Convalescence, as a rule, is long and often complicated with dyspepsia, diar rhcea, palsies or spastic disorders in the limbs (sometimes in form of tetany), and mental troubles. Anaemia is present in a large proportion of cases.
An attack of cholera does not give im munity; so that even after recovery has taken place a new infection is possible.
The clinical f orms of cholera may be very different. The most common is that described, in which the disease runs through its typical periods; but it may limit itself to the first stage, being a choleraic diarrhcea or a, cholerine, or it may, from the beginning, show the grav est symptoms of confirmed cholera, rapidly passing into the algid stage. Between the slight and the grave form there are all the possible intermediate varieties. But there are two other forms worthy of mention: the "foudroyant" and the "dry" cholera. The true cholera fouclroyant or cholera siderans is generally rare and mostly observed in India; the disease then kills in a few bours or even minutes; or—as observed in European epidemics—death ensues after 12 to 24 hours. The name of "dry" cholera is (riven to those cases in which there are no diarrhceic stools; intestinal exudation really takes place, but, probably on ac count of intestinal paralysis, the fluid materials are not thrown out. These cases are often rapidly fatal.
Diagnosis.—In grave cases of cholera the diagnosis is not difficult, especially when an epidemic of the disease exists. Sometimes, however, the clinical appear ance of the disease may be very like that of malarial choleriform pernicious fever and of various kinds of chemical poison ing. The confusion between cholera and malaria may arise especially in countries where both infections are endemic, such as in India. Then, besides the bacterio logical examination showing the specific germ in each of them, the effects of quinine may indicate an important dif ference in the character, malarial fever ordinarily yielding to its action, while cholera generally runs its course despite the largest doses. It may happen, how ever, that both diseases attack a person at the same time, and then symptoms of each are observed, giving rise to a mixed form, while necropsy shows the lesions of either infection distinctly developed. Poisoning by tartar emetic or arsenic, the symptoms of which resemble very much those of the choleraic algid stage, is recognized by the lesions of the mouth and lips, by the vomiting being painful, burning, and preceding diarrhcea, and, in doubtful cases, by chemical analysis of vomited matters.
But a much more important diagnostic question, arising especially at the begin ning of an epidemic or when an invasion of cholera is to be feared, relates to slight or suspected cases, which are marked only by a simple diarrhcea possessing no specific character. It is of the greatest importance to ascertain, on account of prophylactic measures to be at once adopted, whether they are or not of choleraic nature. The diagnosis can only be made by means of bacteriological examination; fortunately this is quite easy, because the cholera vibrios always show themselves in the first diarrliceal stools, and because in many cases the simple examination of a cover-glass preparation of the stools may be suffi cient to make a very probable diagnosis.
When mixed with the serum of im munized guinelt-pigs, and inoculated into the peritoneal cavity of sitseeptible ani mals, virulent cultures of the spirilla in large dose remain innocuous; on subse quent examination of the peritoneal con tents the bacteria eau be seen to have undergone disintegration to a greater or less extent, dependent upon the relative immunizing strength of the serum of the immunized animal. This power of de stroying the cholera spirilla is believed to depend upon the presence in the SC.1100 of certain antagonistic substances which have a distinct inhibiting influence upon the vital processes of the bacteria.
Investigations show that no other spe cies of bacteria is affected in the same way by mixing with the serum. Hence the following test proposed: A loopful of the culture to be tested is mixed with a eubie centimetre of bouillon, to which ten times the amount of serum necessary to protect a guinea-pig of 200 grammes weight from a similar dose of virnlent cholera spirilla has been added, and the whole is at once inoculated into the peritoneal cavity of a young guinea-pig of from 2(10 to 300 grammes weight. In the inoculation care should be taken to avoid injury of the intestines, and the cultures employed should be recent and should have been shown to consist of well-formed and actively moving germs.