Mumps

Disclaimer: This information is intended for educational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Clinical decisions must always be made by a qualified healthcare professional, taking into account the individual circumstances of each patient. Guidelines and recommendations may change over time, and clinicians should always refer to the most current evidence-based resources.

Overview

• Definition: Mumps is an acute, systemic viral illness caused by the mumps virus, a member of the Rubulavirus genus within the Paramyxoviridae family. It is characterized most commonly by non-suppurative inflammation of one or both parotid glands (parotitis) but can also cause other glandular and nervous system involvement.
• Epidemiology:
  • Global: Mumps is endemic worldwide, with periodic outbreaks, particularly in settings with low vaccination coverage. Before widespread vaccination, it was a common childhood disease.
  • United States: Incidence dramatically decreased after the introduction of the mumps-measles-rubella (MMR) vaccine in 1967. However, outbreaks still occur, often in highly vaccinated populations, highlighting the challenge of vaccine effectiveness waning over time or sub-optimal second-dose uptake. Outbreaks are often seen in congregate settings (e.g., colleges, close-knit communities). Peak incidence typically occurs in late winter and spring.
  • Demographics: While primarily a disease of unvaccinated or under-vaccinated children, a significant proportion of recent outbreaks have affected young adults (18-22 years old), often those who received only one dose of the MMR vaccine or for whom vaccine immunity has waned.
• Classification: Mumps is caused by a single type of mumps virus. While there are different genotypes of the virus, these do not lead to distinct clinical classifications or subtypes of the disease itself. The classification is primarily based on clinical presentation (e.g., mumps parotitis, mumps orchitis, mumps meningitis).

Pathophysiology

• Mechanism:
  • The mumps virus is an RNA virus transmitted primarily through direct contact with respiratory droplets or saliva from an infected person, or indirectly via fomites.
  • It replicates in the nasopharynx and regional lymph nodes during the incubation period (typically 16-18 days, range 12-25 days).
  • Following initial replication, viremia occurs, leading to widespread dissemination of the virus to target tissues, including the salivary glands (most commonly parotid), central nervous system (CNS), testes, ovaries, pancreas, and other organs.
  • In the salivary glands, the virus replicates in the ductal epithelial cells, causing inflammation, edema, and characteristic swelling.
  • Viral shedding can occur from 3 days before symptom onset up to 9 days after onset, with peak infectivity shortly before and after parotitis onset.
• Risk Factors:
  • Lack of Vaccination: The most significant risk factor. Individuals who are unvaccinated or incompletely vaccinated (e.g., only one dose of MMR) are highly susceptible.
  • Close Contact: Living in or spending time in congregate settings (e.g., schools, universities, dormitories, military barracks, shared households) increases the risk of exposure and transmission, especially during outbreaks.
  • Immunocompromise: While not a primary risk factor for acquisition, immunocompromised individuals may experience more severe or prolonged illness if infected.
• Protective Factors:
  • Vaccination: The most effective protective measure. Two doses of the MMR vaccine provide approximately 88% (range 62-95%) effectiveness against mumps. One dose provides about 78% (range 49-92%) effectiveness.
  • Prior Infection: Natural infection with mumps virus generally confers lifelong immunity.

Clinical Presentation

Signs and Symptoms

• Cardinal Features:
  • Parotitis: Unilateral or bilateral swelling and tenderness of the parotid glands, which gradually increases over 2-3 days, then subsides within 7-10 days. Swelling often lifts the earlobe upward and outward and obliterates the angle of the mandible. Bilateral involvement occurs in about 70-90% of symptomatic cases, though often asynchronous.
• Early Signs (Prodromal Phase):
  • Non-specific symptoms typically occur 1-2 days before parotitis onset:
    • Low-grade fever (100-101°F / 37.8-38.3°C)
    • Headache
    • Myalgia
    • Anorexia
    • Malaise
    • Earache (often referred pain from parotiditis)
• Advanced Signs (Complications):
  • Orchitis: Swelling, tenderness, and pain in one or both testes (unilateral in 75-85% of cases). Occurs in 20-50% of post-pubertal males with mumps, typically 4-8 days after parotitis onset. Fever, nausea, and vomiting may accompany it.
  • Oophoritis: Lower abdominal pain, fever, and vomiting in post-pubertal females. Occurs in approximately 5% of post-pubertal females, often less clinically apparent than orchitis.
  • Aseptic Meningitis: Headache, fever, stiff neck, vomiting, and photophobia. Occurs in up to 15% of symptomatic cases, and CSF pleocytosis (lymphocytic) can be found in up to 50% of cases even without overt clinical symptoms. Usually benign and self-limiting.
  • Encephalitis: More severe CNS involvement with altered mental status, seizures, focal neurological deficits. Rare (1 in 6,000 cases).
  • Pancreatitis: Abdominal pain, nausea, vomiting, fever. Occurs in 2-5% of cases, typically mild, but can be severe.
  • Sensorineural Hearing Loss: Unilateral or bilateral, usually permanent, though rare (1 in 20,000 cases).
• Atypical Presentations:
  • Subclinical/Asymptomatic Infection: Up to 20-30% of mumps infections are asymptomatic, particularly in young children, but can still transmit the virus.
  • Isolated Complication: Mumps can present with complications (e.g., orchitis, meningitis) without preceding or concurrent parotitis, making diagnosis challenging.

