Lyme Disease Risk
Lyme Disease Risk
Lyme disease is spread by blacklegged ticks. Your risk depends on where you live, time of year, and what precautions you take. This page lets you explore your risk for the whole year and for a specific month, and shows how simple steps (like using repellent and doing daily tick checks) can lower that risk.
Choose Your Inputs
- Where are you located?
- Which month are you curious about?
- How often are you in tick habitats? (think woodlands, hiking spots, forest edges, grasslands, as well as your occupation and any outdoor activities)
- Do you use skin repellent (DEET or picaridin) when you're in tick habitat?
- Are you wearing permethrin-treated clothing?
Note: Permethrin is an insecticide commonly used to protect against pests like ticks or mosquitoes.
- Do you do a daily tick check and remove ticks within 24 hours?
Your Results
- Annual chance (per person per year)
- Monthly chance (for the month you selected)
Tip: Your risk drops a lot when you combine precautions — repellent, treated clothing, and quick tick removal after outdoor time.
Data and Parameters
State-Level Lyme Incidence
| RegionLabel | Lyme_State_Incidence_per100k | Lyme_State_Incidence_Year |
|---|---|---|
|
Alabama |
0.7 |
2023 |
|
Alaska |
0.3 |
2023 |
|
Arizona |
0.2 |
2023 |
|
Arkansas |
0.2 |
2023 |
|
California |
0.3 |
2023 |
|
Colorado |
0.6 |
2023 |
|
Connecticut |
89.9 |
2023 |
|
Delaware |
34.7 |
2023 |
|
District of Columbia |
16.1 |
2023 |
|
Florida |
1.2 |
2023 |
|
Georgia |
0.2 |
2023 |
|
Idaho |
0.6 |
2023 |
|
Illinois |
2.9 |
2023 |
|
Indiana |
3.8 |
2023 |
|
Iowa |
6.6 |
2023 |
|
Kansas |
0.4 |
2023 |
|
Kentucky |
2.7 |
2023 |
|
Louisiana |
0.3 |
2023 |
|
Maine |
213.4 |
2023 |
|
Maryland |
40.0 |
2023 |
|
Massachusetts |
138.9 |
2023 |
|
Michigan |
11.5 |
2023 |
|
Minnesota |
51.4 |
2023 |
|
Mississippi |
0.1 |
2023 |
|
Missouri |
0.3 |
2023 |
|
Montana |
1.0 |
2023 |
|
Nebraska |
0.3 |
2023 |
|
Nevada |
0.4 |
2023 |
|
New Hampshire |
113.4 |
2023 |
|
New Jersey |
77.9 |
2023 |
|
New Mexico |
0.5 |
2023 |
|
New York |
111.7 |
2023 |
|
North Carolina |
2.2 |
2023 |
|
North Dakota |
1.9 |
2023 |
|
Ohio |
11.1 |
2023 |
|
Oklahoma |
0.1 |
2023 |
|
Oregon |
1.4 |
2023 |
|
Pennsylvania |
128.1 |
2023 |
|
Rhode Island |
260.0 |
2023 |
|
South Carolina |
1.1 |
2023 |
|
South Dakota |
0.8 |
2023 |
|
Tennessee |
0.7 |
2023 |
|
Texas |
0.1 |
2023 |
|
Utah |
0.5 |
2023 |
|
Vermont |
223.3 |
2023 |
|
Virginia |
20.2 |
2023 |
|
Washington |
0.3 |
2023 |
|
West Virginia |
181.6 |
2023 |
|
Wisconsin |
106.9 |
2023 |
|
Wyoming |
0.3 |
2023 |
Annual reported Lyme incidence (cases per 100,000 population) for selected states, 2023.'
- CDC: Lyme Disease Surveillance Data ( seasonality, 1996–2023)
- CDC: 2023 Lyme incidence rates by state/locality (CSV)
- [https://www.cdc.gov/lyme/data-research/facts-stats/index.html CDC: Over 89,000 cases reported in 2023
Monthly Seasonality
| SeasonMonthLabel | Lyme_Monthly_Share_Percent | Lyme_Monthly_Share_Notes |
|---|---|---|
|
January |
1 |
Low activity |
|
February |
1 |
Low activity |
|
March |
2 |
Increasing adult activity regionally |
|
April |
6 |
Spring increase |
|
May |
18 |
Peak begins (nymphs emerging) |
|
June |
22 |
Peak month in many regions |
|
July |
20 |
High |
|
August |
12 |
Elevated |
|
September |
8 |
Declining |
|
October |
6 |
Autumn adult activity |
|
November |
3 |
Low |
|
December |
1 |
Low |
Approximate month weights (sum = 100) that reflect CDC-described seasonality (peak in late spring–summer, esp. June–July). Useful for a monthly risk view; replace with a state-specific table if available.
- CDC: Lyme surveillance data (notes seasonality peaks) :contentReference[oaicite:3]{index=3}
- Moore et al. 2014: meteorological influences on Lyme seasonality :contentReference[oaicite:4]{index=4}
- (Optional alt source) Truveta 2025: ~63% of cases May–Aug; June ≈19% :contentReference[oaicite:5]{index=5}
Exposure Levels
| ExposureOptionLabel | Exposure_Multiplier | Exposure_Notes |
|---|---|---|
|
Minimally |
0.1 |
Rare outdoor activity, urban/suburban |
|
Occasionally |
0.4 |
Some outdoor recreation, parks |
|
Regularly |
1 |
Outdoor work, hunting, frequent woods |
|
Pretty Often |
3 |
Relative exposure multiplier |
|
Extremely Often |
8 |
Forestry, field biology, endemic hot spots |
These multipliers are not exact probabilities, and they are not derived from direct tick-count data.
