Tick surveillance plays a critical role in understanding how tick populations change over time. Although several methods exist for surveying ticks, the most commonly used approach is active surveillance, a technique where researchers collect ticks directly from vegetation by dragging or flagging a flannel cloth across the vegetation. When conducted systematically over multiple years and in consistent locations, this type of surveillance can reveal meaningful trends in tick population density, distribution, and seasonal dynamics. However, comprehensive tick surveillance is resource-intensive and therefore rarely implemented on a broad scale. Most efforts are limited in both space and time, which makes it challenging to track long-term changes in tick abundance with confidence.

Despite these limitations, tick surveillance has proven to be an essential tool for documenting the expanding geographic range of ticks. This is especially true for the blacklegged tick (Ixodes scapularis), which is the primary vector of Lyme disease and is responsible for the majority of tick-borne disease cases in the United States.

In contrast to the sporadic nature of tick surveillance, we have continuous and robust data on human cases of tick-borne diseases. These records consistently show a steady increase in reported cases over time. While some of this rise can be attributed to improvements in diagnostic methods, increased public awareness, and better reporting, the broader consensus is clear: tick populations that pose risks to human health are not only increasing in areas where they are already established but are also expanding into new regions. In many of these newly affected areas, human cases of tick-borne diseases are now being reported for the first time, underscoring the urgency of expanding both surveillance and prevention efforts.

Ticks are small, blood-feeding parasites that can transmit dangerous diseases to both humans and animals while they feed. Not every tick species bites people, and different ticks carry different types of pathogens. For example, Lyme disease, the most common tick-borne illness in the United States, is transmitted specifically by blacklegged ticks, also known as Ixodes scapularis in the East and Midwest, and Ixodes pacificus on the West Coast. These ticks also spread other serious diseases such as anaplasmosis, babesiosis, and the potentially deadly Powassan virus.

Among all tick species, Ixodes scapularis poses the greatest threat to human health in the U.S. Lyme disease alone affects an estimated 500,000 people each year. While it is non-fatal, it can cause long-lasting and debilitating symptoms that disrupt daily life for thousands of Americans.

Other tick species, such as the lone star tick (Amblyomma americanum) and the American dog tick (Dermacentor variabilis), also bite humans frequently and are known to transmit diseases like ehrlichiosis and Rocky Mountain spotted fever. These illnesses are less common than Lyme disease but can become life-threatening if not diagnosed and treated quickly with antibiotics.

The tick-borne diseases and tick species posing the greatest level of concern today vary by region but share significant public health impacts. Lyme disease, caused by Borrelia burgdorferi, remains the most common and widely recognized tick-borne illness in North America. The disease affects an estimated 500,000 people annually in the U.S. alone. Although Lyme disease is rarely fatal, it can cause a wide range of symptoms that vary in severity and duration. Early signs often include a characteristic “bull’s-eye” rash, fever, fatigue, headache, and muscle aches. If not diagnosed and treated promptly with antibiotics, the infection can spread to the joints, heart, and nervous system, leading to chronic symptoms such as arthritis or neurological complications such as meningitis and Bell’s palsy. Some patients may develop a condition known as Post-Treatment Lyme Disease Syndrome (PTLDS) that can severely impact quality of life, daily functioning, and mental health for thousands of patients. Public education and awareness are critical, as early detection and prompt antibiotic treatment significantly improve outcomes. Economic costs associated with Lyme disease are also substantial, including healthcare expenses, lost productivity, and long-term disability for affected individuals. Given its widespread impact and growing burden, Lyme disease remains a top priority for surveillance, research, and public health intervention.

Tick-borne illnesses are expected to increase significantly over time due to the ongoing geographical expansion of various tick species. Among these, the blacklegged tick (Ixodes scapularis), the lone star tick (Amblyomma americanum), and the recently introduced Asian longhorned tick (Haemaphysalis longicornis), native to East Asia, are of particular concern. This expansion is leading to increased risk of exposure for millions of Americans, as these ticks carry pathogens that cause diseases such as Lyme disease, ehrlichiosis, anaplasmosis, and others.

Several biotic and abiotic factors contribute to this expansion. One key biotic factor is the population of white-tailed deer, which serve as primary hosts for adult ticks. As deer populations have rebounded in many regions due to reduced hunting and habitat changes, they provide abundant hosts that enable tick populations to thrive and spread. Additionally, small mammals like mice and birds act as reservoirs for pathogens, helping sustain the transmission cycles of tick-borne diseases.

Abiotic factors also play a crucial role. Climate change, including warmer temperatures and milder winters, extends the active season of ticks, allowing them to survive in previously inhospitable northern regions. This results in a northward shift in tick distribution, exposing new human populations to tick bites and associated diseases. Landscape modifications, such as suburban development, deforestation, and the fragmentation of natural habitats, create edge environments that favor tick survival and increase human-tick interactions. These environments bring humans into closer contact with wildlife and tick habitats, further elevating the risk of tick-borne illnesses.

The introduction of the invasive Asian longhorned tick poses additional challenges. Unlike native ticks, this species can reproduce asexually and establish large populations rapidly. It is also capable of carrying pathogens that may impact both human and animal health, although its full public health impact is still being studied.

Public education plays a critical role in reducing tick encounters and lowering the risk of tick-borne diseases. Because ticks often thrive in outdoor environments and can go unnoticed, instructing people on practical prevention strategies reduces the risk of tick bites and subsequent disease transmission. Awareness of ticks’ habitats increases the adoption of protective measures, such as wearing long sleeves, tucking pants into socks, using EPA-approved repellents, and performing daily tick checks. Educated communities also tend to engage more in managing their landscapes to minimize tick habitats around homes, and they are more likely to seek prompt medical care if symptoms of tick-borne illness arise, leading to better health outcomes.

Effective public health messaging combines clear, actionable advice with locally relevant information, making the risk more tangible and relatable. Visual aids, such as infographics that show how to perform tick checks and remove ticks properly, can significantly improve understanding and compliance. Storytelling that shares real-life experiences of those affected by tick-borne diseases can further motivate individuals to take prevention seriously. Additionally, reaching communities through diverse channels such as social media, schools, healthcare providers, and outdoor recreational groups ensures a broader and more impactful reach. Addressing common misconceptions, such as the belief that ticks are only found in deep forests or are only active during summer, helps prevent complacency and reinforces awareness year-round.