Global Importance of Ticks and Associated Infectious Disease Agents

Ticks are medically important ectoparasites that have global distribution. They live in diversified habitats, have close contact with a wide range of vertebrate hosts, and can transmit a variety of disease agents to human beings, domesticated animals, and wildlife. Tick-borne infections can cause acute or chronic illnesses, such as Lyme disease, relapsing fever, Crimean Congo hemorrhagic fever, human babesiosis, Texas cattle fever, Rocky Mountain spotted fever, ehrlichiosis, Boutonneuse fever, tularemia, Colorado tick fever, and encephalitis. Human fatalities have been reported for some of these diseases. Certain tick species are also suspected vectors of Bartonella organisms. Having high reproductive potential, few natural parasites and predators, the ability to live several months or years, and relatively broad host ranges, ticks are well adapted for survival and difficult to control. Certain practices, however, such as early removal of attached ticks from skin, use of repellents, and landscape modifications near human dwellings can reduce tick bites and risk of infection.