Colorado tick fever (CTF)
Colorado tick fever (CTF) is an infectious disease caused by the Colorado tick fever virus, a member of the coltivirus family, primarily transmitted to humans through the bite of an infected Rocky Mountain wood tick (Dermacentor andersoni). This tick species is predominantly found in the western United States, particularly in mountainous regions above 5,000 feet, and is often associated with small mammals like ground squirrels and chipmunks. Symptoms of CTF typically manifest four to five days post-bite, presenting as high fever, chills, severe headaches, muscle pain, and gastrointestinal discomfort, lasting between seven to ten days.
Diagnosis involves a thorough medical history and physical examination, often supplemented by blood tests to detect the virus or antibodies. While there is no specific treatment for CTF, symptoms can be managed with over-the-counter pain relievers. Preventive measures include avoiding tick-infested areas, wearing protective clothing, using insect repellents, and regularly checking for ticks after outdoor activities, especially during peak seasons from April to July. Although complications are rare, reported cases have included aseptic meningitis and encephalitis. Those who recover from CTF are generally believed to gain immunity against future infections.
Colorado tick fever (CTF)
- ANATOMY OR SYSTEM AFFECTED: All
Definition
Colorado tick fever is an infection that is transmitted to humans by the bite of an infected tick.
Causes
Colorado tick fever is caused by the coltivirus, or the Colorado tick fever virus. The Rocky Mountain wood tick is the principal carrier of the Colorado tick virus in the United States, and its geographic range is confined to the western United States and areas above 5,000 feet in elevation. The virus is also carried by other small mammals, including ground squirrels, porcupines, and chipmunks. There have been reports of rare cases of Colorado tick fever caused by exposure in a laboratory setting and through a blood transfusion.
Risk Factors
According to the Centers for Disease Control, 108 cases of Colorado tick fever were reported between 2002 and 2019. There may be more, but they are unreported. Wyoming, Colorado, Idaho, Montana, Oregon, and Utah are responsible for over 80 percent of the cases in the United States. Living or traveling in mountain forest areas at altitudes above five thousand feet in the Rocky Mountain region, especially between April and July, increases one’s chances of developing Colorado tick fever. Cases of Colorado tick fever have been reported in ten western states.
Symptoms
Symptoms usually appear four to five days after a tick bite occurs and include high fever, chills, severe headache, pain behind the eyes, sensitivity to light, muscle pain, lethargy, abdominal pain, vomiting, and nausea.
Screening and Diagnosis
A doctor will ask about symptoms and medical history and perform a physical exam. Tests may include blood tests to identify the virus and tests to identify antibodies to the virus.
Treatment and Therapy
There is no specific treatment for Colorado tick fever. Complications are extremely rare and include aseptic meningitis, encephalitis, and hemorrhagic fever. The fever and pain may be treated with acetaminophen (such as Tylenol) and other pain-relief medications. The symptoms of Colorado tick fever generally last between seven and ten days. Once a person gets Colorado tick fever, they are believed to have immunity against reinfection.
Prevention and Outcomes
To help reduce the chance of getting Colorado tick fever, one should limit exposure to ticks by avoiding tick-infested areas, especially during warmer months. Precautions may also be taken by wearing light-colored clothing, tucking pants into socks when in tick-infested habitats, using tick repellents, regularly inspecting and then removing ticks from the body with fine-tipped tweezers (grasp the tick close to the skin’s surface and pull up steadily), and disinfecting tick bites with soap and water.
Bibliography
"Colorado Tick Fever." MedlinePlus, 4 Dec. 2022, medlineplus.gov/ency/article/000675.htm. Accessed 27 Sept. 2024.
"Colorado Tick Fever Information." Mount Sinai, www.mountsinai.org/health-library/diseases-conditions/colorado-tick-fever. Accessed 27 Sept. 2024.
Padgett, Kerry A., et al. "Colorado Tick Fever Virus in the Far West: Forgotten, but Not Gone." Vector Borne and Zoonotic Diseases, vol. 22, no. 8, 2022, pp. 443-448, https://doi.org/10.1089/vbz.2022.0018. Accessed 27 Sept. 2024.
"Statistics & Maps Colorado Tick Fever." Centers for Disease Control and Prevention, 17 Mar. 2021, www.cdc.gov/coloradotickfever/statistics.html. Accessed 28 Feb. 2023.
Vanderhoof-Forschner, Karen. Everything You Need to Know About Lyme Disease and Other Tick-Borne Disorders. 2d ed., Hoboken, N.J.: John Wiley & Sons, 2003.
Weedon, David. Skin Pathology. 3d ed., New York: Churchill Livingstone/Elsevier, 2010.