Ticks

From IDWiki

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

Further Reading