#Are burrows usually present in numbers?#
No. Several may be found in a single case, but they are rarely numerous, as the irritation caused by the penetration of the parasites leads either to violent scratching and their destruction, or gives rise to the formation of vesicles and pustules, and consequently their formation is prevented.
Chronic and progressive, showing no tendency to spontaneous disappearance.
To the invasion of the cutaneous structures by an animal parasite, the sarcoptes scabiei (_acarus scabiei_). The male mite is never found in the skin and apparently takes no direct part in the production of the symptoms.
[Illustration: Fig. 77. Fig. 78. Sarcoptes scabiei x 100. (_After Duhring._) Female. Ventral surface. Male.]
The disease is contagious to a marked degree, and is most commonly contracted by sleeping with those affected, or by occupying a bed in which an affected person has slept. It occurs, for obvious reasons, usually among the poor, although it is now quite frequently met with among the better classes.
#State the diagnostic features of scabies.#
The burrows, the peculiar distribution and the multiformity of the eruption, the progressive development, and usually a history of contagion.
#How do vesicular and pustular eczema differ from scabies?#
Eczema is usually limited in extent, or irregularly distributed, is distinctly patchy, with often the formation of large diffused areas; it is variable in its clinical behavior, better and worse from time to time, and differs, moreover, in the absence of burrows and of a history of contagion.
#How does pediculosis corporis differ from scabies?#
In the distribution of the eruption. The pediculi live in the clothing and go to the skin solely for nourishment, and hence the eruption in that condition is upon covered parts, especially those parts with which the clothing lies closely in contact, as around the neck, across the upper part of the back, about the waist and down the outside of the thighs; _the hands are free_.
It is favorable. The disease is readily cured, and, as soon as the parasites and their ova are destroyed, the itching and the secondary symptoms, as a rule, rapidly disappear.
Treatment is entirely external, and consists of a preliminary soap-and-hot-water bath, an application, twice daily for three days, of a remedy destructive to the parasites and ova, and finally another bath.