What Is Tick-Borne Relapsing Fever?

Medically Reviewed by Sabrina Felson, MD on August 07, 2022
Written by Sharon Liao
4 min read

Tick-borne relapsing fever (TBRF) is an infection spread by a certain kind of tick. The telltale symptom is a high fever that lasts for a few days, goes away for a week, and then comes back. TBRF is not very common. Most cases happen in Western states, like California, Washington, and Colorado.

In the United States, TBRF is caused by three strains of a bacteria called borrelia: B. hermsii, B. parkeri, and B. turicatae. They’re spread through the bites of infected soft ticks, which live in the nests of small animals like mice, chipmunks, and squirrels. Unlike hard ticks, which stay attached for days, soft ticks only feed for 15 to 30 minutes before they drop off. Their bites are often painless, so you may get bitten and not realize it.

In the United States, most cases happen in the Western part of the country. It’s most common in mountain forests. You can also get TBRF in other parts of the world, like Canada and Mexico. TBRF is linked to sleeping in rustic cabins in these areas. That’s because mice and other small animals tend to build nests in the walls and attics of these buildings. Soft ticks live in these nests. They usually come out during the night to feed.

It’ll take about a week for symptoms to appear after you’re bitten. The main one is a high fever that comes and goes. The fever usually lasts for 3 to 5 days, goes away for 5 to 7 days, and then comes back. If the infection isn’t treated, this cycle repeats itself.

At the end of each feverish period, your temperature may jump. It can reach 106.7 F. This lasts for 10 to 30 minutes. Then your temperature drops, and you sweat heavily.

Other symptoms of TBRF include:

Your doctor will do a physical exam to check your symptoms and ask if you’ve been anywhere soft ticks tend to live. They’ll also take a sample of your blood to test for TBRF, usually when you have a fever. In the lab, a scientist will study a smear of your blood under a microscope and look for the borrelia bacteria. They look like little corkscrews.

Most of the time, it gets better on its own and doesn’t need to be treated. If you’re diagnosed with TBRF, your doctor will prescribe antibiotics to kill the bacteria. The most common ones used to treat TBRF are tetracycline and doxycycline. Pregnant women and children usually get a different class of antibiotics, like erythromycin. Most people feel better within a few days.

Your doctor may want to keep an eye on you for the first few hours after you start taking the antibiotics. For more than half of people who get the treatment, symptoms get worse, with high fever and chills. Doctors call this the Jarisch-Herxheimer reaction. They think it results from the release of toxins by dying bacteria. Most of the time, these symptoms go away on their own. In rare cases, it causes breathing problems that require medical help.

With the right antibiotics, the infection goes away in a few days. Complications aren’t very common. In rare cases, TBRF may damage certain nerves in your eyes or ears. This could cause hearing or vision loss. It may also paralyze your facial muscles for a while, called Bell’s palsy. TBRF can also lead to potentially dangerous inflammation in your heart.

Getting TBRF while you’re pregnant may raise your odds of complications like premature birth or having a baby with a low birth weight.

The best way to steer clear of TBRF is to avoid getting a tick bite. If you’re in a place where there are ticks, wear bug repellent when you go outside. You can use permethrin on your clothes or a DEET product on your skin and clothes. If you’re staying in a cabin, check for signs of rodents, like their droppings. A pest control professional can remove them and their nests.