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Symptoms and Signs of Ticks

Doctor's Notes on Ticks

Ticks are bloodsucking arthropods classified as either hard or soft ticks with over 800 species; hard ticks have a hard plate or scutum on their back while soft ticks do not; both types attach to the skin of humans or other animals by their mouth parts to get blood. Hard ticks may stay attached for days while soft ticks may attach for only hours. The first sign or symptom is seeing a tick (range from small pinpoint-size to about 10 mm and are mainly brownish or grayish in color) attached to your skin or on your clothing. Generally, tick bites are usually painless (except for some soft ticks) but over time, other signs and symptoms develop. The bite site may cause local muscle weakness or even local paralysis. After ticks drop off, bite areas may develop redness or a rash with itching and burning. In addition, soft tick bites may cause localized intense pain. Late signs and symptoms may include developing allergic reactions to red meats or the development of a bite infection with red streaks, swelling and swollen lymph nodes in areas adjacent to the tick bite.

Other signs and symptoms of a tick bite are related to the tick bite as a vector for other pathogens that cause disease. There are at least 14 different diseases transmitted by different tick bites. Various ticks may produce noticeable signs and symptoms, usually after the tick has detached itself. For example, Lyme disease (caused by Borrelia species of bacteria) can produce bull’s-eye target – shaped rashes while Rocky Mountain Spotted Fever (caused by R. rickettsii) can produce a spotty skin rash with a fever and neck stiffness.

The cause of tick bites is the tick needing a blood meal for survival. Secondary symptoms and signs are caused by pathogenic organisms transmitted to humans during the tick bite.

Medical Author:
Medically Reviewed on 3/11/2019

Ticks Symptoms

Tick bites are generally painless. Many people may not even notice the bite and may never find the tick if it falls off. Small ticks, like the deer tick that transmits Lyme disease, are so tiny they may be nearly undetectable. Some nymphal ticks are about as small as the period at the end of this sentence. However, there are some symptoms that may occur that can be directly related to the tick itself; they are due to the tick bite.

Occasionally, a neurotoxin (a substance that is toxic to nerves) secreted at the time of attachment to make the bite unnoticeable to humans and other hosts can cause muscle weakness or paralysis. It rarely causes paralysis that inhibits breathing or may cause neck stiffness. The simple task of removing the tick stops any further neurotoxin production, and the person usually recovers quickly and completely.

The actual bite may cause symptoms only after the tick drops off. However, some people may notice local redness (red spot), rash near the bite, itching, burning, and rarely, localized intense pain (soft ticks) before or after the tick drops off. The majority of tick bites result in few, if any, immediate symptoms. However, saliva from the Lone star tick has been linked to allergic reactions to red meats (beef, pork, venison, for example). Milk allergy may also occur. Researchers suggest an alpha-gal sugar antigen is secreted with tick saliva into humans that produce an immune response to similar antigens in red meats. When red meats are eaten, the immune system responds by causing swelling, hives, and even anaphylactic shock. Occasionally, the tick bite may become infected, causing localized swelling, swollen lymph nodes, and/or red streaks to appear in the skin.

The results of the illnesses or pathogens transmitted by ticks often begin days to weeks after the tick is gone. That's why doctors or affected individuals may not suspect a tick-related illness because many people are not aware of the bites or ignore or forget about barely noticeable "bites." The most important clue about any tick-related illness is to tell the physician about a tick bite. Also, the individual needs to tell their physician about outdoor activity (camping, hiking, etc.) in tick-infested areas even if the person does not remember a tick bite.

After a tick bite, individuals may develop any of these symptoms that may be due to the organism that the tick transmits during its bite:

These symptoms may appear with many different types of tick bites; the symptoms that develop due to the different organisms are included in this list, but readers are advised to use the links provided in this article for more information about specific conditions. This will allow the reader to obtain a more definitive set of symptoms for each different pathogen passed into the host by ticks. For example, Figure 4 shows the "bull's eye" rash seen in patients who develop Lyme disease.

Picture of characteristic bull's eye rash that developed in a patient diagnosed with Lyme disease after a tick bite
Figure 4: Picture of characteristic "bull's eye" rash that developed in a patient diagnosed with Lyme disease after a tick bite. Source: CDC/James Gathany

Lyme Disease Symptoms, Rash, Treatments Slideshow

Lyme Disease Symptoms, Rash, Treatments Slideshow

Lyme disease is caused by spiral-shaped bacteria called Borrelia burgdorferi (found in the U.S.) and Borrelia afzelii (found in Europe). Two different species of ticks, Ixodes scapularis and Ixodes pacificus, transmit the bacteria to humans via bites.

REFERENCE:

Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.

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