Complications are rare but include deafness and a wide range of inflammatory conditions, of which inflammation of the testes, breasts, ovaries, pancreas, meninges, and brain are the most common.
In places where mumps is less common, however, laboratory diagnosis using antibody testing, viral cultures, or real-time reverse transcription polymerase chain reaction may be needed.
[11][12] In modern times, the disease was first described scientifically in 1790 by British physician Robert Hamilton in Transactions of the Royal Society of Edinburgh.
[6] Similar outbreaks in densely crowded environments have frequently occurred in many other countries, including the U.S., the Netherlands, Sweden, and Belgium.
The prodromal phase typically has non-specific, mild symptoms such as a low-grade fever, headache, malaise, muscle pain, loss of appetite, and sore throat.
During the established acute phase, orchitis, meningitis, and encephalitis may occur, and these conditions are responsible for the bulk of mumps morbidity.
[28][10] Other rare complications of infection include: paralysis, seizures, cranial nerve palsies, cerebellar ataxia, transverse myelitis, ascending polyradiculitis, a polio-like disease, arthropathy, autoimmune hemolytic anemia,[11] idiopathic thrombocytopenic purpura, Guillain–Barré syndrome, post-infectious encephalitis[10] encephalomyelitis,[31] and hemophagocytic syndrome.
In non-human primates, placental transmission has been observed, which is supported by the isolation of MuV from spontaneous and planned aborted fetuses during maternal mumps.
Outbreaks continue to occur in places that have vaccination rates exceeding 90%, however, suggesting that other factors may influence disease transmission.
[15] Many aspects of the pathogenesis of mumps are poorly understood and are inferred from clinical observations and experimental infections in laboratory animals.
[11] Following exposure, the virus infects epithelial cells in the upper respiratory tract that express sialic acid receptors on their surface.
[6] In mumps orchitis, infection leads to: parenchymal edema; congestion, or separation, of the seminiferous tubules; and perivascular infiltration by lymphocytes.
The seminiferous tubules also experience hyalinization, i.e. degeneration into a translucent glass-like substance, which can cause fibrosis and atrophy of the testes.
[6][21] In up to half of cases, MuV infiltrates the central nervous system (CNS), where it may cause meningitis, encephalitis, or hydrocephalus.
[11] In laboratory tests on rodents, MuV appears to enter the CNS first through cerebrospinal fluid (CSF), then spreading to the ventricular system.
Ependymal cells have been isolated from CSF of mumps patients, suggesting that animals and humans share hydrocephalus pathogenesis.
[11] Even though MuV has just one serotype, significant variation in the quantity of genotype-specific sera needed to neutralize different genotypes in vitro has been observed.
[27] A differential diagnosis may be used to compare symptoms to other diseases, including allergic reaction, mastoiditis, measles, and pediatric HIV infection and rubella.
[23] MuV can be isolated from saliva, blood, the nasopharynx, salivary ducts,[26] and seminal fluid within one week of the onset of symptoms,[6] as well as from cell cultures.
[29] In CNS cases, a lumbar puncture may be used to rule out other potential causes,[10] which shows normal opening pressure,[28] more than ten leukocytes per cubic millimeter, elevated lymphocyte count in CSF, polymorphonuclear leukocytes up to 25% of the time, often a mildly elevated protein level, and a slightly reduced CSF glucose to blood glucose ratio up to 30% of the time.
[6] False negatives can occur in people previously infected or vaccinated, in which case a rise of serum IgG may be more useful for diagnosis.
[28] In sialadenitis cases, imaging shows an enlargement of the salivary glands, fat stranding, and thickening of the superficial cervical fascia and platysma muscles, which are situated on the front side of the neck.
If parotitis occurs only on one side, then detection of mumps-specific IgM antibodies, IgG titer, or PCR is required for diagnosis.
[17][16] Mild adverse reactions are relatively common, including fever and rash,[26] but aseptic meningitis also occurs at varying rates.
[40] No effective prophylaxis exists for mumps after one has been exposed to the virus, so vaccination or receiving immunoglobulin after exposure does not prevent progression to illness.
Non-medicinal ways to manage the disease include bed rest, using ice or heat packs on the neck and scrotum, consuming more fluids, eating soft food, and gargling with warm salt water.
[6] Acupuncture has been used fairly widely in China to treat children who have mumps, however, no high-quality trials have been conducted to determine the safety or effectiveness of this treatment approach.
[8] Mumps is usually self-limiting and symptoms resolve spontaneously within two weeks as the immune system clears the virus from the body.
Infertility is linked to severe cases of orchitis affecting both testes followed by testicular atrophy, which may develop up to one year after the initial infection.
Risk factors include age, exposure to a person with mumps, compromised immunity, time of year, travel history, and vaccination status.