EPIZO'A. This term is applied to those parasitic creatures which live on the bodies of other animals, and derive their nourishment from the skin. Our space will only allow of our noticing those that infest man. They may be divided into two groups:. (1) Those which live upon the surface of the skin, and (2) those which live in the skin. Fleas, lice, bugs, ticks, etc., belong to the first group; the itch-insect or sarcoptes, the pimple-mite or demodex folliculorum, and possibly some other species of the acaridcr, to the second.
In a zoological point of view, all the E. that infest the human subject are insects or arachnidans. The parasitic insects are: I. Pulicida, or I/cc/8, including-1. The common flea, or pub= irritans; 2. The sand-flea, or pulex penetrans, known also as the chigo, ger, etc. II. Acanthida, or soft bugs, including the common bed-bug or acanthia (s. cimex) lectularia. III. Pediculida, or lice, including-1 The common louse, or pediculus capitis; 2. The body louse, or pediculus vestimenti; 3, The crab louse, or pediculus (s. phthirius) pubis; 4. The louse occurring in phthiriasis, or pediculus tabescentiurn.
The parasitic archnidans belong to the order of acarida, or mites; indeed, most of the animals forming the different families of this order lead a parasitic existence. We have—I. Demodicida, including the pimple-mite or demodex (s. acarus) folliculfirum (the dog and the sheep possess each a special demodex. II. Sarcoptida, including the itch
mite or sarcoptes (s. acarus) scabiel. (Most of our domestic animals seem to be infested by a special sarcoptes, the species of which are numerous.) III. /xodida or ticks. including 1. The American tick or ixodes hominis (common in Brazil); 2. The common wood-tick (dogs' tick), or ixodes ricinus. There are probably many species of ixodes which are occasionally found on man. IV. Gamasida, or beetle lice, including-1. The bird-mite, or dermanyssus arium (occasionally found on sickly persons); 2. The 3liana bug, or argas persicus (common in some parts of Persia, and especially at Miana); 3. The chincha bug, or argas chinche (occurring in Columbia). V. Orobatida, or grass-lice, including the harvest-bug, or leptus autumnalis. See the articles Bus, FLEA, ITCH-MITE, LOUSE, Ticxs.
EPIZoOVICS (Gr. epi, upon, and etion, an animal) are diseases of animals which manifest a common character, and prevail at the same time over considerable tracts of country. Like epidemics, they appear to depend upon some peculiar and not well ascertained atmospheric causes; where the cases are neglected or overcrowded, they also frequently become contagious; they are apt to take on a low type of fever. and are better treated by supporting than by reducing remedies. Influenza in horses, and pleuro-pneumonia and vesicular epizootic in cattle, are examples.