Rocky Mountain Spotted Fever (RMSF) is a bacterial disease
(Rickettsia rickettsii) transmitted by ticks of the
genus Dermacentor.
These ticks are most common during spring and summer. Rocky
Mountain Spotted Fever is very rare in San Mateo County.
How is Rocky Mountain Spotted Fever transmitted?
RMSF is transmitted through the bite of an infected tick.
If I am bitten by a tick, will I get Rocky Mountain Spotted
Fever?
There have been cases of this disease in San Mateo County but it
is extremely rare.
What are the signs and symptoms of Rocky Mountain Spotted Fever?
Sudden onset of fever
Nausea
Vomiting
A red, spotted, non-itchy rash covering much of the body
including the palms of hands and soles of feet
Lack of appetite
Severe headache
The rash first appears six days after the onset of fever and is
often not present or may be very subtle when the patient is
initially seen by a physician. Younger patients usually develop
the rash earlier than older patients. Most often it begins as
small, flat, pink, non-itchy spots (maculae) on the wrists,
forearms, and ankles. These spots turn pale when pressure is
applied and eventually become raised on the skin. This type of
rash occurs in only 35% to 60% of patients with Rocky Mountain
Spotted Fever. The rash involves the palms or soles in as many as
50% to 80% of patients; however, this distribution may not occur
until later in the course of the disease. As many as 10% to 15%
of patients may never develop a rash.
Three key diagnostic signals are 1) a previous tick bite 2) a
rash covering the trunk 3) severe illness with a sudden onset.
