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Rocky Mountain spotted fever

Spotted fever

 

Rocky Mountain spotted fever is a disease caused by a type of bacteria carried by ticks.

Causes

 

Rocky Mountain spotted fever is caused by the bacteria Rickettsia rickettsii (R. Rickettsii) , which is carried by ticks. The bacteria spread to humans through a tick bite.

In the western United States, the bacteria are carried by the wood tick, and in the eastern U.S. they are carried by the dog tick. Other ticks spread the infection in the southern U.S. and in Central and South America.

Contrary to the name "Rocky Mountain," most recent cases have been reported in the eastern United States, including North and South Carolina, Virginia, Maryland, Georgia, Tennessee, and Oklahoma. Most cases occur in the spring and summer and are found in children.

Risk factors include recent hiking or exposure to ticks in an area where the disease is known to occur. The bacteria are unlikely to be transmitted to a person by a tick that has been attached for less than 20 hours. Only about 1 in 1,000 wood and dog ticks carry the bacteria. Bacteria can also infect people who crush ticks they have removed from pets with their bare fingers.

 

Symptoms

 

Symptoms usually develop about 2 to 14 days after the tick bite. They may include:

  • Chills and fever
  • Confusion
  • Headache
  • Muscle pain
  • Rash -- usually starts a few days after the fever; first appears on wrists and ankles as spots that are 1 to 5 mm in diameter, then spreads to most of the body. About one-third of infected people do not get a rash.

Other symptoms that may occur with this disease:

  • Diarrhea
  • Light sensitivity
  • Hallucinations
  • Loss of appetite
  • Nausea and vomiting
  • Thirst

 

Exams and Tests

 

The health care provider will perform a physical examination and ask about the symptoms.

Tests that may be done include:

  • Antibody titer by complement fixation or immunofluorescence
  • Complete blood count (CBC)
  • Kidney function tests
  • Partial thromboplastin time (PTT)
  • Prothrombin time (PT)
  • Skin biopsy taken from the rash to check for R. rickettsii
  • Urinalysis to check for blood or protein in the urine

 

Treatment

 

Treatment involves carefully removing the tick from the skin. To get rid of the infection, antibiotics such as doxycycline or tetracycline need to be taken. Pregnant women are usually prescribed chloramphenicol.

 

Outlook (Prognosis)

 

Treatment usually cures the infection. About 3% of people who get this disease will die.

 

Possible Complications

 

Untreated, the infection may lead to health problems such as:

  • Brain damage
  • Clotting problems
  • Heart failure
  • Kidney failure
  • Lung failure
  • Meningitis
  • Pneumonitis (lung inflammation)
  • Shock

 

When to Contact a Medical Professional

 

Call your health care provider if you develop symptoms after exposure to ticks or a tick bite. The complications of untreated Rocky Mountain spotted fever are often life-threatening.

 

Prevention

 

When walking or hiking in tick-infested areas, tuck long pants into socks to protect the legs. Wear shoes and long-sleeved shirts. Ticks will show up on white or light colors better than on dark colors, making them easier to see and remove.

Remove ticks immediately by using tweezers, pulling carefully and steadily. Insect repellent may be helpful. Because far fewer than 1% of ticks carry this infection, antibiotics are not usually given after a tick bite.

 

 

References

McElligott SC, Kihiczak GG, Schwartz RA. Rocky Mountain spotted fever and other rickettsial infections. In: Lebwohl MG, Heymann WR, Berth-Jones J, Coulson I, eds. Treatment of Skin Disease: Comprehensive Therapeutic Strategies . 4th ed. Philadelphia, PA:Elsevier Saunders; 2014:chap 212.

Walker DH, Blaton LS. Rickettsia rickettsii and other spotted fever group rickettsiae (Rocky Mountain spotted fever and other spotted fevers). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases . 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 188.

 
  • Rocky mountain spotted fever, lesions on arm - illustration

    This is the appearance of the rash of Rocky Mountain Spotted Fever on the hands and forearms. The rash starts on the hands and feet and later spreads to the trunk. It is caused by a bacteria transmitted to humans by a tick bite. (Image courtesy of the Centers for Disease Control and Prevention.)

    Rocky mountain spotted fever, lesions on arm

    illustration

  • Deer ticks - illustration

    Diseases are often carried by ticks, including Rocky Mountain Spotted Fever, Colorado Tick Fever, Lyme disease, and tularemia. Less common or less frequent diseases include typhus, Q-fever, relapsing fever, viral encephalitis, hemorrhagic fever, and babesiosis.

