SN3 SHORT NOTE 5M ★ High-yield

Describe mumps with its clinical features, complications and prevention.

Microbiology · 2nd Professional — Para-Clinical

The Virus and Clinical Features

A paramyxovirus — enveloped, helical, single-stranded negative-sense RNA, with one serotype, so immunity after infection or vaccination is lifelong
Spread by respiratory droplets and saliva; incubation 16 to 18 days; infectious from about 2 days before to 5 days after the swelling appears
Up to a third of infections are subclinical but still transmissible
Parotitis is the characteristic feature — painful swelling of one and then usually both parotid glands, obliterating the angle of the jaw and lifting the ear lobe outward and upward, with pain on chewing and on taking sour food. The opening of Stensen duct is red and swollen
Distinguishing parotid from lymph node swelling — parotid swelling obscures the angle of the mandible, whereas cervical lymphadenopathy does not; this is the practical bedside discriminator

Complications

Complication	Features
Orchitis	In about 20 to 30% of post-pubertal males, usually unilateral and appearing as the parotitis settles; painful swelling with fever. Testicular atrophy may follow, but sterility is rare because involvement is usually unilateral — a point worth stating clearly, since patients and families fear otherwise
Meningitis and encephalitis	Aseptic meningitis is common and usually benign; mumps was a leading cause of viral meningitis before vaccination. It may occur without parotitis
Pancreatitis	Abdominal pain and vomiting; serum amylase is raised, but amylase also rises with parotitis alone, so lipase is needed to confirm
Deafness	Unilateral sensorineural deafness — historically a leading cause of acquired childhood deafness; usually permanent
Oophoritis	In about 5% of post-pubertal women; does not impair fertility
Others	Myocarditis, arthritis, thyroiditis, nephritis; abortion if infection occurs in the first trimester, but NO congenital malformation

CLINICAL PEARL

Mumps orchitis is painful and frightening but rarely causes sterility. It affects perhaps a quarter of post-pubertal men and is usually unilateral, so even where atrophy follows, the other testis preserves fertility. Reassuring patients and families explicitly is part of the management, because the belief that mumps causes infertility is widespread and causes considerable and unnecessary distress.

Diagnosis, Treatment and Prevention

The diagnosis is usually clinical where parotitis is present; confirmed by mumps IgM, a fourfold rise in IgG, or RT-PCR on saliva, a buccal swab, urine or cerebrospinal fluid, which is preferred in vaccinated populations where the IgM response may be blunted
Serum amylase is raised in parotitis alone, so it cannot distinguish parotitis from pancreatitis; lipase is needed
Differential diagnosis of parotid swelling — suppurative parotitis (unilateral, with pus from the duct, usually in a dehydrated or elderly patient), calculus, tumour, Sjögren syndrome, HIV-associated parotid enlargement, and drugs
Treatment is supportive — analgesia, fluids, soft food and avoidance of sour or acidic items; scrotal support and anti-inflammatory drugs for orchitis. There is no specific antiviral
Prevention — the live attenuated mumps vaccine, given as MMR; two doses are needed for reliable protection, and waning immunity with outbreaks in vaccinated young adults has been documented. Mumps vaccine is not part of India's Universal Immunisation Programme, though MMR is widely used in the private sector

Applied Aspects

Reassure about fertility in mumps orchitis, since the fear is far greater than the actual risk
Consider mumps in aseptic meningitis even without parotitis, since central nervous system involvement may occur alone
Distinguish parotitis from cervical lymphadenopathy by whether the angle of the jaw is obscured, and from suppurative parotitis by expressing the duct
Isolate for 5 days after the swelling appears, and exclude from school and work for that period
Mumps remains common in India because the vaccine is not in the national programme, and outbreaks in schools and hostels are regularly reported
Take a vaccination history in any parotid swelling; in a vaccinated patient the illness may be atypical and the IgM response unreliable, so PCR is preferred

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