FAQ: Tick-Borne Diseases

deer tick

Although Lyme disease is the most prevalent tick-borne infection in the U.S., experts are seeing more serious tick-borne illnesses -- some of them fatal if not treated right away.

A recent CDC report showed that vector-borne diseases -- those transmitted by ticks, mosquitoes, and fleas -- tripled to roughly 650,000 cases between 2004 and 2016. The vast majority -- or 75% -- were caused by ticks. The report says seven new tick-caused illnesses were discovered between 2004 and 2016. 

It’s difficult to predict from year to year how many cases of tick-borne diseases will be reported in the U.S. The tiny bugs are now in 50 states, and as a result, more people are at risk every spring, summer, and fall.

“Each year there are many billions of ticks and hundreds of thousands of tick-borne disease cases estimated in the U.S.,” says Christopher Paddock, MD, of the CDC. Paddock specializes in rickettsial infections, or spotted fevers, including Rocky Mountain spotted fever, typhus, anaplasmosis, and ehrlichiosis.

Here’s what you need to know about tick-borne illnesses.

Q. Are cases of tick-borne illnesses on the rise?

A. From 2004 to 2016, tick-borne diseases, including Rocky Mountain spotted fever, have risen dramatically:

  • Lyme disease: 36,429, up from 19,804 in 2004 (Experts believe the annual number is around 300,000, based on surveillance.)
  • Anaplasmosis/ehrlichiosis: 5,750, up from 875 in 2004
  • Rocky Mountain spotted fever: 4,269, up from 1,713 in 2004
  • Babesiosis: 1,910, up from 1,128 in 2011, when tracking started for the disease
  • Tularemia: 230, up from 134 in 2004
  • Powassan virus: 22, up from 1 in 2004

Q. Where are ticks found?

A. The blacklegged tick -- responsible for Lyme disease, the Powassan virus, babesiosis, and anaplasmosis -- is now in almost half of all U.S. counties. The geographic range of other ticks, including the lone star, American dog, brown dog, and Rocky Mountain wood tick, has also expanded throughout North America. They cause Rocky Mountain spotted fever, anaplasmosis, ehrlichiosis, and other infections.

Q. How are tick-borne diseases treated?

A. A simple antibiotic, doxycycline, can be used to snuff out most of the diseases -- if they are recognized and treated early.

Q. How long does a tick have to stick to you to transmit infections?

A. For Rocky Mountain spotted fever, it takes 2 to 96 hours; for Lyme disease, it depends on the tick. One transmits the infection between 4 and 72 hours; the other from 48-96 hours. For anaplasmosis and ehrlichiosis, a tick needs to be attached for 24 to 50 hours. It is unknown how long a tick needs to be attached to transmit Powassan or Heartland virus.

Q. What is the East Asian or longhorned tick?

A. This tick, discovered on a New Jersey sheep farm in late 2017, is known to transmit severe fever with thrombocytopenia syndrome. This potentially fatal disease causes low

platelet and low white blood cell counts. The tick was also found in another New Jersey county. Scientists at Rutgers University are looking at ways to eliminate the tick, which is hard to detect on animals and people. The ticks so far have tested negative for pathogens dangerous to humans or animals.

Q. What is Rocky Mountain spotted fever, and how is it transmitted?

A. You can get this disease from the American dog tick, the brown dog tick, and the Rocky Mountain wood tick. This disease is most commonly reported in the “tick belt,” which stretches from Oklahoma to North Carolina. According to the CDC, more than 3,000 cases of the disease are reported each year in this region.

But Native American reservations in southeast Arizona have seen epidemic levels of the disease -- a result of human contact with stray dogs that carry the ticks. In poorer areas like these, says Paddock, people who have dogs may not be able to afford tick control treatments or to neuter or spay their animals.

Between 2002 and 2017, public health officials reported more than 300 cases of Rocky Mountain spotted fever in reservations in eastern Arizona, and more than 20 people have died from the disease.

tick map

Q. What are symptoms of Rocky Mountain spotted fever?

A. They aren’t much different from the flu -- fever, headache, muscle aches. But within 3-10 days, a rash will begin on your arms and legs and spread to your chest and stomach. At that point, the disease may be doing serious damage to your organs. Some people go on to have permanent disabilities like gangrene, learning disabilities, and problems walking, says Paddock.

Q. How is Rocky Mountain spotted fever treated?

A. Doxycycline is the most effective antibiotic to prevent severe illness and death from Rocky Mountain spotted fever if a patient gets it in the first 5 days of illness. A recent study in Arizona showed that as many as 50% of people with the disease who are not treated with doxycycline die within 8 or 9 days, Paddock says.

“Without immediate treatment, RMSF [Rock Mountain spotted fever] can be fatal within days. It’s critical for health care providers to know the signs and symptoms and know if RMSF is common in their area. This knowledge can save lives,” he says.

Q: Which other tick-borne diseases are fatal?

A. The death rate from Rocky Mountain spotted fever, anaplasmosis, and ehrlichiosis has remained at less than 1% since 2010, according to the CDC.

