Multisystem infection caused by a paramyxovirus

Aetiology

Risk factors

• Vaccination status
  • Its prevalence has decreased considerably due to the introduction of the MMR vaccine in the 1980s, but there have been a number of outbreaks in unvaccinated/partially vaccinated groups
  • Most of these were in universities, and half the cases were men over the age of 19 years
• International travel
• Exposure to a known case or outbreak

Clinical features

• Parotitis: the parotid glands are almost always affected, usually bilaterally (though can be unilateral)
  • Swelling can be severe enough to prevent the mouth from being opened and usually lasts 3-4 days
  • Prior to parotitis, there may be flu-like symptoms such as headache, malaise and myalgia
• Orchitis: epididymo-orchitis is the second most common extra-salivary symptom of mumps, which presents as severely painful swelling of one or both testicles and/or backache
  • It usually develops 4-5 days after onset of parotitis
  • 7% of post-pubertal females get oophoritis, with rare cases of infertility and premature menopause as a result
• Aseptic meningitis: a relatively common complication in 4-25% of cases
  • Usually mild and self-limiting
• Encephalitis: rare complication presenting as headache, vomiting, seizures, unconsciousness
• Deafness: a rare cause of acute or insidious sensorineural hearing loss (usually unilateral) in children
• Other: pancreatitis, nephritis, arthritis, thyroiditis, pericarditis

Investigations

• Usually clinical - need to notify the local Health Protection Unit whenever it is considered
• Need laboratory confirmation using oral fluid sample (salivary IgM)
• Can use serum serology (IgM or IgG)High-resolution ultrasound can differentiate orchitis from torsion

Management

• Supportive, symptomatic treatment only: fluids, analgesia, antipyretics
• The disease is usually benign and self-limiting