Tick Bite

Ticks are small arachnids. Ticks require blood meals to complete their complex life cycles. Ticks are scientifically classified as Arachnida (a classification that 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. Tickborne diseases occur worldwide.

Ticks have a complex life cycle that includes eggs, larvae, nymphs, and adult male and female ticks. The larvae, nymphs (also termed seed ticks), 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, fly, or drop. 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 tick species. 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 transmitters (vectors) 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 which can kill up to 90% of yearling cows. Ticks act as vectors when microbes 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.

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. However, the common name "red" may be used by people to describe almost any tick that has had a blood meal (engorge with blood).

• People who go through grassy areas and woods are at higher risk for tick bites, especially during the months from April through September.
• People who travel through such areas out of necessity or for recreation are at higher risk than those that protect themselves with appropriate clothing like long-sleeved shirts, long pants, and DEET-containing repellents (see prevention section below).
• In addition, people who have pets treated with flea and tick repellents decrease their risk of tick bites.
• People who live in areas surrounded by tall grassy areas or woods have a higher risk for tick bites, but the prevention section below describes ways to reduce risks.

Unfortunately for the purpose of detection, the tick bite is usually painless and remains that way even after the tick stops the blood meal and falls off of the skin. Later, the bite site may develop

• itching,
• burning,
• redness or red spot, and
• rarely, localized intense pain like in the joints (some soft tick bites) in some individuals.

A few individuals may be sensitive or allergic to tick bites (tick saliva secretions) and develop

• rash near the bite,
• shortness of breath,
• swelling,
• numbness, or
• paralysis (for example, neck stiffness).

However, the majority of individuals with tick bites develop no symptoms, and many people do not remember getting bitten.

Some immediate symptoms that infrequently or rarely develop during or immediately after a tick bite initially may be flu-like and include

• fever,
• shortness of breath,
• weakness and/or achiness,
• vomiting,
• swelling at the bite site and/or lymph nodes,
• weakness or paralysis,
• headache,
• confusion, or
• palpitations.

Individuals with these symptoms should be seen immediately by a doctor.

Recently, researchers have found that the tick bite (mainly the saliva produced by the lone star tick) has caused thousands of people to become allergic to red meat, termed a meat allergy (beef, pork, venison, and occasionally, milk). People can eat poultry (chicken, turkey) and have no allergic reactions. When they eat red meat, they develop swelling and hives. Some may develop anaphylaxis. The reaction is thought to be due to an alpha-gal antigen in the tick's gut and/or saliva that stimulates an immune response that results in an allergic reaction when red meat is consumed. Occasionally, a tick bite may become red, swollen with red streaks; these are signs that the bite has become infected.

What are the symptoms and signs of diseases transmitted by ticks?

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 example, erythema migrans (a rash that occasionally resembles a "bull's eye") is often the first sign of Lyme disease transmitted by a tick bite.

Other symptoms may seem flu-like and can include

• weakness,
• nausea,
• fever,
• vomiting,
• palpitations,
• rash,
• joint pain,
• swelling,
• numbness, and
• confusion.

This is not an all-inclusive list, and other symptoms and signs can develop depending on the pathogen transmitted by the tick bite. More than one disease may be transmitted with tick bites; for example; some individuals may be infected with Lyme disease and babesiosis at the same time.

Although most tick bites need no special treatment, occasionally such specialists in infectious disease, internal medicine, allergists, and/or individuals who have special training in treating such diseases as Lyme disease may be consulted.

Ticks & Diseases Transmitted Chart

Although most tick bites do not transmit pathogens, some bites do. It is not possible to determine if a tick is carrying pathogens visually. The following is a list of all of the major tick-borne diseases, the usual tick vector(s) or common ticks, and the pathogen(s) of the tick species that, if known, transmits them in the United States.

