INFECTION AND CONTAGION.

H

CHAP. X.

INFECTION AND CONTAGION.

Infection is designated a febrific agent, produced by the de-composition of animal and vegetable substances. It usually existsin the state of miasm or gas, and, in this form, occurs in filthyhouses, ships, jails, hospitals, and cities ; and also in marshes, andfenny and low districts of country. Under the denominations ofmarsh, or paludal miasmata, exhalations of the soil, vcgeto-animal ef-fluvium, malaria, human effluvia, febrile and putrid contagion, its va-rious specific effects are detailed in the works of practical writers,as having a decided influence on the human body.*

Contagion is a poison generated by morbid animal secretion,possessing the power of inducing a similar morbid action in healthybodies, whereby it is reproduced, and indefinitely modified. Thiscontagion can only be known by its effects, and can only be divi-ded into genera by classifying it with the diseases it produces :e.g. 1st, Contagion communicable exclusively by contact, the spe-cies of which are as follows : itch, syphilis, sibbens, loanda of Afri-ca, frambesia or yaws, elephantiasis, hydrophobia, and s/nall-pozAThese diseases cannot be conveyed through the medium of the air,but require actual contact. Hence they are strictly contagious, inthe etymological sense of the word. 2d, Contagion communica-ble both by contact and by the atmosphere. These are liable tobecome epidemic, in contradistinction to those of the first genera.In this the species are, small-pox, measles, chicken-pox, scarletfever, hooping-cough, «fee.

One of the laws which govern these contagions is, that theyare communicable in every season, in the heat of summer as wellas in the cold of winter, in a pure as well as an impure air. An-other law is, general insusceptibility to future attacks of the samedisease, but with exceptions.

Many diseases are infectious. Every person ought, therefore, asfar as he can, to avoid all communication with the diseased. The com-mon practice of visiting the sick, though often well meant, hasmany ill consequenees. Far be it from me to discourage any actof charity or benevolence, esj>ecially towards those in distress ; butI cannot help blaming such as endanger their own or their neigh-bours' lives, by a mistaken friendship, or an impertinent curiosity.

The houses of the sick, especially in the country, are generallycrowded from morning till night with idle visiters. It is custom-ary in such places, for servants and young people to wait upon the

* It has erroneously, we conceive, been denied that animal substances have anything to do in the production of tebrific miasmata. An unequivocal proof, however,has lately beeh exhibited of the contrary opinion, or rather fact, produced by opening agrave in the island of Lenten. See Med. Chirurg. Review.

f To these, Dr. Hossack, of New York, adds influenza, and cynancha maligna, or pu-trid sore throat, although Dr. Smith, whose modification of Dr. H.'s classification wehave given, says, though without proof, that the former is evidently not contagious, andthat the latter is either a modification of scarlatina, or an atmospheric disease.