++
Mumps is a communicable systemic
viral illness usually characterized by parotitis. With the widespread
use of mumps vaccine, the disease has become less common. A significant
number of infections are asymptomatic.
++
Humans are the only known natural hosts of mumps virus. The virus
can be recovered from patients with active disease from saliva, cerebrospinal
fluid (CSF), urine, blood, breast milk, and infected tissue.1,2 Mumps
virus infections are spread by respiratory droplet or by direct
contact with infected saliva. Virus can be demonstrated in respiratory
secretions up to 7 days before through 9 days after the onset of
parotitis.2 Secondary attack rates of mumps among
susceptible household contacts have been shown to be less than that
of measles or varicella, suggesting a less efficient transmission
of the mumps virus.3 The normal incubation period
is from 16 to 18 days (range 12–25 days). In susceptible,
unimmunized populations, 60% to 70% of infections
are associated with parotitis.4 However, there
is a substantial subclinical attack rate produced by the mumps virus.
Approximately 20% of mumps infections may go unrecognized,
especially in adults, because they do not have evidence of parotitis.2,5 Given
the number of subclinical cases, information regarding a patient’s
history of mumps infection is notoriously inaccurate. Mumps virus
infection is most communicable from 1 to 2 days prior to parotid
swelling until 5 days after parotid swelling begins.2 Introduction
of infection onto a hospital ward in areas where vaccine is not
routinely given may lead to widespread nosocomial transmission because
some patients may develop subclinical infection, and patients are contagious
prior to onset of parotid swelling, making it extremely difficult
to prevent transmission.6
++
Introduction of an effective, live-attenuated virus vaccine (Jeryl Lynn
strain) in 1967, combined with the introduction of school laws regarding
mumps vaccination, led to a marked reduction in the number of reported
cases of mumps in the United States, from more than 185,000 cases
in 1968 to 2982 in 1985.7 Following a brief resurgence
of disease, a revised recommendation for two doses of measles-mumps-rubella
(MMR) vaccine in 19894 and subsequent changes in
school laws requiring two doses of vaccine, the annual number of
mumps cases further declined. From 2001 to 2005, fewer than 300 cases
of mumps were reported annually in the United States.8 In
2006, a multistate mumps outbreak with more than 5700 cases, many
involving older adolescents and young adults, demonstrated that
although two doses of vaccine were more protective than a single dose,
protection from infection, even with two doses of vaccine, was not
100%.5,9 Outside the United States, mumps remains
endemic in many countries throughout the world.10,11 In
2005, only 57% of World Health Organization member-countries
reportedly used mumps vaccine.11
++
A single attack of mumps is believed to confer permanent immunity
against a subsequent attack, regardless of whether the patient had
evidence of parotitis. Mumps antibody is transferred across the placenta
and persists during the first several months of the infant’s life. Similar
to measles, infants born to mothers who had mumps disease may have
higher antibody titers than those infants born to mothers who received
immunization and did not have disease.
++
Mumps is caused by a paramyxovirus, which is closely related
antigenically to parainfluenza virus. Virons are approximately 150
nm and contain RNA. Mumps virus can be propagated in a variety of cell
cultures and in embryonated eggs. Mumps virus produces a generalized,
systemic infection. Although parotid involvement has been emphasized,
mumps can definitely occur without parotid swelling. Meningitis
and renal involvement may be considered part of the disease. A majority
(50–60%) of infected persons have cerebrospinal
fluid (CSF) pleocytosis, even in the absence of clinical signs of
meningitis. Adults, and males, are at greater risk of developing
meningitis than are children.2,7 Of note, boys
more frequently have meningitis than girls.2 Viruria
occurs frequently in cases of uncomplicated mumps; hematuria and
proteinuria may occur, and abnormalities of renal function have
been reported. Although orchitis is a known complication of postpubertal
males and may lead to some degree of testicular atrophy, sterility
is rare.16,17 Oophoritis is relatively uncommon
(5%) in postpubertal females. Other organs may be involved
infrequently. Death due to mumps virus is rare; fatalities are more frequent
in those older than 19 years. In such rare patients, virus has been
recovered from multiple organs at autopsy.
