How many diseases are transmitted by ticks? - briefly
Ticks transmit roughly 30 distinct diseases to humans, encompassing bacterial infections such as Lyme disease, viral illnesses like Powassan encephalitis, and protozoan conditions such as babesiosis. The number may rise as emerging pathogens are identified.
How many diseases are transmitted by ticks? - in detail
Ticks transmit a wide range of pathogenic agents. Scientific surveys list at least 30 distinct tick‑borne illnesses that are confirmed to cause human disease, and some authorities record more than 40 when emerging and region‑specific conditions are included.
The pathogens fall into four major groups:
- Bacteria – Lyme disease (caused by Borrelia burgdorferi), Rocky Mountain spotted fever (Rickettsia rickettsii), Anaplasmosis (Anaplasma phagocytophilum), Ehrlichiosis (Ehrlichia chaffeensis), Tularemia (Francisella tularensis), Q fever (Coxiella burnetii), Tick‑borne relapsing fever (Borrelia spp.).
- Viruses – Powassan virus disease, Tick‑borne encephalitis, Colorado tick fever, Heartland virus disease, Bourbon virus infection, Crimean‑Congo hemorrhagic fever (transmitted by Hyalomma spp.).
- Protozoa – Babesiosis (Babesia microti), Human granulocytic anaplasmosis, Theileriosis (rare in humans, reported in Asia).
- Rickettsial organisms – Mediterranean spotted fever, African tick‑bite fever, Japanese spotted fever.
Geographic distribution influences the disease spectrum. In North America, Lyme disease, Rocky Mountain spotted fever, Anaplasmosis, Ehrlichiosis, and Powassan virus dominate. Europe reports Lyme disease, Tick‑borne encephalitis, and Mediterranean spotted fever. Asia contributes Severe fever with thrombocytopenia syndrome and Japanese spotted fever. Africa and the Middle East add Crimean‑Congo hemorrhagic fever and African tick‑bite fever.
When all recognized agents are summed, the global tally of human diseases transmitted by ticks exceeds three dozen. Continuous surveillance identifies new viral agents, suggesting the count will rise as diagnostic capabilities improve.