Ticks are the blood-sucking arthropods that transmit the greatest variety of pathogens to humans and animals, capable of transmitting over 25 known diseases.

Lyme disease — caused by Borrelia burgdorferi and transmitted by hard ticks of the genus Ixodes — early symptoms include the classic erythema migrans (EM) rash: an expanding red annular rash around the bite site, with central clearing, resembling a bullseye.

Tick-borne encephalitis (TBE) — caused by a flavivirus — clinical manifestations range from mild meningitis to severe meningoencephalitis, with a case fatality rate of 1–2%; TBE endemic areas exist in northeastern and northwestern China.

Severe Fever with Thrombocytopenia Syndrome (SFTS) — an emerging tick-borne infectious disease caused by a novel bunyavirus, first identified in China in 2009; clinical manifestations include high fever, a sharp drop in platelets, and multiple organ dysfunction, with a case fatality rate of approximately 6–30%.

Other tick-borne diseases such as babesiosis, anaplasmosis, and ehrlichiosis are distributed globally.

The most effective method to prevent tick-borne diseases remains avoiding tick bites.