Physical Examination

• Inspection:
  • Parotid Glands: Visible swelling anterior to and below the earlobe, extending to the angle of the mandible. The earlobe may be lifted outward and upward. Swelling can be unilateral or bilateral. Skin over the gland may appear tense and shiny.
  • Other Glands: Less commonly, submandibular or sublingual gland swelling may be observed.
  • Testes/Ovaries: In males, inspection of the scrotum for unilateral or bilateral testicular swelling, redness, and tenderness. In females, abdominal tenderness related to oophoritis.
• Palpation:
  • Parotid Glands: Tender, firm, and rubbery consistency. Palpation may elicit pain, particularly when chewing or swallowing acidic foods.
  • Stensen's Duct (Parotid Duct): Erythema and swelling of the papilla opposite the upper second molar. Pressure on the gland may yield cloudy or purulent fluid if there is secondary bacterial infection (rare in mumps).
  • Lymph Nodes: Cervical lymphadenopathy may be present.
  • Testes: Palpation reveals exquisitely tender and swollen testes in orchitis.
• Special Tests:
  • No specific "special tests" for mumps itself.
  • Neurological Examination: For suspected meningitis/encephalitis: assess for nuchal rigidity, Kernig's sign, Brudzinski's sign, altered mental status, focal deficits.

Diagnostic Approach

History Taking

• Key Questions:
  • Symptom Onset and Progression: When did symptoms begin? How have they evolved? Is there parotid swelling, and is it unilateral or bilateral?
  • Prodromal Symptoms: Fever, headache, myalgia, malaise before swelling.
  • Exposure History: Recent contact with anyone with mumps or parotitis? Exposure in congregate settings (school, dorm)?
  • Vaccination Status: MMR vaccine history (number of doses, dates).
  • Travel History: Especially to areas with current mumps outbreaks.
  • Complications: Symptoms suggestive of orchitis (testicular pain/swelling), oophoritis (lower abdominal pain), meningitis (stiff neck, severe headache, photophobia), or pancreatitis (epigastric pain, nausea, vomiting).
  • Concurrent Illnesses: Rule out other causes of parotitis (e.g., bacterial parotitis, salivary gland stones, HIV-associated parotitis, drug-induced parotitis).
• Red Flags:
  • Signs of Meningitis/Encephalitis: Severe headache, nuchal rigidity, altered mental status, seizures, focal neurological deficits.
  • Severe Testicular Pain/Swelling: To rule out testicular torsion (though less common in mumps, always consider this surgical emergency).
  • Severe Abdominal Pain with Vomiting: Suggestive of pancreatitis.
  • Difficulty Breathing or Swallowing: May indicate extensive swelling or airway compromise (rare).

