Mumps

Andreea C. Cazacu

Gail J. Demmler

Mumps is a contagious disease characterized by swelling of the salivary glands, particularly the parotid glands. Inapparent infections may occur in 40% of infected individuals. In 1934, experiments by Johnson and Goodpasture demonstrated a mumps-like illness in rhesus monkeys receiving parotid secretions from patients with mumps. Filtered parotid secretions from infected monkeys could be passed to other monkeys with resulting parotitis from a filterable agent, a virus.

Mumps virus subsequently was propagated in eggs, which allowed production of mumps antigen for a complement fixation test. Attenuation of the virus in vitro was accomplished by Enders in the 1940s; this accomplishment proved useful for
vaccine development, and a vaccine was prepared and licensed in 1968.

ETIOLOGY

Mumps is a single-stranded RNA virus and a member of the family Paramyxoviridae, genus Paramyxovirus. It has two major surface glycoproteins: the hemagglutinin-neuraminidase and the fusion protein. Mumps virus is sensitive to heat and ultraviolet light.

EPIDEMIOLOGY

Mumps is transmitted by direct contact or infected droplets from the oropharynx. Communicability is present before parotid swelling occurs (1 to 7 days, but usually 1 to 2 days) and 7 to 9 days after onset of parotid swelling. The incubation period of mumps is approximately 18 days, but may be longer. Mumps occurs in winter and spring seasons and had its highest attack rates in 5- to 9-year-old children in the prevaccine era. Ascertaining the epidemiologic features of mumps is difficult because of the high incidence of inapparent infections and a common incidence of parotitis caused by other pathogens.

PATHOGENESIS AND PATHOLOGY

Mumps virus produces a generalized infection. After entry into the oropharynx, viral replication takes place, causing subsequent viremia and involvement of the glands or nervous tissue. The virus may be isolated from saliva, blood, urine, and cerebrospinal fluid (CSF). Affected glands show edema and lymphocyte infiltration.

CLINICAL MANIFESTATIONS

Parotitis

The classic illness of mumps is swelling of the parotid gland (i.e., parotitis). Systemic symptoms include low-grade fever, headaches, malaise, anorexia, and abdominal pain. Acid-containing foods may aggravate discomfort of the parotid gland. Ordinarily, the parotid gland is not palpable, but in mumps cases, it rapidly progresses to maximum swelling over several days. Unilateral swelling usually occurs first, followed by bilateral parotid involvement. Occasionally, simultaneous involvement of both parotid glands occurs. Unilateral parotid disease occurs in fewer than 25% of patients. Fever subsides within 1 week and disappears before swelling of the parotid glands resolves, which may require as long as 10 days. Other salivary glands may be involved, including both submaxillary and sublingual, and orifices of the ducts may be erythematous and edematous (Table 203.1).

Orchitis and Oophoritis

About one-third of postpubertal males develop unilateral orchitis. It usually follows parotitis within 1 week but may precede it or occur in the absence of it. Bilateral orchitis occurs much less frequently, and although gonadal atrophy may follow orchitis, sterility is rare, even with bilateral involvement. Prepubertal boys also may develop orchitis, but it is uncommon in those younger than 10 years. Orchitis is accompanied by high fever, severe pain, and swelling. Nausea, vomiting, and abdominal pain are also common findings. Fever and gonadal swelling usually resolve in 1 week, but tenderness may persist.

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