Health risks associated with common tick species

Larval, nymph and adult ticks feed on blood. After inserting their mouth parts, they inject chemicals that prevent itching and inflammation, maintain blood flow, and cement the tick to its host. They feed for multiple days. If you’re not doing tick checks regularly, you may not notice them right away. 

One tick bite can have many consequences

Different tick species can make you sick in many ways from spreading germs and causing allergies to blood loss and even paralysis.

Ticks can do many things with one bite. 

How common are tick-borne diseases?

The risk of acquiring a tick-borne disease depends on where you live in the country. For example, data from 2015 showed that more than 95% of all Lyme disease cases were reported from 14 Northeast and Midwest states. Even though the disease is reported from a limited area, Lyme disease is the most common vector-borne disease in the United States, and is the second most commonly reported National Notifiable Disease, second to Chlamydia (#1) and before Gonorrhea (#3), which are both sexually transmitted diseases that occur throughout the country. Each year in the US, approximately 30,000 cases of Lyme disease are reported to the Centers for Disease Control and Prevention (CDC). But recent estimates suggest that this is only a fraction of the actual incidence rate. The CDC currently estimates that between 300,000 and 400,000 people are infected with the bacteria that cause Lyme disease each year, with children aged 5 to 9 at the greatest risk of exposure. In addition to Lyme disease, ticks in the northeast transmit the pathogens that cause Anaplasmosis, Babesiosis, Ehrlichiosis, Powassan Virus, Rocky Mountain Spotted Fever, Tularemia and a bacteria related to the agent of Lyme disease called Borrelia miyamotoi. Tick-borne disease is very common in the Northeast. For more information see Lyme Disease by the Numbers (2017).

Who is at risk of tick-borne disease?

You don’t have to be an outdoor adventurer to encounter a tick and be exposed to a tick-borne disease. In fact, people encounter ticks where they live, work, learn and play. Fetching a ball from the woods edge, pushing a friend on the swings, walking near the edge of the sidewalk, running or biking on the side of the road, gardening, having a barbeque or picnic, raking leaves, or any other perfectly normal activity could put you in contact with a tick. One group that is most at risk of exposure to tick-borne disease is children, because of their play outdoors (CDC Lyme Disease Graphs). Any person that encounters a tick has the same level of risk of acquiring tick-borne disease.

Do all ticks transmit pathogens that cause human disease?

In the Northeastern US, we are primarily concerned with three tick species that transmit pathogens to humans: blacklegged, lone star and American dog ticks. However, not every tick in an area carries pathogens that cause human disease.

Larval ticks, the stage that hatch from eggs and have only six legs (nymphs and adults have eight legs), are not thought to play a major role in pathogen transmission. However, when larval ticks take their first blood meal, they can potentially acquire pathogens if they fed on an infected animal. Once pathogens have been acquired through feeding on an infected animal, the tick can now transmit pathogens as a nymph and adult (Note: there is some evidence that Powassan virus, carried by the blacklegged tick, can be transmitted from a female to her offspring, and that larval blacklegged ticks can transmit Borrelia miyamotoi, a bacteria that is related to the pathogen that causes Lyme disease).

Nymph blacklegged ticks are responsible for the greatest number of cases of tick-borne disease. This life stage is about the size of a poppy seed and is active in the spring when people are not thinking about ticks. For this reason, daily tick checks are needed year round.

Some nymphs and adults never acquire pathogens. Not every tick in nature is infected, and the rate of infection among ticks differs throughout the region.

If I find a tick crawling on me, am I at risk for disease?

No. Ticks transmit pathogens while they are attached and feeding, with their mouthparts inserted into your skin (see How do ticks transmit disease?). After feeding the tick typically drops off, and would not be found crawling on your skin. If you find a tick crawling on you, you can quickly kill the tick by placing it in a small jar or bottle with rubbing alcohol. You may wish to keep such a jar close by while spending time outdoors or hiking. It is never a good idea to squish ticks with your fingers, and brushing them off your clothing may not work.

How do ticks transmit disease?

Ticks are considered disease vectors because they acquire pathogens from one organism and transmit them to another. For this to occur, ticks have to insert their mouthparts into the host organism and drink the host’s blood. As ticks feed, there is an exchange of fluids between the host and the tick: blood is drawn out of the host and some saliva enters the host bloodstream, possibly carrying pathogens. The time required for pathogens to pass from tick to host is variable. While viruses such as Powassan virus can be transferred within minutes, some bacteria may take longer to transmit. Feeding ticks will be firmly attached to the host, and require proper technique to remove. 

How long does a tick have to be attached to transmit disease?

The short answer to this complicated and elusive question is minutes to hours, depending on the pathogen. There is some question in the medical literature about the time required for transmission of the bacteria that causes Lyme disease. However, the same blacklegged tick can transmit Powassan virus in a matter of minutes. Therefore, safe removal as soon as possible is the best recommendation. Note: it may take a tick up to two hours to find an ideal location to attach, and ticks can remain attached to the host for several days to feed.

What are the signs and symptoms of tick-borne disease?

As a pest management program, we do not offer medical advice about tick-borne disease treatment and diagnosis. In truth, this is a complicated topic. Rashes may or may not develop, and disease symptoms, including rashes, vary among people. However, a few thoughts:

If you remove a tick, place it in a zippered plastic bag and label with the date, the species, if the tick was attached (versus walking on your skin), and if the tick had fed and was partially engorged. This is useful if you decide you’d like to test the tick for pathogens.

