Ticks are responsible for several diseases like Lyme disease, Rocky Mountain spotted fever, tularemia, anaplasmosis, and ehrlichiosis. Here is what you need to know about the types of ticks, the diseases they cause, and how to prevent them.
What Are Ticks?
Ticks are tiny arachnids that live in dense wooded or grassy regions. They can crawl onto your skin as you near such areas and survive by sucking your blood.
They are responsible for the transmission of human-to-human and animal-to-human diseases. Transmission usually occurs when a tick bites an infected animal or human and gets infected by the parasite (bacteria, virus, or other disease-causing microorganisms). The parasite enters the new host when the infected tick bites another human.
Although ticks are widely considered insects, they belong to the arachnid family, like spiders and scorpions. Adult ticks have four pairs of legs and no antennae and firmly attach to the host during a blood meal. Though they’re slow feeders, they usually escape notice for long periods.
Different tick species act as vectors for certain diseases. Ticks are also more likely to transmit diseases during specific stages in their life cycle. They typically have four life stages — egg, larva (with six legs), nymph (with eight legs), and adult.
How Many Different Types of Ticks Are There?
Ticks are broadly categorized into two types — soft ticks (Argasidae) and hard ticks (Ixodidae). Out of the different tick species, there are 700 types of hard ticks and 200 types of soft ticks worldwide, responsible for all tick diseases.
But only around 60 types of ticks bite and transmit diseases to humans. Tick-borne diseases are increasing in the U.S., with over 200,000 cases between 2014 and 2018.
What Are the Different Types of Ticks?
Here are some common human-biting ticks in the U.S. and the parts of the country where you’re most likely to encounter them.
Black-legged tick (Ixodes scapularis). This tick has a distinct reddish-orange body with a black shield and legs. The black-legged tick is a known carrier of Borrelia burgdorferi, the bacteria that causes Lyme disease. It’s also responsible for the transmission of Borrelia mayonii (another bacteria that causes a Lyme-like illness), Borrelia miyamotoi and Borrelia hermsii (which cause Borreliosis fever), Babesia microti (babesiosis), and Ehrlicia muris (ehrlichiosis).
Black-legged ticks inhabit the eastern, northern, central, and southern parts of the U.S. While all stages of black-legged ticks bite humans, nymphs and adult females are the most common culprits.
Groundhog tick (Oxodes cookei). Also known as the woodchuck tick, it has a light brown or blonde appearance. It’s the primary vector for the Powassan virus disease and is prevalent in the eastern U.S. These ticks bite humans during all life stages.
Brown dog tick (Rhipicephalus sanguineus). The brown dog tick is brown and has a relatively narrow body compared to other ticks. It can transfer Rocky Mountain spotted fever (Rickettsia rickettsia), Q fever, and different types of rickettsiosis to humans during all life stages. Dogs are the primary carriers of these ticks. You can eradicate brown dog ticks by treating the infected pets and sanitizing your dog’s habitat.
Pacific coast ticks (Dermacentor occidentalis). Male and female Pacific coast ticks have blotchy brownish-black backs. These ticks transmit Rocky Mountain spotted fever to humans during all life stages. They can also transmit the Colorado tick fever virus, 364D rickettsiosis (Rickettsia phillipi), and tularemia (Francisella tularensis). They are most commonly found all over California and in Oregon.
American dog tick (Dermacentor variabilis). These ticks have dark brown bodies. Females usually have an off-white shield, while the color in males is not distinctive (either spotted or smeared). The American dog tick inhabits the regions east of the Rocky Mountains and along the Pacific coast. Most cases involve the transmission of Rocky Mountain spotted fever and tularemia due to adult female tick bites.
Lone star tick (Amblyomma americanum). Lone star ticks are typically reddish-brown, with female species carrying a distinctive white spot on their backs. This tick transmits the Ehrlichia chaffeensis and Ehrlichia ewingii, which cause human ehrlichiosis. The Lone star tick, which is widely prevalent in the eastern and southern parts of the U.S., also transmits the Bourbon virus and Heartland virus that cause the Bourbon virus disease and Heartland virus disease, respectively. Females cause these diseases during their nymph and adult stages.
Gulf coast tick (Amblyomma maculatum). The adult tick transmits a specific form of spotted fever called Rickettsia parkeri rickettsiosis in humans. Its usual habitats are the southeastern U.S., which includes the Gulf Coast of Mexico.
Western black-legged tick (Ixodes pacificus). Nymph and adult female ticks commonly transmit Borrelia burgdorferi (causing Lyme disease) and Anaplasma phagocytophilum (that causes anaplasmosis). Sometimes, these ticks transmit Borrelia miyamotoi, a relapsing fever. The ticks have a reddish body, a black shield, and black legs and thrive in the states lining the Pacific coast.
Rocky Mountain wood tick (Dermacentor andersoni). Adult ticks, commonly found in the Rocky Mountain states, are responsible for transmitting Rocky Mountain spotted fever, Colorado tick fever, and tularemia. They are usually reddish-brown, with adult males having a cream-colored shield, and they populate in regions that are 4,000 feet above sea level.
Soft ticks (Ornithodoros). As the name suggests, these ticks lack a hard shell on their back and resemble large raisins. They’re widely prevalent in the western U.S. in regions between 900 meters to 2,000 meters above sea level. Reports of soft tick bites are common among mountain cabin dwellers, and rodents that infest mountain cabins carry these ticks. Some diseases caused by these ticks include tick-borne relapsing fever (caused by Borrelia hermsii and Borrelia turicatae).
How Can You Prevent Tick Bites?
The Centers for Disease Control and Prevention lists a few ways to avoid tick bites and prevent the spread of serious diseases:
- Check which ticks are common in your area, and when they are active. Although tick bites are prevalent throughout the year, many ticks are active during summer.
- Check your body and clothes for ticks when you return home after being outdoors. Some of the most common places where you can find ticks include the area behind your ears, hair, inside your belly button, armpits, around the waist, groin, and the back of your knees
- If you have pets, treat them to make sure they’re not carrying any disease-causing vectors. Ticks typically live in bushy parts or on animals. Avoid woody and bushy areas, especially those that have tall grass.
- Treat your gear (clothes, boots, and other materials) with 0.5% permethrin if you think you’ve been in a place infested with ticks.