What is relapsing fever? tick

Relapsing fever is a bacterial infection caused by Borrelia spirochetes. Relapsing fever can be:

  • Tick-borne: usually in western states, where people sleep in rodent-infested cabins in the mountains
  • Louse-borne: transmitted through human body louse, usually in refugee settings in developing countries

How is relapsing fever transmitted?

Tick-borne relapsing fever (TBRF) is transmitted to humans through the bite of an infected soft-tick. Soft-ticks are different than hard-ticks (dog tick/deer tick), because their bite usually does not last longer than half an hour and they live in rodent burrows. Humans normally come into contact with soft-ticks by sleeping in rustic, rodent filled cabins in the mountains.

Soft-tick bites are painless and usually happen during the night when people are sleeping. Soft-ticks can live up to 10 years, so they may remain in the homestead until a rodent nest is removed.   There are multiple types of soft-ticks that can infect humans:

  • Ornithodoros hermsi tends to be found at higher altitudes (1500 to 8000 feet) where it is associated primarily with ground or tree squirrels and chipmunks.
  • Ornithodoros parkeri occurs at lower altitudes, where they inhabit caves and the burrows of ground squirrels and prairie dogs, as well as those of burrowing owls.
  • Ornithodoros turicata occurs in caves and ground squirrel or prairie dog burrows in the plains regions of the Southwest, feeding off these animals and occasionally burrowing owls or other burrow- or cave-dwelling animals.

Where is TBRF most common?

TBRF typically occurs in the summer months, but it is possible to catch it during the winter months as well. States where TBRF is common include: Arizona, California, Colorado, Idaho, Kansas, Montana, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah, Washington, and Wyoming.

What are the symptoms of TBRF?

  • High fever
  • Headache
  • Muscle and joint aches

Symptoms can reoccur. A normal pattern includes a fever that lasts around 3 days, stops for 7 days, and comes back for another 3 days.   This can repeat several times without antibiotic treatment.

How is TBRF treated?

Antibiotics can be used to treat TBRF.   Talk to your doctor if you believe you may have relapsing fever.

How can I prevent TBRF? insect repellents

  • Avoid rodent-infested buildings. Although you may not see rodent nests, droppings can be a sign that rodents are present.
  • Prevent tick bites with insect repellent
  • Contact the landlord if you are staying in a house infested with rodents
  • If you are the owner of a rodent-infested house, contact a licensed pest control professional to remove them

Why should I avoid removing rodent nests myself?

Removing rodent nests can put you at risk for Hantavirus, which is potentially fatal. Hantavirus can occur when you breathe in particles from deer mouse droppings, urine, saliva, or nesting materials

For more information about relapsing fever, click here.