Ticks and the Diseases They Spread in the United States

In the United States, ticks can carry bacteria, viruses and parasites (pathogens) that cause disease in people. They pass them on while they feed, and many of the illnesses they cause look alike.

Diseases ticks can spread

Ticks in the United States carry pathogens behind these diseases, among others:

• Alpha-gal syndrome
• Anaplasmosis
• Babesiosis
• Bourbon virus
• Colorado tick fever
• Ehrlichiosis
• Hard tick relapsing fever
• Heartland virus
• Lyme disease
• Powassan virus
• Rickettsia parkeri rickettsiosis
• Rocky Mountain spotted fever
• Soft tick relapsing fever
• Southern tick-associated rash illness (STARI)
• Tularemia
• 364D rickettsiosis

Symptoms

If you develop any of the following within a few weeks of a tick bite, see a healthcare provider:

• Fever or chills. Every tickborne disease can cause fever.
• Aches and pains. Headache, tiredness and muscle aches; people with Lyme disease may also have joint pain.
• Rash. Lyme disease, STARI, Rocky Mountain spotted fever, ehrlichiosis and tularemia can each cause a distinctive rash.

Before deciding on treatment, the provider should weigh your symptoms, the region where you were bitten and, depending on those two, lab tests.

Tick paralysis

A toxin in the saliva of an attached tick is thought to cause tick paralysis: weakness or paralysis that gradually moves up the body. It can resemble other nerve conditions, such as Guillain-Barré syndrome or botulism. People usually move normally again within 24 hours of the tick being removed. More from MedlinePlus.

How ticks find a host

Ticks detect an animal's breath and body odours, or sense its body heat, moisture and vibrations; some species can even recognise a shadow. They pick a place to wait by finding well-used paths, then rest on the tips of grasses and shrubs.

Ticks cannot fly or jump. Many species wait instead in a posture called questing: they hold on to leaves and grass with their third and fourth pairs of legs and stretch the first pair out. When a host brushes the spot, the tick climbs aboard. Some attach quickly; others wander in search of thinner skin, such as the ear.

How ticks spread disease

• Getting ready. Depending on the species and its stage of life, a tick takes from 10 minutes to 2 hours to prepare to feed. Once it finds a spot, it grasps the skin and cuts into the surface.
• Anchoring. It inserts its feeding tube, which can have barbs that hold it in place. Many species also secrete a cement-like substance that keeps them attached through the meal.
• Going unnoticed. Ticks can also secrete small amounts of saliva that numbs the skin, so the animal or person does not feel the bite. In a sheltered spot a tick can go unnoticed.
• Feeding. Ticks suck blood for anything from minutes to days, depending on the species. If the host has a bloodborne infection, the tick takes in the pathogen with the blood.
• Infecting. Small amounts of the tick's saliva can enter the host's skin during feeding. If the tick carries a pathogen, that is how it can pass to the host.
• Moving on. After feeding, most ticks drop off and prepare for their next life stage. At their next meal they can pass an infection they picked up to a new host.

Sources

• Centers for Disease Control and Prevention, "About Ticks and Tickborne Disease." https://www.cdc.gov/ticks/about/index.html