Understanding Lyme and Other Tickborne Diseases

Tickborne diseases increasingly threaten the health of people in the United States. Improved understanding about reported tickborne illnesses, expanding geographic ranges for ticks, and risk factors will help prevent and control tickborne disease. New tools for preventing tickborne diseases are urgently needed, and everyone can take steps to help protect themselves from tick bites.

COVID-19 pandemic and tickborne disease reporting

CDC expects that the COVID-19 pandemic will result in fewer cases of Lyme and other tickborne diseases being reported by state health departments in 2020 and 2021. These decreases in reported cases likely result from the effects of the COVID-19 pandemic on tickborne disease surveillance rather than an actual decrease in the numbers of tickborne diseases. Data shows that during the pandemic people continued to spend time outdoors and seek information on tick removal. However, medical care for tick bites and testing for tickborne diseases like Lyme disease may have been reduced compared to prior years.

Surveillance is more than counting cases

Understanding the full effects of tickborne diseases on human health requires more than counting numbers of people getting the disease. It requires studying the timing, the location, and costs of the infections. To supplement data from traditional surveillance techniques, CDC began several new efforts to better understand the burden of tickborne diseases:

• In 2021, CDC released a Tick Bite Data Tracker that shows emergency department (ED) visits for tick bites on a week-by-week and regional basis. The visual dashboard lets people across the country know when they are most at risk and gives healthcare providers and public health personnel access to timely data that can improve tick bite prevention efforts.
• A 2021 estimate based on insurance records suggests that each year approximately 476,000 Americans are diagnosed and treated for Lyme disease. CDC continues to pursue other records-based methods of estimating tickborne disease diagnoses.
• CDC recently published research that shows the economic burden of Lyme disease in the United States is between $345 million and $968 million each year (2016 U.S. dollars). Additionally, the average patient cost was approximately $1200 per infection and patients with later stages of disease had double the costs of those with early disease.

Taken together, these findings underscore the need for early and accurate diagnosis of tickborne diseases and improved prevention tools, including vaccines to reduce the number of people infected by, and costs associated with tickborne diseases.

Complicated interactions between people and nature

A number of factors likely contribute to the increasing case numbers and widening geographic extent of tickborne diseases. For example, the spread of Lyme disease over the past several decades has been linked to changes in land use patterns, including reforestation in the northeastern United States. Suburban development in these areas has brought people, deer, rodents, ticks, and the germs ticks carry into close contact with each other.

Changing climate patterns can alter the natural environment and longstanding ecological relationships. Since tickborne diseases have strong environmental links, we expect that changes in seasonality and location may occur. We don’t know what those changes will be, but we know that climate is only one of several very important factors that influence the distribution and occurrence of tickborne diseases.

Every year is a big year for tickborne diseases

Predicting the number of Lyme disease, anaplasmosis, Rocky Mountain spotted fever, or Powassan virus cases is complicated. In any given year, the number of ticks in an area will be different from region to region, state to state, and even county to county. Numbers of reported tickborne disease cases are also affected by healthcare provider awareness and by testing and reporting practices.

However, each year nearly half a million people will be diagnosed and treated for a tickborne disease. In that sense, every year is a big year for tickborne diseases.

Know about risks in your area

Knowing that thousands of people are bitten by ticks and get sick each year, people should take steps to avoid ticks in the areas where they live, work and play. While not all ticks spread the same germs, ticks can be found in every state. However, in the United States, some diseases occur more frequently in some areas than others:

• Reported cases of Lyme disease, anaplasmosis, babesiosis, and Powassan virus disease are concentrated in the Northeast, mid-Atlantic, and upper Midwest, with pockets of risk along the Pacific coast. The range of the tick that transmits Lyme disease also is expanding.
• Other serious tickborne diseases include Rocky Mountain spotted fever, ehrlichiosis, and Rickettsia parkeri rickettsiosis. More than 75 percent of spotted fever rickettsiosis cases (including RMSF) occur in seven states: Arkansas, Missouri, North Carolina, Oklahoma, Virginia, Alabama, and Tennessee.
• Growing evidence suggests that alpha-gal syndrome, or red meat allergy, may be triggered by the bite of lone star ticks and possibly other tick species. A recent study showed that the states with the highest number of people testing positive for alpha-gal antibodies per 100,000 were Arkansas, Virginia, Kentucky, Oklahoma, and Missouri.

