Tick-Borne Dangers

Last Editorial Review: 1/30/2005

Summer is the prime season for tick bites. Here's what you need to know to protect yourself.

WebMD Feature

June 19, 2000 -- The 22-year-old soldier wasn't worried. He had been bitten by a few ticks while out on military maneuvers, but that wasn't unusual for soldiers at the base in Tennessee. Even when he developed a fever, he wasn't alarmed.

But instead of getting better, his condition steadily worsened. "By the time they brought him to the emergency department [here], the oxygen levels in his blood were beginning to fall dangerously," says Greg S. Martin, MD, a physician at Vanderbilt University Medical Center in Nashville, Tenn., who wrote a description of the case in the September 2, 1999 issue of The New England Journal of Medicine. "This poor kid was in bad shape. And very, very scared."

The diagnosis was a tick-borne disease called ehrlichiosis. "We had him on three powerful antibiotics to treat the infection. And by all rights he should have recovered," says Martin. He didn't. Within hours the young man's lungs and liver began to fail. His blood clotted in his veins. Two days after he was admitted, he went into seizures and died.

Blood-Sucking Bugs

What makes ticks so dangerous? Their vampire-like eating habits. Most ticks feed on the blood of unwitting victims at least twice and in some cases up to four times during their lifecycles. If a tick happens to carry a virus, bacterium, or protozoan when it bites you, it can transmit the disease-causing organism.

Take a hike in the woods almost anywhere from California to Connecticut and you could easily find yourself on the receiving end of a tick's hypostome -- the long sword-like extension it uses to penetrate the skin and begin its blood meal.

Tick-borne illnesses are a large and growing health threat in many parts of the United States, say experts from the U.S. Centers for Disease Control and Prevention (CDC) -- especially in the summer months, when ticks become most active. The disease that killed the young recruit in Tennessee is just one of 10 serious human illnesses carried by ticks.

New Reasons to Shudder

The most common infection carried by ticks is Lyme disease, which struck nearly 17,000 Americans in 1998, according to the CDC -- the highest number of cases ever reported. Symptoms include fatigue, chills and fever, headache, muscle and joint pain, and a characteristic circular rash. Untreated, Lyme disease can lead to joint and nervous system damage including arthritis, numbness, chronic pain, and heart rhythm problems.

Another serious illness spread by ticks, Rocky Mountain spotted fever, strikes some 300 to 400 Americans a year according to the CDC. Symptoms include a spotted rash that spreads from the wrists and ankles, high fever, and muscle pain. Some years, as many as 5% of victims have died.

Ehrlichiosis, which killed the soldier in Tennessee, was first discovered in the 1980s. In 1998, scientists reported on four people in Oklahoma who had been infected with a form of this disease long thought to afflict only dogs. Four more cases turned up in people in Missouri, Oklahoma, and Tennessee in 1999, according to a report in the September 15, 1999 issue of The New England Journal of Medicine.

Meanwhile, researchers have turned up other reasons to worry about ticks. On January 13, 2000, The New England Journal of Medicine reported the case of a 6-year-old girl who nearly died of tick paralysis, a rare condition caused by toxic substances produced by ticks themselves.

Taking Aim at Ticks

Luckily, simple precautions can help hikers and campers avoid being bitten by ticks this summer. (For more details, see How to Defend Yourself.) Even if you do get bitten, most illnesses carried by ticks can be treated successfully with a course of antibiotics. Get medical attention if a rash appears on your skin or you experience flu-like symptoms after you?ve been out in tick country.

Researchers are moving on many fronts to reduce the danger of tick-borne diseases. Most of the efforts target Lyme disease because it takes the biggest toll. But some of the strategies may also prove useful against other infections carried by these little bloodsuckers.

At the University of Rhode Island, researchers have created a robot-like device used in the woods to lure deer with scented bait. When a deer approaches, sensors zero in on heat given off by the animal's head and trigger the release of an aerosol spray containing a tick-killing fungus. The scientists hope that this strategy, being tested on Prudence Island in Rhode Island's Narragansett Bay, may slow the transmission of Lyme disease by reducing the tick population.

A relatively new Lyme disease vaccine has been found effective in preventing illness in people bitten by ticks. If you live in areas of the East Coast where Lyme disease is endemic -- including New England and the Southeastern states -- and you spend time in wooded areas, ask your doctor about the vaccine, called LYMErix. You'll need three separate shots over the course of a year for maximum protection. Some concerns have been raised about possible side effects of the vaccine (such as pain in the joints), so it may not be right for everybody.

Of course, the best prevention is to avoid being bitten in the first place. But if you remove a tick quickly, you can usually prevent the spread of most tick-borne illnesses. Ticks typically require at least 24 to 48 hours to transmit the Lyme bacterium, according to Robert Lane, PhD, an entomologist and tick expert at the University of California at Berkeley. In the case of tick paralysis, removing the bug offers a complete cure. Once the flow of toxins produced by the tick stops, the paralyzing effect quickly dissipates. In some cases, patients close to death have recovered completely with 24 hours.

Why the young soldier succumbed remains a mystery, says the physician who treated him. "Luckily, rapidly fatal infections like that are very rare," says Martin. "But they also serve as a warning for us to take tick bites very, very seriously."

Peter Jaret, a freelance writer based in Petaluma, Calif., has written for Health, Hippocrates, and many other national publications. He is a contributing editor for WebMD.

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