Navigating Tickborne Disease Testing Amid Rising U.S. Tick Activity

Tick activity has traditionally peaked during the warmer months but that seasonal window appears to be expanding. Changing climate patterns resulting in milder winters are allowing more ticks to survive, contributing to earlier emergence in the spring.

In April, emergency department (ED) visits for tick bites were higher than usual, prompting a recent statement from the CDC. According to CDC data on tick bites by month, emergency room visits increased 54% in April 2026, reaching 105 cases compared with 68 cases in April 2025. While many tick bites can be managed outside of an emergency setting, increased ED visits may be due to concerns of possible infection or symptoms that require evaluation. The CDC says that after someone is bitten by a tick, they should seek medical care if they begin to experience fever, aches, or a rash.

A changing landscape: more ticks, more places

Not only are tick exposures occurring more frequently and earlier in the year than many clinicians and patients expect, but they are also appearing in more places.

All regions are seeing above-average rates of tick activity. The most tick bite cases were reported in the Northeast, followed by the Midwest, both regions for recurring incidence of Lyme disease during the warmer months.

Lyme disease is transmitted through blacklegged (or deer) ticks. Untreated disease may result in neurological complications and/or arthritis. Persistent symptoms, even after treatment, are possible.

At the same time, certain tick species continue to expand their range. For example, the lone star tick, historically concentrated in the southeastern U.S., has been increasingly identified in more central and northern states. These shifts raise new considerations for clinicians practicing in areas where tickborne disease may not have been top of mind in the past.

Lone star tick bites can cause alpha-gal syndrome, a condition that causes the immune system to develop a severe allergy to meat and dairy products.

Other tickborne diseases include Rocky Mountain spotted fever, babesiosis, and anaplasmosis. Tickborne infections often present with overlapping, nonspecific symptoms such as fever, chills, fatigue, and muscle aches, which can make clinical diagnosis challenging. Laboratory testing plays an important role in differentiating tickborne infections and distinguishing them from other parasitic or infectious causes. Accurate and timely diagnosis is critical to guiding appropriate treatment and improving patient outcomes.

Supporting appropriate testing and timely care

According to Patricia R. Slev, PhD, D(ABCC), medical director of Microbial Immunology, Serologic Hepatitis and Retrovirus at ARUP Laboratories, "Molecular methods (such as PCR) may be most useful for some tickborne diseases but for some, like Lyme disease, which is the most common tickborne disease in the U.S., serology is the recommended approach for diagnosis. Knowing which testing is appropriate for the specific tickborne disease is critical for timely diagnosis and treatment. Testing too early or selecting an inappropriate method can yield inconclusive or misleading results, complicating clinical decision-making."

Selecting the right test at the right time is important for obtaining clinically meaningful results. ARUP Laboratories offers test selection resources on ARUP Consult^®.

ARUP Consult is a free educational resource funded entirely by ARUP Laboratories. Content is developed and reviewed by ARUP medical directors, who are active faculty members at the Spencer Fox Eccles School of Medicine at the University of Utah, Department of Pathology.

The ARUP Consult Tickborne Diseases topic provides:

• Quick answers to frequently asked questions
• Indications for appropriate testing
• Detailed laboratory testing recommendations for Lyme disease, Rocky Mountain spotted fever, tickborne relapsing fever, babesiosis, anaplasmosis, ehrlichiosis, and tularemia

Users can subscribe to receive monthly emails about updates and additions to ARUP Consult. ARUP also welcomes feedback and suggestions via the Feedback page on arupconsult.com.

For more information about ARUP's tickborne disease testing options, complete the Infectious Disease Testing Inquiry Form to be contacted by an ARUP representative.

Alice To, mailto:[email protected]