A handful of deaths have been reported from Bourbon, Heartland, and Powassan viruses.

Q. What is the Bourbon virus?

A. The Bourbon virus is likely spread through the bite of a lone star tick or an insect, the CDC says. A handful of cases of the virus have been reported in the Midwest and South, including some that have resulted in death. Symptoms of the virus can include rash, fever, nausea, body aches, tiredness, headache, and vomiting. There is no cure for an infection. Treatment may include IV fluids and pain medications, Paddock says.

Q. What is the Heartland virus?

A. The Heartland virus is caused by the lone star tick. As of July 2017, 30 cases have been reported in the Midwest and South, a few of which resulted in death. Symptoms may include fever, headaches, fatigue, muscle aches, and diarrhea. There are no vaccines to prevent this virus or medications to treat it.

Q. What are seed ticks?

A. The phrase "seed ticks" refers to tick larvae. The larvae look like poppy seeds on your skin. Even at this young stage, they can still bite. The bites are commonly painless. The ticks can crawl up your body under clothing and bite you in places that are hard to see.

Q. Should we be worried about the Powassan virus this year?

A. Health officials have received more reports of Powassan, thoiught to be transmitted by the blacklegged and two other ticks, but that’s probably because of heightened awareness, says Erin Staples, MD, PhD, a CDC medical epidemiologist.

“There has been evidence of the expansion of ticks, but we don’t know if the virus is spreading,” she says.

As of 2016, 22 Powassan cases were reported.

Unlike the other tick-borne infections, Powassan is a virus. That means antibiotics don’t work to treat it. No antiviral drugs seem to work against it, and there is a high risk of long-term disability and death, Staples says.

Powassan is rare -- only 100 cases reported in the last decade -- but its numbers could rise as more people come into contact with ticks.

Q. Where are the most cases of Powassan reported?

A. Cases are concentrated in the northeast U.S. and in the Great Lakes region -- especially in Minnesota.

An infection can happen within 15 minutes of the tick attaching, Staples says. “By the time a person notices a tick, transmission may have occurred. We encourage people to do thorough tick checks.”

Q. What are the symptoms of Powassan, and are they different from other tick-borne infections?

A. Powassan strikes with fever, chills, muscle aches, and headache, and as the virus progresses, it can lead to seizures and brain and spinal cord inflammation -- conditions that you should go to the hospital for. Unlike other tick-borne diseases, the symptoms of Powassan do not include a rash.

Q. How do you treat the disease?

A. Mainly with supportive care -- painkillers for headache, and hospitalization for people with severe illness. It may include breathing support, intravenous fluids and medications to redu8ce swelling in the brain. Some people report fatigue for a few months after the serious symptoms pass, Staples says. The disease can be fatal for people who weren’t able to recover from Powassan-caused encephalitis, she says. Other patients end up with long-term memory problems or even paralysis.

Q. Can Powassan affect pets, and are the symptoms in animals different than in humans?

A. The research is scanty, but some of it suggests that household pets do have the same symptoms, Staples says.

Q. How can I prevent tick bites?

A. Paddock and Staples emphasize that prevention is the only way to avoid infection:

  • Limit your exposure to tall grass; walk in the center of trails. Ticks generally latch onto your foot or leg and crawl up your body, often to your head or ears. They don’t jump or fly.
  • Remove leaf litter and clear tall grass and brush around your home and the edge of your yard.
  • Use a 3-foot-wide barrier of wood chips or gravel between your yard and wooded areas to keep ticks from coming into your yard.
  • Mow your lawn frequently.
  • Keep decks, playground equipment, and patios away from trees and the edge of your yard.
  • Wear insect repellent with 20% or more DEET, picaridin, or IR3535 on skin that is exposed.
  • Treat clothing with the chemical permethrin. Sawyer makes a spray.
  • If you’ve been outside where ticks may live, do a full-body check once you get in, or examine your skin in the shower.
  • If you see a tick, remove it with tweezers as close to the skin as possible, pulling it straight out. Dispose of it by flushing it down the toilet or throwing it back outside. Don’t crush it between your fingers.
  • Dogs pick up ticks and bring them inside. Check your pet’s skin for ticks, and use tick collars, sprays, shampoos, and medications to prevent ticks.
  • Tumble dry clothes in a dryer on high heat for 10 minutes to kill ticks on dry clothing after you come indoors.

check for ticks

WebMD Article Reviewed by Arefa Cassoobhoy, MD, MPH on May 22, 2018



Christopher Paddock, MD, Centers for Disease Control and Prevention.

Erin Staples, MD, PhD, Centers for Disease Control and Prevention.

Richard, S. Environments, 2017.

Entomology Today, Jan. 18, 2016.

University of Rhode Island TickEncounter Resource Center.

State of New Jersey Department of Agriculture: “Exotic Tick Species Found in Middlesex County.”

CDC: “Severe Fever with Thrombocytopenia Syndrome Virus, South Korea, 2013.”

Clinical Infectious Diseases, June 1, 2015.


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