What can ticks transmit?

What can ticks transmit? - briefly

Ticks can transmit a variety of pathogens—bacteria, viruses, and protozoa—that cause illnesses such as Lyme disease, Rocky Mountain spotted fever, ehrlichiosis, and babesiosis. Transmission occurs when an attached tick injects infected saliva into the host’s bloodstream.

What can ticks transmit? - in detail

Ticks serve as vectors for a wide spectrum of pathogenic agents that affect humans, livestock, and wildlife. The organisms transmitted include bacteria, viruses, protozoa, and, in rare cases, toxins that cause paralysis.

• Bacterial pathogens

  • Borrelia burgdorferi – causes Lyme disease; transmitted primarily by Ixodes species.
  • Anaplasma phagocytophilum – responsible for human granulocytic anaplasmosis; Ixodes scapularis and Ixodes pacificus are common carriers.
  • Ehrlichia chaffeensis – agent of human monocytic ehrlichiosis; spread by Amblyomma americanum.
  • Rickettsia rickettsii – produces Rocky Mountain spotted fever; vectors include Dermacentor variabilis and Dermacentor andersoni.
  • Rickettsia parkeri – causes a milder spotted fever; transmitted by Amblyomma maculatum.
  • Francisella tularensis – causative organism of tularemia; Dermacentor and Ixodes ticks are involved.
  • Coxiella burnetii – agent of Q fever; transmitted by several hard‑tick species, especially Dermacentor and Hyalomma.
  • Rickettsia conorii – Mediterranean spotted fever; vector is Rhipicephalus sanguineus.

• Viral agents

  • Tick‑borne encephalitis virus (TBEV) – prevalent in Europe and Asia; Ixodes ricinus and Ixodes persulcatus are primary vectors.
  • Powassan virus – neuroinvasive flavivirus; transmitted by Ixodes cookei and Ixodes scapularis.
  • Crimean‑Congo hemorrhagic fever virus – severe hemorrhagic disease; Hyalomma marginatum is the main carrier.
  • Heartland virus – emerging phlebovirus in the United States; Amblyomma americanum implicated.
  • Bourbon virus – novel thogotovirus; also linked to Amblyomma americanum.

• Protozoal parasites

  • Babesia microti – causes babesiosis; transmitted by Ixodes scapularis.
  • Babesia divergens – bovine babesiosis; vector is Ixodes ricinus.
  • Theileria spp. – tropical theileriosis in cattle; transmitted by Hyalomma and Rhipicephalus ticks.
  • Babesia canis – canine babesiosis; vector is Dermacentor reticulatus.

• Toxin‑mediated condition

  • Tick paralysis – neurotoxic protein produced by several species (e.g., Ixodes holocyclus in Australia, Dermacentor spp. in North America); results in acute, reversible paralysis if the tick remains attached.

Geographic distribution of these agents follows the range of their tick vectors. Ixodes species dominate temperate regions of North America and Europe, delivering most bacterial and protozoal infections. Dermacentor and Amblyomma ticks are prevalent in North America’s southern and central zones, responsible for spotted fevers and ehrlichioses. Hyalomma ticks occupy Africa, the Middle East, and parts of Asia, mediating viral hemorrhagic fevers and livestock parasites.

Understanding the specific tick‑host‑pathogen relationships is essential for diagnosis, prevention, and control strategies. Prompt removal of attached ticks reduces the risk of toxin‑related paralysis, while personal protective measures and habitat management limit exposure to the diverse infectious agents they convey.