Mumps is an acute generalized viral infection that is usually characterized by nonsuppurative swelling and tenderness of one or both parotid and other salivary glands after a few days of prodromal symptoms. It is caused by mumps virus, a single-stranded RNA paramyxovirus, of which humans are the only natural host.

Viral parotitis

Parotitis

• Mumps was first described by Hippocrates in the fifth century BC as swelling near the ears, often accompanied by testicular swelling. The virus was first isolated in 1945.
• Mumps occurs worldwide.

• Clinical symptoms typically develop 16 to 18 days after exposure and last for less than 10 days.¹
• Prodromal period: Includes low-grade fever, myalgias, malaise, anorexia, and headache.
• Salivary gland involvement
  1. Parotid swelling and tenderness; often the first signs of infection:
     1. Progresses over 2 to 3 days. The opposite side may become involved. Contralateral parotitis within weeks to months after apparent recovery has been described.²
     2. Unilateral parotitis in 25% of cases.
     3. Symptoms: Considerable pain with parotid swelling, causing trismus and difficulty with mastication and pronunciation. Pain is exacerbated by eating or drinking citrus and other acidic foods.
     4. Enlarged, firm, tender parotid gland that lifts the earlobe upward and outward and obscures the angle of the mandible.
     5. Possible fever, ranging up to 40° C (104° F).
     6. Swelling usually resolves within 1 wk.
  2. Submandibular and salivary glands enlarged, tender in ∼10% of cases.
     1. Significant pharyngolaryngeal edema from submandibular swelling is rare but when present, often responds to steroid therapy.
• Central nervous system involvement
  1. May occur from 1 wk before to 2 wk after the onset of parotitis or even in its absence.
  2. Up to 50% of mumps positive patients have been noted to have cerebrospinal fluid (CSF) pleocytosis.²
  3. Meningitis
     1. Occurs in 1% to 10% of patients with mumps parotitis.
     2. Occurs three times more often in males than females.
     3. Symptoms: Headache, fever, nuchal rigidity, and vomiting.
     4. Full recovery with no sequelae.
  4. Encephalitis
     1. Widespread vaccination has led to the near disappearance of mumps encephalitis.
     2. May develop early, as a result of direct viral invasion of neurons, or late, around the second week after onset of parotitis, and is a postinfectious demyelinating process.
     3. Symptoms: Fever, alterations in the level of consciousness, possible seizures, paresis or paralysis, and aphasia. Fever up to 41° C/105.8° F.
     4. Cerebellitis and hydrocephalus are serious complications of mumps encephalitis.
     5. May result in permanent sequelae or death (1.5% mortality).
• Genitourinary system involvement
  1. Epididymo-orchitis
     1. Most common extra salivary gland complication of mumps in adult men.
     2. Occurs in 7% of vaccinated and 30% of unvaccinated postpubertal males who have mumps.
     3. Only bilateral in 15% to 20% of males who develop this complication.
     4. May precede development of parotitis and may be the only manifestation of mumps.
     5. Two thirds of cases develop during first week of parotitis.
     6. Symptoms: Severe pain, swelling, and tenderness of the testes, scrotal erythema, fever and chills.
     7. Some degree of testicular atrophy in 50% of cases, months to years later.
     8. Sterility from bilateral orchitis is rare.
  2. Oophoritis
     1. Occurs in 1% to 5% of post-pubertal women with mumps.
     2. Symptoms: Fever, nausea, vomiting, and lower abdominal pain.
     3. May rarely result in decreased fertility and premature menopause.
  3. Glomerulonephritis
     1. Transient renal impairment.
     2. Manifested by hematuria and proteinuria.
• Other disease manifestations:
  1. Pancreatitis
     1. Uncommon
     2. Symptoms: Abdominal pain, fever, vomiting.
  2. Arthritis
     1. Migratory polyarthritis is most frequent.
     2. Infrequently affects adults with mumps.
     3. Affects more men than women with mumps.
     4. Self-limited, with complete resolution.
  3. Deafness
     1. Before widespread vaccination, mumps was the most common cause of acquired sensorineural hearing loss in children.
     2. Most often presents acutely with unilateral, high frequency hearing loss, though more indolent and bilateral courses have also been described.
     3. Sometimes presents with concurrent vestibular symptoms.
     4. Most patients recover, but permanent deafness also occurs.
     5. Permanent unilateral deafness reported in 1 in 20,000 cases.
  4. Myocarditis
     1. Uncommon.
     2. Transient ST depression on ECG can occur in up to 15% of patients.
     3. Rarely causes progressive and fulminant fatal myocarditis with dilated cardiomyopathy.
  5. Mastitis
     1. Symptoms: Fever, erythematous swelling, and tenderness.
  6. Thyroiditis
     1. Rare complication associated with parotitis.
     2. Symptoms: Thyroid gland swelling, hoarseness, dysphagia.