+++
Clinical Manifestations
++
A patient with mumps rarely has severe systemic manifestations. Temperatures
are only moderately elevated, usually for 3 to 4 days. Symptoms
such as headache, anorexia, and abdominal discomfort may precede
parotid swelling by 1 to 2 days. Parotid swelling may be the first
sign of illness; swelling may last 7 to 10 days and be observed
on one or both sides (Fig. 318-1). Two or
3 days after the onset of swelling on one side, the opposite side
may become involved. The submandibular glands may swell along with
or in the absence of parotid swelling. Presternal edema is sometimes
present.
++
++
The entire parotid gland is swollen, including the uncinate lobe,
which extends under the back of the ear lobe. The borders of the
gland are usually not discrete. Pressure on the parotid gland causes
pain, and trismus (spasm of the masticator muscles) may occur.
++
Parotid swelling produces a fair amount of discomfort. Eating or drinking acidic
foods, such as orange juice, is said to elicit much discomfort.
Inflammation of the orifice of the Stenson duct may or may not be
present.
++
Older patients with mumps frequently complain of headache, which
probably represents involvement of the meninges. Other signs of
meningeal irritation may also be present, although fewer than 10% have
symptoms of central nervous system infection.7 Evidence
of encephalitis, such as convulsions or disturbances of mentation,
occurs rarely.
++
Anorexia is a frequent complaint. Some patients may complain
of abdominal pain, which may represent involvement of the pancreas or
of the ovaries in the female. Serum amylase is usually elevated during
the infection. In severely ill patients, vomiting may be a significant
problem.
++
A substantial portion of patients with mumps infection will go
unrecognized. They may have fever and other systemic symptoms of illness.
Mumps meningitis may occur in the absence of parotid swelling.
++
The most feared complication of mumps in males is orchitis. Although
this is seen most frequently in postpubertal males, orchitis has been
reported in children as young as 3 years of age. From 14% to 35% of
persons who have mumps develop orchitis. The highest rate of orchitis
is observed in those 15 to 29 years of age.17
++
The onset of orchitis is usually heralded by fever toward the
end of the first week of illness. There is severe pain, swelling,
and tenderness; tenderness may persist for weeks. Orchitis may also
occur before or in the absence of parotitis. The involvement is
most often unilateral, but bilateral involvement has been reported
to occur. Atrophy may occur after orchitis. Unilateral atrophy will
not result in sterility, but bilateral orchitis may.16 Development
of malignancies in affected testes has been reported.17 Appropriate
therapy for orchitis includes use of analgesics and adequate support
of the testes. Application of ice has occasionally been useful.
++
In addition to involvement of testis, other glands may occasionally
be involved; oophoritis, mastitis, and pancreatitis may occasionally accompany
mumps. Mastitis is estimated to occur in 31% of females
older than 15 years with mumps.7 Oophoritis is
usually manifested by emesis, fever, and lower abdominal pain. Involvement
of the thyroid has also been reported.
++
Mumps virus is neurotropic. Meningitis or meningoencephalitis
occurs with mumps virus infection more commonly than encephalitis. Symptoms
of central nervous system (CNS) involvement typically occur 3 to
10 days after the onset of parotid gland swelling. Lethargy, nuchal
rigidity, and vomiting are common.
++
Cerebrospinal fluid (CSF) usually contains normal or slightly
elevated protein, normal or slightly decreased glucose, and pleocytosis. Cells
are usually predominantly lymphocytic with the counts ordinarily
under 500 cells/μL. Counts of more than
1000/μL, however, are not rare. Virus
can be isolated from CSF during the first few days of meningoencephalitis.
++
Infection of the CNS is usually self-limited, and cases of meningitis
generally have a favorable prognosis. Encephalitis may result in
some permanent sequelae or even death. Hydrocephalus, retrobulbar
neuritis, and paralysis, developing following mumps infection, have
been described.7
++
Deafness is a complication associated with mumps occurring in
approximately 1 per 20,000 reported cases.4 It
is often unilateral. The exact frequency is difficult to ascertain. In
a prospective study of hearing impairment following mumps in Finnish
Army personnel, about 4% of patients had acute deafness.7 Higher
tone frequencies tend to be affected most severely. The onset is
sudden and results in permanent damage to patient’s hearing.
Deafness is not related to CNS involvement.
