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.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Ticks are scientifically classified as Arachnida (which includes spiders). The fossil record suggests ticks have been around at least 90 million years.
Most tick bites do not transmit pathogens.
There are a variety of tick-borne diseases.
There is a wide range of symptoms that usually develop days to weeks after the tick bite. The symptoms that become manifest depend on the particular microbe (pathogen) that is transmitted.
For all tick bites, local cleansing and antibiotic cream may be applied.
There are safe and effective methods for the removal of all types of ticks.
What are ticks?
Ticks are small arachnids. Ticks require blood meals to complete their complex life cycles. Ticks are scientifically classified as Arachnida (which includes spiders). The
fossil record suggests ticks have been around at least 90 million years. There
are over 800 species of ticks throughout the world, but only two families of
ticks, Ixodidae (hard ticks) and Argasidae (soft ticks), are known to transmit
diseases or illness to humans. Hard ticks have a scutum, or hard plate, on their
back while soft ticks do not.
Ticks have a complex life cycle that includes eggs, larvae, nymphs, and adult
male and female ticks. The larvae, nymphs, and adults all need blood meals.
Usually, the female adult (hard tick) is the one causing the most bites as males
usually die after mating. Ticks do not jump or fly. They simply reach out with
their legs and grab or crawl onto a host. Although some larvae have preferred
hosts, most ticks in the nymph or adult phase will attach a get a blood meal
from several different kinds of animals, including humans. Except for a few
species of larval ticks, the immature phases (larvae, nymphs) usually are even
less selective about where they get a blood meal and are known to bite snakes,
amphibians, birds, and mammals. Larvae are very small (about 1/32 of an inch with
six legs), while nymphs are about 1/16-1/8 inch with eight legs and adults about
3/16-1/4 inch with eight legs. The complex life cycles are described in the last
web
citation below, and all of the web citations include pictures of various species
of ticks. Although ticks will die eventually if they do not get a blood meal,
many species can survive a year or more without a blood meal. 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. It may take hours
before a hard tick transmits pathogens. Soft ticks usually feed for less than
one
hour. Disease transmission can occur in less than a minute with soft ticks. The
bite of some of these soft ticks produces intensely painful reactions.
Ticks are vectors (transmitters) of diseases for humans and animals. Ticks can
transmit disease to many hosts; some cause economic harm such as Texas fever
(bovine babesiosis) in cattle that can kill up to 90% of yearling cows. Ticks act
as vectors when pathogens in their saliva and mouth secretions get into the
host's skin and blood. Ticks were understood to be vectors of disease in the
mid-1800s, and as investigative methods improved (microscopes, culture
techniques, tissue staining), more information showed the wide variety of
diseases that could be transmitted by ticks.
Picture of a tick
There are many common names for various ticks (for example, dog tick, deer tick, and African tick), and these names appear in the scientific literature, too. Most common names represent a genus of ticks (see below). However, the common name "red" may be used by people to describe almost any tick that has had a blood meal.
Reviewed by William C. Shiel Jr., MD, FACP, FACR on 7/25/2012
Medical Author: William C. Shiel Jr., MD, FACP, FACR
Lyme
diseaseis caused by infection with a bacterium called a spirochete(Borrelia burgdorferi) and is transmitted to
humans by infected ticks (Ixodes scapularis and I. Pacificus). Patients with
early stage Lyme disease have a characteristic rash(erythema migrans) accompanied by nonspecific symptoms (for
example, fever, malaise, fatigue, headache, myalgia, and arthralgia). Lyme disease can usually be treated successfully with standard antibiotics.
The U.S. Centers for Disease Control and Prevention
(CDC) released the results of a six-year survey study of Lyme disease from 1992 to
1998. During this period, a total of 88,967 cases of Lyme disease were reported
to CDC by 49 states and the District of Columbia, with the number of cases
increasing from 9,896 in 1992 to 16,802 in 1998. The researchers concluded that
the increase in reported cases is probably a result of both a true increase in
incidence within known high-risk areas as well as more complete reporting as a result of enhanced Lyme disease surveillance. They noted that surveillance capabilities and public awareness of Lyme disease have increased during this period.
Researchers also note that Lyme disease remains underreported with an estimated
seven to 12 cases for each reported case.
Lyme disease is a bacterial illness, which is spread by ticks when they bite the skin. Initially the disease affects the skin causing a reddish rash associated
The word "rash" means an outbreak of red bumps on the body. The way people use this term, "a rash" can refer to many different skin conditions. The most
Itching can be a common problem. Itches can be localized or generalized. There are many causes of itching to include: infection (jock itch, vaginal itch),
Headaches can be divided into two categories: primary headaches and secondary headaches. Migraine headaches, tension headaches, and cluster headaches are
Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered
The majority of spiders in the United States are harmless. Two exceptions include the black widow spider and the brown recluse spider. Symptoms of a harmless
Nausea is an uneasiness of the stomach that often precedes vomiting. Nausea and vomiting are not diseases, but they are symptoms of many conditions. The
Rocky Mountain spotted fever (RMSF) is an infectious disease that's transmitted by the bite of a tick infected with the Rickettsia rickettsii bacterial
Bug bites and stings have been known to transmit insect-borne illnesses such as West Nile virus, Rocky Mountain spotted fever, and Lyme disease. Though
West Nile virus (West Nile encephalitis) is a brain infection caused by a virus. People become infected with the virus after they're bitten by a mosquito
Tularemia (rabbit fever) is an infection caused by the Francisella tularensis bacteria. People can become infected with tularemia by coming into contact
Travelers should prepare for their trip by visiting their physician to get the proper vaccinations and obtain the necessary medication if they have a medical
Viral hemorrhagic fever(s), or VHFs are a group of illnesses caused by distinct families of viruses. Many of these viruses are life-threatening, and classified
Viral hemorrhagic fevers (VHFs) refer to a group of illnesses that are caused by several distinct families of viruses. In general, the term "viral hemorrhagic fever" is used t"...
