Ticks

Background

Microbiology

• Organised broadly into hard and soft ticks
  • Hard ticks: typical tick with a dorsal plate (scutum; a hard shell on the back), and can easily see mouth parts
  • Soft ticks: no distinct shell or dorsal plate; short mouths, often can't see mouth parts from above
    • Tend to drop off the host after feeding
• "Questing" is when they hang out on tops of grass or plants, reaching out to grasp onto hosts that pass by

Identification

• Dorsal plate
  • Can be ornate
• Festoons are specific decorations on the back; notches along the outside of the back
• Certain ticks (such as Ixodes scapularis) will have an anal groove
• Males and females look different
  • Mature females feed and have large sacks behind the dorsal plate that fills up with blood upon feeding
• Nymphs are much harder to identify
• By species:
  • Ornate black and white dorsal shield, with festoons, short mouth parts (unlike Amblyomma), and eyes: Dermacentor variabilis
  • Black and white dorsal shield with some ornate markings, with festoons, long mouth parts, and eyes: Amblyomma americanum
    • Female has a single white marking on the dorsal shield, hence lone star tick
  • Plain dark dorsal shield, long mouth parts, no festoons, no eyes: Ixodes scapularis
    • Also has an anal groove surrounding the anus in a U shape that opens posteriorly
  • Soft tick lacking dorsal shield, with small mouth parts: most commonly Ornithodoros
    • Rarely identified because they fall off after feeding

Tick-Borne Diseases

• See tick-borne infections

Further Reading

• INSPQ Identification Guide for Quebec