++
Diabetes mellitus has been reported to occur after onset of mumps. Mumps
virus may invade the pancreas and can infect beta cells in
vitro. Pancreatic damage has never been documented in cases
of diabetes mellitus occurring after mumps disease or vaccination.7 Joint
involvement is an uncommon complication of mumps that is very rare
in children. Large joints, especially the knees, are most frequently
affected; involvement may be multiple or monoarticular. Complete
recovery is usual, but symptoms may be protracted.
++
Mumps in pregnant women has been reported to be associated with
an increased rate (25%) of fetal wastage in the first trimester.18 There
is no evidence that mumps virus infection produces congenital malformations.19 Although
it was once postulated that subendocardial fibroelastosis might
be associated with fetal mumps infection, mumps virus does not appear
to cause other types of myopathy.7 Maternal mumps
near term has resulted in transmission to the newborn infant. Mumps
virus has been isolated from breast milk.
++
With a decrease in the numbers of cases of mumps in the United States
following the introduction of an effective vaccine, many health
care providers have not seen cases of mumps and have become less
likely to suspect mumps in patients presenting with parotits.8
++
When confronted with an infant, child, or adolescent with bilateral or
unilateral parotid swelling, a differential diagnosis should, in addition
to mumps, include drug effects, metabolic diseases, systemic lupus
erythematosus, parotid duct obstruction, and other infectious agents,
both bacterial and viral.2 Parotid swelling has
been reported in infants and children with HIV infection. Bacterial
infection of the parotid gland may be accompanied by purulent discharge from
the Stenson duct. The approach to neck masses is discussed in Chapter 373.
++
Confirmation of the diagnosis of mumps infection depends on (1) the
isolation of virus in culture or detection by reverse transcriptase-polymerase
chain reaction (RT-PCR), (2) by demonstrating a significant rise
in specific IgG antibodies to mumps virus antigens over time, or
(3) by identifying mumps-specific IgM antibody.9 The
virus can be readily isolated in culture from throat swabs obtained
48 hours before to 7 days after parotid swelling begins. Virus has
also been isolated from urine and cerebrospinal fluid (CSF). RT-PCR
can be highly useful in detection of virus from clinical specimens.20-22 Antibodies
to parainfluenza viruses may occasionally interfere with complement
fixation and hemagglutination inhibition assays for mumps antibody.
A negative serologic test in an immunized individual does not eliminate
the diagnosis of mumps because of the test’s insensitivity
to detect infection in all persons with clinical illness.9 In
an immunized individual, the serologic response may be delayed and
the period of virus excretion shortened.9 The mumps
skin test is inaccurate and should not be used to test for immunity.
++
Conservative therapy is indicated in the treatment of mumps.
Adequate attention to hydration and alimentation is essential. Patients may
have difficulty with acidic foods, such as orange juice. The diet
should be light, with a generous offering of fluids.
++
Analgesics may occasionally be necessary for severe headache
or discomfort caused by parotitis. Stronger analgesics may be needed
for orchitis. It is unusual for vomiting to be severe enough to require
intravenous fluids. In these instances, however, electrolytes lost
by vomiting should be replaced.
++
Mumps vaccination is discussed in Chapter 244.
After a single dose of vaccine, antibodies develop in 95% to
98% of all those susceptible.7
++
Based on the Centers for Disease Control and Prevention (CDC)
2006 recommendations,24 children and adults can
be considered to have presumptive evidence of immunity to mumps
if (1) they have documentation of physician-diagnosed mumps, (2)
they have documentation of vaccination with one dose of live mumps
virus vaccine on or after their first birthday for preschool children
and adults not at high risk and two doses for school-age children
and adults at high risk, (3) they have laboratory evidence of mumps
immunity, or (4) they were born before 1957. Adults at high risk
are defined by the CDC as persons who work in health care facilities,
international travelers, and students at post–high school
educational institutions.24
++
Immunoglobulin is not effective in preventing mumps infection
after an exposure and is not recommended. Based on a review of several
studies, which included culture and/or reverse transcriptase-polymerase
chain reaction (RTPCR) data, the AAP, HICPAC, and CDC now recommend
a shorter isolation period of 5 days after the onset of parotitis
in mumps patients, in both community and health care settings.27