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What Diseases Do Ticks Carry?

There are over 899 species of ticks in the world, 90 of them found in the United States. Some of these ticks carry diseases that are harmful to humans, the most recognized being Lyme disease.

Disease: Tick Carrier/Symptoms

The following is a list of the 10 most common diseases carried by ticks of the United States, which tick is likely to transmit the disease, and where the ticks are normally found.

Lyme disease

• Tick carrier: Blacklegged tick, Western blacklegged tick
• Located: northeastern US, upper Midwestern US, Pacific coastline

Rocky Mountain Spotted Fever (RMSF)

• Tick carrier: American dog tick, Rocky Mountain wood tick, brown dog tick
• Located: throughout US

Tickborne Relapsing Fever (TBRF)

• Tick carrier: soft ticks
• Located: Arizona, California, Colorado, Idaho, Kansas, Montana, Nevada, New Mexico, Ohio, Oklahoma, Oregon, Texas, Utah, Washington, and Wyoming

Southern Tick-Associated Rash Illness (STARI)

• Tick carrier: lone star tick
• Located: southeastern US, eastern US

Tularemia

• Tick carrier: dog tick, wood tick, lone star tick
• Located: throughout US

Anaplasmosis

• Tick carrier: blacklegged tick
• Located: northeastern US, upper Midwestern US, Pacific coast

Ehrlichiosis

• Tick carrier: lone star tick
• Located: south central US, eastern US

Rickettsiosis

• Tick carrier: Gulf coast tick
• Located: Gulf coast

364D Rickettsiosis

• Tick carrier: Pacific coast tick
• Located: California

Babesios

• Tick carrier: blacklegged tick
• Located: eastern US

How Does a Tick Transmit Disease?

Ticks transmit diseases during feeding. The tick has special piercing sucking mouthparts designed to penetrate the host's skin and extract blood. During the feeding process, the tick will excrete a ‘pathogen' through its saliva that helps to prevent the host's blood from clotting. It also acts like an anesthetic, suppressing the host's immediate immune response. It is during this action that the chance of disease passing from the tick to the host occurs.