Is it spotted fever? Doubtful

Research finds the tick-borne illness is rare in state

For years, experts and public health officials watched, perplexed, as hundreds of North Carolinians were diagnosed with Rocky Mountain spotted fever, a potentially fatal tick-spread illness.

In 2004, the state became the national leader for the disease, prompting health leaders to team with N.C. State University researchers to figure out what was going on.

A lot, it turns out. But not Rocky Mountain spotted fever.

The scientists found another culprit for people's ailments -- a related bacterium that causes similar symptoms but cannot kill.

"Ninety-five percent of [spotted fever] cases are just probably this milder illness," said Charles Apperson, the NCSU entomologist who led the tick research.

Apperson, along with public-health sleuths, discovered the disease after an expedition to Chatham County -- busy country for both ticks and tick-borne illnesses.

More than 99 percent of the ticks that researchers collected in fields and forests were an aggressive variety known as Lone Star ticks, which aren't typically carriers of Rocky Mountain spotted fever. Only 25 of the 6,000 ticks picked up were American dog ticks, the type most associated with the disease.

After testing dozens of patients with tick-borne illness, researchers could not confirm a single case of spotted fever. Meanwhile, laboratory tests of the collected Lone Star ticks showed they carried bacteria called Rickettsia amblyommii. It is related to the germ that causes spotted fever but had never been thought to cause human illness.

An informal test, run on the blood of the North Carolina patients, at the U.S. Centers for Disease Control and Prevention confirmed the suspicion that most of the cases are likely spotted fever's milder cousin. Both illnesses respond to the same antibiotics.

"We put two and two together," Apperson said. He expects to publish the project's findings.

Barry Engber, a state medical entomologist who worked alongside Apperson, said the Chatham project provides strong evidence that Lone Star ticks are the major vehicle for tick-borne disease in the state. An abundant population of deer, which adult Lone Star ticks feed on, is helping them thrive. Population growth across the state, which has resulted in more housing developments in once-wooded areas, also has people rubbing elbows and ankles with ticks.

And Lone Star ticks may be especially likely to transmit disease. Unlike other varieties of ticks in the state, they bite humans at every stage of the life cycle: larva, nymph and adult.

"That makes them three times worse than other ticks," Engber said. "If it weren't for the Lone Star, we probably wouldn't be hearing much about tick problems."

Lois Weldon of Garner, 87, and her daughter, Linda Snow, could not imagine that Weldon would be susceptible to a tick-borne illness. Weldon moved in with Snow a few years ago, and seldom ventures outdoors except to go to church on Sundays.

In late June, Weldon developed a bad headache. Her arms seemed to go numb, and she developed chills and fever. When Snow found her mother lying unconscious beside her bed one morning, she called an ambulance. Emergency room doctors took one look at Weldon and diagnosed Rocky Mountain spotted fever. The giveaway: a purplish, blotchy rash that covered Weldon's body.

Both mother and daughter were shocked. Neither had even noticed the rash. They were even more stunned when a nurse discovered a tick in Weldon's back.

"They took him off, and he was still wriggling his little black legs," Weldon recalls.

The doctors who treated Weldon were so sure she had spotted fever they did not order the full series of blood tests needed to confirm it. Even in milder cases with less obvious symptoms, blood tests often aren't done, said Dr. Jeff Engel, state epidemiologist. Still, despite uneven reporting, the state last year logged 842 cases of spotted fever -- an all- time high.

The record may need to be corrected.