Lyme disease is caused by the bacteria Borrelia burgdorferi and is transmitted to humans through the bite of infected blacklegged ticks. Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, the infection can spread to the joints, heart, and nervous system. While Lyme disease is treatable, especially in the early stages, some people wonder if it can ever be fatal. Here we look at the evidence surrounding Lyme disease and mortality risk.
How Common is Lyme Disease?
According to the Centers for Disease Control and Prevention (CDC), approximately 476,000 people are diagnosed with Lyme disease each year in the United States. This makes Lyme disease the most commonly reported vector-borne illness in the country. Lyme disease is concentrated heavily in the Northeast and upper Midwest, with 14 states accounting for over 96% of cases – Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and Wisconsin. The number of cases has been on the rise in recent decades as the ticks that transmit Lyme have expanded their geographical range.
What Are the Symptoms of Lyme Disease?
In the early localized stage, the most common symptom of Lyme disease is a rash at the site of the tick bite. This rash expands gradually over several days, ultimately growing to >5cm in diameter. It may feel warm to the touch but is rarely itchy or painful. Flu-like symptoms are also common in early Lyme, including fever, chills, headache, fatigue, and muscle and joint aches. If the disease remains untreated, it can progress to the disseminated stage when the bacteria spread throughout the body. Symptoms of later stage Lyme include:
- Severe headaches and neck stiffness
- Additional EM rashes on other areas of the skin
- Facial palsy (loss of muscle tone or droop on one or both sides of the face)
- Intermittent pain in tendons, muscles, joints, and bones
- Heart palpitations or an irregular heart beat (Lyme carditis)
- Episodes of dizziness or shortness of breath
- Nerve pain
- Shooting pains, numbness, or tingling in the hands or feet
- Problems with short-term memory
Late stage symptoms can begin anytime from weeks to years after the initial tick bite.
Can Lyme Disease Be Fatal?
Deaths directly attributable to Lyme disease are rare. However, Lyme can cause potentially life-threatening complications when it affects the heart. These include:
Heart Block
Heart block refers to an interruption in the electrical signals that coordinate the heartbeat. It causes an abnormally slow heart rate. First-degree heart block is mild and often causes no symptoms. Higher degrees of heart block compromise the amount of blood pumped to the rest of the body. Complete heart block can be catastrophic.
Cardiomyopathy
Cardiomyopathy is a weakening of the heart muscle that reduces its ability to pump blood effectively. It can lead to heart failure.
Carditis
Carditis is inflammation of the heart muscle and membranes that can impair its electrical system.
According to one study, fatal cardiac complications from Lyme disease are rare, occurring in 0.5% of all Lyme carditis cases. The research found that untreated patients with active heart conditions were more likely to have poor outcomes. Prompt treatment with antibiotics improves prognosis.
Other Causes of Death Related to Lyme
While death solely due to Lyme disease is uncommon, the illness can contribute to fatal outcomes in other ways:
Suicide
A 2020 study in the International Journal of Infectious Diseases looked at the causes of death among Lyme disease patients in the U.S. Suicide was found to be the third most common cause, behind heart disease and cancer. Researchers proposed several possible reasons for increased suicide risk:
- Severe, chronic pain leading to depression
- Inflammation causing changes in brain function
- Borrelia bacteria directly affecting neurological and hormonal processes
- Side effects of medications used to treat Lyme
Opportunistic Infections
People with Lyme sometimes have weakened immune systems, making them more susceptible to other infections. While not directly due to Lyme, these opportunistic infections can be fatal.
Allergic Reactions
Some people have severe allergic reactions to antibiotics used for treating Lyme, such as doxycycline. In rare cases, these reactions can progress to anaphylaxis and death when not treated promptly.
Complications from Misdiagnosis
Because the symptoms of disseminated Lyme can be vague and mimic other diseases, cases sometimes go undiagnosed and untreated for long periods. The bacteria may spread to the heart or nervous system before the correct diagnosis is made. Delayed treatment with antibiotics is associated with more severe outcomes.
