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Tick-borne illness

What are tick-borne illnesses?

Tick-borne illnesses are caused by bacteria or viruses that are transmitted when ticks attach to a person’s skin and feed on that person’s blood. Bites from ticks found in Colorado (American dog ticks, Rocky Mountain wood ticks, and Brown dog ticks) can transmit several tick-borne diseases, though most are infrequently seen in Colorado. 

Signs and symptoms

  • Colorado Tick Fever: fever, chills, headache, body aches, and feeling tired. Some patients have sore throat, vomiting, abdominal pain, or skin rash. About half of patients have several days of fever, feel better for several days, then have a second short period of fever and illness. Weakness and fatigue may last several weeks but most people recover completely. In rare cases, severe illness affecting the central nervous system may occur.
  • Tick-borne relapsing fever (TBRF): high fever (e.g., 103° F), headache, muscle and joint aches. Symptoms can recur, producing a telltale pattern of fever lasting roughly three days, followed by seven days without fever, followed by another three days of fever. Without antibiotic treatment, this process can repeat several times.
  • Rocky Mountain Spotted Fever (RMSF): Early signs and symptoms are not specific and include fever and headache. However, the disease can rapidly progress to a serious and life-threatening illness. Rash may not appear, but may develop two to four days after fever begins. The look of the rash can vary widely over the course of illness. Some rashes can look like red splotches and some look like pinpoint dots.Rash often does not appear early in illness, which can make RMSF difficult to diagnose.
ticks

Incubation period

  • Tick bites are not painful and many people do not know that they’ve been bitten.
  • Colorado Tick Fever: Ranges from one to 14 days from the time of the tick bite.
  • Tick-borne relapsing fever: Approximately seven days from the time of the tick bite.
  • Rocky Mountain Spotted Fever: Three to 12 days from the time of the tick bite.

Contagious period and spread

Most tick-borne diseases in Colorado are not spread person-to-person. The exception is Colorado tick fever which can potentially be transmitted to others through blood or bone marrow donations, so it is advised not to donate for six months following this viral infection.

  • Colorado Tick Fever: Caused by a virus spread from Rocky Mountain wood tick bites.
  • Tick-borne relapsing fever: Caused by bacteria transmitted from the bite of soft ticks (commonly Ornithodoros hermsi in Colorado), which are often found in rodent nests associated with rustic cabins in forested high-elevation habitats. As long as rodents such as chipmunks or tree squirrels are available for the soft ticks to feed on, they will stay in rodent nests, but if the rodents leave or are removed, the soft ticks will attach and feed on people for short periods at night while they sleep. They don’t stay attached like the hard ticks do, so exposure often goes unnoticed. 
  • Rocky Mountain Spotted Fever: Caused by bacteria transmitted from the bite of Rocky Mountain wood ticks, American dog ticks, and Brown dog ticks. 

Public health reporting requirements

Tick-borne illnesses are reportable to local or state public health within four days of diagnosis.

Control of spread

  • Most diseases are not spread person-to-person.
  • Educate children and staff about tick prevention.
  • Treat clothing and gear and use insect repellants.
  • Check children for ticks after outdoor activities and safely remove attached ticks.

Treatment

  • Colorado Tick Fever: There are no medications to treat this viral infection. Severe cases may require hospitalization for supportive care. 
  • Tick-borne relapsing fever (TBRF): Treated with antibiotics. Cases require close observation during initiation of treatment; about 50% of cases have a severe reaction when treatment is started.
  • Rocky Mountain Spotted Fever (RMSF): Early treatment with doxycycline can prevent death or severe illness. Treatment must be started before the diagnosis can be confirmed due to the delay in detectable antibodies, which do not reliably appear until two to three weeks after illness onset.

Exclusion

Exclusion is not necessary since tick-borne diseases are not spread person-to-person.

Role of teachers, caregivers, and family

  • Locate play areas away from areas with lots of trees, tall grass, and brush.
  • Use barriers of dry wood chips or gravel between play areas and areas with trees, tall grass, and brush.
  • Inspect children’s skin and scalp after possible exposure, and wear gloves to remove attached ticks as soon as possible.
  • Use veterinary-approved tick preventative products on pets.

Resources