Idiopathic parotitis, parotitis epidemica, or mumps, as it is variously named, is an acute contagious inflammation of one or both parotid glands, which usually appears but once in a lifetime, and which, although by no means limited to children, is commonly met with between the second year and the age of puberty. In certain exceptional cases the disease affects the submaxillary glands alone.
NATURE.—The undoubted contagiousness of mumps, with the fact of its frequently occurring in extended epidemics, entitles it to a place among the zymotic diseases, from which it differs, however, in the marked disproportion between the local and constitutional symptoms, the former being well developed, the latter but slight or altogether absent.
ETIOLOGY.—While it is more than probable that, like the other diseases of the zymotic class, mumps is due to a contagium that finds its way into the body in the inspired air or with the food or drink, nothing is known of the nature of this infecting principle.
The predisposing agencies are better understood. Age is one of these, the greater number of cases occurring, as already stated, between the second and the fifteenth year. Infants at the breast are almost entirely exempt, and so, too, are individuals advanced in years. In extended epidemics it is not unusual to meet with cases in adults, but it will generally be found on careful examination that these patients have escaped the disease during childhood. Sex exerts some influence, a much larger percentage of males being attacked than females. Epidemics appear more frequently in the spring and fall than at the other seasons of the year, so that cold and dampness of the atmosphere must be looked upon as predisposing causes. Mumps bears a peculiar relation to measles, scarlet fever, and diphtheria, epidemics being apt to occur directly before, during, or immediately after the prevalence of either of these affections, especially the first. The popular idea of mutual protection is entirely without foundation.
Certain peculiarities are presented by the disease in its mode of occurrence and in the duration and intensity of its epidemics. Thus, some localities are visited annually, others only at intervals of thirty years or more; again, one epidemic may last but a few weeks and affect a small number of individuals, while another extends over months and attacks all the children and many of the adults in the affected region.
ANATOMICAL APPEARANCES.—The exact pathological lesion in mumps is obscure, since the trifling nature of the disease and the almost invariable termination in recovery afford no opportunity for post-mortem investigation. According to Foerster, who seems to have made examinations in cases where mumps occurred as one of the accidental complications of other and fatal diseases, the affected gland at first becomes hyperæmic, and is then the seat of serous exudation. It is reddened, swollen, and on section presents a uniform flesh-like, moist appearance, in place of the ordinary granular aspect. The tumor is often greatly increased in size by a simultaneous serous infiltration of the periglandular connective tissue, and occasionally this tissue alone is involved, the gland itself being entirely free from lesion. The great point in favor of this view of the pathology is the rapid and complete subsidence of the parotid swelling by resolution—a termination to be expected only when the inflammatory process stops short of suppuration or fibrinous exudation.
Virchow regards all cases of parotitis as the result of an extension of a more or less malignant catarrh originally affecting the gland-ducts. This is undoubtedly true in some cases, but that it is far from being the rule is proved by the infrequency of parotitis as a secondary complication of catarrhal affections of the mucous membrane of the mouth.
COURSE AND SYMPTOMS.—The course of the disease is susceptible of a division into three stages—a period of incubation, of invasion, and of actual attack.
The stage of incubation extends over a period variously estimated as from seven to fourteen days. It is marked by no symptoms, though sometimes a history of impaired appetite and digestion, irregular bowels, and languor during the last two or three days may be obtained.
The period of invasion is short, lasting only twelve, or at the most twenty-four, hours. The patient is pale and languid, has slight rigors, pains in the breast and head, and loss of appetite; later, local pain in the parotid region on moving the jaws or on taking acid liquids into the mouth. The surface temperature increases from hour to hour, and just before the glandular swelling appears it reaches 100° or 101° F. In some cases the invasion is characterized by the same train of symptoms that ushers in the acute exanthemata, such as repeated vomiting, diarrhoea, restlessness and anxiety, a disposition to syncope, and, in very irritable children, convulsions. Contrasted with this violent invasion other cases are met with, in which there are no prodromes whatever except a gradual rise in temperature, imperceptible without the use of the thermometer.