Population Most at Risk of Dying from Lyme
While healthy individuals may fully recover with antibiotic treatment, even in late stage infection, some groups are at higher risk for life-threatening complications:
- People over age 50
- Those with compromised immune systems
- Patients with existing heart conditions
- Individuals with central nervous system dysfunction
For reasons not fully understood, men appear to be more prone to serious cardiac effects from Lyme disease than women. Other risk factors for severe outcomes include lack of treatment, delayed treatment, treatment resistance, and reinfection.
Mortality Statistics for Lyme Disease
Hard statistics on Lyme disease deaths are limited. However, the available data indicates fatalities directly attributable to Lyme are rare:
- A 1999 study found only 1 death over a 34 year period could be ascribed solely to Lyme carditis.
- Of 5,565 Lyme disease-related deaths between 1999-2003, just 114 (2%) listed Lyme disease as the underlying cause.
- A 2020 analysis found 4 deaths out of 1,368 patients hospitalized for Lyme carditis in the United States.
To put this into context, according to the CDC Lyme disease accounts for less than 0.01% of all deaths in the U.S. each year. You are far more likely to die from common conditions such as heart disease, cancer, stroke, and respiratory diseases.
This table summarizes the mortality risk from Lyme compared to other selected causes:
| Cause of Death | Annual Mortality Rate (per 100,000 population) |
|---|---|
| All cancers | 149.5 |
| Heart disease | 165.0 |
| Chronic lower respiratory diseases | 40.9 |
| Stroke | 37.6 |
| Alzheimer’s disease | 30.5 |
| Diabetes | 21.6 |
| Influenza and pneumonia | 15.2 |
| Kidney disease | 13.0 |
| Suicide | 14.5 |
| Lyme disease | 0.01 |
Can Lyme Be Cured?
In most cases, Lyme disease can be cured, especially when treated early. The Infectious Diseases Society of America recommends the following antibiotics for treating the various stages of Lyme:
- Doxycycline, amoxicillin, or cefuroxime for early localized disease.
- Doxycycline, amoxicillin, or ceftriaxone for disseminated early Lyme.
- Ceftriaxone, cefotaxime, or penicillin for late Lyme disease.
For symptoms that linger after antibiotic treatment, further 4-6 week courses may provide additional benefit. Long-term antibiotic therapy lasting months or years is not recommended as it has not been shown to be helpful. However, approximately 10-20% of properly treated Lyme patients continue to have persistent symptoms like fatigue, muscle aches, and joint pain that can last for more months or years after finishing antibiotics. This condition is called Post-treatment Lyme Disease Syndrome (PTLDS). While not a cure per se, symptoms of PTLDS often improve over time.
How to Prevent Lyme Disease
Reducing exposure to ticks is the best form of Lyme disease prevention:
- Avoid areas with high grass, brush, and leaf litter.
- Walk in the center of hiking trails to avoid overgrown vegetation.
- Use EPA approved insect repellents when outdoors.
- Wear long sleeves, long pants, and closed-toe shoes when in wooded or brushy areas.
- Treat clothing with permethrin to kill ticks.
- Check your body for ticks and remove them promptly after being outdoors.
- Shower soon after coming indoors.
- Reduce ticks around your home by keeping grass mowed, removing leaf litter, trimming bushes, and creating borders between wooded areas and lawns.
The Lyme disease vaccine approved for use in Europe may eventually become available in the U.S. Researchers are also working to develop new vaccines targeting different surface proteins of the Lyme bacterium.
Conclusion
Deaths solely attributable to Lyme disease are exceptionally rare given the number of cases diagnosed each year. The most lethal complication is Lyme carditis causing heart block, cardiomyopathy, or carditis, though fatalities remain uncommon. Lyme more often contributes indirectly to mortality through suicide, opportunistic infections, medication reactions, or delayed diagnosis. Prompt diagnosis and antibiotic treatment, especially during early infection, is key to preventing severe outcomes. With appropriate treatment most people fully recover, though a minority may experience persistent symptoms after finishing antibiotics. Practicing prevention measures and recognizing early signs of Lyme remain the best way to avoid potential complications of this disease.