• Tularemia -- Dermacentor variabilis (American dog tick; several species are also known as a wood tick) (hard tick) and Amblyomma americanum or lone star tick (hard tick) -- vectors for Francisella tularensis bacteria
• Anaplasmosis (human granulocytic anaplasmosis or HGA) -- Ixodes species (hard tick) -- vectors for Anaplasma phagocytophilum bacteria
• Colorado tick fever -- Dermacentor andersoni (hard tick) -- vectors for Coltivirus, an RNA virus
• Powassan encephalitis -- Ixodes species and Dermacentor andersoni (both hard ticks) -- vectors for Powassan encephalitis virus (Powassan virus), an RNA arbovirus
• Babesiosis -- Ixodes species (hard ticks) -- vectors for Babesia, a protozoan
• Ehrlichiosis -- Amblyomma americanum or lone star ticks; see photo below with "lone star" mark on the dorsal surface (hard ticks) -- vectors for Ehrlichia chaffeensis and Ehrlichia ewingii bacterial species
• Rocky Mountain spotted fever -- Dermacentor variabilis (American dog tick, see picture below) and Rocky Mountain wood tick (Dermacentor andersoni) (hard tick) are the primary vectors, and occasionally the brown dog tick (Rhipicephalus sanguineus); Amblyomma cajennense (hard tick) is the vector in countries south of the U.S. -- vectors for Rickettsia bacteria
• Lyme disease -- Ixodes species including deer ticks and white-footed mouse ticks, also known as black-legged ticks (hard ticks, see photo below) -- vectors for Borrelia species of bacteria
• Heartland virus disease -- a viral disease caused by the Heartland virus discovered in 2012 and transmitted by Amblyomma americanum or lone star tick
• Tick-borne relapsing fever -- Ornithodoros moubata or African tick; see illustration below (soft tick) -- vectors for Borrelia species of bacteria
• Q fever -- Rhipicephalus sanguineus, Dermacentor andersoni (see photo below), and Amblyomma americanum (all three are hard ticks) -- vectors for Coxiella burnetii, a bacterium
• Southern tick-associated rash illness (STARI) -- Amblyomma americanum or lone star tick (hard tick) -- infectious agent not yet identified according to U.S. Centers for Disease Control and Prevention (CDC)
• Bourbon virus disease -- This disease, caused by an RNA virus in the genus Thogotovirus, was first identified in 2014 in Kansas. This rare virus is likely to tick vector-borne (tick species vector unknown but possibly lone star tick). A Missouri state park employee died from the infection in 2017.

This list shows that some ticks (for example, Ixodes) can transmit more than one type of pathogenic microbe (virus, bacteria, and protozoa). It is possible to transmit more than one pathogen in a single tick bite, although this rarely occurs. Outbreaks of tick-related illnesses follow seasonal patterns (about April to September in the U.S.) as ticks evolve from larvae to adults.

No tests exist that either identify tick bites or the type of tick once the tick dislodges from the host's body. However, doctors can examine the entire body, looking for ticks still attached, rashes, or signs of a tick-caused disease. If a tick is identified, the physician can better choose what additional tests should be done because some ticks are likely to transmit certain pathogens. Again, the web citations below have photos of ticks that can help distinguish ticks from biting insects, such as fleas, mites, or bedbugs.

Identification of the tick genus and species may help the physician determine what further tests may be scheduled. For example, blood tests for diseases such as Lyme disease, Rocky Mountain spotted fever, ehrlichiosis, and tularemia are generally not positive for weeks after the exposure, even though symptoms may be present. Knowledge of the type of tick that caused the bite can help narrow the physician's possible diagnoses and even allow the physician to proceed with early therapy before a positive diagnosis is made.

Exams and tests should be done if an individual exhibits symptoms after a tick bite. Most tick bites do not have symptoms. If symptoms develop after a tick bite, the determination of which tests need to be performed can be optimized in consultation with an infectious-disease specialist.

For all tick bites, local cleansing and antibiotic cream may be applied. If the bite area develops itching, preparations containing diphenhydramine (Benadryl) are recommended. These Benadryl compounds can be applied directly to the skin for itching or administered orally by tablets. This is usually the only treatment needed.

However, treatment of the pathogens that the tick may pass to a person depends on other factors, such as the type of tick, length of time of attachment to the host, diseases in the community, and symptoms developed by the patient. Specific treatment is based on the identity of the pathogen transmitted. For example, oral antibiotics may be prescribed for some patients with tick bites if they live in an area where Lyme disease is endemic. With more significant symptoms, antibiotics may need to be given intravenously and the patient may need to be hospitalized.

The best approach to treatment is to diagnose which pathogen has been transmitted to the patient (for example, Borrelia species of bacteria) and then use the specific treatment recommended to reduce or kill the pathogen.

The following is a step-by-step method that is suggested for the safe and effective removal of all types of ticks.

1. Wear hand protection such as gloves so you don't spread pathogens from the tick to your hands; use fine-tipped forceps or tweezers to grab the tick at skin level.
2. Grasp the tick firmly with the tweezers as close to the skin as possible without crushing the tick. Apply gentle pulling motion upward until the tick comes free. Twisting or turning the tick does not make removal easier because the mouthparts are barbed; in fact, such actions may break off the head and mouthparts, thereby increasing the chances of infection. The second web citation illustrates the proper removal of a tick.
3. Once the tick is removed, don't crush the tick because it may release pathogens. Consider keeping it in a tightly closed jar or taped to a piece of paper. Show the tick to the doctor if the person bitten becomes ill after the tick bite. Flush any removed ticks not kept for identification down the toilet or sink.
4. The area of the bite should leave a small crater or indentation where the head and mouthparts were embedded. If portions of the head or mouthparts remain, they may be removed by a doctor.
5. Thoroughly cleanse the bite area with soap and water or a mild disinfectant. Observe the area for several days for the development of a reaction to the bite (rash or signs of infection). Apply antibiotic cream to the area as a precaution. Application of an antibiotic to the area may help prevent a local infection but usually does not affect the chance of developing diseases transmitted by the tick.
6. Wash hands thoroughly after handling any tick or instruments that touched a tick. Clean and disinfect any instruments that were used.

