Mumps is an acute contagious viral infection, most commonly manifested by nonsuppurative swelling of the parotid glands. Other salivary glands, the testes, pancreas, and central nervous system are among the various organs that may also be involved.
Etiology.
Mumps is an RNA virus, a member of the myxovirus family that includes the influenza and parainfluenza viruses. These agents all have the property of agglutinating chicken, human, an; other erythrocytes. In monkeys, mumps virus induces parotitis, and in suckling mice or hamsters it may cause fatal meningoencephalitis. The vsrcs multiplies in embryonated chick embryos in a variety of tissue culture cells. For primary radiation (usually from saliva), eggs or preferably cell cultures derived from monkeys or humans are used. In tissue cultures the presence of the virus is recognized either by the appearance of cytopathic changes or by means of the hemadsorption test, which depends on the ability of the virus-infected cells to adsorb guinea pig erythrocytes. In infected cultures these are seen firmly attached to the cell sheet, whereas in control tubes the erythrocytes float in the media.
Epidemiology.
Mumps is a common disease, endemic all over the world. It occurs throughout the year, but there is a seasonal prevalence, with a regular increase in cases in winter and spring. Epidemics are frequent, large outbreaks tending to have a seven- or eight-year cycle. The disease incidence is the same in both sexes, but males are more prone to develop central nervous system complications. Most cases occur between the ages of 5 and 15 years; young adults are nevertheless sometimes susceptible, as evidenced by epidemics in military camps and schools.
The only known reservoir of infection is man. In experiments in volunteers, Henle et al. showed that the virus may be present in the saliva from two to six days before the occurrence of parotid swelling, and as long as seven to nine days after onset. Transmission is thought to be by direct contact, air-suspended droplets, or fomites contaminated with saliva. Rather more solid contact appears to be necessary for transmission of mumps than is the case with measles or chickenpox.
Although it is a common disease, only about 60 per cent of the. adult population gives a positive history, in contrast to more than 90 per cent for measles. The difference is due in part to the frequency of inapparent infection with mumps virus. About 50 per cent of those with a negative history give a positive serologic test, indicating previous silent infection. One experience with mumps virus appears to confer lifelong immunity.
Pathogenesis and Pathology.
The widespread involvement of glandular and other tissues in the body indicates that mumps is a systemic infection. The virus apparently enters and multiplies first in the upper respiratory tract; it then invades the blood stream, localizes in the salivary as well as other glands, and in the central nervous system. The parotids are one of many target organs, the greater frequency with which they are involved being simply a reflection of greater sensitivity.
Limited observations on pathologic specimens indicate that the reaction in the parotid gland is a nonspecific inflammatory one, which is not extensive. The testes and pancreas also demonstrate inflammatory and degenerative changes. Lesions induced by the virus in the central nervous system are uncertain, because in the few cases that have terminated fatally the findings have been those of postinfectious encephalomyelitis.
Clinical Manifestations
The incubation period is 17 to 21 days, usually 18; extremes of 12 and 35. days have been reported. In most cases, pain and swelling in the parotid region are the first signs of the disease, although occasionally in adults pain in the testicle may be the initial symptom. Rarely, meningitis appears first, followed later by parotitis. In more severe cases, there is often a prodromal period, sometimes lasting as long as two or three days, with fever, malaise, headache, chills, sore throat, earache, and tenderness along the region of the parotid ducts.
Parotid swelling is first observed below the ear, usually obliterating the hollow between the mastoid process and the ascending ramus of the lower jaw. The gland increases in size over a two- to three-day period, but there is great variation in the degree of swelling; in mild cases it may be scarcely apparent, but in severe ones the associated edema may eventually spread superiorly to the eyes, posteriorly to the mastoid region, and inferiorly below the chin and over the anterior aspect of the neck.
For the first two days, unilateral involvement is the rule, but eventually both glands are affected in about 70 per cent of cases. The skin over the swollen parotids is not usually reddened, but is tense and tender on pressure. Not infrequently the submaxillary and sublingual glands are also affected. Involvement of the sublingual glands can result in swelling of the tongue, with attendant painful swallowing. Presternal pitting edema is also occasionally present, apparently because of obstruction of the lymphatics by the enlarged salivary glands.
The patient seldom suffers severe pain except on movement of the jaws, e.g., in talking or chewing. If Stensen’s duct becomes partially occluded as the gland swells, there is sharp pain on taking food or an acid drink, which stimulates the secretory mechanism. Because this occurs only with partial occlusion of the duct, it is not a constant sign. The papillae at. the opening of Stensen’s or Wharton’s duct may be reddened, but this also is inconstant.
