May 16, 1997

Warm months signal start of tick season

Warm months signal start of tick season

The warm spring sunshine beckons to more than gardeners and sunbathers, pediatric infectious disease experts at Vanderbilt Children's Hospital warn.

In Middle Tennessee, "tick season" kicked off in April, when nymph-stage ticks began searching for a blood meal so they could develop into adults. Aside from being a pretty disgusting nuisance, these blood suckers can carry some potentially serious – and sometimes life-threatening – diseases, including Rocky Mountain Spotted Fever.

Doctors at Vanderbilt University Medical Center typically see several patients each spring and summer with Rocky Mountain Spotted Fever, ranging from mild cases to more serious ones that require hospitalization, says Dr. Mark R. Denison, assistant professor of Pediatrics in the division of Pediatric Infectious Disease.

"The region including Middle and East Tennessee has a significant amount of Rocky Mountain Spotted Fever cases," Denison said. "In fact, the disease occurs in the Cumberland Plateau and Smoky Mountains areas much more frequently than in the Rocky Mountains.

"It is an illness that we see every year, but it's preventable and it's treatable."

The season for tick-borne diseases peaks in this area in June and July before tapering off through September.

Rocky Mountain Spotted Fever is caused by a microorganism called a rickettsia, which is most commonly transmitted to humans by the common dog tick. The disease causes an infection of the blood vessels, which can result in a variety of symptoms, including headache, abdominal pain, sensitivity to light, fever, general malaise and blood-shot eyes.

Headache is an important clue because headaches are not common among children, Denison said.

But the classic sign is a characteristic spotty rash. The rash is petechial, which means the spots do not blanch when you press against them.

"A petechial rash in children is always a relative emergency," Denison said. "In Rocky Mountain Spotted Fever, the rash begins as little blood spots, often on the wrists and ankles. The spots enlarge and spread elsewhere on the body, often including the palms of the hands and soles of the feet."

Unrecognized and untreated, Rocky Mountain Spotted Fever may develop into a severe disease including life-threatening complications of the central nervous system, heart, lungs, kidneys or other organs.

The rash is helpful in making a diagnosis, but in some cases it appears late in development of the disease, if at all.

Rocky Mountain Spotted Fever is treated with antibiotics, and early treatment is important to prevent complications, Denison said.

Ehrlichiosis and Lyme Disease are two other tick-borne illnesses that are important for families to know about, Denison said.

Ehrlichiosis is usually a milder disease caused by a rickettsial organism similar to that which causes Rocky Mountain Spotted Fever. The tick that transmits ehrlichiosis is not known, but the disease is found in this area, Denison said.

Symptoms of ehrlichiosis include headache, chills, malaise, muscle and joint aches, nausea, vomiting, loss of appetite and acute weight loss. A rash is also possible, but less frequent than with Rocky Mountain Spotted Fever.

"It can have a more variable course than Rocky Mountain Spotted Fever," Denison said. "People usually recover from it, and they usually don't have complications. In most cases, it's either not recognized or runs its course."

In cases that do require treatment, antibiotics are used.

Lyme Disease, caused by a microorganism called a spirochete, is transmitted by the tiny deer tick. Lyme Disease is uncommon in this area, but it is a common infection elsewhere in the United States, so travelers should take caution, Denison said.

"People should be aware of it, especially if they're traveling in the area around Connecticut and Long Island Sound," he said. "It also occurs in the upper Midwest and the western United States."

A distinctive rash is also associated with Lyme Disease. The rash, called erythema migrans, begins at the site of the tick bite and typically expands to form a larger rash with a clearing in the center. Other rash sites away from the tick bite are also possible.

Lyme Disease can also cause a number of other symptoms, including fever, general malaise, headache, severe fatigue, joint and muscular pains, and redness and swelling around the eyes.

"The findings in Lyme Disease can be much more variable and prolonged than Rocky Mountain Spotted Fever and ehrlichiosis," Denison said. "If Lyme Disease remains unrecognized and untreated, a person may develop later complications over a long period of time."

The disease may be trickier to recognize, too, because the symptoms tend to be variable and intermittent, he said. In addition, because the deer tick is so tiny, many people never realize they've been bitten.

Lyme Disease, like the other two illnesses, is treated with antibiotics.

Prevention of tick bites, early removal of ticks and early recognition and treatment of tick-borne illnesses are all important safeguards, Denison said.

Tips for being tick-safe include:

€ When possible, avoid tick-infested areas such as high weeds or woods.

€ Although it is sometimes impractical in Middle Tennessee's warm and muggy climate, long sleeves and pants tucked into socks are best if you are going hiking or plan some other outdoor activity.

€ Spray boots or shoes and socks with insect repellent.

€ Inspect yourself and your family (bodies, hair and clothing) thoroughly and as soon as possible after outdoor activities.

€ If you find an attached tick, remove it promptly. The length of time the tick is attached has been associated with the risk of infection.

€ To remove a tick, use forceps (tweezers) to grasp the tick close to the skin. Pull straight up with steady, even pressure.

€ Monitor the bite for signs of local infection, and take note of when the bite occurred. Then, if illness develops, you can let the physician know to take the risk of tick-borne illness into account.

Taking antibiotics immediately after a tick bite has not been shown to be useful in preventing infection and is not recommended.