Take steps to protect against tick bites

Taking steps to protect yourself and your family from getting a tick bite is the best defense against tickborne diseases. CDC recommends that people:

• Avoid areas with high grass and leaf litter and walk in the center of trails when hiking.
• Use Environmental Protection Agency (EPA)-registered insect repellentsexternal icon containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone. EPA’s search toolexternal icon can help you find the product that best suits your needs. Always follow product instructions.
• Use products that contain permethrin to treat clothing and gear, such as boots, pants, socks and tents or look for clothing pre-treated with permethrin.
• Treat dogs for ticks. Dogs are very susceptible to tick bites and to some tickborne diseases. They may also bring ticks into your home. Talk to your veterinarian about the best tick prevention products for your dog.
• Bathe or shower as soon as possible after coming indoors to wash off and more easily find crawling ticks before they bite you.
• Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body upon returning from tick-infested areas. Parents should help children check thoroughly for ticks. Remove any ticks right away.
• Put dry clothes in a dryer on high heat for 10 minutes to kill ticks after you come indoors. If clothes are damp, dry thoroughly and then tumble dry on high for 10 more minutes.

Spokespersons

Paul Mead, MD, MPH

Biography

“The number of Lyme disease cases reported in the United States has doubled since 2000, and the number of counties considered high-risk for Lyme disease has tripled. We urgently need new tools for preventing tickborne diseases. In the meantime, people can help protect themselves by using insect repellents and permethrin-treated clothing, checking for ticks daily, and showering soon after coming indoors.”

Paul Mead, MD, MPH – Chief, Bacterial Diseases Branch, National Center for Emerging and Zoonotic Infectious Diseases

Lyle Petersen, MD, MPH

Biography

“Tickborne diseases are on the rise and a public health priority. CDC has been working with state health departments to alert healthcare providers and the public about these diseases, equip state health laboratories to test for them, and to monitor their occurrence. New environmentally friendly control measures are needed, and we are working with researchers around the country to develop them. Prevention is key and taking steps to protect against tick bites should be on everybody’s radar.”

Lyle R. Petersen, MD, MPH – Director, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases

Gil Kersh, PhD

Biography

“People are getting bitten by ticks and infected with tickborne germs in greater numbers than we have ever observed. Many of the most severe tickborne diseases in the United States are caused by Rickettsia. Early diagnosis and proper treatment are important to prevent serious consequences from rickettsial diseases. CDC is working to better diagnose, treat, and prevent rickettsial diseases and other complications from tick bites that threaten public health.”

Gil Kersh, PhD – Chief, Rickettsial Zoonoses Branch, National Center for Emerging and Zoonotic Infectious Diseases

Highlights from Recent CDC Tick Studies

CDC estimates the burden of Lyme disease in the U.S.

Knowing the number of people diagnosed with Lyme disease can help guide public health action. Using anonymous health insurance claims data from 2010 to 2018, CDC estimated that 476,000 people in the U.S. were diagnosed and treated for Lyme disease annually. Take steps to protect yourself and your family: wear repellent, check for ticks daily, shower soon after coming indoors, call your healthcare provider if you get a fever or rash.

Alpha-gal syndrome (AGS) is a serious and potentially life-threatening reaction to read meat or products containing alpha-gal

More than 34,000 people tested positive for alpha-gal IgE antibodies in the United States during 2010-2018.

Of samples submitted to a large commercial laboratory: 43% of males tested were positive for alpha-gal antibodies, 26% of females tested were positive for alpha-gal antibodies, and average age for people testing positive was 47 years. The states with the highest number of people testing positive per 100,000 were Arkansas, Virginia, Kentucky, Oklahoma, and Missouri

AGS may be more common than previously thought. The geographic distribution of people who tested positive is consistent with the range of lone star ticks.

Results of a survey evaluating acceptability of a potential Lyme disease vaccine

3,313 people in four states with high incidence of Lyme disease responded to a survey regarding acceptability of a potential Lyme disease vaccine. Approximately two-thirds of respondents (64%) reported willingness to receive a Lyme disease vaccine if one were available, 30% reported being uncertain, and 7% reported being unwilling. Clinicians are a trusted source of Lyme disease and vaccine information. Effective communication of vaccine safety and efficacy by clinicians may increase uptake, especially among uncertain respondents.

Knowledge, attitudes, and behaviors about tickborne disease prevention in the Upper Midwest

2,713 people were surveyed in the Upper Midwest about: tickborne disease knowledge, attitude, and prevention, and willingness to use and pay for various tick control methods. Reported rates of tick bite prevention behaviors were high: 58% performed tick checks, 43% used insect repellents, and 81% would support county-wide tick control programs. These findings can help health departments optimize messages, resources, and future research.

Economic burden of Lyme disease in the United States

Researchers conducted a cost of illness study among people recently diagnosed with Lyme disease in four states (CT, MD, MN, NY). They estimated the total patient out-of-pocket costs and total societal costs of Lyme disease. The average patient cost was approximately $1,200 per illness. Total societal costs due to Lyme disease could be $345 million to $968 million annually (2016 U.S. dollars). Patients with later stages of disease had double the costs of those with early disease. These findings underscore the need for improved prevention methods, such as a vaccine, to reduce morbidity and associated costs of Lyme disease.