Laboratory Tests

• First-Line (for suspected acute infection):
  • Reverse Transcription-Polymerase Chain Reaction (RT-PCR):
    • Specimen of choice for acute diagnosis: Buccal (oral) swab or saliva (collected within 3 days of parotitis onset, up to 9 days).
    • CSF: For suspected mumps meningitis/encephalitis (collected within 10 days of CNS symptom onset).
    • Urine: Can be used for detection, especially in later stages of illness (up to 2 weeks after onset).
    • Sensitivity/Specificity: High, considered the most reliable method for confirming acute infection.
• Confirmatory (for acute infection and serological evidence):
  • Mumps IgM Antibodies: Detectable 2-3 days after symptom onset and persist for several weeks to months. A positive IgM typically indicates recent infection. False positives can occur.
  • Mumps IgG Antibodies (paired acute and convalescent): A four-fold or greater rise in IgG antibody titer between acute-phase (collected within 7 days of onset) and convalescent-phase (collected 10-21 days later) serum samples confirms acute infection. Single positive IgG indicates past infection or vaccination immunity.
• Monitoring:
  • Complete Blood Count (CBC): May show leukopenia with relative lymphocytosis. Not diagnostic.
  • Amylase/Lipase: Elevated in parotitis and significantly elevated in pancreatitis.
  • CSF Analysis (for suspected meningitis/encephalitis):
    • Typical Findings: Lymphocytic pleocytosis (cell count typically <500 cells/µL, though can be higher), normal or mildly elevated protein, normal glucose.
    • RT-PCR on CSF: Crucial for definitive diagnosis of mumps meningitis/encephalitis.

Imaging

• Recommended:
  • No routine imaging is recommended for uncomplicated mumps parotitis. Diagnosis is clinical, supported by lab tests.
• Advanced (when needed for complications or atypical presentations):
  • Ultrasound of Parotid Glands: Can confirm parotid inflammation and help differentiate mumps from other causes of parotitis (e.g., bacterial sialadenitis, salivary gland stones, Sjogren's syndrome, masses). Rarely needed for typical mumps.
  • Testicular Ultrasound (Doppler): Essential for evaluating acute scrotal pain and swelling to differentiate mumps orchitis from testicular torsion (which requires emergent surgery) or epididymitis. Mumps orchitis will show diffuse enlargement and hyperemia of the testicle(s), while torsion shows decreased or absent blood flow.
  • CT/MRI of Brain: For suspected encephalitis or other severe CNS complications, to rule out other pathologies (e.g., abscess, tumor, stroke) or to characterize the extent of inflammation.

Management

Acute Management

• Immediate (Supportive Care):
  • Isolation: Patients with mumps should be isolated from others for 5 days after the onset of parotitis to prevent transmission. In healthcare settings, implement droplet precautions.
  • Hydration: Encourage oral fluid intake, especially soft, non-acidic foods and liquids, as chewing and swallowing can be painful.
  • Analgesia and Antipyretics:
    • Acetaminophen (Paracetamol): 500-1000 mg orally every 4-6 hours as needed (max 4g/day for adults).
    • NSAIDs (e.g., Ibuprofen): 400-600 mg orally every 6-8 hours as needed.
• Stabilization:
  • Rest: Adequate rest is important for recovery.
  • Local Comfort Measures: Cold or warm compresses to the swollen parotid glands may provide relief.
  • Scrotal Support (for orchitis): Elevating the scrotum (e.g., with a towel roll or supportive underwear) and applying cold packs can help reduce pain and swelling in orchitis.
• Emergency:
  • Severe Complications: Management of mumps complications (e.g., severe encephalitis, severe pancreatitis, hydrocephalus) requires hospitalization and specialized supportive care. There is no specific antiviral treatment for mumps.
  • Testicular Torsion Exclusion: In cases of acute orchitis, promptly rule out testicular torsion, which is a surgical emergency.

Chronic Management

• Mumps is an acute, self-limiting viral illness. There is no "chronic mumps" disease.
• Pharmacological: No specific chronic pharmacological management for the mumps virus itself.
• Non-pharmacological: Focus on managing long-term sequelae:
  • Hearing Loss: Patients with confirmed or suspected mumps should have hearing evaluated, especially in children. Referral to an audiologist and otolaryngologist for assessment and management (e.g., hearing aids) if sensorineural hearing loss occurs.
  • Testicular Atrophy/Infertility: Unilateral orchitis rarely causes infertility. Bilateral orchitis can lead to testicular atrophy and, in rare cases, sterility, but this is uncommon. Follow-up with urology may be considered for severe cases or fertility concerns.
• Monitoring:
  • Post-recovery: No routine long-term monitoring for uncomplicated mumps.
  • For complications: Monitor for resolution of symptoms and long-term sequelae, e.g., audiometry for hearing, fertility assessment if bilateral orchitis.

