What is harmful in a tick? - briefly
Ticks transmit bacteria, viruses, and protozoa—such as Borrelia burgdorferi, Rickettsia spp., and Babesia—that cause Lyme disease, Rocky Mountain spotted fever, babesiosis, and related illnesses. Their saliva also contains anticoagulants and immunomodulatory proteins that facilitate pathogen entry and provoke host tissue damage.
What is harmful in a tick? - in detail
Ticks transmit a range of biologically active agents that pose health risks to humans and animals. Their saliva contains proteins that suppress host immune responses, facilitate blood feeding, and trigger local inflammation. Pathogens introduced during feeding include bacteria, viruses, and protozoa, each associated with specific disease syndromes.
-
Bacterial agents
- Borrelia burgdorferi complex – causative agent of Lyme disease; induces joint, cardiac, and neurological manifestations.
- Anaplasma phagocytophilum – responsible for human granulocytic anaplasmosis; produces fever, leukopenia, and thrombocytopenia.
- Rickettsia spp. – cause spotted fever group rickettsioses; lead to rash, headache, and vasculitis.
- Ehrlichia chaffeensis – triggers human monocytic ehrlichiosis; characterized by fever, hepatitis, and respiratory distress.
-
Viral agents
- Tick-borne encephalitis virus – flavivirus that can cause meningitis or encephalitis with long‑term neurological deficits.
- Powassan virus – orthomyxovirus linked to severe encephalitis and high mortality rates.
- Crimean‑Congo hemorrhagic fever virus – induces hemorrhagic fever with rapid progression and organ failure.
-
Protozoal agents
- Babesia microti – intra‑erythrocytic parasite causing babesiosis; manifests as hemolytic anemia, fever, and renal impairment.
- Theileria spp. – affect livestock; provoke fever, lymphadenopathy, and immunosuppression.
In addition to these microorganisms, tick saliva contains anticoagulants (e.g., apyrase, factor Xa inhibitors) that prevent clot formation, enhancing pathogen transmission. Histamine‑binding proteins and protease inhibitors modulate host inflammation, extending feeding duration and increasing exposure risk.
The cumulative effect of these components is a heightened probability of systemic infection, tissue damage, and, in severe cases, organ failure. Prompt removal of attached ticks and early diagnostic testing for the listed agents are essential measures to mitigate adverse outcomes.