Lyme disease is a bacterial infection transmitted through tick bites that can cause a range of symptoms affecting the skin, joints, heart, and nervous system. While cases are reported in Colorado, Lyme disease is not considered endemic to the state. Most individuals diagnosed with Lyme disease in Colorado acquired the infection in other regions where the disease is more prevalent.
Lyme Disease in Colorado
Lyme disease is rare in Colorado because the primary tick species responsible for its transmission in the United States, the blacklegged tick (Ixodes scapularis), is not established in the state. Similarly, the western blacklegged tick (Ixodes pacificus), another vector, is not known to have an established population in Colorado. Cases of Lyme disease reported in Colorado are “travel-related,” meaning the infection was acquired in an area where disease-carrying ticks are commonly found. The Colorado Department of Public Health and Environment (CDPHE) monitors these cases, with surveillance data indicating that very few cases originate within the state. For instance, between 2007 and 2017, only seven cases were recorded as originating from outside Colorado.
Understanding Lyme Disease Transmission
Lyme disease is caused by the bacterium Borrelia burgdorferi, which is primarily transmitted to humans through the bite of infected blacklegged ticks, also known as deer ticks. For transmission to occur, an infected tick needs to be attached to the host for a significant period, often 36 to 48 hours or more. The tick’s life cycle involves feeding on various animals, which can include small rodents and deer, allowing the bacteria to spread.
Tick-Borne Illnesses in Colorado
While Lyme disease is uncommon, Colorado is home to several other tick-borne illnesses that pose a more direct risk to residents and visitors. The Rocky Mountain wood tick (Dermacentor andersoni) and the American dog tick (Dermacentor variabilis) are two common tick species in the state that can transmit pathogens. Colorado Tick Fever is the most frequently reported tick-borne disease in Colorado, caused by a virus transmitted by the Rocky Mountain wood tick. Symptoms often include fever, chills, headache, muscle aches, and fatigue. Rocky Mountain Spotted Fever (RMSF), though less common in Colorado than its name suggests, is a more severe bacterial infection also transmitted by the Rocky Mountain wood tick and American dog tick. Symptoms of RMSF can include fever, headache, and a rash that appears several days after the fever begins. Tularemia is another bacterial disease that can be transmitted by these ticks, presenting with symptoms such as fever, chills, fatigue, and sometimes a skin ulcer at the bite site.
Preventing Tick Bites and What to Do
Preventing tick bites is the most effective way to avoid tick-borne illnesses. When spending time outdoors, particularly in wooded, grassy, or brushy areas, it is advisable to use EPA-registered insect repellents containing active ingredients like DEET, picaridin, or permethrin. Wearing long-sleeved shirts and pants, and tucking pant legs into socks, can create a physical barrier against ticks.
After outdoor activities, performing a thorough tick check is important. Examine clothing and all parts of the body, including areas like:
- Under the arms
- In and around the ears
- Inside the belly button
- Behind the knees
- Between the legs
- In the hair
If a tick is found attached, remove it promptly using fine-tipped tweezers. Grasp the tick as close to the skin’s surface as possible and pull upward with steady, even pressure, avoiding twisting or jerking. After removal, clean the bite area with soap and water or rubbing alcohol. If symptoms such as fever, rash, or body aches develop within several weeks of a tick bite, seeking medical attention is recommended.