May is Lyme Disease Awareness Month. An estimated 476,000 Americans are diagnosed and treated for Lyme disease each year. While Lyme disease is the most common tickborne illness in the United States, numerous other tickborne diseases occur including anaplasmosis, babesiosis, ehrlichiosis, Rocky Mountain spotted fever, and tularemia, as shown on the map below. Ticks can also cause medical conditions such as Alpha-gal syndrome, a potentially life-threatening allergy to food and consumer products derived from mammals that can develop after being bitten by a lone star tick (Amblyomma americanum).
Image
![Reported Cases of Selected Tickborne Diseases](https://public3.pagefreezer.com:443/content/HHS.gov/17-10-2023T05:13/https://www.hhs.gov/sites/default/files/report-cases-selected-tbd.png)
Figure: Geographic distribution of select tickborne diseases. For more information, visit the interactive map at www.cdc.gov/ticks/ data-summary/geographic-distribution.html
Risk of exposure to ticks and tickborne disease varies based on time of year, geographic location, and time spent outdoors in tick habitat. Along with deer abundance and land use patterns, climate is one of several factors that define when and where Lyme and other tickborne diseases are most likely to occur. Different climates throughout the U.S. support different species of ticks, which spread different diseases. Changing climate patterns can alter the natural environment and longstanding ecological relationships. Mild winters and warmer early spring temperatures are expanding the seasons when ticks are active, resulting in more weeks of the year that Americans are at risk of tick encounters. To track current trends on tick exposure in your region, visit the CDC website on transmission.
Outdoor workers are at increased risk of tickborne diseases if they work at sites where ticks are common. Worksites with woods, bushes, high grass, or leaf litter are likely to have more ticks. Children ages 5 to 15 years are also at increased risk of tick-borne diseases, especially if they play in tick-prone areas.
The Expanding Distribution of Lyme Disease
The geographic range of infected ticks is changing, putting an increasing number of communities at risk for Lyme and other tickborne diseases. For example, although the reported nationwide incidence of Lyme disease remained fairly stable from 2008 to 2019 at approximately 11 cases per 100,000 people per year, some states saw marked increases in incidence.
Image
![Reported Cases of Lyme Disease Distribution in 2008](https://public3.pagefreezer.com:443/content/HHS.gov/17-10-2023T05:13/https://www.hhs.gov/sites/default/files/reported-cases-of-lyme-disease-2008.png)
Image
![Reported Cases of Lyme Disease Distribution in 2019](https://public3.pagefreezer.com:443/content/HHS.gov/17-10-2023T05:13/https://www.hhs.gov/sites/default/files/reported-cases-of-lyme-disease-2019.jpg)
Figure: Lyme disease occurs primarily in the upper midwestern, mid-Atlantic, and northeastern United States. It is transmitted by blacklegged (deer) ticks, which also transmit the agents of anaplasmosis, babesiosis and Powassan virus disease. The lack of dots in Massachusetts in 2019 is due to a difference in reporting standards, not an absence of Lyme disease.
The greatest per capita increases in Lyme disease from 2008 to 2019 have been reported in Vermont, which had an incidence rate of 170 cases per 100,000 people in 2019 (versus 65 cases per 100,000 people in 2008); Maine, which had an incidence rate of 161 cases per 100,000 people in 2019 (versus 69 cases per 100,000 people in 2008); Rhode Island, which had an incidence rate of 92 cases per 100,000 people in 2019 (versus 20 cases per 100,000 people in 2008); Pennsylvania, which had an incidence rate of 70 cases per 100,000 people in 2019 (versus 30 cases per 100,000 people in 2008); and West Virginia, which had an incidence rate of 49 cases per 100,000 people in 2019 (versus 7 cases per 100,000 people in 2008).
In areas of the eastern United States where Lyme disease is common, people are most likely to be bitten by blacklegged (deer) ticks during two times of the year: from April through July when nymphs are active, and again from September through November when adults are most active. Though people can get bitten any time ticks are present.
Image
![Emergency Department Visits for Tick Bites by Month, United States, 2021-2023](https://public3.pagefreezer.com:443/content/HHS.gov/17-10-2023T05:13/https://www.hhs.gov/sites/default/files/emergency-department-visits-tick-bites.png)
Figure: Emergency department (ED) visits for tick bites by month for 2021–2023. This graph shows 2023 following a similar pattern to previous years, with tick bites spiking in the spring. A second, smaller spike occurs in the fall when adult ticks are active. More information can be found at: www.cdc.gov/ticks/tickedvisits/index.html
Nymphal blacklegged ticks pose the greatest risk of spreading disease due to their abundance and small size (about the size of a poppy seed), which makes their detection difficult. In fact, Lyme disease patients are often not even aware of a tick bite before getting sick. Adult deer ticks are active in the spring and fall; however, due to their larger size (about the size of a sesame seed), adult ticks are more likely to be detected and removed from people before disease transmission can occur.
Image
![In general, adult ticks are approximately the size of a sesame seed and nymphal ticks are approximately the size of a poppy seed](https://public3.pagefreezer.com:443/content/HHS.gov/17-10-2023T05:13/https://www.hhs.gov/sites/default/files/tick-diagram.png)
Image source: https://www.cdc.gov/lyme/transmission/index.html
Figure: The different sizes of the blacklegged tick through 4 stages: egg, larvae, nymph, and adult.
How to Prevent Tick Bites and Tickborne Diseases
Avoiding tick bites is the first line of defense against Lyme and other tickborne diseases. Tick bite prevention can take place before and after spending time outside. Before you go outdoors, use Environmental Protection Agency (EPA)-registered insect repellents, treat clothing and gear with products containing 0.5% permethrin, and talk to your veterinarian about the best tick prevention products for your dog. If possible, when spending time outside, avoid wooded and brushy areas with high grass and leaf litter where ticks may live. After spending time outdoors, check your body for ticks, take a shower within 2 hours, and check your clothing, gear, and pets for ticks that may have caught a ride into your home. You may also consider using landscaping methods to prevent ticks in the yard. If you discover a tick on you or your pet, follow the recommended steps for proper tick removal as soon as possible
The Centers for Disease Control and Prevention (CDC) Ticks website and Tickborne Diseases of the United States manual has information on specific tickborne diseases including information on how to avoid tick bites, common symptoms, and treatment. The Tick Bite Bot can assist you in removing attached ticks and seeking health care, if appropriate, after a tick bite. CDC has also issued guidance for clinicians on caring for patients after a tick bite. CDC has additional interactive maps displaying tick surveillance data of four tick species and surveillance of tickborne pathogens identified in blacklegged and western blacklegged ticks.
The Food and Drug Administration (FDA) has additional information on Lyme disease symptoms, treatment, and prevention for people and pets. The Environmental Protection Agency (EPA) has a tool to help find the insect repellent that is right for you.
Image
![Life Cycle and Hosts graphic](https://public3.pagefreezer.com:443/content/HHS.gov/17-10-2023T05:13/https://www.hhs.gov/sites/default/files/life-cycle-and-hosts.png)
Figure: The life cycle of the blacklegged tick, Ixodes scapularis, generally lasts 2 years, during which it goes through 4 stages: egg, larvae, nymph, and adult. More information can be found at: https://www.cdc.gov/ticks/life_cycle_and_hosts.html