Tick borne disease is a disease transmitted by ticks, arachnids found widely in many regions of the world. Bacteria, protozoa, viruses, and toxins can all be transmitted by ticks, causing illness in humans and other animals. Some tick borne diseases are zoonotic, crossing the species boundary, and some explicitly rely on ticks to thrive, with part of the life cycle of the disease-causing organism involving a stay in a tick's intestinal tract. Transmission of disease by ticks is a major cause of concern in some regions.
People contract tick borne diseases when ticks bite them. Ticks typically produce secretions to slow blood clotting, which can cause a reaction by introducing toxins or organisms into the body, and they can also transmit disease with contaminated mouth parts which introduce organisms into the wound. The people most at risk for tick borne disease are individuals who work outdoors, and people who live in communities in heavily wooded areas. Increasing settlement in formally forested natural areas has contributed to a rise in tick borne disease in some regions.
Many tick borne diseases cannot be tested for with routine bloodwork and medical testing, which makes them difficult to diagnose. In addition, patients can be coinfected with several diseases by the same tick, which complicates diagnosis by creating a constellation of symptoms which may lead a doctor to rule out tick borne disease because the symptoms do not fit any single disease. Diagnosis and treatment of some tick borne diseases is also controversial, which can make rapid intervention difficult for patients.
In some cases, the bite which carries disease develops distinctive symptoms, such as redness, swelling, or the development of a rash. In other instances, nothing unusual may accompany the bite, with symptoms of tick borne disease appearing later. Common symptoms include fatigue, muscle weakness, joint pain, muscle aches, fever, and headaches. Symptoms may wax and wane, depending on the nature of the disease, which can add additional confusion to diagnosis as patients may experience periods in which they feel quite well without treatment, leading them to believe that the symptoms were simply a mild flu.
Some pathogens carried by ticks include the organisms responsible for Colorado tick fever, babesiosis, Lyme disease, Powassan encephalitis, Q fever, anaplasmosis, Southern tick-associated rash illness, tularemia, Rocky Mountain Spotted Fever, and tick-borne relapsing fever. People who live and work in areas where tick borne disease is common should take precautions to avoid bites, such as wearing heavy clothing which covers the body, including high boots, and applying tick repellent before working in the woods or garden.