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Missouri sees sharp rise in certain tick-borne illnesses

Tuesday, October 8, 2013 | 6:00 a.m. CDT; updated 3:39 p.m. CDT, Thursday, October 10, 2013
MU researchers have studied a trend among animals with tick-borne infections. The researchers inoculate the animal with a tick-borne illness, then treat the infection with antibiotics when the animal begins to show signs of disease. The researchers then place ticks on the animal and test the blood the ticks consume. The tests show that even when the animal shows no signs of the disease, the infection remains in their blood. In most cases, this leads to a relapse of the disease.

COLUMBIA —  You spent time outdoors this past summer, maybe at a state park or in your own backyard. Later, you felt the pull of a tick attached to your skin and pried it loose.

Soon after, you developed redness at the spot where the tick was attached. You felt tired, achy and feverish. You headed to the doctor, who said it was probably from the tick and prescribed a short course of antibiotics.

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Sound familiar? You're not alone. Ticks thrive in Missouri in the summer and carry with them the risk of various illnesses. And this summer was particularly bad.

So far this year, there have been big increases in cases of certain tick-borne illnesses, such as Ehrlichia chaffeensis and Ehrlichia ewingii, according to Missouri Department of Health and Senior Services data.

Through early September, there has been a 101.5 percent increase in Ehrlichia chaffeensis, the most common tick-borne disease in the state, and a 160 percent increase in Ehrlichia ewingii for the year.

In addition, a study on a new tick-borne disease, Heartland virus, was released in July. The virus is believed to have originated near St. Joseph.

And a recent Al-Jazeera report tells the story of a Missouri woman who developed a meat allergy believed to be caused by a tick bite.

The second most common tick-borne disease in Missouri — Rocky Mountain Spotted Fever — saw a 6 percent decrease through September of this year.

On the national stage, another tick-borne illness, Lyme disease, has become a topic of debate, with patient organizations and medical professional groups at odds over the correct diagnosis and treatment of the disease.

Lyme disease, sometimes characterized by a bull's-eye rash, fever and body aches, is actually uncommon in Missouri. On average, only eight cases are reported each year in the state, according to data from the Missouri Department of Health and Senior Services.

However, on Aug. 19, the Centers for Disease Control and Prevention warned that Lyme disease might be underreported throughout the United States. The CDC estimates there could be up to 10 times more cases of the disease each year than official reports suggest. That would place the annual nationwide total at somewhere around 300,000 rather than the 30,000 cases reported.

In Missouri, tick-borne illnesses are a concern for both doctors and patients alike. But with their similar symptoms and unreliable lab testing, it's unclear whether the data collected by the Missouri Department of Health and Senior Services presents an accurate picture of the magnitude of the problem.

Reporting tick-borne illnesses

Although the Missouri Department of Health and Senior Services expects doctors to report any cases of tick-borne illnesses they see, it doesn't always happen, said Karen Yates, vector-borne disease program coordinator.

Yates said physicians might treat a patient with antibiotics if they suspect a tick-borne illness without confirming the diagnosis through a laboratory test. She said the reasoning for this might be "because they feel they can make the decision empirically based on what they see in the office."

"When we do outreach, people will say, 'I was diagnosed with Ehrlichiosis, but I was never tested. It's just what my physician told me, and since I got better, it could be correct,'" she said. "But those cases do not get reported."

Yates said doctors sometimes diagnose a patient with a tick-borne illness without ordering a laboratory test, and those lab results are the measure the department uses to count cases.

"I'm not sure (physicians) make the connection that what we require in most cases is a laboratory result," Yates said.

Yates said even when physicians diagnose a case without ordering a laboratory test, it is still the policy of the Department of Health and Senior Services that it be contacted.

"Whether there is a laboratory result or not, the physician should be calling the (state) health department, the local health department or both," Yates said.

Lyme disease in the Show-Me State

It is widely believed by physicians and health officials that Lyme disease is not present in Missouri. This thinking starts with the tick — Ixodes scapularis — more commonly known as the deer tick or blacklegged tick. Not all ticks transmit all tick-borne diseases, and Lyme disease is only known to be transmitted through ixodes scapularis.

Deer ticks can be found in many places in the U.S., but are most common in northeastern states and the northern Midwest. They can be found in the southern United States, which includes Missouri, but they do not often transmit Lyme disease here.

“There’s something unique about the ecology of the tick in the southern U.S.,” said Roger Stich, a professor of parasitology at the MU School of Veterinary Medicine.

Stich said deer ticks in the southern United States might not feed on animal hosts that harbor the infection that causes Lyme disease. In order for the disease to be transmitted to humans, a tick must first feed on a Lyme-infected animal host.

In Missouri, Ambylomma americanum, or the lone star tick, is much more common. Lone star ticks do not carry the infection that causes Lyme disease, but instead carry Southern Tick-Associated Rash Infection, or STARI. This infection is often mistaken for an early sign of Lyme disease, making it hard for doctors to diagnose correctly, said Gordon Christensen, a professor at the MU School of Medicine who specializes in infectious diseases.

There are two steps doctors can take to determine if a patient has Lyme disease, Christensen said.

First, a physician can talk to the patient about his or her symptoms, including the characteristic “bull's-eye rash.” But Christensen said the rash is not always a bull's-eye shape, and not all bull's-eye rashes are indicative of Lyme disease.

