How does an infected and non‑infected tick look? - briefly
An uninfected tick shows a uniform, light‑colored dorsal shield (scutum) and a slender, non‑distended body. An infected tick often appears darker, with a mottled or reddish abdomen, possible swelling, and occasional discoloration caused by the pathogen.
How does an infected and non‑infected tick look? - in detail
A tick that has acquired a pathogen often shows subtle but observable differences from a tick that has not. These variations involve coloration, engorgement pattern, and microscopic features.
- Body coloration: Uninfected individuals typically display a uniform brown or reddish‑brown hue. Infected ticks may develop a slightly darker or mottled abdomen, especially after feeding, due to changes in hemolymph composition.
- Engorgement shape: When attached to a host, a pathogen‑free tick expands symmetrically, producing a round, balloon‑like abdomen. Ticks carrying bacteria such as Borrelia or viruses can exhibit irregular swelling, with one side appearing more distended.
- Leg and mouthpart condition: Healthy specimens have smooth, glossy legs and a clearly defined hypostome. Infected ticks sometimes present a roughened cuticle and a slightly enlarged hypostome, reflecting tissue degradation caused by the pathogen.
- Surface texture under magnification: Microscopic examination reveals that non‑infected ticks possess a regular, tightly packed set of sensilla on the dorsal surface. Pathogen‑laden ticks often show disrupted sensilla patterns and occasional micro‑lesions where the organism breaches the cuticle.
- Internal appearance: Dissection of a clean tick shows clear, straw‑colored hemolymph. In contrast, an infected tick’s hemolymph may appear cloudy or tinged with red‑brown pigments, indicating hemocyte activation and possible hemorrhagic processes.
These characteristics are not absolute; environmental factors and the tick’s developmental stage can modify appearance. Nonetheless, the listed traits provide a reliable basis for distinguishing between pathogen‑free and pathogen‑bearing specimens during laboratory analysis or field assessment.