Mumps

Mumps is a multisystem infection caused by paramyxovirus that is characterised by bilateral parotitis (swelling of the parotid gland).

Due to the introduction of the MMR vaccine in the 1980s, there have been few outbreaks in unvaccinated patients.

Pathophysiology

It is spread by respiratory droplets, direct contact or by fomites. It incubates for 14-18 days and is most contagious 1-2 days before symptoms occur. The main site of viral replication is the upper respiratory tract, but the virus rapidly spreads to lymphoid tissue and blood (viraemia). It has a particular affinity for glandular epithelium and it most often occurs in the parotid gland → local oedema, inflammation and painful swelling.

1-2% of cases are believed to be re-infection, but life-long immunity normally develops.

⚠️ Risk factors

• Vaccination status
• International travel
• Exposure to case

High fever and organ involvement is typical:

• Fever
• Headache
• Malaise and myalgia

Organ involvement

• Parotitis - almost always affects the parotid glands bilaterally, but is unilateral initially. The swelling can be severe enough to prevent the mouth from opening and may last 3-4 days. It is usually preceded by a viral prodrome. Patients complain about earache and pain when eating.
• Orchitis - this is the second most common extra-salivary symptoms. It may present as painful swelling of one or both testcles ± backache.
• Oophoritis occurs in 7% of post-pubertal females → infertility and premature menopause.
• Aseptic meningitis - in 4-25% of cases. It is mild and self-limiting.
• Encephalitis - presents with headache, vomiting, seizures and unconsciousness.
• Deafness - unilateral sensorineural hearing loss (mainly in children) but is transient.
• Pancreatitis
• Myocarditis