What does a scabies mite look like and what are its symptoms? - briefly
The scabies mite is a microscopic, oval‑shaped arachnid about 0.3 mm long, translucent, with four pairs of legs that creates tunnels in the epidermis. Infestation produces intense nocturnal itching and a rash of tiny papules and serpentine burrows, commonly on the fingers, wrists, and torso.
What does a scabies mite look like and what are its symptoms? - in detail
The scabies mite, Sarcoptes scabiei var. hominis, is an eight‑legged arthropod measuring 0.2–0.4 mm in length. Its body is oval, covered with a hard, translucent exoskeleton. The anterior region bears short, hook‑shaped fore‑legs adapted for burrowing, while the posterior legs are longer and free‑moving. Females are larger than males and possess a rounded abdomen that expands after blood meals.
Mite activity occurs beneath the stratum corneum. After a fertilized female penetrates the epidermis, she creates a tunnel approximately 2–10 mm long, where she deposits eggs. Each female can lay 10–30 eggs over a two‑week lifespan. The resulting larvae, nymphs, and adult mites remain within the same burrow or migrate to adjacent sites, perpetuating the infestation.
Symptoms manifest as:
- Intense nocturnal pruritus caused by allergic response to mite proteins and feces.
- Linear or serpentine burrows visible as thin, gray‑white or flesh‑colored tracks.
- Papules, vesicles, or nodules developing at the ends of burrows.
- Eczematous plaques resulting from chronic scratching.
- Secondary bacterial infection, frequently Staphylococcus aureus or Streptococcus pyogenes, indicated by crusted lesions or pustules.
The clinical picture typically appears 2–6 weeks after initial exposure in naïve individuals; in previously infested hosts, symptoms may emerge within 24–48 hours. Characteristic distribution includes interdigital spaces, wrists, elbows, axillae, waistline, genitalia, and, in infants, the scalp, face, and palms. Lesions often spare the back and lower legs.
Diagnosis relies on the identification of mites, eggs, or fecal pellets in skin scrapings examined under microscopy. Dermoscopy may reveal the characteristic “delta‑wing” sign, a triangular structure corresponding to the mite’s head within a burrow. Prompt recognition enables targeted treatment and interruption of transmission.