• Virus is spread via direct contact with respiratory droplets, saliva, and household fomites.
• The virus initially infects respiratory epithelium, followed by local infection of salivary glands. From there, viremia carries the virus to other exocrine glands, including the testes, ovary, pancreas, breasts, and other organs.^3,4
• Patients are contagious from 48 h before to 9 days after parotid swelling.
• Transmission can also occur among asymptomatic individuals.

• Other viruses that may cause acute parotitis:
  1. Parainfluenza types 1 and 3
  2. Coxsackie viruses
  3. Influenza A
  4. Cytomegalovirus
  5. Epstein-Barr virus
  6. HIV
     1. Bilateral parotid swelling is frequently seen in HIV-infected children.
• Suppurative parotitis
  1. Most often caused by Staphylococcus aureus, less often by nontuberculous mycobacterium.
  2. May be differentiated from mumps clinically by:
     1. More rapid onset of swelling, tenderness, induration, and erythema overlying the gland.
     2. Most commonly only unilateral gland affected.
     3. Ability to express pus from Stensen duct or massage of parotid.
• Other conditions that may present with parotid enlargement or swelling:
  1. Autoimmune: Sjögren syndrome
  2. Neoplasm: Leukemia or solid tumor
     1. Tumors may be painless unless advanced and must be diagnosed by biopsy.
  3. Anatomic: Obstruction resulting from stones (often due to dehydration and poor oral hygiene) and/or strictures (associated with duct trauma or repeated infections).
     1. Diagnosed by sialography.
  4. Other: Diabetes mellitus, malnutrition, cirrhosis, and uremia all cause reduction in salivary production and flow.
• Drugs that cause parotid swelling:
  1. Phenothiazines
  2. Phenylbutazone
  3. Thiouracil
  4. Iodides
• Other conditions that may cause epididymo-orchitis:
  1. Viral causes include coxsackieviruses and parvovirus.
  2. Bacterial etiologies include chlamydia, gonorrhea, and enteric organisms.

• Diagnosis based on history of exposure and physical finding of parotid tenderness with mild to moderate constitutional symptoms.
• Diagnosis is confirmed by a variety of serologic tests or isolation of the virus.
• CDC categorizes mumps infection into the following:
  1. Suspect: Patient with parotitis, orchitis, or oophoritis without more likely diagnosis or asymptomatic patient with positive lab result.
  2. Probable: Patient with parotitis, orchitis, or oophoritis without more likely diagnosis and either positive serum mumps IgM antibody or epidemiologic link to known case/outbreak setting.
  3. Confirmed: Patient with parotitis, orchitis, oophoritis, meningitis, encephalitis, mastitis, or pancreatitis with either positive mumps viral culture or polymerase chain reaction (PCR).

