Synonym: epidemic parotitis

• It can infect any organ but usually affects the salivary glands and, less often, the pancreas, testis, ovary, brain, mammary gland, liver, kidney, joints and heart.²
• The incubation period is between 14 and 21 days.³ Of those who are infected, 30-40% have subclinical disease.⁴
• The virus is highly infectious with transmission by droplets spread in saliva via close personal contact.
• Before vaccination, the peak incidence was in late winter or early spring in 3-year cycles.^3,5
• Infected persons excrete the virus for 6 days before symptoms appear and for up to 5 days afterwards.⁶

Initially, the virus infects the upper respiratory tract and then spreads to draining lymph nodes. This produces viraemia and spreads to many organs.⁴ The ducts in both the salivary glands and seminiferous tubules of the testes are blocked by lymphocytic infiltration and destruction of periductal cells.⁷ Lymphatics surrounding the parotid glands become obstructed, producing a gel-like oedema. The virus may also invade the nervous system.⁸

Since the introduction of the measles, mumps and rubella (MMR) vaccine, mumps has become a notifiable disease to help monitor the effectiveness of the vaccine. There is a surveillance form for confirmed cases.⁹

Epidemiology¹⁰

Either clinical or subclinical infection used to be very common in childhood but with the introduction of the MMR vaccine in 1987, numbers dwindled considerably. However, Health Protection Agency (HPA) statistics show that whilst confirmed cases in England and Wales were 94 in 1996, the figure notified in 2005 was 43,378. These statistics suggest that the disease has moved from being almost completely eliminated in the 1990s to making a very significant resurgence. This is thought to be due to parental concern about the link between MMR vaccine and autism, despite Government campaigns to reassure the public that no such link exists.¹¹ The figure in 2008 was down to 2,403, which may be due to subsequent promotional campaigns by the Department of Health reassuring the public about the safety of the vaccine.

Presentation⁸

Typically, there is pain at or near the angle of the jaw and fever may be as high as 39.5°C without rigors in small children. Swelling causes distortion of the face and neck with skin over the gland hot and flushed but there is no rash. With severe swelling, the mouth cannot be opened and is dry because the salivary ducts are blocked. Discomfort lasts for 3 or 4 days but may be prolonged when one side clears and the other side swells. Usually just the parotid glands are involved but rarely, the submaxillary and sublingual salivary glands are affected and this may be difficult to distinguish from inflammation of lymph nodes in that area.

Orchitis⁷

Orchitis may occur 4 or 5 days after the start of parotitis but it often appears without it. This can sometimes lead to the diagnosis being missed.¹² Orchitis presents with chills, sweats, headache and backache with swinging temperature and severe local testicular pain and tenderness. The scrotum is swollen and oedematous so that the testes are impalpable. The problem is usually unilateral but may be bilateral. Sometimes, as one side resolves, orchitis strikes the other side 3 or 4 days later.

This complication is unusual before puberty but develops in around 40% of cases of mumps in adolescent males. In a third of cases, there is some degree of atrophy of the testicle. There has not been much concern about mumps as a cause of male infertility in the past, although a recent increase in the incidence of orchitis raises the possibility of it becoming a signficant factor.

Meningitis and encephalitis

The great fear of mumps is usually orchitis in adolescent males but meningo-encephalitis is much more serious and affects both sexes. It usually occurs without parotitis. Meningitis is usually mild and self-limiting although occasionally there may be transient paralysis of limbs. Cerebrospinal fluid (CSF) protein and lymphocytes are increased. With encephalitis, the patient is confused and may lapse into coma and remain so for days, weeks or months. The fatality rate is 2%.¹ A recent outbreak has re-emphasised its importance in the list of differential diagnoses.¹³

Mumps arthritis

Arthropathy is an unusual but significant complication.¹⁴ It affects predominantly young men. There is involvement of large and small joints before or after parotitis or in its absence. Fever, leukocytosis and elevated erythrocyte sedimentation rate (ESR) sometimes accompany a protracted course. The possibility of mumps arthritis should be considered in patients with acute-onset, obscure, or febrile seronegative arthritis.¹⁵

Differential diagnosis^8,16

• By far the most common presentation of mumps is with parotitis. High temperature, pain and swelling in the neck are common with many other infections including tonsillitis, viral pharyngitis and infectious mononucleosis. The tender, swollen parotid glands emerge from behind the ramus of the mandible and can be distinguished from lymph nodes in that on palpation it is not possible to feel in front of the parotid glands.
• HIV infection should be considered.
• Patients with a stone in the parotid duct tend to be older but a much more important feature is that the gland swells and becomes more painful on chewing as saliva is produced.
• Mumps must be in the differential diagnosis of viral meningitis and encephalitis.
• Mumps orchitis typically strikes the same age as torsion of the testis. In torsion, the testis is usually still palpable with the long axis horizontal. There is no pyrexia and there are no other aches and pains.

Investigations

• In most cases the diagnosis can be made clinically without recourse to investigations.⁸
• In patients with meningitis but without parotitis, the diagnosis may be confirmed by detection of mumps-specific antibodies in the serum. Salivary immunoglobulin M (IgM) against mumps may be detected. Confirmation of clinical diagnosis by oral fluid testing is offered by the HPA.³ Specific antibody levels may not rise for several days and so, if the result is negative but clinical suspicion is strong, it is worth repeating the test.
• A rapid real-time test using mumps RNA present in serum has been developed.¹⁷ This is particularly useful if salivary IgM is negative but clinical suspicion is high.
• High-resolution and colour Doppler ultrasound has been used to differentiate mumps orchitis from torsion.¹⁸

Management^8,16

Nondrug

Keep up fluids and keep the mouth moist.

