Lyme Disease Risk in Missouri: What You Need to Know

When most people think about tick-borne disease, they think of Lyme disease. But in Missouri, Lyme disease is not the primary tick-borne disease concern — ehrlichiosis and Rocky Mountain Spotted Fever are reported at significantly higher rates in the state. Understanding the actual disease risk landscape in central Missouri helps residents prioritize the right precautions and know what symptoms to watch for after tick exposure.

Lyme Disease in Missouri: Lower Risk Than You May Think

Lyme disease is caused by the bacterium Borrelia burgdorferi and is primarily transmitted by the blacklegged tick (Ixodes scapularis). Missouri sits on the western fringe of the established blacklegged tick range, and reported Lyme disease cases in Missouri are significantly lower than in northeastern and upper midwestern states where the disease is endemic.

This does not mean the risk is zero — blacklegged ticks are present in Missouri, particularly in forested areas with abundant deer populations, and cases are reported annually. But residents in central Missouri's Franklin and Gasconade counties are statistically at greater risk from ehrlichiosis (transmitted by lone star ticks, which are very common here) than from Lyme disease.

Missouri's More Prevalent Tick-Borne Disease Concerns

Ehrlichiosis

Missouri consistently ranks among the top states nationally for human ehrlichiosis cases. The disease is transmitted primarily by the lone star tick — Missouri's most aggressive and abundant human-biting tick. Symptoms typically appear 1 to 2 weeks after a bite and include sudden fever, severe headache, muscle aches, fatigue, and sometimes nausea. Without prompt antibiotic treatment, ehrlichiosis can be severe. It is very responsive to doxycycline when treated early.

Rocky Mountain Spotted Fever (RMSF)

Despite the name, RMSF is most common in the south-central and southeastern United States, including Missouri. It is transmitted primarily by the American dog tick. The characteristic spotted rash usually appears 2 to 5 days after fever onset and can spread across the entire body including the palms and soles. RMSF can be rapidly fatal without treatment — it is one of the most medically serious tick-borne diseases in the country. Doxycycline is the treatment of choice and is effective when started early.

Heartland Virus

First identified in Missouri in 2009, Heartland virus is a tick-borne phlebovirus transmitted by lone star ticks. Cases have been confirmed in multiple Missouri counties. Symptoms resemble ehrlichiosis but there is no specific antiviral treatment — management is supportive. Most reported cases have been in older adults with outdoor exposure.

Lyme Disease Symptoms to Know

Even with the lower relative risk, knowing Lyme disease symptoms is important:

• Early localized (days 3–30 after bite): The classic expanding bull's-eye rash (erythema migrans) at the bite site, present in 70–80% of infections. Fatigue, fever, headache, muscle and joint aches.
• Early disseminated (days to weeks after bite): Multiple rashes, facial palsy, heart rhythm problems, numbness or tingling.
• Late disseminated (months after bite): Arthritis, particularly in large joints like the knee; neurological symptoms.

Any expanding bull's-eye rash after a tick bite warrants immediate medical evaluation regardless of location — this is one of the most specific signs of Lyme disease and should not be watched and waited on.

After Any Tick Bite in Missouri

• Remove the tick promptly using fine-tipped tweezers — grasp close to the skin and pull steadily upward without twisting
• Save the tick in a sealed bag or container if possible — species identification can be useful information for your doctor
• Note the date of the bite and the approximate attachment time if known
• Monitor for symptoms for 30 days — fever, rash, headache, or muscle aches warrant prompt medical evaluation
• See our full guide on what to do after a tick bite for complete instructions

Reducing Your Risk

Tick avoidance and prompt tick checks after outdoor activity are the most effective personal protection measures. For properties with significant tick pressure — wooded lots, properties adjacent to fields or brushy areas, homes with deer activity — professional yard treatment can dramatically reduce tick populations in the areas where you and your family spend time. See our article on yard tick treatment for more on how professional treatment works.