Each year, nearly 500,000 individuals in the United States are estimated to be diagnosed and treated for Lyme disease, contributing to medical and related costs nearing $1 billion. This trend is escalating, with cases reported well beyond the traditional Northeastern US, partly due to climate change. Lyme disease accounts for approximately 80% of vector-borne infections reported in the US.
Climate change is a significant factor in the two-decade rise of various vector-borne diseases transmitted by blood-feeding arthropods, including Lyme disease, Rocky Mountain Spotted Fever, and multiple pathogens carried by Lone Star and Gulf Coast ticks. There is also an increasing threat from mosquito-borne illnesses such as dengue, Zika, chikungunya, and West Nile virus.
Emergency department visits for tick bites have seen a notable increase, reaching 65 per 100,000 people nationally, up from 47 per 100,000 last year. Preliminary figures for this year suggest a potential peak since 2017. In June, there were 112 tick-related ER visits per 100,000 people, consistent with 2025 trends for the same period. The CDC reported higher-than-expected ER visits for tick bites across much of the US in April, marking the highest levels for that time of year since 2017.
This rise reflects expanding tick populations, changing environmental conditions, and increased human exposure during warmer months. States are struggling to monitor tick locations, identify pathogens, and warn residents. Beyond Lyme disease, concerns include conditions like Alpha-gal syndrome, caused by Lone Star ticks, which triggers a red meat allergy and has seen a 100-fold increase in positive antibody tests between 2013 and 2024. The federal Centers for Disease Control and Prevention (CDC) estimates that around 476,000 people may be diagnosed and treated for Lyme disease annually, though this figure can include those treated based on clinical suspicion without confirmed infection.
Despite ticks causing 90% of vector-borne illnesses, 80% of local public health agencies' vector control efforts focus on mosquitoes, with only 10-11% dedicated to ticks. This disparity is attributed to insufficient funding and policy support for tick control. Lawmakers are addressing this, with proposed funding increases for alpha-gal and other tick-borne diseases, including a $1 million boost for the CDC's Vector-Borne Diseases division and a $10 million increase for the National Institutes of Health's Lyme and tick disease research. Discussions are also underway to reauthorize funding via the Kay Hagan Tick Act and classify alpha-gal as a major food allergen for labeling purposes.
