Tickborne Diseases

In the United States, ticks carry many different pathogens that can cause a variety of human diseases. One of the most common of these is Lyme disease. Many tickborne diseases are challenging to diagnose because their symptoms imitate other common illnesses. The prevention of tickborne disease involves avoidance of tick-infested areas, the appropriate use of proper clothing, and insect repellents.

Upon completion of the course, you will be able to do the following:

• Explain how ticks infect their host.
• Identify how Lyme disease is spread.
• Describe the signs and symptoms of Lyme disease.
• Discuss the methods for diagnosing and treating Lyme disease.
• Describe other tickborne diseases found in the United States.
• List ways to prevent tickborne diseases and properly remove a tick.

There are many different tickborne diseases in the United States. The most commonly known is Lyme disease. However, more than a dozen lesser-known tick-related diseases have been identified in the United States, and approximately six tickborne diseases are present globally. The focus of this course is on tickborne diseases in the United States, with a primary focus on the most well-known and most commonly seen— Lyme disease. A brief summary of several other tick-related diseases is also presented.

How ticks infect their hosts

Ticks cannot fly or jump so they find a host by resting on the tips of grasses and shrubs in a position called “questing.” They hold onto the grass or leaves with their lower legs and their upper pair of legs are outstretched, waiting to climb onto a passing host. When the host brushes the spot where the tick is resting, it quickly climbs onto the host and then finds a place to bite the host and obtain its “blood meal” (Centers for Disease Control and Prevention [CDC], 2015a).

The tick feeding process makes it particularly adept at transmitting infections (CDC, 2015a):

• Depending on the species and age of the tick, preparing to feed can take from 10 minutes to 2 hours. The tick searches for a feeding spot, grasps the skin and cuts into the surface. It then inserts its feeding tube and many will also secrete a cement-like substance that keeps them firmly attached during their meal. The feeding tube can have barbs, which also helps keep the tick in place.
• Ticks often secrete a small amount of saliva with anesthetic properties so the host cannot feel the tick bite. If the tick is in a less visible location, it can often go unnoticed.
• Once a tick attaches to its host and begins sucking, it can suck the blood slowly for several days. If the host has bloodborne pathogens (such as the bacteria that cause Lyme disease), the tick often ingests the pathogen and becomes infected. When the infected tick later feeds on a human, the human can become infected. Once infected, the tick can transmit infection throughout its life.
• After feeding, the tick drops off the host and begins its next life cycle stage.
• If a tick is removed quickly (within 24 hours), the chances of obtaining a tickborne disease are greatly reduced. The longer the tick is attached, the greater the risk of acquiring a disease.