Morphology and Biological Properties
The pathogen is roughly spherical with a diameter of about 150 nm. Inside, the nucleocapsid is associated with the matrix protein (M) and contains the nucleoprotein (N). Externally, the virion is enveloped (supercapsid) and embeds:
- Glycoprotein spikes: hemagglutinin-neuraminidase (HN) and fusion protein (F).
- Transmembrane protein: SH (small hydrophobic protein), located among the spikes.
The mumps virus exhibits neuraminidase activity and can agglutinate red blood cells of humans and certain animals (chickens, guinea pigs). It is also characterized by syncytium-forming activity—the ability to induce the fusion of infected cells. The virus is relatively fragile in the external environment.
Epidemiology and Pathogenesis
Mumps is a highly contagious anthroponosis. Humans are the only natural hosts, most frequently children aged 5 to 15 years. Transmission occurs primarily via airborne droplets, and less commonly through fomites contaminated with saliva. A patient becomes infectious at the end of the incubation period (1–2 days before symptom onset) and continues to shed the virus for the first 8 days of illness.
Pathogenesis:
- Entry: The virus enters through the mucous membranes of the upper respiratory tract.
- Primary replication: Occurs in the respiratory epithelium and parotid glands.
- Viremia: The virus enters the bloodstream.
- Target organ involvement: Disseminates to organs rich in glandular tissue (pancreas, thyroid, gonads) and penetrates the meninges.
Clinical Features and Complications
The incubation period lasts from 14 to 20 days. The onset is acute, presenting with fever, headache, and malaise. The hallmark symptom is inflammation of one or both parotid glands (glandula parotis). The illness lasts about a week and is frequently asymptomatic.
The greatest danger stems from complications due to the virus's tropism for other organ systems:
- Orchitis (inflammation of the testes), which can lead to infertility.
- Pancreatitis.
- Meningitis and meningoencephalitis.
Recovery confers lifelong, robust immunity.
Diagnosis and Prevention
Laboratory diagnosis is rarely required due to the distinct clinical presentation. When necessary, saliva, cerebrospinal fluid (CSF), urine, or blood serum is analyzed via virological methods (cell cultures, embryonated eggs) or serological assays (ELISA, complement fixation test [CFT], hemagglutination inhibition [HAI] assay assessing rising antibody titers).
Prevention and Management:
- Active prophylaxis: Routine vaccination with a live attenuated vaccine for children older than 1 year (monovalent or combined measles-mumps-rubella [MMR]).
- Post-exposure prophylaxis and treatment: Administration of specific immunoglobulin.