New tick infection: As wicked as Lyme - and just a much a mystery

Questions? Comments? Write: National Lyme Report Editor Derek Clontz. He reads and answers all e-mails, usually within minutes and always within one business day.

Editor's Note: As if Lyme disease wasn't bad enough, researchers are now investigating Southern tick-associated rash illness, a tick disease as serious and debilitating as Lyme and every bit as baffling and mysterious. Read on to find out what's driving one young researcher to look for answers. You'll be inspired by his work - and frightened by the illness ... and more convinced than ever that when it comes to ticks, you must be ever vigilant to avoid sickness.

Tick tracker takes aim at new illness St. Louis Post-Dispatch, United States

By Molly McElroy
St. Louis Post-Dispatch

It's a miserably muggy morning, and Brian Allan is tucking the pant legs of his white cotton jumpsuit into his socks.

A mysterious new tick-borne disease has sickened people and puzzled doctors, and Allan, a Washington University graduate student, is out to track down its source.

Trudging through woods at the Tyson Research Center , he pauses every 20 feet to inspect a white cotton cloth about the size of an American flag that he's dragging. He also inspects himself.

On this particular July morning, the search so far is not very tickful for Allan, who can usually find a tick within one minute.

He has traveled throughout the Midwest to collect ticks. He's been all over Missouri , southern Indiana and to Land Between the Lakes in Kentucky and Tennessee.

This month, he'll have a tick collecting spree in southern Missouri. Allan is part of a Washington University effort to find which animals are passing on tick-borne diseases, including the new elusive one.

Last year, Missouri had 213 reports of tick-borne diseases, including Lyme disease, erhlichiosis and Rocky Mountain spotted fever.

The actual number of cases is most likely higher, because these diseases can be difficult to diagnose.

Missouri long has been considered a hot spot for tick-borne diseases.

"Rural Missouri is a hazardous place to be in the summer," said Dr. Gregory Storch, an infectious disease expert at Washington University. The most tick bites occur in April through September, he said.

The new pathogen, which causes rashes and flulike symptoms, has Storchand his fellow researchers on a mission.

"It's out there in nature, but no one knows where," said Robert Thach, one of the study's collaborators. "Why are people in St. Louis coming down with this disease? Where are they getting it? Where are the ticks getting it?"

The disease is considered an emerging infection, and too little is known about its causes to be classified by the Centers for Disease Control as a nationally reportable disease.

But the disease does have a name: Southern tick-associated rash illness. Dr. Donald Kennedy, professor of internal medicine at St. Louis University School of Medicine, treated two patients with the illness in May. He said that for now, the illness is considered a clinical syndrome because the pathogen that causes it has not been identified.

"Some of these techniques in identification lag the presentation of the clinical illness," Kennedy said.

The same was true for other infectious diseases, including AIDS, polio and smallpox, he said.

Part of the new disease's mystery is that its victims show symptoms similar to those of people with Lyme disease.

Both cause a bull's-eye rash, and victims complain of headaches, muscle aches and fatigue. But tests for the organism causing Lyme disease come back negative for patients with the new illness.

While some researchers suspect that the organism causing the new tick disease is related to the bacterium that causes Lyme disease, they're also convinced that this new disease is not Lyme.

What is known is the type of tick that transmits the illness: the lonestar tick. Named for the white spot on the adult female's back, the lonestar tick is the most frequently encountered tick in Missouri.

This spider relative's habitat stretches from Florida to Texas to Maine.

"The lonestar tick has expanded its range in the past 20 to 30 years," said Hannah Gould, an epidemiologist at the division of vector-borne infectious diseases at the Centers for Disease Control. "It's an aggressive tick and feeds readily on humans."

The lonestar tick also resides in Illinois, especially in the southern two thirds of the state. In some areas, 50 lonestar ticks can be collected within a few minutes, said Linn David Haramis, program manager of vector control at the Illinois Department of Public Health.

Haramis said that it is unclear whether people in Illinois have been afflicted by the new illness.

Most ticks seek their blood meals by clinging to tall grasses with their six rear legs and waving their front two as they wait for a host - such as a human, deer, chipmunk or bird - to brush by it. Not so for the lonestar tick.

"A lonestar will actually run toward a host and try getting on that way," said Karen Yates, an ecologist at the Missouri Department of Conservation. "It's a supertick."

When Allan scores some ticks on his cloth, he plucks them off with tweezers and places them in small vials containing ethanol.

The ethanol preserves the ticks so that Lisa Goessing, a Washington University researcher, can isolate a tick's last blood meal, which may have occurred as long as eight months before.

The blood meal contains DNA that identifies the animal that the tick fed on, as well as any pathogens the animal was carrying. This information will show the researchers which animals are more or less likely to pass on disease.

Goessing extracts DNA from the ticks by grinding them up with a small mortar and pestle. The tick's last blood meal is part of a solution that Goessing puts into tiny holes on a tray. She adds DNA samples of known pathogens and hosts.

"If the DNA from the tick binds to the known sample, then a dark spot shows up," said Goessing, holding up a piece of film speckled with various shades of black.

"So far, the most common tick hosts have been various types of birds, squirrels, shrews and deer," she said.

Researchers hope that by identifying which animals pass on diseases to ticks that they will learn how to reduce disease by managing wildlife.

This strategy is based on evidence that not all species pass on diseases as readily as others.

If different species of varying disease-spreading abilities live near one another, and diseases are distributed among them, then risk diminishes compared to if only highly efficient disease-spreaders lived in the area.

© 2006, St. Louis Post-Dispatch. Visit the Post-Dispatch on the World Wide Web at http://www.stltoday.com

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