    Deer ticks

    illustration

  • Ticks - illustration

    There are many species of ticks. Of these, a large proportion are capable of carrying disease. Diseases carried by ticks include Lyme disease, Erlichiosis, Rocky Mountain Spotted Fever, Colorado Tick Fever, tularemia, typhus, hemorrhagic fever, and viral encephalitis. (Image courtesy of the Centers for Disease Control and Prevention.)

    Ticks

    illustration

  • Rocky mountain spotted fever on the arm - illustration

    Rocky Mountain Spotted Fever is a disease transmitted to humans by a tick bite. The spots begin as flat (macular) red (erythematous) patches that may bleed into the skin, causing purplish spots (purpura). The disease is named after its characteristic spots. (Image courtesy of the Centers for Disease Control and Prevention.)

    Rocky mountain spotted fever on the arm

    illustration

  • Tick imbedded in the skin - illustration

    This is a close-up photograph of a tick embedded in the skin. Ticks are important because they can carry diseases such as Rocky Mountain spotted fever, tularemia, Colorado tick fever, Lyme disease, and others.

    Tick imbedded in the skin

    illustration

  • Rocky mountain spotted fever on the foot - illustration

    Rocky Mountain spotted fever is caused by the organism Rickettsia rickettsii and is transmitted by a tick bite. It is a serious infection that produces a classical rash in about 90% of infected individuals. This is the typical appearance of the rash. There are many symptoms that affect the entire body (systemic).

    Rocky mountain spotted fever on the foot

    illustration

  • Rocky mountain spotted fever, petechial rash - illustration

    Rocky Mountain spotted fever is a potentially fatal infection transmitted to humans by ticks. This photograph shows the classical appearing rash which often begins on the wrists and ankles, and spreads rapidly towards the center of the body. The rash may also be present on the palms and soles.

    Rocky mountain spotted fever, petechial rash

    illustration

  • Antibodies - illustration

    Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.

    Antibodies

    illustration

    • Rocky mountain spotted fever, lesions on arm - illustration

      This is the appearance of the rash of Rocky Mountain Spotted Fever on the hands and forearms. The rash starts on the hands and feet and later spreads to the trunk. It is caused by a bacteria transmitted to humans by a tick bite. (Image courtesy of the Centers for Disease Control and Prevention.)

      Rocky mountain spotted fever, lesions on arm

      illustration

    • Deer ticks - illustration

      Diseases are often carried by ticks, including Rocky Mountain Spotted Fever, Colorado Tick Fever, Lyme disease, and tularemia. Less common or less frequent diseases include typhus, Q-fever, relapsing fever, viral encephalitis, hemorrhagic fever, and babesiosis.

      Deer ticks

      illustration

    • Ticks - illustration

      There are many species of ticks. Of these, a large proportion are capable of carrying disease. Diseases carried by ticks include Lyme disease, Erlichiosis, Rocky Mountain Spotted Fever, Colorado Tick Fever, tularemia, typhus, hemorrhagic fever, and viral encephalitis. (Image courtesy of the Centers for Disease Control and Prevention.)

      Ticks

      illustration

    • Rocky mountain spotted fever on the arm - illustration

      Rocky Mountain Spotted Fever is a disease transmitted to humans by a tick bite. The spots begin as flat (macular) red (erythematous) patches that may bleed into the skin, causing purplish spots (purpura). The disease is named after its characteristic spots. (Image courtesy of the Centers for Disease Control and Prevention.)

      Rocky mountain spotted fever on the arm

      illustration

    • Tick imbedded in the skin - illustration

      This is a close-up photograph of a tick embedded in the skin. Ticks are important because they can carry diseases such as Rocky Mountain spotted fever, tularemia, Colorado tick fever, Lyme disease, and others.

      Tick imbedded in the skin

      illustration

    • Rocky mountain spotted fever on the foot - illustration

      Rocky Mountain spotted fever is caused by the organism Rickettsia rickettsii and is transmitted by a tick bite. It is a serious infection that produces a classical rash in about 90% of infected individuals. This is the typical appearance of the rash. There are many symptoms that affect the entire body (systemic).

      Rocky mountain spotted fever on the foot

      illustration

    • Rocky mountain spotted fever, petechial rash - illustration

      Rocky Mountain spotted fever is a potentially fatal infection transmitted to humans by ticks. This photograph shows the classical appearing rash which often begins on the wrists and ankles, and spreads rapidly towards the center of the body. The rash may also be present on the palms and soles.

      Rocky mountain spotted fever, petechial rash

      illustration

    • Antibodies - illustration

      Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.

      Antibodies

      illustration

    A Closer Look

     

    Talking to your MD

     

      Self Care

       

        Tests for Rocky Mountain spotted fever

         

           

          Review Date: 5/1/2015

          Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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