They are relative exposure weights used to separate people into broad risk bands.
This is necessary because state incidence already reflects a mix of low-, medium-, and high-exposure people, so it should be broken down.
Skin Repellent Effectiveness
| RepellentOptionLabel | Lyme_Repellent_Reduction_Percent | Lyme_Repellent_Notes |
|---|---|---|
|
No skin repellent |
0 |
Baseline |
|
DEET or picaridin used correctly |
30 |
Conservative aggregate estimate for tick bite reduction |
Skin-applied repellent reduces tick bites; efficacy varies. Modeled here as a conservative 30% reduction applied multiplicatively with other measures.
- General CDC prevention guidance and literature reviews (see also clothing/permethrin evidence below).
Permethrin-Treated Clothing
| PermethrinOptionLabel | Lyme_Permethrin_Reduction_Percent | Lyme_Permethrin_Notes |
|---|---|---|
|
No permethrin-treated clothing |
0 |
Baseline |
|
Factory-impregnated/treated clothing |
58 |
~58% average reduction in tick bites over 2 years among outdoor workers |
Effectiveness of long-lasting permethrin-impregnated clothing in randomized trials.
- Mitchell et al. 2020: ~65% first year, ~50% second year; ~58% average :contentReference[oaicite:6]{index=6}
- Sullivan et al. 2019: up to ~82% reduction reported :contentReference[oaicite:7]{index=7}
Tick Check and Early Removal
| TickCheckOptionLabel | Lyme_TickCheck_Reduction_Percent | Lyme_TickCheck_Notes |
|---|---|---|
|
No routine tick checks |
0 |
Baseline |
|
Daily tick check & remove within 24 hours |
80 |
Most transmission requires >24h attachment; early removal greatly reduces infection risk |
Early tick removal substantially lowers infection risk (transmission often requires ≥24–36 h). Modeled as an 80% reduction in infection given exposure.
- CDC: "If you remove a tick within 24 hours, you can greatly reduce your chances…" :contentReference[oaicite:8]{index=8}
- Lindsay et al. 2015 review: prevention methods incl. early removal :contentReference[oaicite:9]{index=9}
- FDA: transmission often requires 36–48 h :contentReference[oaicite:10]{index=10}
Risk Models
RiskModel: Lyme Disease Risk:Lyme_Annual_Exposure_Adjusted
Content:
Among people with similar exposure patterns in your state, Lyme disease is expected to occur about {{One_In_X|{{#expr:
({Lyme_State_Incidence_per100k} / 100000)
* ({Exposure_Multiplier})
* (1 - ({Lyme_Repellent_Reduction_Percent} / 100))
* (1 - ({Lyme_Permethrin_Reduction_Percent} / 100))
* (1 - ({Lyme_TickCheck_Reduction_Percent} / 100))
}} }} per '''year'''.
''How this works'': We start with your state's reported Lyme disease incidence (cases per 100,000 people per year). This represents an average across people with very different lifestyles. We adjust this rate using your selected exposure category to reflect how often you are likely to encounter tick habitat relative to the population average, then apply general reductions for preventive measures. This result is an expected rate among similar people, not a guaranteed personal probability.
RiskModel: Lyme Disease Risk:Lyme_Monthly_Exposure_Adjusted
Content:
Among people with similar exposure patterns in your state, Lyme disease is expected to occur about {{One_In_X|{{#expr:
({Lyme_State_Incidence_per100k} / 100000)
* ({Exposure_Multiplier})
* ({Lyme_Monthly_Share_Percent} / 100)
* (1 - ({Lyme_Repellent_Reduction_Percent} / 100))
* (1 - ({Lyme_Permethrin_Reduction_Percent} / 100))
* (1 - ({Lyme_TickCheck_Reduction_Percent} / 100))
}} }} per '''person-month'''.
''How this works'': We distribute the annual expected Lyme disease rate across months using generic seasonal weighting, then adjust for exposure category and preventive measures. This reflects how often Lyme disease tends to occur among people with similar exposure patterns during this month, not a constant monthly personal risk.
Previous Models
RiskModel: Lyme Disease Risk:Lyme_Annual_Per_Person
Content:
Your '''Lyme disease''' risk is {{One_In_X|{{#expr:
({Lyme_State_Incidence_per100k} / 100000)
* (1 - ({Lyme_Repellent_Reduction_Percent} / 100))
* (1 - ({Lyme_Permethrin_Reduction_Percent} / 100))
* (1 - ({Lyme_TickCheck_Reduction_Percent} / 100))
}} }} per '''year'''.
''How this works'': We convert your selected state's incidence (per 100,000) to an annual probability, then apply multiplicative reductions for your chosen precautions (repellent, permethrin-treated clothing, daily tick checks).
RiskModel: Lyme Disease Risk:Lyme_Monthly_Per_Person
Content:
Your '''Lyme disease''' risk is {{One_In_X|{{#expr:
({Lyme_State_Incidence_per100k} / 100000)
* ({Lyme_Monthly_Share_Percent} / 100)
* (1 - ({Lyme_Repellent_Reduction_Percent} / 100))
* (1 - ({Lyme_Permethrin_Reduction_Percent} / 100))
* (1 - ({Lyme_TickCheck_Reduction_Percent} / 100))
}} }} per '''month'''.
''How this works'': Annual probability is apportioned to the selected month using the generic seasonality weights (replace with state-specific weights when available), then reduced by your chosen precautions.
Initially created by GPT-5 Thinking