Rocky mountain spotted fever (patient information)
For the WikiDoc page for this topic, click here
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
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.
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 of Rocky Mountain spotted fever may include:
- fever
- nausea
- vomiting
- muscle pain
- lack of appetite
- severe headache
Later signs and symptoms of Rocky Mountain spotted fever include:
- rash
- abdominal pain
- joint pain
- 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.
What are the causes of 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.
Who is at risk for Rocky Mountain spotted fever?
The frequency of reported cases of Rocky Mountain spotted fever is highest among males, Caucasians, and children. Two-thirds of the Rocky Mountain spotted fever cases occur in children under the age of 15 years, with the peak age being 5 to 9 years old. Individuals with frequent exposure to dogs and who reside near wooded areas or areas with high grass may also be at increased risk of infection. 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.
How to know you have Rocky Mountain spotted fever
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 (decreased platelets), hyponatremia (low blood sodium), and elevated liver enzyme levels.
When to seek urgent medical care
Contact your healthcare provider when symptoms such as a fever and a rash occur after exposure to ticks or any known tick bites. The complications of untreated Rocky Mountain spotted fever can be life threatening.
Treatment options for Rocky Mountain spotted fever
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 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.
Diseases with similar symptoms to Rocky Mountain spotted fever
- Babesiosis (Babesia Infection)
- Crimean-Congo Hemorrhagic Fever
- Diseases Related to Insects and Their Relatives
- Lyme Disease
- Southern Tick-Associated Rash Illness (STARI)
- Tick-Borne Relapsing Fever
Where to find medical care for Rocky Mountain spotted fever
Directions to Hospitals Treating Rocky Mountain spotted fever
Prevention of Rocky Mountain spotted fever
Limiting exposure to ticks reduces the likelihood of infection with tickborne diseases. 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 take the following precautions to protect yourself when exposed to natural areas where ticks are present:
- 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.
- 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.
Check 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.
Tick Removal
For information on tick removal click here
Prognosis for Rocky Mountain spotted fever
Treatment usually cures the infection. Complications are rare but can include paralysis, hearing loss, nerve damage, and, rarely, death. Rocky Mountain spotted fever can be a severe illness, and the majority of patients are hospitalized. 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. Possible complications include:
- Brain damage
- Clotting problems
- Heart failure
- Kidney failure
- Lung failure
- Meningitis
- Pneumonitis (lung inflammation)
- Shock