Disease Report Investigation Process
What is relapsing fever?
Relapsing fever is an infectious disease caused by
spiral-shaped bacteria (spirochetes).
Who can contract relapsing fever?
Anyone can be infected with relapsing fever. Most
people become infected in rural, wooded,
mountainous areas, often at summer homes or cabins.
How is relapsing fever transmitted?
In the United States, people get relapsing fever when
they are bitten by an infected Ornithodoros tick.
ticks that can transmit relapsing fever may be found
rodents bring the ticks into their nests, inside homes,
under flooring, and between walls.
Ornithodoros is a
small, soft tick, that usually gets its blood meal from rodents, but may seek out other warm-blooded
animals, including humans.
Soft ticks feed quickly,
usually at night, within 10 to 45 minutes. Then they drop off their host, so people usually don’t know they have been bitten.
The disease is not
communicable from person to person.
What are the symptoms of relapsing fever?
Relapsing fever is characterized by a high fever that lasts for 3 to 7 days.
Fever appears suddenly along
Other possible symptoms include:
The symptoms may
continue for several days and then disappears. The symptoms then return days later. These relapses
may recur up to 10 times.
How is relapsing fever diagnosed?
Anyone with the above symptoms should consult
their health care provider. Relapsing fever is
diagnosed by clinical laboratory tests, and is treated
What can be done to avoid getting relapsing
The best protection against relapsing fever is
knowing where and how people get it and avoiding
that exposure. Watch out for potential risks when
visiting or camping in mountainous or wooded
If you stay in a cabin:
Check the sleeping areas for evidence of
rodents, for example:
Holes in the floor or walls
Shredded material from mattresses
feces on counters or in cupboards
Avoid sleeping on the floor or on a bed that
touches the wall.
If the dwelling has been unoccupied, change and
wash all bedding before use.
Because rodents spread many diseases, household
rodent control is an important health measure.
Follow these steps:
Thoroughly check the outside walls and
foundation of the building for any openings
through which rodents might enter.
external doors and windows close with a tight
Keep all food and garbage in tightly sealed
Promptly clean up any leftover or
spilled food and pet food.
Avoid feeding squirrels, chipmunks, and other
rodents around dwellings.
Eliminate wood piles in, near, or under the
Store firewood outside, away from walls.
Stack wood on pallets or raise a few inches off
the ground; this will discourage rodents from
using these areas as nesting sites.
Even if a building is rodent free, direct control of
ticks in an infested building is necessary for
comprehensive prevention of relapsing fever.
Hungry ticks still seek out other mammals upon
which to feed if rodents are unavailable. Contact a
licensed professional exterminator to discuss best
tick control measures for your dwelling.
Where can I get more information?
Contact your physician or the Southern Nevada Health District, Office of Epidemiology at (702) 759-1300.