Treatment Algorithms

• First-Line:
  1. Symptomatic and Supportive Care:
     • Rest, hydration.
     • Analgesics/Antipyretics (Acetaminophen, NSAIDs).
     • Local comfort measures (e.g., compresses for parotitis, scrotal support for orchitis).
  2. Isolation: 5 days from onset of parotitis.
• Second-Line: No second-line antiviral treatment. Management shifts to symptom control and addressing specific complications.
  • For mumps orchitis with severe pain, corticosteroids are sometimes used, but evidence for their efficacy in preventing testicular atrophy is limited and controversial. Dosing for prednisone could be 40-60 mg/day tapering over 7-10 days, but this is not standard practice.
  • For severe pancreatitis, standard medical management for pancreatitis (NPO, IV fluids, pain control).
  • For mumps meningitis/encephalitis, supportive care, neurologic monitoring, and management of increased intracranial pressure or seizures if present.
• Refractory Cases: Mumps itself generally resolves. Refractory cases refer to severe or persistent complications that require specialized management as outlined above.

Complications

• Common:
  • Orchitis: Most common complication in post-pubertal males (20-50%).
  • Aseptic Meningitis: Up to 15% of symptomatic cases, and CSF pleocytosis in up to 50%, often subclinical.
• Serious:
  • Encephalitis: Rare but potentially severe, leading to long-term neurological sequelae or death.
  • Pancreatitis: Usually mild, but can rarely be severe or lead to diabetes mellitus.
  • Sensorineural Hearing Loss: Rare (1 in 20,000 cases), but often permanent and unilateral.
• Long-term:
  • Testicular Atrophy: In 30-50% of affected testes after mumps orchitis, rarely leading to infertility, especially if bilateral.
  • Diabetes Mellitus: Very rare, potential long-term consequence of severe pancreatitis.
  • Neurological Deficits: Rare, following severe encephalitis.

Prognosis

• Factors:
  • Age: Complications (orchitis, pancreatitis, hearing loss) are more common and severe in adults, especially post-pubertal males. Children generally have a milder course.
  • Vaccination Status: Vaccinated individuals who contract mumps typically experience milder disease with fewer complications.
  • Severity of Initial Illness: Predicts risk of complications.
• Survival: Mumps is rarely fatal. Mortality rates are extremely low, generally less than 1 death per 10,000 cases, usually due to severe encephalitis.
• Quality of Life: Most individuals recover completely without long-term sequelae. However, complications like permanent hearing loss or, rarely, infertility can significantly impact quality of life.

Prevention

• Primary (Preventing initial occurrence):
  • Vaccination: The primary preventive strategy. The MMR (Measles, Mumps, Rubella) vaccine is a live attenuated vaccine.
    • Schedule (CDC/ACIP recommendations):
      • First dose: Routinely administered at 12-15 months of age.
      • Second dose: Routinely administered at 4-6 years of age (before school entry).
    • Catch-up Vaccination: For individuals without evidence of immunity (documentation of 2 MMR doses, laboratory evidence of immunity, or birth before 1957):
      • Healthcare personnel, international travelers, college students: 2 doses of MMR, separated by at least 28 days.
      • Other adults: Generally 1 dose.
    • During Outbreaks: A third dose of MMR vaccine may be recommended for individuals at increased risk (e.g., college students in outbreak settings) who have already received two doses. This aims to boost waning immunity and improve protection, although evidence for its effectiveness is still accumulating.
  • Hygiene: Hand hygiene, covering coughs and sneezes can help reduce transmission.
• Secondary (Early detection and intervention):
  • Rapid Diagnosis and Isolation: Prompt identification of mumps cases and isolation of infected individuals for 5 days from parotitis onset to prevent further spread, especially in congregate settings.
  • Contact Tracing: Identify and assess contacts for vaccination status and potential exposure.
  • Post-exposure Prophylaxis (PEP): MMR vaccine given after exposure to mumps is not effective in preventing mumps, as the incubation period of the vaccine is similar to that of the natural disease. Immune globulin is not recommended for post-exposure prophylaxis of mumps.
• Tertiary (Preventing complications):
  • Timely supportive care and monitoring for complications (as described in management).
  • Early recognition and management of severe complications (e.g., orchitis, meningitis, pancreatitis).