• Laboratory tests can help verify a mumps infection given lack of reliability in clinical diagnosis.
• Diagnosis is aided by immunoglobulin M (IgM) and/or IgG serology, culture, and PCR testing.
• Fluid samples for PCR and viral culture:
  1. From parotid duct or other affected salivary gland duct, throat, urine, CSF.
  2. Highest yield from buccal swab after 30 sec of massaging salivary glands.
  3. Highest yield within 3 days (no more than 8 days) from onset of parotitis.
• Serology:
  1. Mumps IgM (enzyme immunoassay or immunofluorescence) indicates acute infection. Sometimes will turn positive with repeat testing days to a week later.
  2. Seroconversion from negative to positive IgG (after 2 to 3 wk) or a 4 times rise in antibody titer also indicates acute infection.
  3. Serologies are less reliable (false-negative IgM) in patients who have been vaccinated, and negative serologies do not rule out mumps as the diagnosis in those with clinically compatible symptoms.²
• Virus can be cultured from CSF in patients with meningitis during the first 3 days of meningeal findings. More rapid confirmation of mumps in the CSF is done through RT-PCR.
• In mumps meningitis, CSF studies mimic bacterial meningitis:
  1. Low glucose, mildly elevated protein, and pleocytosis up to 2000 white blood cells (WBCs).
• Virus can be detected in urine during the first 2 wk of infection.
• WBC count:
  1. May be normal or possible mild leukopenia with a relative lymphocytosis
  2. Leukocytosis with left shift with extra salivary gland involvement, such as meningitis, orchitis, or pancreatitis
• Serum amylase:
  1. Elevated in the presence of parotitis. Not specific for a diagnosis of mumps.
  2. May remain elevated for 2 to 3 wk
  3. May be differentiated from other etiologies of hyperamylasemia by isoenzyme analysis or serum pancreatic lipase

• Supportive treatment
• Adequate hydration and nutrition

• Analgesics and antipyretics to relieve pain and fever
• Warm compresses for parotitis
• Narcotic analgesics, along with bed rest, ice packs, and a testicular bridge, to relieve pain associated with mumps orchitis
• Intravenous fluids for patients with frequent vomiting associated with mumps pancreatitis or meningitis

• Most patients recover without incident. Patients may require hospital admission for hydration/supportive care and monitoring of neurologic status.

• To a neurologist if significant neurologic complications develop during or following mumps (myelitis, encephalitis, cranial nerve involvement, cerebellar ataxia, etc.)
• To a cardiologist if viral myocarditis develops
• To a urologist if orchitis develops
• To an infectious disease specialist if difficulty with diagnostic workup and interpretation
• To an audiologist if noticeable hearing impairment has occurred

• Attenuated live mumps virus vaccine has been available since 1967.
  1. Usually given in combination with MMR or as a measles-mumps-rubella-varicella vaccine (MMRV). A monovalent mumps vaccine is no longer available.
  2. Either vaccine should be given at 12 to 15 mo of age and again at 4 to 6 yr of age.
  3. 2 doses of the vaccine are ∼88% effective in preventing mumps infection, versus 78% for one dose.
  4. Mumps is increasingly being reported in vaccinated individuals. Thus those in the midst of a mumps outbreak who are at increased risk for acquiring mumps should receive an additional dose of the vaccine to improve immunity.^2,5
  5. Unvaccinated students may be held out of school during outbreaks, with readmission after vaccination. If students remain unimmunized, they should be excluded until at least 26 days after onset of parotitis in the last person with mumps at the affected school.
  6. Mumps immunoglobulin is not effective or available as postexposure prophylaxis in the U.S.
  7. Mumps vaccine is contraindicated in pregnant women and immunocompromised patients. Household contacts of immunocompromised persons are still recommended to receive the MMR vaccine.
  8. International travelers >12 mo should preferably have received 2 doses of the vaccine (administered >27 days apart) prior to departure. There is no recommendation for mumps vaccination in children <12 mo, but those age 6 to 11 mo are advised to receive a dose of the MMR vaccine for measles protection prior to departure.
  9. Patients with asymptomatic HIV infection and patients with symptomatic HIV infection, in the absence of severe immunosuppression, can safely receive the MMR vaccine.
  10. Adverse events of vaccination include local pain, induration, thrombocytopenic purpura, Guillain-Barré syndrome, and cerebellar ataxia.
  11. Adults born before 1957 are considered immune. Those born after 1957 who lack documentation of immunization are considered susceptible. Adults can receive two vaccine doses 1 mo apart.
• The CDC and American Academy of Pediatrics (AAP) recommend that patients with mumps stay home from work or school for 5 days after onset of clinical symptoms.¹
• Because virus may be shed before the onset of parotid swelling, isolation is possibly not of great value in limiting spread of infection. Use droplet precautions as per CDC and AAP recommendations.
• Mumps is a reportable disease in all U.S. states for all probable and confirmed cases.

Mumps (Patient Information)