Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted bytick bites. Tick-borne illnesses are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa. Because individual ticks can harbor more than one disease-causing agent, patients can be infected with more than one pathogen at the same time, compounding the difficulty in diagnosis and treatment. As of 2016, 16 tick-borne diseases of humans are known (four discovered since 2013).
As the incidence of tick-borne illnesses increases and the geographic areas in which they are found expand, health workers increasingly must be able to distinguish the diverse, and often overlapping, clinical presentations of these diseases.
In general, specific laboratory tests are not available to rapidly diagnose tick-borne diseases. Due to their seriousness, antibiotic treatment is often justified based on clinical presentation alone.
Ticks tend to be more active during warmer months, though this varies by geographic region and climate. Areas with woods, bushes, high grass, or leaf litter are likely to have more ticks. Those bitten commonly experience symptoms such as body aches, fever, fatigue, joint pain, or rashes. People can limit their exposure to tick bites by wearing light-colored clothing (including pants and long sleeves), using insect repellent with 20%–30% DEET, tucking their pants legs into their socks, checking for ticks frequently, and washing and drying their clothing (in a hot dryer).
For a person or companion animal to acquire a tick-borne disease requires that that individual gets bitten by a tick and that that tick feeds for a sufficient period of time. The feeding time required to transmit pathogens differs for different ticks and different pathogens. Transmission of the bacterium that causes Lyme disease is well understood to require a substantial feeding period.
For an individual to acquire infection, the feeding tick must also be infected. Not all ticks are infected. In most places in the US, 30-50% of deer ticks will be infected with Borrelia burgdorferi (the agent of Lyme disease). Other pathogens are much more rare. Ticks can be tested for infection using a highly specific and sensitive qPCR procedure. Several commercial labs provide this service to individuals for a fee. The Laboratory of Medical Zoology (LMZ), a nonprofit lab at the University of Massachusetts, provides a comprehensive TickReport  for a variety of human pathogens and makes the data available to the public. Those wishing to know the incidence of tick-borne diseases in their town or state can search the LMZ surveillance database.
Regions : Primarily in Africa, Spain, Saudi Arabia, Asia in and certain areas of Canada and the western United States
Symptoms: Relapsing fever typically presents as recurring high fevers, flu-like symptoms, headaches, and muscular pain, with less common symptoms including rigors, joint pain, altered mentation, cough, sore throat, painful urination, and rash
Treatment: Antibiotics are the treatment for relapsing fever, with doxycycline, tetracycline, or erythromycin being the treatment of choice.
Typhus Several diseases caused by Rickettsia bacteria (below)