Author: Marie Hartley, Staff writer, 2009. Updated by A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. December 2017. Show
What is Rocky Mountain spotted fever?Rocky Mountain spotted fever (RMSF) is a tick-borne infection caused by small bacteria called Rickettsia rickettsii. Various species of Dermacentor ticks are the typical vectors. Rickettsiae are introduced into humans after an infected tick is attached to the skin for at least 24 hours. RMSF occurs throughout the United States, Canada, Mexico, and South America. Most infections occur in the spring and summer. Around 350–1500 cases of RMSF are reported in the United States per year with the highest incidence in children aged 5–9 years old. Seropositivity studies in patients without a previous history of the disease indicate some RMSF infections go unnoticed. Rickettsiae cause disease by damaging blood vessels in various tissues and organs. Other species of rickettsiae are responsible for a range of spotted fever diseases in different geographic locations. Clinical features of Rocky Mountain spotted feverSymptoms generally appear within 14 days of a tick bite. However the tick bite is painless and frequently goes unnoticed. The classic symptoms are fever, severe headache, and a rash. Fever and headache generally precede the rash by 2–5 days. Myalgias (muscle aches) are also common. Other symptoms that may be present include:
More severe illness is experienced when treatment is delayed. The case-fatality rate of RMSF is 1–4%. Patients aged younger than 5 years or older than 70 years are at highest risk of death. Skin manifestations of Rocky Mountain spotted feverAlthough the majority of patients with RMSF have a rash, in 4–26%, the rash is absent.
Diagnosis of Rocky Mountain spotted fever
Treatment of Rocky Mountain spotted feverTetracyclines are the preferred treatment for RMSF. Doxycycline should be used for children of any age, including those less than 9 years old (the risk of stained teeth is outweighed by the improved efficacy of doxycycline in treating this potentially life-threatening disease). Chloramphenicol is an alternative drug and can be used to treat pregnant women. Treatment should be continued until there has been no fever present for at least 2 or 3 days. Prevention of Rocky Mountain spotted fever
Can you have a mild case of Rocky Mountain spotted fever?The severity of the spotted fever rickettsioses may vary greatly. Some spotted fevers usually cause mild symptoms, while others may potentially lead to life-threatening complications. As noted above, RMSF is usually considered the most potentially severe form of the spotted fevers.
What mimics Rocky Mountain spotted fever?Other mimics include typhoid fever, secondary syphilis, Lyme disease, leptospirosis, toxic shock syndrome, scarlet fever and rheumatic fever, rubella, parvovirus infection, Kawasaki disease, idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), and Henoch-Schönlein purpura/hemolytic- ...
Is Rocky Mountain spotted fever rash itchy?What are the symptoms of Rocky Mountain spotted fever? The following are the most common symptoms of RMSF: A non-itchy rash that usually starts on the hands, arms, feet, and legs and occurs 5 to 10 days after the bite. The rash consists of flat, pink spots.
How long can RMSF go untreated?If not treated correctly, death can often occur within eight days of symptoms starting. People who do recover from serious RMSF infections may be left with life-altering damage, including amputation of arms, legs, fingers, or toes (from lack of blood flow), hearing loss, paralysis, or mental disability.
Can Rocky Mountain spotted fever go away on its own?Most people recover within a few days. An infection that isn't treated right away can cause serious health problems, which can affect the brain, lungs, heart, and kidneys. Someone with these problems may need long-lasting treatment. RMSF that isn't treated can be life-threatening.
Can you have RMSF and not know it?While almost all patients with RMSF will develop a rash, it often does not appear early in illness, which can make RMSF difficult to diagnose.
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