Ticks

1. Take the Lyme Disease Quiz
2. Lyme Disease Slideshow Pictures
3. Bad Bugs Slideshow Pictures

Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

View Full Profile

Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

View Full Profile

• Ticks Overview and Life Cycle
• Tick-Borne Diseases
• Tick Bite Symptoms and Signs
• When to Seek Medical Care
• Tick Bite Diagnosis
• Tick Bite Treatment
• Self-Care at Home
• Medical Treatment
• Tick Prevention
• Tick Bite Prognosis
• For More Information
• Synonyms and Keywords
• Authors and Editors
• Read more on Ticks from Healthwise
• Take the Lyme Disease Quiz
• Pictures of Lyme Disease - Slideshow
• Pictures of Bad Bugs - Slideshow
• Viewer Comments: Ticks - Experience
• Viewer Comments: Ticks - Preventive

Ticks are small bloodsucking arthropods and are composed of two families, Ixodidae (hard ticks) and Argasidae (soft ticks), that each contain different genera and species of ticks.

Ticks are the leading carriers (vectors) of diseases to humans in the United States, second only to mosquitoes worldwide. It is not the tick bite but the toxins, secretions, or organisms in the tick's saliva transmitted through the bite that causes disease.

Ticks are arthropods, like spiders. There are more than 800 species of ticks throughout the world. Many organisms that bite humans for a blood meal are not ticks and should not be confused with ticks. Some common examples are bedbugs and fleas (both are insects, not arthropods). If it is possible to bring into the doctor's office what has caused a "bite," the physician may be able to determine what potential vector caused the "bite."

Two families of ticks, Ixodidae (hard ticks) and Argasidae (soft ticks), are important to humans because of the diseases or illnesses they can transmit or cause. Hard ticks have a tough back plate or scutum that defines their appearance. The hard ticks tend to attach and feed for hours to days. Disease transmission usually occurs near the end of a meal, as the tick becomes full of blood. Figure 1 shows several hard ticks and the various stages in their life cycle. The stages are part of the life cycle of ticks; the smallest stages, larva and nymph, are sometimes generally referred to as "seed ticks" because they resemble small plant seeds.

Figure 1: The life cycle of ticks. Source: CDC

Soft ticks have more rounded bodies and do not have the hard scutum found in hard ticks. These ticks usually feed for less than one hour. Disease transmission from these ticks can occur in less than a minute. The bite of some of these ticks produces intensely painful reactions. Ticks can transmit disease to many hosts; some diseases cause economic harm such as Texas fever (bovine babesiosis) in cattle that can kill up to 90% of yearling cows. Figure 2 shows the body of a soft tick; there is no hard scutum, only the soft body. The adult soft ticks are about the same size as adult hard ticks (see Figures 1 and 2).

Figure 2: Picture of a soft tick. Source: CDC

Must Read Articles Related to Ticks

Encephalitis Encephalitis is an acute infection and inflammation of the brain itself. This is in contrast to meningitis, which is an inflammation of the layers covering the ...learn more >>

Insect Bites Stings and bites from insects are common. They often result in redness and swelling in the injured area. Sometimes a sting can cause a life-threatening allergic...learn more >>

Lyme Disease Lyme disease, sometimes referred to as Lyme infection, is a bacterial illness, transmitted to humans by the bite of deer ticks (Ixodes ticks) carrying a bacteri...learn more >>

See the Entire Ticks Topic Guide »