Be aware of flu-like symptoms occurring a week or more after activity that might have put you in contact with ticks. This is true all year round, but especially after the peak of nymphal black-legged tick activity in the spring and adult activity in the fall.

See your physician and mention the possibility of a tick encounter. Bring any ticks that you might have collected.

Can tick bites really cause a red meat allergy?

There is strong evidence that a bite from the lone star tick can cause an allergic reaction to red meats. This is known as alpha-gal syndrome, which is named from a substance secreted by the tick as it feeds on humans. In some cases, the human body recognizes this substance as an allergen, and mounts an allergic response the next time it enters the system. Unfortunately, this same substance is found in most red meats, causing an allergic reaction when red meat is consumed. It is not known how long this sensitivity lasts, but there is some evidence that it may not be permanent as long as the individual is not exposed to the bite of a lone star tick again.

Can tick bites really cause paralysis?

Tick Paralysis is a worldwide phenomenon caused by different tick species across the globe. In the US, cases of tick paralysis are most often diagnosed from the Northwest from May to June (Diaz 2015 verified 55 cases in the US from 1946-2014, including two from NY and two from NJ). In the Northeastern US, female American dog ticks are most often associated with the syndrome. Tick Paralysis occurs when a tick attaches to a host and initiates feeding. The female tick secretes a toxin that can cause paralysis starting in the feet and moving upward. If the tick is found and removed, the symptoms go away with no long-term damage. However, if the tick is not found, paralysis can affect the respiratory system and become life threatening. Symptoms typically appear in two to six days of attachment, highlighting the need for daily tick checks. Tick paralysis is sometimes misdiagnosed as Guillain-Barré syndrome due to similar symptoms.

How old is Lyme disease?

Lyme disease was recognized for the first time in 1975 from patients in Old Lyme, Connecticut, despite a long history in Europe. However, the disease and bacteria that cause it have likely been around for millions of years – even if doctors did not have a name for it or understand how it was transmitted. The bacteria responsible for causing Lyme disease, Borrelia burgdorferi, was identified in 1981, but there is evidence that it has been present on the North American continent for 60,000 years (Genomic insights into the ancient spread of Lyme disease across North America). Ötzi the iceman may be the oldest human body showing evidence of Lyme disease from 5,300 years ago (Iceman Mummy May Hold Earliest Evidence of Lyme Disease), and an ancient tick preserved in amber contains what is likely an ancestor of the Lyme bacteria from 15-20 million years ago (Lyme Disease’s Possible Bacterial Predecessor Found in Ancient Tick). Lyme disease is also prevalent across Europe and Russia.

What role do deer play in tick-borne disease?

Deer are the primary host of lone star and adult blacklegged ticks, which gives them the special designation as reproductive hosts because the female tick will create and lay eggs after feeding on a deer. Based on their ability to move great distances, deer are also important dispersal hosts for ticks, moving them to new locations. Deer do not play a role in infecting ticks with the pathogens that cause Lyme disease and several other diseases, although they are the reservoir host of Ehrlichia chaffeensis. In the transmission cycle of Lyme disease, ticks most often acquire pathogens from mice, small mammals and even some birds, which are known as reservoir hosts.

What role do mice play in tick-borne disease?

Field mice (and other small, outdoor mammals) are the primary reservoir hosts of tick-borne disease. This term means that ticks acquire pathogens after feeding on the mice, and are then infected for the rest of their lives with the ability to transmit pathogens that cause disease. As reservoir hosts, mice are not negatively affected by the pathogens, and individual mice can be infected with multiple pathogen types. It is important to note that field mice (white-footed mice and deer mice: Peromyscus species) live outdoors most of the year, and may enter homes during the winter. They have two distinct fur tones: a gray or tan back and a white belly, along with large ears and eyes. They are different than house mice (Mus species), which have the same color fur on their whole body, and smaller eyes and ears than field mice. House mice are typically indoor pests that live in buildings year round.

Research from the Cary Institute of Ecosystem Studies suggests that there is an interaction between mice, acorns and tick populations. Acorns are an important food source for field mice, and mast years occur sporadically when a huge crop of acorns are produced (Year 1). Because of this surplus in food availability, field mouse populations are often very large the next year (Year 2). With plenty of hosts to feed on, tick populations are often high in Year 3. Thus, after a mast year, tick populations are predictably high two years later if other weather-related conditions are ideal for ticks (for example, no drought). It is important to note that acorn masts may not occur across broad regions and can vary by oak (tree) species. In addition, other factors like winter temperatures can influence subsequent nymphal populations. Therefore, the ability to predict tick populations can vary across a region and depends on other environmental factors.

What role do other wildlife play in tick-borne disease cycles?

A number of small and medium-sized mammals, and even some birds, are important hosts for ticks. One animal that is less ideal as a host is the opossum. These animals have been shown to destroy over 90% of the ticks on their bodies. Foxes serve as hosts to ticks, but foxes hunt, kill and eat white-footed mice, the primary reservoir of Lyme disease. For the lone star tick, wild turkeys are an important alternate host that may play a role in moving ticks great distances.

portrait of Joellen Lampman
Joellen Lampman

Extension Support Specialist

NYS Integrated Pest Management

Joellen Lampman