PATHOLOGY. 
S5S 
Genus VI. Ecpyrjia, [skttvco, to fuppurate, of wvov, pus.] 
Kunning Tetter. Generic charadlers—Eruption of finall 
puftules, diftinfi or confluent; hardening into cruftular 
plates. There are four fpecies, with numerous varieties. 
i. Ecpyefis impetigo, the common running fcald, or 
tetter: puftules cluttering, yellow, itching; terminating 
in a yellow fcaly cruft, interfered with cracks. 
Impetigenous eruptions are diftinguiftied from thofe of 
an herpetic nature by their being preceded by fmall 
pvjiules, while the latter are always preceded by veficles. 
The difcharge, too, from the Impetigo is, generally 
fpeaking, more profufe than that from Herpes. Not- 
withftanding this diftindlion, it may be doubted whether 
the two fpecies do not fometimes run into one another. 
It is no uncommon thing to fee both veficles and puftules 
on the fame perfon. This combination, which is very 
painful and difficult of cure, appears chiefly on the 
hand, the veficles of which feem to contain a very acri- 
moneous fluid, fince, whenever this runs, the fkin is 
gradually denuded. The veficles are flower in their pro- 
grefs than the puftules; and, when broken, have a mor¬ 
bid fore, fecreting a thin ichor. There are fix varieties. 
«. I. fparfa, (fee fig. 3, Plate X.) Clutters loofe; 
irregularly fcattered ; chiefly over the extremities ; often 
fucceeded by freffi crops, and forming in old and debili¬ 
tated perfons troublefome ulcers. 
£. I. herpetica, (fig. 4.) (Impetigo figurata, Bate¬ 
man. Herpes, Cullen.) Clutters circular ; crowded with 
puftules, intermixed with veficles; often with exte¬ 
rior concentric rings furrounding the interior area as 
it heals ; itching accompanied with heat and fmarting. 
Chiefly on the hands and wrifts. 
This is the molt common variety of the nroitt tetter. 
It appears in circumfcribed patches, of various figure 
and magnitude, which are ufually fmaller and more 
circular on the upper, and larger, oval, and irregular, on 
the lower, extremities. The patches coniift v at firft of 
ciufters of the yellow plydracious puftules,'fet clofe 
together, and furrounded by a flight inflammatory bor¬ 
der ; the whole being fomewhat raifed, but the puftules 
not very prominent or acuminated. In a few days the 
puftules break, and difcharge their fluid ; the furface 
becomes red and excoriated, fliining as if it were ftretched, 
but exhibiting numerous minute pores, from which a 
confiderable ichorous difcharge is poured out, accompa¬ 
nied with much troublefome itching, heat, and fmarting. 
The difcharge foon concretes partially into thin yellowifti 
or greenilh fcabs ; but ftill continues to ooze from under 
the fcab, which it forms. In the courfe of three or four 
weeks, as the quantity of the difcharge diminiffies, the 
fcabs dry and fall off, leaving the furface of the cuticle 
red, rough, and fomewhat thickened, and at the fame 
time extremely brittle, and liable to crack and to be ex¬ 
coriated ; fo that the ichorous difcharge and fcabbing are 
eafily reproduced, and the difeafe is often thus much 
prolonged in its duration. Occafionally frefn crops of 
the pfydracious puftules re-nppear, as at the commence¬ 
ment; and the whole courfe of the eruption is repeated. 
When the Impetigo herpetica is beginning to heal, 
the patches undergo a procefs fomewhat fimilar to that 
which takes place in the Lepriafis vulgare. The amend¬ 
ment commences at the centre of the patch, which firft: 
fubfides, leaving the border elevated : at length this alfo 
ciifappears; but the cuticle, which was the feat of the 
patch, remains for.fome weeks red, fliining, and tender. 
The Impetigo herpetica and fparfa are fometimes con¬ 
founded with two contagious difeafes, of the puftular 
order-) Porrigo and Scabies. The appellation of ring- 
norm, which is popularly given to the oval or circular 
patch of the firft, has partly contributed to occafion this 
miftake. They differ, however, from the contagious cir¬ 
cles of Porrigo, inafmuch as the I. figurata feldom afrefls 
children, occurs principally on the extremities, and they 
do not continue to difcharge a purulent and glutinous, 
but, after the firft eruption, an ichorous humour; nor 
do they form the thick, foft, and copious, fcabs of Porrigo: 
not to mention the abfence of contagion. 
