What does a brucellosis tick look like? - briefly
A tick capable of transmitting brucellosis is a small, oval arachnid, typically reddish‑brown when unfed and becoming noticeably engorged and darker after a blood meal. It possesses a hard dorsal shield (scutum), six legs visible from the dorsal view, and mouthparts (hypostome) adapted for deep attachment to the host.
What does a brucellosis tick look like? - in detail
The tick responsible for transmitting brucellosis belongs to the genus Rhipicephalus and exhibits the typical hard‑tick (Ixodidae) morphology. The dorsal shield (scutum) is brown to reddish‑brown, often with a slightly lighter posterior margin. In unfed adults, the scutum covers the entire dorsal surface of males, while females possess a partial scutum, allowing the abdomen to expand dramatically during blood feeding.
Size varies with feeding stage. Unengorged males measure 2–3 mm in length and 1.5–2 mm in width; unengorged females are 3–4 mm long, expanding to 8–12 mm when fully engorged. The mouthparts (capitulum) project forward, featuring a short, robust hypostome equipped with backward‑pointing barbs that facilitate attachment to the host’s skin.
Key identification characteristics include:
- Six legs in the larval stage, eight in nymphs and adults.
- Rounded, oval body shape with a smooth, glossy integument.
- Presence of festoons (small rectangular areas) along the posterior edge of the body, typically 11 in number.
- Eyes located laterally on the scutum, each comprising a pair of simple ocelli.
- Anal groove positioned anterior to the anus, a distinguishing feature of hard ticks.
Engorgement changes coloration: the abdomen becomes pale, almost translucent, and the overall silhouette shifts from a compact oval to a more balloon‑like form. The ventral surface displays a lighter, sometimes whitish hue, while the dorsal shield retains its brown coloration throughout feeding.
Microscopic examination reveals a densely packed arrangement of setae (sensory hairs) on the legs and a characteristic pattern of punctate pits on the scutum. These pits appear as small, evenly spaced depressions that aid in species differentiation.
«The combination of a complete scutum in males, a partially covered abdomen in females, distinct festoons, and the specific arrangement of dorsal pits provides reliable morphological criteria for recognizing the brucellosis vector tick».