The comical spectacle of the unhappy young man with face distorted by painful edematous enlargement of parotid and other salivary glands, unable lo eat or talk without discomfort, is familiar music-hall fare, often spiced with the innuendo that the case is complicated by a well-deserved orchitis! Epi-didymoorchitis is indeed a painful development which occurs in 25% of all mumps cases in postpubertal males and may lead to atrophy of the affected testicle. A wide variety of other glands may be involved, including the pancreas (quite commonly), ovary, thyroid, and breast (more rarely). Benign meningeal signs are detectable in at least 10% of all cases of mumps, and clinical meningitis, sometimes presenting without parotid involvement, occurs often enough to make mumps the most common single cause of this disease. For-
Mumps tunately, the prognosis is very much better than with bacterial meningitis, and sequelae are rare. Mumps encephalitis, on the other hand, though much less frequent, is a more serious development. Unilateral nerve deafness is an uncommon but important long-term consequence. In infants, mumps infections are often symptomless or present as respiratory infections.
The classic case of mumps (Fig. 28-5) can be identified without help from the laboratory, but atypical cases and meningoencephalitis present a diagnostic problem. Virus can be isolated from saliva (or from swabs taken from the orifice of Stensen's duct), from urine (mumps virus being one of the few viruses readily isolated from the latter source), or from CSF in patients with meningitis. Primary cultures of primate kidney cells have been largely replaced by continuous human cell lines such as H292, derived originally from a human lung mucoepidermoid carcinoma. The readout is hemadsorption, and immunofluorescence confirms the diagnosis. However, mumps is more commonly diagnosed by serology. IgM capture EfA allows rapid diagnosis of mumps meningoencephalitis, while EIA can also be used to screen for IgG to monitor immune status in vaccination studies.
Mumps is transmissible by direct contact with saliva or by droplet spread, from a few days before the onset of symptoms until about a week after. Mumps does not show the dramatic periodicity of the other paramyxoviruses but tends to cause sporadic cases throughout all seasons, with winter-spring epidemics every few years. A dramatic decline in the incidence of mumps has been recorded in the United States since the introduction of the vaccine (see Fig. 15-1).
The live attenuated vaccine, derived by passage in chick fibroblasts, may be used alone in adolescent males, for example, military recruits, but in many countries including the United States is administered to 15 month old infants in the form of a combined measles/mumps/rubella (MMR) vaccine. Protective levels of antibody against mumps are conferred by a single subcutaneous injection in at least 90% of recipients and persist for at least 20 years. The vaccine is relatively free of side effects, although occasional mild allergic reactions occur.
in the United States, there have been indications recently that the 98% reduction in the incidence of mumps since the introduction of the vaccine is not being consistently maintained and that cases are now occurring in unvac-cinated adolescents and young adults, in whom the risk of complications is higher. As with measles, this points up the importance of attaining universal coverage whenever a policy of widespread immunization of infants is adopted, and reinforces the desirability of a booster dose of MMR vaccine on entering high school or college.
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