Drugs

• There is no specific treatment but drugs such as paracetamol and ibuprofen may give symptomatic relief.
• For mumps orchitis, treatment is initially conservative with bedrest, fluids,and scrotal elevation. Analgesia may be required and opiates may be necessary for one or two days if discomfort is severe. Surgical incision into the tunica albuginea to reduce testicular pressure has largely been abandoned. Likewise, oral steroids and adrenocorticotropic hormones used in the past to reduce inflammation and swelling are now avoided because of evidence that they can induce testicular atrophy. Some authorities recommend broad-spectrum antibiotics to prevent secondary infection.⁷

Complications^1,8,16

Although rarely fatal, complications of mumps can include :

• Aseptic meningitis (in 15% of cases, usually without further complications).
• Orchitis, usually unilateral.
• Oophoritis, which may cause pain in 5% of postpubertal females; sterility seldom occurs.
• Profound deafness (in one ear in 1 in 15,000 of cases, which is usually transient).
• Encephalitis (rare - rates reported range from 0.02 to 0.3% of cases).
• Pancreatitis, neuritis, arthritis, nephritis, thyroiditis and pericarditis.
• Transient and mild mastitis (uncommon, can occur in either sex).¹⁹
• Mild upper abdominal pain (may be related to the pancreas in 50% of cases).
• Mumps in the first trimester of pregnancy may increase the rate of spontaneous abortion but virus is not teratogenic.

Prognosis^8,16

Most cases see full recovery. The mortality rate from central nervous system involvement is about 1%. Deaths from other causes are rare, more than half the cases arising in men over the age of 19.

Prevention

MMR vaccine is given in the national immunisation programme at 12 to15 months and at 4 years of age. There is no upper age limit and, where required, two doses can be given separated by at least a one-month interval. The second dose is especially important for the mumps' component as, of the three components, this is the one that is least adequately covered by a single dose.²⁰

Evidence of the safety of the MMR vaccine is overwhelming but concordance is best obtained by giving parents an opportunity to voice their fears and by offering them factual information. Links to various resources can be found on the NHS immunisation information website. Some private clinics offer single vaccines; however, the Department of Health recommends that parents be discouraged from using them. One study identified four cases of anaphylaxis following single component measles or rubella vaccine and has called for the NHS standards of data reporting to be extended to the private sector.

Normal hygiene measures to prevent droplet infection should be instituted in the household of a patient who has mumps. Children should be excluded from school for nine days.⁸

Document references

1. Galazka AM, Robertson SE, Kraigher A; Mumps and mumps vaccine: a global review.; Bull World Health Organ. 1999;77(1):3-14. [abstract]
2. Hviid A, Rubin S, Muhlemann K; Mumps. Lancet. 2008 Mar 15;371(9616):932-44. [abstract]
3. Mumps, Health Protection Agency
4. Hunt M; Measles and Mumps Viruses Microbiology, 3rd Ed., Chapter 55m 2008
5. Anderson RM, Grenfell BT, May RM; Oscillatory fluctuations in the incidence of infectious disease and the impact of vaccination: time series analysis. J Hyg (Lond). 1984 Dec;93(3):587-608. [abstract]
6. Mumps Virus; Baron S, Medical Microbiology, 1996
7. Lane TM, Hines J; The management of mumps orchitis. BJU Int. 2006 Jan;97(1):1-2.
8. Demirci CS et al; Mumps, eMedicine, Nov 2009
9. Surveillance form for measles, mumps and rubella, Health Protection Agency
10. Confirmed Cases of Mumps by Age and Region 1996-2006, Health Protection Agency. Last reviewed 2008.
11. MMR The facts, Dept of Health, March 2003
12. Emerson C, Dinsmore WW, Quah SP; Are we missing mumps epididymo-orchitis? Int J STD AIDS. 2007 May;18(5):341-2. [abstract]
13. Cooper AD, Wijdicks EF, Sampathkumar P; Mumps encephalitis: return with a vengeance. Rev Neurol Dis. 2007 Spring;4(2):100-2. [abstract]
14. Gordon SC, Lauter CB; Mumps arthritis: unusual presentation as adult Still's disease. Ann Intern Med. 1982 Jul;97(1):45-7. [abstract]
15. Gordon SC, Lauter CB; Mumps arthritis: a review of the literature.; Rev Infect Dis. 1984 May-Jun;6(3):338-44. [abstract]
16. Gupta RK, Best J, MacMahon E; Mumps and the UK epidemic 2005. BMJ. 2005 May 14;330(7500):1132-5.
17. Boddicker JD, Rota PA, Kreman T, et al; Real-time reverse transcription-PCR assay for detection of mumps virus RNA in clinical specimens. J Clin Microbiol. 2007 Sep;45(9):2902-8. Epub 2007 Jul 25. [abstract]
18. Vijayaraghavan SB; Sonographic differential diagnosis of acute scrotum: real-time whirlpool sign, a key sign of torsion. J Ultrasound Med. 2006 May;25(5):563-74. [abstract]
19. Quintanan E; Pediatrics, Mumps, eMedicine, Jul 2009
20. Erlewyn-Lajeunesse M, Manek R, Lingam R, et al; Anaphylaxis following single component measles and rubella immunisation. Arch Dis Child. 2008 Nov;93(11):974-5. [abstract]

Internet and further reading

• MMR vaccine and autism, Bandolier (2005)

Acknowledgements