spend time outdoors in tick-infested environments are at increased risk of exposure. In the Midwest, risk of exposure is greatest from spring through late autumn, but some ticks can become active any time of year if the temperature is warm enough (about 40 degrees Fahrenheit or more at ground level).

Illness due to ehrlichiosis can be so mild that no medical care is sought or the illness can be severe and sometimes fatal. Symptoms are generally non-specific and other diagnoses may be considered. The more common complaints are fever, headache and muscle aches. Persons with ehrlichiosis also may experience loss of appetite, nausea and vomiting. A rash can occur but is usually not present.

Symptoms typically begin between one and three weeks after exposure. Any person experiencing illness with a fever following a tick bite should consult his or her physician and advise the physician of the tick bite.

If the symptoms of an illness suggest ehrlichiosis, special blood tests can be performed to detect the Ehrlichia agent itself or the presence of antibodies against the bacterium. Certain other laboratory tests can suggest a diagnosis of ehrlichiosis. These include a low white blood cell count, low blood sodium level and certain elevated liver function tests.

The disease responds well to treatment with doxycycline or other tetracyclines. And, fortunately, diseases due to other tickborne agents--Rocky Mountain spotted fever and Lyme disease--also respond to these drugs. Treatment with antibiotics should be considered if ehrlichiosis is suspected because delayed treatment while awaiting laboratory confirmation of the disease may increase the risk for adverse outcomes.

Persons spending time outdoors in tick-infested areas should take precautions against all tickborne diseases:

• Wear light-colored, protective clothing-long-sleeved shirts, long trousers, boots or sturdy shoes, and a head covering. Tuck trouser cuffs in socks. Tape the area where pants and socks meet so ticks cannot crawl under clothing.
• Apply insect repellant containing DEET primarily to clothes. Apply sparingly to exposed skin (except the face). Be sure to wash treated skin after coming indoors. Use repellents containing permethrin to treat clothes (especially pants, socks and shoes)-but not skin. Always follow label directions; do not misuse or overuse repellents. Always supervise children in the use of repellents.
• Walk in the center of trails so weeds do not brush against you.
• Check yourself, children and other family members every two to three hours for ticks. Most ticks seldom attach quickly and rarely transmit a tickborne disease until they have been attached for four or more hours. If your pets spend time outdoors, regularly check them for ticks, too.
• Remove any tick promptly. Do not burn the tick with a match or cover it with petroleum jelly. Do not use bare hands. The mouthparts of a tick are shaped like tiny barbs and may remain embedded and lead to infection at the bite site if not removed properly. The best way to remove a tick is to grasp it with tweezers as close to the skin as possible and gently, but firmly, pull it straight out. Do not twist or jerk the tick. If tweezers are not available, grasp the tick with a piece of tissue or cloth or whatever can be used as a barrier between your fingers and the tick. If the mouthparts do break off, consult your physician about removing them. If you want to have the tick identified, put it in a small vial of rubbing alcohol and contact your local health department for assistance.
• Wash the bite area and your hands thoroughly with soap and water, and apply an antiseptic to the bite site.
• Make sure the property around your home is unattractive to ticks. Keep your grass mowed and keep weeds cut.

Grasp the tick as close to the skin's surface as possible with tweezers and pull straight back in a slow, steady motion without twisting. Avoid crushing the tick's body because it may contain infectious fluid. If you do not have tweezers, you can use your fingertips but they should be covered (with tissue paper or gloves). After the tick is removed, wash the bite site and your hands with soap and water and apply a disinfectant or antibiotic ointment to the site.

• IQuery
• Vector Control & Surveillance
• Tickborne Diseases of the United States, Reference Manual for Health Care Providers
• Information for Hunters on Ticks
• Tick Identification