How does a tick look when it is engorged with blood on a human? - briefly
«An engorged tick appears as a markedly enlarged, balloon‑shaped organism, often 3–5 mm long, with a grayish‑white or reddish abdomen that stretches the surrounding skin». The body becomes translucent, exposing the blood‑filled gut and making the tick clearly visible against the host’s skin.
How does a tick look when it is engorged with blood on a human? - in detail
An engorged tick attached to human skin expands dramatically compared to its unfed state. The abdomen swells to a round, balloon‑like form that can reach 5–10 mm in length, often exceeding the length of the head and legs. The dorsal surface becomes glossy and translucent, allowing the underlying blood to give a reddish‑purple hue. The ventral side appears smoother and less sclerotized, with the mouthparts (hypostome) still visible as a small, darker projection at the front.
Key visual characteristics:
- Size: length up to 10 mm, width proportionally increased, creating a spherical silhouette.
- Color: deep crimson, dark purple, or black, depending on the tick species and the amount of blood ingested.
- Texture: surface glistens due to the fluid content; the cuticle stretches but remains intact, preventing leakage.
- Shape: abdomen dominates, while the anterior capitulum remains narrow; legs may be retracted or splayed outward, appearing thin relative to the swollen body.
- Location on host: most commonly found in warm, protected areas such as the scalp, armpits, groin, and behind the knees; attachment sites display a small, sometimes erythematous, puncture wound.
Temporal changes:
- Initial attachment: tick measures 2–3 mm, brownish, with a compact body.
- Mid‑feeding (24–48 h): abdomen enlarges, color darkens, legs become more visible.
- Full engorgement (72–96 h): abdomen reaches maximum volume, surface becomes highly lustrous, and the tick appears almost translucent.
Species variations affect appearance. For example, the American dog tick (Dermacentor variabilis) often shows a bright reddish abdomen, whereas the black‑legged tick (Ixodes scapularis) may retain a darker, almost black hue even when fully engorged. The presence of a clear, fluid‑filled cuticle distinguishes engorged specimens from other arthropods that may infest humans.
Recognition of these features enables prompt removal and reduces the risk of pathogen transmission.