Rocky Mountain Spotted Fever (RMSF)

Rocky Mountain spotted fever (RMSF) is rare in Minnesota, but isolated cases have been reported from various parts of the state. The disease is most commonly reported in south-central and southeastern states. The illness is caused by bacteria called Rickettsia rickettsii, which is transmitted locally by the tick species Dermacentor variabilis (American dog tick, also called the wood tick). American dog ticks are found in grassy or wooded areas throughout Minnesota. They are most active from spring thru mid-summer.

Signs and Symptoms

Signs and symptoms include an abrupt onset of fever, malaise, headache, muscle aches, loss of appetite, nausea, vomiting, and a rash. The typical rash first appears as spots on the wrists and ankles which then spread to the trunk and also sometimes the palms and soles. The rash often appears two to five days after onset of fever. RMSF can result in organ failure and death.

Supportive laboratory findings include thrombocytopenia, increased serum hepatic aminotransferase levels, and hyponatremia.

Treatment

Doxycycline is the first line treatment for adults and children of all ages. New research shows no evidence of tooth staining from short courses of doxycycline. Treatment should be undertaken with the assistance of an infectious disease specialist. Empiric treatment should be initiated as soon as RMSF is suspected to prevent serious complications or death.

Links

• Rocky Mountain Spotted Fever
  CDC: Viral and Rickettsial Zoonoses Branch website about Rocky Mountain Spotted Fever.
• Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever, Ehrlichiosis, and Anaplasmosis - United States
  CDC: Morbidity and Mortality Weekly Report May 13, 2016 / 65(2);1-44: A Practical Guide for Health-Care and Public Health Professionals.
• Rocky Mountain Spotted Fever (and other tickborne diseases) Toolkit for Healthcare Providers with Continuing Education
  CDC: a clinical toolkit for health care providers, epidemiologists, and public health practitioners on the diagnosis and treatment of Rocky Mountain Spotted Fever and other tickborne diseases, as well as Continuing Education opportunities

Reporting

• Reporting Rocky Mountain Spotted Fever
  Minnesota Rules Governing Communicable Diseases require health care providers to report confirmed or suspected cases of Rocky Mountain spotted fever to the Minnesota Department of Health (MDH) within 1 working day.

MDH staff also are available to provide clinical consultation regarding diagnosis and treatment of Rocky Mountain spotted fever and other tickborne diseases. Call 651-201-5414 for a clinical consultation.