What does a pasture tick transmit? - briefly
Pasture ticks, chiefly Rhipicephalus (Boophilus) microplus, transmit the protozoa that cause bovine babesiosis (Babesia bovis and Babesia bigemina) and the bacterium that causes anaplasmosis (Anaplasma marginale). These agents induce fever, anemia and can result in fatal hemolytic disease in cattle.
What does a pasture tick transmit? - in detail
Pasture ticks act as vectors for a range of infectious agents that affect humans and domestic animals. The most important pathogens are:
- Rickettsia rickettsii – causes Rocky Mountain spotted fever; transmitted during the tick’s feeding stage; symptoms appear 2–14 days after bite and include fever, headache, and a characteristic rash.
- Francisella tularensis – agent of tularemia; infection may follow a tick bite, inhalation, or contact with infected animals; clinical forms include ulceroglandular and pneumonic disease.
- Ehrlichia chaffeensis – responsible for human monocytic ehrlichiosis; transmitted by the adult stage; early signs are fever, myalgia, and thrombocytopenia.
- Anaplasma phagocytophilum – causes human granulocytic anaplasmosis; the bacterium infects neutrophils; disease manifests with fever, leukopenia, and elevated liver enzymes.
- Borrelia burgdorferi sensu lato – the Lyme disease spirochete; transmitted after the tick remains attached for ≥36 hours; early stage presents with erythema migrans, later stages may involve arthritis, neurologic deficits, or cardiac involvement.
- Tick‑borne encephalitis virus (TBEV) – a flavivirus endemic in parts of Europe and Asia; infection leads to biphasic illness with meningitis, encephalitis, or meningoencephalitis.
- Babesia microti and related Babesia spp. – intra‑erythrocytic protozoa causing babesiosis; clinical picture ranges from asymptomatic to severe hemolytic anemia, especially in immunocompromised hosts.
- Coxiella burnetii – agent of Q fever; transmission by ticks is less common than aerosol routes but documented; infection may be acute or chronic, affecting lungs and liver.
Geographic distribution of these agents mirrors the habitat of the tick species. In North America, the American dog tick (Dermacentor variabilis) predominates in grassy fields and transmits R. rickettsii, F. tularensis, and Ehrlichia spp. In Europe and parts of Asia, Ixodes ricinus occupies similar environments and carries B. burgdorferi, A. phagocytophilum, TBEV, and Babesia spp. Preventive measures include regular inspection of livestock and humans after exposure, prompt removal of attached ticks, and use of acaricides in high‑risk areas. Early diagnosis and appropriate antimicrobial or antiviral therapy reduce morbidity and mortality associated with these vector‑borne diseases.