The lone star tick, Amblyomma americanum, is an aggressive biter recognized by the single white or silvery spot on the adult female’s back. As its geographical territory continues to expand, the tick’s movement into new regions introduces health risks to populations previously unfamiliar with this particular arachnid.
Established and Expanding Range
Historically, the lone star tick has been most common in the southeastern and eastern United States. Its established range stretches from Texas, Oklahoma, and Missouri eastward to the Atlantic coast, where it is a prevalent species in wooded and brushy areas. This core territory represents the tick’s traditional habitat.
In recent years, the tick has significantly expanded its territory northward and westward. This movement has led to established populations in the Midwest, including states like Illinois and Iowa, and throughout the Northeast. For instance, a notable increase in lone star ticks has been documented on Martha’s Vineyard, Massachusetts.
This expansion is significant, as researchers have documented new encounters in over 300 counties where the ticks were not previously recorded. This rapid colonization demonstrates the tick’s adaptability and its capacity to thrive in a broader range of environments than previously understood.
Factors Driving Range Expansion
Climate change is a primary force behind the lone star tick’s northward movement. Warmer average temperatures and less severe winters enable the tick to survive in latitudes that were once too cold. These milder conditions allow its eggs and larvae to endure the winter, leading to population growth in northern states.
The expansion is also linked to the movement of host animals, particularly the white-tailed deer. As growing deer populations shift habitats, they act as transportation for lone star ticks, carrying them into new forests, grasslands, and even suburban areas. This host-facilitated dispersal is a direct mechanism for the tick’s geographic spread.
Public Health Implications of the Expanding Range
As the lone star tick moves into new regions, more people are exposed to its bite and associated health risks. A primary consequence is the potential development of alpha-gal syndrome. This condition is an allergy to red meat and products derived from mammals, causing reactions from hives to severe anaphylaxis hours after consumption.
Beyond the red meat allergy, the lone star tick is a vector for several other pathogens. It transmits bacteria that cause diseases such as ehrlichiosis and tularemia, both of which can lead to fever, headache, and muscle aches if not treated. Ehrlichiosis cases have been increasing, and the disease can be fatal if left untreated.
The tick is also associated with Southern Tick-Associated Rash Illness (STARI), which presents with a rash similar to that of Lyme disease. The growing presence of this tick also brings emerging viruses, such as Heartland and Bourbon viruses, into new communities. These viruses can cause illnesses with symptoms that mimic other tick-borne diseases, complicating diagnosis.