Special Populations

• Pediatric:
  • Mumps is typically a childhood disease.
  • Children generally experience milder symptoms and have lower rates of complications like orchitis and pancreatitis compared to adults.
  • Vaccination is crucial in this age group as per the routine schedule.
• Geriatric:
  • Mumps is less common in older adults due to widespread immunity from natural infection or vaccination.
  • If infection occurs, older adults may be at increased risk for severe symptoms and complications.
• Pregnancy:
  • Mumps infection during pregnancy is generally mild in the mother.
  • There is an increased risk of spontaneous abortion, particularly during the first trimester (up to 25% risk).
  • There is no clear evidence of mumps virus causing congenital malformations (teratogenicity) or congenital mumps syndrome.
  • MMR vaccine is contraindicated during pregnancy due to the live attenuated viral components. Pregnant women without evidence of immunity should be vaccinated postpartum.
• Comorbidities:
  • Immunocompromised Individuals: Individuals with compromised immune systems (e.g., HIV, transplant recipients, chemotherapy) may have an altered response to the mumps vaccine or natural infection. Live vaccines like MMR are generally contraindicated in severely immunocompromised individuals. If infected, they may experience more severe or prolonged illness and should be managed in consultation with infectious disease specialists.

Clinical Pearls

• Diagnostic:
  • Always consider mumps in patients with parotitis, especially those with incomplete vaccination history or in outbreak settings, even if vaccinated.
  • Remember that mumps can present without parotitis (e.g., isolated orchitis or meningitis), making diagnosis challenging. RT-PCR is crucial in these cases.
  • A positive IgM in the context of parotitis strongly suggests mumps, but false positives can occur (e.g., due to rheumatoid factor, recent MMR vaccination). RT-PCR on buccal swabs is often preferred for definitive diagnosis, especially during outbreaks.
  • In a male with acute testicular pain, always rule out testicular torsion, which is a surgical emergency, before attributing it to mumps orchitis.
• Treatment:
  • Treatment is entirely supportive. There is no specific antiviral.
  • Focus on pain relief, hydration, and managing symptoms of complications.
  • Educate patients on the importance of isolation to prevent spread.
• Pitfalls:
  • Misdiagnosis: Confusing mumps parotitis with bacterial sialadenitis (which typically presents with purulent discharge from Stensen's duct, higher fever, and more severe local symptoms) or other causes of salivary gland swelling.
  • Underestimating Complications: Assuming all mumps cases are benign. While true for most, vigilance for rare but serious complications (encephalitis, severe pancreatitis, hearing loss) is critical.
  • Vaccine Hesitancy: Not addressing patient or parent concerns about vaccine safety, leading to incomplete vaccination and increased risk of infection.
  • Incomplete Vaccination: Many outbreak cases occur in individuals who only received one MMR dose. Emphasize the importance of two doses for optimal protection.

Recent Updates

• Guidelines:
  • CDC/ACIP Recommendations: Continually emphasize two-dose MMR vaccination. During recent outbreaks, a third dose of MMR vaccine has been considered for specific populations at high risk (e.g., college students) who have already received two prior doses, aiming to boost waning immunity. This is a targeted recommendation for outbreak control, not a universal change to the standard schedule.
• Evidence:
  • Recent studies have further highlighted the phenomenon of "waning immunity" following MMR vaccination, particularly after one dose, contributing to outbreaks even in highly vaccinated populations.
  • Research continues into the potential for new mumps vaccine formulations or booster strategies to enhance long-term protection.
• Controversies:
  • Optimal Vaccination Strategy during Outbreaks: The effectiveness and necessity of a third MMR dose for outbreak control in highly vaccinated populations is an area of ongoing debate and research. While generally supported by public health agencies, its long-term impact on population immunity and outbreak prevention is still being evaluated.
  • Mumps Vaccine Effectiveness: Ongoing discussion about the precise effectiveness of the current MMR vaccine against circulating mumps genotypes, particularly in light of continued outbreaks.

Key References

• Guidelines:
  • Centers for Disease Control and Prevention (CDC): Mumps (Mumps Virus Infection) information for healthcare professionals and prevention guidelines (ACIP recommendations). Available at cdc.gov/mumps.
  • Advisory Committee on Immunization Practices (ACIP): Mumps vaccine recommendations, part of the comprehensive ACIP guidelines on immunization.
  • World Health Organization (WHO): Mumps fact sheets and immunization recommendations. Available at who.int.
• Studies:
  • Landmark studies on mumps vaccine efficacy and effectiveness after introduction.
  • Recent epidemiological studies analyzing mumps outbreaks in vaccinated populations (e.g., college outbreaks), often published in journals like New England Journal of Medicine, JAMA, MMWR, Clinical Infectious Diseases.
• Reviews:
  • Comprehensive reviews on mumps pathophysiology, diagnosis, and management can be found in major infectious disease textbooks (e.g., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases) and reputable medical databases (e.g., UpToDate, PubMed reviews).