Constitutional symptoms vary greatly and may be virtually absent. They are especially mild in children, but tend to be more severe in adults, in whom the incidence of extra parotid lesions is higher. Fever varies with the extent of involvement, ranging between 101 and 103° F. in full blown, uncomplicated cases, but going as high as 105 and 106° F. if orchitis, meningoencephalitis, or both develop.
The duration of parotid swelling and fever is dependent upon the extent and severity of the process. Usually the temperature is normal within five days, and swelling has disappeared by seven to ten days. A peculiar tendency to relapse with recurrence of parotid swelling has been noted in buglers, horn players, and others whose occupations involve similar exertion.
Diagnosis of Mumps Disease.
Sudden onset of parotitis in a previously healthy patient with a negative history of mumps presents no diagnostic problem. Other causes of parotid swelling are suppurative parotitis, an acute bacterial infection in which there is marked tenderness, the skin over the gland is red and hot, and pus can often be expressed from the duct; preauricular and anterior cervical lymphadenopathy; and salivary calculi obstructing the duct and giving rise to recurrent parotitis. Chronic enlargement of the gland occurs with tumors, Mikulicz’s disease, and uveoparotid fever of sarcoidosis.
Mumps infection in the absence of parotitis is often difficult to recognize. Orchitis can be due in rare instances to infection with other viruses such as Coxsackie B, echo-, and lymphocytic choriomeningitis virus. A variety of viral agents cause aseptic meningitis or meningoencephalitis that cannot be distinguished clinically from central nervous system involvement caused, by mumps. In such situations specific laboratory tests are necessary to establish the etiology. Mumps virus can be isolated from saliva, urine, and, in meningitis, from the cerebrospinal fluid.
More commonly, confirmation of the diagnosis is based cn the demonstration of a significant rise in antibody titer (either complement-fixing, or hemagglutination- inhibiting) when acute and convalescent serum samples are tested. If only a single convalescent specimen is available, the presence of a high titer is suggestive of recent infection. The skin test is of no value in diagnosis, because dermal hypersensitivity usually does not develop until three to four weeks after onset; it is less reliable than serologic tests in determining immune status.
Routine laboratory tests frequently indicate a relative lymphocytosis in uncomplicated parotitis; with orchitis, pancreatitis, or aseptic meningitis, the total leukocyte count often reaches 15,000 to 20,000, with a high percentage of polymorphonuclear cells. The blood amylase is usually elevated as a result of parotitis and is therefore not a reliable indication of pancreatic involvement.
Prognosis.
Complete recovery is the rule, and mortality is virtually nil. A few fatal cases of postinfectious encephalitis have been reported; bilateral testicular atrophy with resultant sterility (vide supra and permanent nerve deafness are rare residua.
You Must Know The Mumps Treatment And Home Remedies.
Bed rest and symptomatic therapy are all that can be offered. For parotid pain, aspirin or codeine is effective. Some patients find an ice bag applied to the parotid region comforting, but others prefer heat. The headache associated with meningitis may be relieved by lumbar puncture. If orchitis is mild, no special treatment is required; if severe, meperidine (Demerol) (0.05 to 0.1 gram) or morphine (0.01 to 0.015 gram) may be necessary to control the pain. Local support and provision of warmth by means of a nest of absorbent cotton are more effective than an ice bag to the scrotum. Corticosteroids relieve the pain but do not appear to alter the duration of illness, nor do they protect against the subsequent development of atrophy. They are not indicated in mild cases, but in severe ones hydrocortisone, 10 mg. per kilogram per day, may be given for three to four days.
Prevention of Mumps.
A live attenuated mumps virus vaccine, grown in tissue cultures of chick embryo cells, was licensed in 1968. To date, some 4 million persons have been immunized in the United States. The vaccine, given subcutaneously in a 0.5-ml. dose, causes virtually no clinical reaction, and induces antibody conversions in more than 95 per cent of susceptibles. The serum titers are lower than those following natural infection, but they have persisted satisfactorily for the four-year period over which antibodies have been tested. Vaccines have been shown to be resistant to mumps when subsequently exposed to siblings with the disease.
Until there is further evidence of the long-term duration of protection induced by the vaccine, immunization is indicated primarily for (1) susceptible children, especially boys approaching puberty; and (2) adolescents and adults (males particularly) with a negative history of the disease. If the vaccine is given after exposure, it is unlikely that it will protect. However, it may be given under these circumstances so that if contact infection failed to develop in a susceptible subject who was exposed, he will be protected when he next meets the virus.Mumps vaccine should not be given to persons with allergies to egg proteins or to neomycin. It is contraindicated for those with any disease that is in compromised immune mechanisms and far salients on immunosuppressive therapy.