The prevalence of tranfparent veficles in the patches 
of Impetigo, may miftead an incautious or inexperienced 
obferver into a fufpicion that the difeafe is Scabies: but 
the diftribution of the eruption in patches, the copious 
exudation of ichor, the rough, reddened, and fiflured, 
cuticle, the magnitude and flow' progrefs of the veficles, 
and the heat and fmarting, which accompany the itching, 
in Impetigo, will ferve, in general, to determine the 
diagnofis. In the ftriftly purulent form of Scabies, the 
puftules about the hands arife to a much greater magni¬ 
tude and elevation than the pfydracia ; they are filled 
with a thick yellow pus, and are more confiderably in¬ 
flamed round their bafe. The Impetigo, in its advanced 
ltage is, however, more liable to be miltaken by common 
oblervers, and is in faff daily miftaken, for Pforiafis or 
Lepra ; as a fufficient difcrimination is not made between 
the laminated and fcale-like concretions of the ichorous 
matter, and the exfoliations of morbid cuticle, which 
conftitute the true fcab. But the fcaly clifeafes emit no 
fluid; and the very exiftence of a difcharge, however flight, 
is fufficient to determine the diagnofis of the eruption. 
In the incipient ftate of thefe two forms of Impetigo, 
it is ufeful to adminifter fulphur internally, in fuch 
quantities as not to induce purging; and, if there is 
much irritability or inflammation of the cuticle, a por¬ 
tion of foda, nitre, or cryftals of tartar, may be advanta- 
geoufly combined with it. The Impetigo fparfa com¬ 
monly yields to thefe medicines, if diligent ablution 
with tepid water be at the fame time employed. But, 
when the difeafe is of long (landing, it requires a treat¬ 
ment fomewhat fimilar to that recommended for invete¬ 
rate Pforiafis; namely, the diet-drinks, decoflions of 
farfaparilla and cinchona, with the fixed alkalis, and 
antimonials. The mercurial alteratives, however, in 
this affection, are of effential affiftance to this plan of 
cure; fuch as fmall dofes of cinnabar, the hydrargyrus 
cum creta, or the pill of Dr. Plummer. 
The external applications adapted to thefe forms of 
Impetigo, are the mild deficcative unguents; for, in the 
majority of cafes, the irritable furface of the tetter will 
not bear ftimulants with impunity. When the difcharge 
is confiderable, the ointments prepared with the oxyd 
of zinc, alone, or united with faturnine ointment, or 
with the white precipitated oxyd of mercury, are the 
moll efficacious, in allaying the inflammatory condition 
of the excoriated furface, and in reducing the quantity 
of the difcharge. When there is lefs of this irritability 
and exudation, the tar-ointment, or the ointment of the 
nitrate of mercury, much diluted, will be found benefi¬ 
cial. But the too adive employment of this or any other 
llimulating unguent, often does harm. 
In thefe irritable forms of Impetigo, in which veficles 
abound, the zinc, and faturnine applications, and even 
Ample lard, occafion an aggravation of the fymptoms. 
In thefe cafes it is particularly neceflary to keep the parts 
covered, with a view to avoid the effects of friftion from 
the clothes, as well as of heat and of cold ; to waffi the 
furface daily with fome emollient fluid, fuch as milk and 
water, or an infufion of bran ; to interdict the ufe of 
foap ; and to befmear the parts with cream, or an emulfion 
of almonds. A lotion prepared by boiling mallow, 
digitalis, and poppy-heads, has been found ferviceable, 
where the parts were very painful. In many cafes, how¬ 
ever, the ftiffnefs, which enfues upon the fpeedy drying 
of thefe lotions, renders it impoflible to ufe them, and it 
is neceflary to cover the part lightly with dry lint only, 
or to interpofe between it and the difeafed furface a 
fprinkling of the oxyd of zinc : fometimes, however, the 
application of linen dipped in melted fuet, affords relief, 
when no other greafy lubftance can be ufed. 
In the drier and lefs irritable forms of the Impetigo, 
the ufe of the waters of Harrowgate is the moll effeflual 
remedy, and likewife the be.ft preventive of its return.: 
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