How many types of encephalitis‑carrying ticks exist? - briefly
Four tick species are recognized as primary vectors of encephalitis viruses. They include Ixodes ricinus and Ixodes persulcatus for tick‑borne encephalitis, and Ixodes scapularis and Ixodes cookei for Powassan virus.
How many types of encephalitis‑carrying ticks exist? - in detail
Encephalitis‑transmitting ticks are limited to a small group of hard‑tick species that serve as vectors for several flaviviruses and flavivirus‑related agents. The most widely recognised vectors include:
- Ixodes ricinus – primary carrier of the European tick‑borne encephalitis (TBE) virus; prevalent in temperate forests of Europe and parts of North Africa.
- Ixodes persulcatus – eastern counterpart of I. ricinus, responsible for TBE transmission across Siberia, the Russian Far East, and northern China.
- Ixodes scapularis – North‑American vector of the Powassan virus, a flavivirus capable of causing severe encephalitis; also implicated in transmission of the deer tick virus subtype.
- Ixodes cookei – secondary Powassan virus vector, especially in the northeastern United States; maintains the virus in small mammal reservoirs.
- Ixodes marxi – occasional Powassan virus carrier in the Midwestern United States; feeds on ground‑dwelling rodents and can transmit the virus to humans.
- Dermacentor reticulatus – associated with the transmission of the Siberian subtype of TBE virus in parts of Eastern Europe; less efficient than Ixodes species but documented in field studies.
- Dermacentor andersoni – linked to the Rocky Mountain spotted fever complex; rare cases of encephalitic disease have been reported, suggesting a limited role in virus transmission.
These seven species constitute the recognized tick fauna capable of harbouring and delivering encephalitis‑causing viruses to humans. Their distribution reflects ecological niches: Ixodes ticks dominate forested and grassland habitats across Eurasia and North America, while Dermacentor species occupy more open, temperate zones. Vector competence varies among species; I. ricinus and I. persulcatus are the most efficient for the classic TBE virus, whereas I. scapularis and I. cookei dominate Powassan virus cycles. Understanding the specific tick‑virus associations is essential for targeted surveillance and preventive measures.