To remove the tick without tweezers, there have been several suggestions that may or may not work. The following are two examples that individuals claim work well and cause the tick to release itself from the skin with all of its mouthparts intact:

• Find the tick on the skin, and with your finger (preferably a gloved finger), rotate the body of the tick clockwise or counterclockwise for about a minute or so. This irritates the tick enough to cause it to let go of the skin and then the tick can be removed by simply touching the tick with scotch tape.
• Put liquid soap on a cotton ball and cover the tick with the soaked cotton ball for about 15 to 20 seconds; the tick will supposedly release itself from the skin and get caught up in the cotton ball. You can dispose of the tick by placing it and the cotton ball in a sealable plastic bag.

These methods are mentioned because sometimes tweezers are not available; nonetheless, if these methods remove the tick along with its intact mouthparts, individuals should thoroughly wash their hands and disinfect any areas with which the tick may have come in contact.

Other ways to remove ticks, such as using a hot match head or painting the tick with nail polish, gasoline, or other materials, are not advised. Such treatments can cause the tick to release more fluids back into the bite and increases the chance to transmit disease before the tick releases itself from the skin.

Acaricides are chemicals that will kill ticks and mites (anti-tick medication). Acaricides have been used in high-use, confined areas where ticks might be prevalent, such as yards or deer blinds. Reductions of tick habitats (for example, removal of leaf litter, tall grasses, and brush) have been effective in small-scale trials. Newer methods of control include applying acaricides to animal hosts by using baited tubes, boxes, and feeding stations in areas where infected ticks are endemic (for example, in some areas with dense deer populations). Biological control with fungi, parasitic nematodes, and parasitic wasps may also help reduce the tick population. Avoid tick season completely by staying away from outdoor areas where ticks thrive, usually, from April through September in the U.S. Besides, application of acaricides (chemicals that kill ticks and mites) can be applied to large areas of land to reduce the tick and mite population. Removing litter and brush from areas where people live and work may reduce exposure to ticks.

The third web citation below has the CDC recommended methods (tips) for outdoor workers (and others) to avoid getting tick bites (how to become relatively tick-safe) and is summarized here:

1. Avoid grassy areas and shrubs where ticks populations may be high and where they reside, waiting to grab a ride on a potential host.
2. Wear light-colored clothing so ticks can be easily seen, and brush them off.
3. Tuck pants into boots or socks to avoid ticks crawling up loose pant legs.
4. Apply insect repellant and use the brands designed to repel ticks. Follow label instructions. Avoid the use of DEET-containing repellents on children. Carefully follow instructions and apply some repellents directly to the skin and others to clothing. DEET-containing repellents with concentrations of 15% or less may be suitable for children. These should be carefully applied strictly following label directions. Insect repellents containing permethrins may be applied to clothing but not to the skin. In areas that have a high tick population, DEET-containing repellents may need to be reapplied more frequently than for repelling mosquitoes. Follow the package label instructions carefully.
5. Promptly check yourself, others, and pets if exposed to areas where ticks are likely to be located.

Consider wearing tick-repellent clothing if you spend a significant amount of time in potential tick areas. Be sure to treat pets with flea and tick repellents. If ticks are removed from pets, manage them the same way you would remove a tick on a person. Protect yourself from potential exposures with gloves. People who live in a tick-infested area and have experienced a fever within the last two months should not donate blood.

The great majority of people who get tick bites have no problems during or after the bite. For people with suppressed immune systems (HIV, cancer, chemotherapy patients), the prognosis is still good, but they should contact their physicians and inform them about a tick bite. Also, the faster the tick is removed after a bite, the less likely the tick will transmit pathogens.

The overall prognosis for an individual person changes if the tick transmits a pathogen. The prognosis can range from good to poor and is determined by the disease transmitted, the time to diagnosis, the stage of the disease, and the condition of the patient. Immune-suppressed patients usually have a worse prognosis than otherwise healthy people. Consultation with an infectious-disease specialist is one of the best ways to determine the prognosis for the many diseases that ticks can transmit to people.

Additional information on ticks is available at these web sites:

1. "Ticks: Geographic Distribution," CDC
2. "Ticks," CDC
3. "Tick-Borne Diseases," CDC
4. "Tick-Borne Diseases," Medscape.com
5. "CDC Reports More Cases of Heartland Virus Disease," CDC