Why is a tick dangerous?

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Reports of tick-borne illnesses have doubled between 2019 and 2022. An estimated 31 million people (1 in 10 people) are bitten by ticks every year in the US. Emergency Department (ED) visits for tick bites start increasing in March, stay elevated through July, start dropping a bit in August, and then start to rise again in September through December. In the Northeast, we have seen high tick activity for the past month, including ticks in city parks and urban areas.

Importantly, more guys than gals have emergency room visits for ticks, AND many of these visits are for children.

Lyme disease is the most common tickborne disease in the US and an estimated 476,000 patients are treated for Lyme disease each year (CDC 2025). Unfortunately, this is probably an underestimate; Lyme disease is a nationally notifiable condition, but many cases go undiagnosed. Lyme disease, is caused by a bacteria, Borellia bergdorferi. Unfortunately, ticks carry many other diseases. Diseases caused by bacteria in ticks include: Ehrlichiosis (Ehrlichia chaffeensis), Anaplasmosis (Anaplasma phagocytophilum), and Rocky Mountain Spotted Fever (Rickettsia rickettsia). In contrast, Babesiosis is caused by a parasite (Babesia microti) and Powassan disease is caused by a virus (flavivirus). Bourbon disease, first described in 2014, is a rare disease caused by a virus.

Not all ticks carry disease or all these pathogens, but ticks may carry multiple bacteria and cause multiple diseases. As of 2019, over half of the black-legged ticks in Suffolk County, Long Island were infected with at least one pathogen, with the Lyme disease bacteria the most common (Borrelia burgdorferi; 57% in adults, 27% in nymphs), followed by Babesia microti (14% in adults, 15% in  nymphs), and Anaplasma phagocytophilum (14% in adults, 2% in nymphs).

Symptoms of these diseases can vary between diseases and between individuals. Symptoms may include fatigue, fever, and/or aches including headaches and muscle aches, joint pain, difficulty concentrating. Sometimes Lyme disease has a typical rash (the bull’s eye rash), but the absence of a rash does not mean you don’t have the disease. Some of these diseases also have gastrointestinal symptoms. Most of these symptoms appear days to weeks after a tick bite and can be confused as a viral illness.

Alpha-gal syndrome is not an infection, but is an allergic reaction to a sugar (galactose-a-1,3-galactose; a-gal, alpha-gal). This is usually associated with the lone star tick, but more recently, has been associated with the blacklegged tick, which can also have a-gal in their saliva and salivary glands. Reports of a-gal syndrome have increased significantly in the past few years, although the real numbers of individuals with this syndrome are unknown. The a-gal sugar is in many mammals, but not in humans or monkeys. The tick can transfer alpha-gal from its saliva into a person’s blood. Because this is not a normal human sugar, the human immune system sees this as foreign, and some people create IgE (allergic antibodies to the a-gal sugar) that circulate in the blood. When an individual is re-exposed because they ate red meat (beef, pork, lamb, venison, rabbit, some dairy projects) or other products from mammals (some medications and non-food products), they can develop an allergic reaction. Unlike many allergic reactions, this one can take hours to develop, making the diagnosis difficult. The symptoms may include classic allergic symptoms of hives (a skin rash), shortness of breath, swelling of the lips or throat. Stomach symptoms of nausea, vomiting and stomach pain may also occur. Not all of these symptoms need to be present.  The diagnosis is based on the history and a blood test for antibodies can be performed. 

Common name Disease Greatest time of risk
Blacklegged tick Lyme disease, Anaplasmosis, Ehrlichiosis, Babesiosis, Powassan disease Spring, summer, fall, but even winter
American dog tick Rocky Mountain spotted fever, Tularemia Spring and summer
Lone star tick

Ehrlichiosis, Southern tick-associated rash illness, Heartland virus disease, Tularemia, Bourbon disease, a-gal red meat allergies

 Spring through fall


Early recognition and treatment decrease the risk of severe infection, however sometimes the disease can be difficult to diagnose and not all people remember having been bitten by a tick. Because of these difficulties, it’s most important to prevent a bite in the first place. Wear TheTickSuit™.

Some references and data sources

There is a lot of information on the web and in the lay and scientific literature about ticks and tickborne diseases. Here are a few references that we his summary – there are many more and thisyear.

Websites and interesting articles

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