Answer to Case 531

Answer toParasite Case of the Week 531:Sarcoptes scabei,var. hominis, the human " itch " mite. Seen here are mites, eggs and fecal pellets (scybala).Old one nicely described the biology and morphology of these arthropods:Sarcoptes scabeioccur in a number of host species. Primarily in swine here in Minnesota but occasionally in humans. The male mites range in size from 213-285 μm long by 162-240 μm wide and the female mites range from 300-504 μm long to 230-420 μm wide.Sarcoptesare round to ovoid when viewed from the back; when viewed from the side they are ventrally flattened and dorsally rounded (similar to a turtle). They possess short stumpy legs, and have no internal or external respiration apparatus (stigmata or tracheae). The ventral surface contains a number of chitinized plates called apodemes, the dorsal surface is partially covered by wide-angled, V-shaped-spines (>). The cuticular surface is sculptured into numerous parallel ridges which superficially resemble human finger prints, and the anus is at the posterior end of the mite (this is the characteristic used to differentiateSarcoptesfromNotoedreswhich has a dorsal anus and sometimes infests humans) The morphology of the developmental stages ofSarcoptesvaries. You can, however, differentiate the adult stages from other mite species using easily recognized characteristics. The last segment (tarsus) of legs 1, 2, and 4 on males and legs 1 and 2 on females have a long, unjointed empodium or stalk with a small...

Source: Creepy Dreadful Wonderful Parasites - February 10, 2019 Category: Parasitology Source Type: blogs