“(The rash) comes in a variety of shapes and sizes,” Christensen said. “If they know what the rash is supposed to look like, they may say ‘I had the bull's-eye rash’ when in fact, they didn’t.”

In Missouri, STARI is much more common than Lyme disease. Its traits also include a bull's-eye rash and mild, flu-like symptoms.

“Many people in Missouri will call this Lyme disease,” Christensen said. He added that this may account for the notion that Lyme disease is more common in Missouri than it actually is, given that there were only eight reported cases this year.

“Here in Missouri, the whole thing gets much worse because we don’t know that we have Lyme disease, but we do get the same condition of complaints,” he said.

After discussing these symptoms with a patient, the doctor can perform a lab test using a blood sample from the patient. The test, however, is often inconclusive because there is a high rate of false-positive results.

At the Department of Health and Senior Services, Yates said she does not believe there are many cases of Lyme disease in Missouri going undetected and unreported.

"We get lots of testing that is very savvy, and the physicians understand that you have to combine multiple tests together to reduce the likelihood of getting a false-positive," she said.

To test for Lyme disease, physicians perform an initial screening test. If that test comes back positive, they perform a second, less sensitive test to confirm the diagnosis.

"I just can't believe that all physicians in the state of Missouri refuse to test for Lyme disease," she said.

Christensen said he has only diagnosed what he believes are “true” cases of Lyme disease in Missouri two to four times from 1999 to 2013.

Chronic or not

The looming question about Lyme disease and other tick-borne illnesses is whether they are chronic. 

According to the Infectious Diseases Society of America, Lyme disease is usually treated with a few weeks of antibiotics. But it is not uncommon for patients to believe they have Lyme disease for an extended period of time and cite crippling fatigue and pain.

Christensen said he believes most of these patients are not suffering from chronic Lyme disease but fibromyalgia, which is characterized by complaints of fatigue and pain.

“The actual Lyme disease is an acute illness, and it’s very clear that the patient is sick,” Christensen said. Fibromyalgia is a chronic illness, which Christensen said is difficult for a doctor to test for and can make daily tasks impossible.

“The amount of suffering is actually quite high,” he said. “It’s astonishing.”

The CDC calls this Post-Treatment Lyme Disease Syndrome and says it's caused by “residual damage to tissues and the immune system that occurred during the infection.”

Other sources, such as LymeDisease.org, say Lyme disease can be chronic and should be treated as such. Some physicians will treat patients who believe they have a case of chronic Lyme disease with long-term antibiotics.Charles Crist in Columbia is among them. 

Crist said in an email that he treats patients with persistent Lyme disease symptoms with long-term antibiotics. 

"Muscle pains get better or resolve in 97 percent of these patients with long-term antibiotics, as does their fatigue," Crist said. "Patients get worse off antibiotics if antibiotics are stopped before they are symptom-free."

The Infectious Diseases Society of America says long-term use of antibiotics is dangerous and can cause bacterial resistance.

Christensen has strong reservations, too. He said some physicians only use long-term antibiotics to prey on patients suffering from an undiagnosed illness because it forces the patients to make repeated return visits. Still, he said, others truly believe these treatments work.

“If the physician believes this really is the right way and is not out to make money off the patient, it is what we call unconventional medicine," he said.

Chronic tick-borne infections

Although the Infectious Diseases Society of America said Lyme disease is an acute illness that will not linger in a body, some studies have found that other tick-borne infections do.

Stich has studied the tick-borne pathogen Ehrlichia canis in dogs and was surprised by what he found.

In the study from 2007, students in Stich's lab treated dogs infected with Ehrlichia canis with the antibiotic doxycycline, which is most often used to treat dogs infected with the disease.

Researchers used xenodiagnosis, a process in which ticks feed on the potentially infected host, to detect if the infection is still present after treatment with antibiotics. Most of the dogs in the study showed signs of recovery from clinical disease, when given the antibiotic, but the xenodiagnosis revealed the infection was still present.

“The data suggests that tick-borne infections can persist in the vertebrate host,” Stich said. He said similar studies have been done on cattle, mice and macaques, and each time the infection was still present.

Based on these findings, Stich said he could see a possibility that humans can be infected with Lyme disease, even once the clinical disease has subsided.

But there's much that remains unknown about tick-borne illnesses, and most of what is known about Lyme disease is very recent. Scientists didn’t connect the disease to ticks until 1981.

Lyme disease still generates significant debate among medical professionals and patients who have confirmed cases or who believe they are suffering from the disease. Christensen said he believes the controversy is coming from untreated patients who are suffering.

“I think that’s part of the problem around all of this,” he said. “We have a population of patients who have a chronic illness.”

But whether Lyme disease and other tick-borne illnesses are accurately reported and correctly treated remains to be seen.

Supervising editor is Katherine Reed.

MU researchers have studied a trend among animals with tick-borne infections. The researchers inoculate the animal with a tick-borne illness, then treat the infection with antibiotics when the animal begins to show signs of disease. The researchers then place ticks on the animal and test the blood the ticks consume. The tests show that even when the animal shows no signs of the disease, the infection remains in their blood. In most cases, this leads to a relapse of the disease. Graphic by Graciela Aguilarleon



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