What does the ixodid tick transmit? - briefly
The hard tick vector carries several pathogens, notably Borrelia burgdorferi, Anaplasma phagocytophilum, Ehrlichia spp., Babesia microti, and Rickettsia rickettsii. These agents cause Lyme disease, anaplasmosis, ehrlichiosis, babesiosis, and spotted fever, respectively.
What does the ixodid tick transmit? - in detail
Ixodid (hard) ticks are vectors for a broad spectrum of infectious agents that affect humans and animals. Their capacity to acquire, maintain, and deliver pathogens stems from a multi‑stage life cycle that includes larva, nymph, and adult phases, each capable of feeding on different hosts.
Bacterial agents
- Borrelia burgdorferi complex – causative agents of Lyme disease, transmitted primarily by Ixodes species.
- Anaplasma phagocytophilum – causes human granulocytic anaplasmosis; maintained in tick populations through transstadial transmission.
- Ehrlichia chaffeensis – agent of human monocytic ehrlichiosis, associated with the lone‑star tick (Amblyomma americanum).
- Rickettsia rickettsii – Rocky Mountain spotted fever pathogen, spread by the American dog tick (Dermacentor variabilis) and the Rocky Mountain wood tick (D. andersoni).
- Rickettsia parkeri – causes a milder spotted fever, transmitted by the Gulf Coast tick (A. maculatum).
Viral agents
- Powassan virus – a flavivirus transmitted by several Ixodes species, capable of causing severe encephalitis.
- Tick‑borne encephalitis virus (TBEV) – prevalent in Eurasia, spread by Ixodes ricinus and I. persulcatus.
- Crimean‑Congo hemorrhagic fever virus – associated with Hyalomma ticks, producing a severe hemorrhagic disease.
Protozoan agents
- Babesia microti – responsible for human babesiosis, transmitted mainly by Ixodes scapularis in North America.
- Babesia divergens – causes bovine babesiosis, spread by Ixodes ricinus in Europe.
Helminths
- Theileria spp. – tick‑borne parasites affecting livestock; transmitted by various hard tick species such as Rhipicephalus and Haemaphysalis.
- Babesia spp. in animals – some species are classified as protozoa but are often discussed alongside helminths due to similar clinical impact.
Transmission mechanisms include:
- Acquisition during a blood meal from an infected host.
- Maintenance across developmental stages without loss of infectivity (transstadial passage).
- Propagation to progeny in some cases (transovarial transmission), especially for rickettsial bacteria and certain viruses.
- Inoculation into a new host via saliva during subsequent feeding.
The epidemiological significance of ixodid ticks derives from their broad host range, long attachment periods, and ability to harbor multiple pathogens simultaneously, leading to co‑infection risks. Effective control measures focus on habitat management, acaricide application, and personal protective strategies to interrupt the tick‑borne transmission cycle.