Tick-borne Diseases

When the weather warms up, people naturally spend a lot more time outdoors. But the warm weather also beckons all kinds of insects to come out from their winter dormancy, including pesky ticks. The Southeast is a favorite breeding ground for ticks, and many Atlanta physicians are familiar with the diseases they can carry. Atlanta Medicine recently spoke with two infectious disease specialists who are well acquainted with treating tick-borne diseases.

Lyme Disease
Lyme disease, or borreliosis, is the most common tick-borne infectious disease in the U.S. It is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of an infected black-legged deer tick. It can be difficult to diagnose because some symptoms – fever, chills, headache, fatigue, muscle and joint aches, swollen lymph nodes – often mimic other illnesses such as flu.

Marshall Lyon, M.D., a professor of medicine and infectious disease specialist with Emory School of Medicine, says that while there have not been many innovations in the treatment of Lyme disease, there has been an advancement in the screening process.

“The C6 enzyme-linked immunosorbent assay (EIA) is an improvement over the traditional EIA for Lyme disease,” he says. “It’s a more specific and sensitive diagnostic test that has a higher accuracy in diagnosing Lyme.”

The traditional testing for Lyme includes a two-tiered method that can miss detection or give false-positive results. The C6 EIA employs the C6 peptide, a 26-amino acid sequence that is a marker for infection with the Borrelia burgdorferi spirochete. It offers a more sensitive detection of antibodies in both early and late Lyme disease.

Lyon says that he hopes more physicians will start using the C6 EIA to diagnose or rule out Lyme disease.

“I think that if we can move people away from the old test and to the new test, we can get more true diagnoses,” he says. “It is particularly helpful in keeping patients from going down the Lyme path who don’t have it. I see a lot of patients who have been referred to me for evaluation, the majority who whom probably don’t have Lyme disease.”

The treatment for Lyme disease remains unchanged – for most people, a course of antibiotics (doxycycline, amoxicillin, or cefuroxime axetil) is prescribed.

“If you catch it early, a two-to-four week course of antibiotic is more than adequate to take care of the infection. For someone who has a more advanced case of Lyme disease, we usually prescribe a four-week cycle,” Lyon says. “However, if the patient’s nervous system, joints or peripheral nervous system are involved, a two-to-four week treatment of intravenous ceftriaxone is the best treatment.”

Rocky Mountain Spotted Fever and Ehrlichiosis
Lee Durham, M.D., an infectious disease specialist with Northside and Emory Saint Joseph’s hospitals, says that another tick-borne disease is actually more prominent in Georgia than Lyme disease.

“Rocky Mountain Spotted Fever is a tick-borne disease that can actually be fatal. That’s why early diagnosis is so critical,” he says.

Rocky Mountain SF, transmitted by the American dog tick and the Rocky Mountain wood tick, can present with a number of symptoms including headache, nausea, vomiting and stomach or muscle pain. But the most recognizable signs are a fever followed by the development of a rash a few days later.

“Most of the patients I see who are likely to have Rocky Mountain SF are referred by their doctors when they haven’t felt well … maybe have had a fever … for four or five days with no explanation,” Durham says.

Doxycycline is the recommended treatment, and Durham says he doesn’t waste any time getting a patient started on it if he suspects Rocky Mountain SF.

“First I take CBC and RSMF serologies, but I don’t wait for the results to start treatment. I go ahead and put the patient on doxycycline because it has a relatively low risk for complications,” he says. “You can really get into trouble if the disease goes untreated for a couple of weeks. It can cause multiple organ failure.”

Durham adds that Ehrlichiosis, another tick-borne disease, can also be deadly. Ehrlichiosis is spread by the lone star tick and the blacklegged tick.

“People who have Ehrlichiosis usually have flu-type symptoms like fever, chills, headache and muscle aches,” he says. “This is another disease that can be fatal, so early diagnosis and treatment is important.”

Again, a regimen of doxycycline is the recommended course of treatment.

Tick-borne Illnesses on the Rise
According to the Centers for Disease Control (CDC), tick-borne diseases increasingly threaten the health of people in the United States. The growing threat includes newly discovered disease-causing germs, an increasing number of reported tick-borne illnesses, expanding geographic ranges for ticks and a novel tick species found in the U.S.

Over the past two decades, seven new tick-borne germs that can cause illness have been identified in the United States. New laboratory tests that look for DNA are finding new germs in ticks and people.

In 2017, state and local health departments reported a record number of cases of tick-borne diseases. The reported numbers of cases of Lyme disease, anaplasmosis/ehrlichiosis, spotted fever rickettsiosis (including Rocky Mountain spotted fever), babesiosis, tularemia and Powassan virus disease all increased – from a total of 48,610 reported cases in 2016 to a total of 59,349 reported cases in 2017. Reported cases, however, capture only a fraction of the overall number of people with tick-borne illnesses. The number of reported cases of Lyme disease in the United States has tripled since the late 1990s. Aside from causing infections, recent studies in the United States and other countries suggest that ticks may play a role in causing an allergy – called alpha-gal allergy – to mammalian meat, such as beef, lamb, pork and goat meat.

Dangerous New Tick Species Surfaces
A new tick species, Haemaphysalis longicornis (the Asian longhorned tick) has been identified for the first time in the United States. In other parts of the world like Asia, Australia and New Zealand, bites from longhorned ticks are known to spread pathogens that make people and animals seriously ill.

The longhorn tick’s unique quality is its ability to reproduce without mating. A female tick can lay as many as 2,000 eggs on a single animal, which is bad news for farmers and pet owners.

The first documented longhorn tick bite in this country occurred last year in upstate New York. This spring, the tick has also been found in Kentucky and Tennessee.