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Rocky Mountain Spotted Fever Home > Questions and Answers
Questions and Answers
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What is Rocky Mountain spotted fever?
Rocky Mountain spotted fever (RMSF) is the most severe tick-borne
rickettsial illness in the United States. This disease is caused
by infection with the bacterial organism Rickettsia rickettsii.
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How do people get Rocky Mountain spotted fever?
The organism that causes Rocky Mountain spotted fever
is transmitted by the bite of an infected tick. The
American dog tick (Dermacentor variabilis) and
Rocky Mountain wood tick (Dermacentor andersoni)
are the primary athropods (vectors) which transmit Rocky
Mountain spotted fever bacteria in the United States.
The brown dog tick Rhipicephalus sanguineus has
also been implicated as a vector as well as the tick
Amblyomma cajennense in countries south of the
United States.
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What are the symptoms of Rocky Mountain spotted fever?
Patients infected with R. rickettsii usually visit a physician in their first week of illness, following an incubation
period of about 5-10 days after a tick bite. The early clinical
presentation of Rocky Mountain spotted fever is often nonspecific and
may resemble many other infectious and
non-infectious diseases. Initial symptoms may include fever, nausea,
vomiting, muscle pain,
lack of appetite and severe
headache. Later signs and symptoms include rash, abdominal pain, joint pain,
and diarrhea. Three important components of the clinical presentation are
fever, rash, and a previous tick bite, although one or more of these
components may not be present when the patient is first seen for medical
care. Rocky Mountain spotted fever can be a severe illness, and
the majority of patients are hospitalized.
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In the United States, where do most cases of Rocky
Mountain spotted fever occur?
Rocky Mountain spotted fever is a seasonal disease
and occurs throughout the United States during the months
of April through September. Over half of the cases occur
in the south-Atlantic region of the United States (Delaware,
Maryland, Washington D.C., Virginia, West Virginia,
North Carolina, South Carolina, Georgia, and Florida).
The highest incidence rates have been found in North
Carolina and Oklahoma. Although this disease was first
discovered and recognized in the Rocky Mountain area,
relatively few cases are reported from that area today.
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How is Rocky Mountain spotted fever diagnosed?
A diagnosis of Rocky Mountain spotted fever is based on a combination of
clinical signs and symptoms and specialized confirmatory laboratory tests. Other
common laboratory findings
suggestive of Rocky Mountain spotted fever include thrombocytopenia,
hyponatremia, and elevated liver enzyme levels (see Glossary for definition of terms).
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How is Rocky Mountain spotted fever treated?
Rocky Mountain spotted fever is best treated by using
a tetracycline antibiotic, usually doxycycline. This
medication should be given in doses of 100 mg every
12 hours for adults or 4 mg/kg body weight per
day in two divided doses for children under 45 kg (100
lbs). Patients are treated for at least 3 days after
the fever subsides and until there is unequivocal evidence
of clinical improvement. Standard duration of
treatment is 5 to 10 days. Because laboratory confirmation
is generally not available during acute illness, treatment
is initiated based on clinical and epidemiological information.
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Can a person get Rocky Mountain spotted fever more than
once?
Infection with R. rickettsii is thought to provide
long lasting immunity against re-infection. However,
prior illness with Rocky Mountain spotted fever should
not deter persons from practicing good tick-preventive
measures or visiting a physician if signs and symptoms
consistent with Rocky Mountain spotted fever occur,
especially following a tick bite, as other diseases
may also be transmitted by ticks.
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How can Rocky Mountain spotted fever be prevented?
Limiting exposure to ticks reduces the likelihood of
infection with Rocky Mountain spotted fever. In persons
exposed to tick-infested habitats, prompt careful inspection
and removal of crawling or attached ticks is an important
method of preventing disease. It may take extended attachment
time before organisms are transmitted from the tick
to the host.
It is unreasonable to assume that a person can completely
eliminate activities that may result in tick exposure.
Therefore, prevention measures should emphasize personal
protection when exposed to natural areas where ticks
are present:
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- Wear light-colored clothing which allows you to
see ticks that are crawling on your clothing.
- Tuck your pants legs into your socks so that ticks cannot
crawl up the inside of your pants legs.
- Apply repellents to discourage tick attachment. Repellents containing
permethrin can be sprayed on boots and clothing, and
will last for several days. Repellents containing
DEET (n, n-diethyl-m-toluamide) can be applied to
the skin, but will last only a few hours before reapplication
is necessary. Use DEET with caution on children.
Application of large amounts of DEET on children has
been associated with adverse reactions.
- Conduct a body check upon return from potentially
tick-infested areas by searching your entire body for ticks. Use a
hand-held or full-length mirror to view all parts of your body. Remove
any tick you find on your body.
- Parents should check their children for ticks, especially
in the hair, when returning from potentially tick-infested
areas. Ticks may also be carried into the household
on clothing and pets and only attach later, so both
should be examined carefully to exclude ticks.
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What is the best way to remove a tick?
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| Removal of an embedded
tick using fine-tipped tweezers |
1. Use fine-tipped tweezers or notched tick extractor,
and protect your fingers with a tissue, paper towel,
or latex gloves. Persons should avoid removing ticks
with bare hands.
2. Grasp the tick as close to the skin surface as
possible and pull upward with steady, even pressure.
Do not twist or jerk the tick; this may cause the
mouthparts to break off and remain in the skin. (If
this happens, remove mouthparts with tweezers. Consult
your health care provider if illness occurs.)
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| Tick Removal |
3. After removing the tick, thoroughly disinfect
the bite site and wash your hands with soap and water.
4. Do not squeeze, crush, or puncture the body of
the tick because its fluids may contain infectious
organisms. Skin accidentally exposed to tick fluids
can be disinfected with iodine scrub, rubbing alcohol,
or water containing detergents.
5. Save the tick for identification in case you become
ill. This may help your doctor to make an accurate
diagnosis. Place the tick in a sealable plastic bag
and put it in your freezer. Write the date of the
bite on a piece of paper with a pencil and place it
in the bag.
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Do folklore remedies work?
No. Folklore remedies, such as the use of petroleum jelly or hot matches,
do little to encourage a tick to detach from skin. In
fact, they may make matters worse by irritating the
tick and stimulating it to release additional saliva
or regurgitate gut contents, increasing the chances
of transmitting the pathogen. These methods of tick
removal should be avoided.
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How can ticks be controlled?
Strategies to reduce vector tick densities through
area-wide application of acaricides (chemicals that
will kill ticks and mites) and control of tick habitats
(e.g., leaf litter and brush) have been effective in
small-scale trials. New methods being developed include
applying acaricides to animal hosts by using baited
tubes, boxes, and feeding stations in areas where infected
ticks are endemic. Biological control with fungi, parasitic
nematodes, and parasitic wasps may play supportive roles
in integrated tick control efforts. Community-based
integrated tick management strategies may prove to be
an effective public health response to reduce the incidence
of tick-borne infections. However, limiting exposure
to ticks is presently the most effective method of prevention
of tick-transmitted diseases.
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Date last reviewed: 05/20/2005 |
