Mumps
Mumps is an acute contagious RNA paramyxovirus disease
seen mainly in childhood,
involving chiefly the salivary glands,
most often the parotids,
but
other tissues may be affected,
including the meninges
and in postpubertal males the testes (1).
Infection occurs in susceptible children (2)
but it is rare in infancy, presumably due to the persistence of maternal antibodies.
Mumps is transmitted via direct contact with infected droplet nuclei
or fomites contaminated with infected saliva and possibly urine.
Purely a disease affecting humans (no animal reservoirs) (1)
The virus has a low infectivity rate
Some cases are subclinical
Incubation period is about 18 days (may vary between 14 to 25 days) (3)
Patients are infectious from 2 days before the onset of symptoms to 9 days afterwards
(even asymptomatic patients may be infectious) (1)
Intrauterine infection may develop as a result of infection early in pregnancy.
The peak incidence of mumps in temperate climates is noticed in winter & spring.
In tropical climates cases can occur regularly right through the year (1).
Mumps is a notifiable disease in UK (since October 1988) (3).
Reference:
(1) Senanayake S.N. Mumps: a resurgent disease with protean manifestations. MJA 2008; 189 (8): 456-459
(2) Gupta R.K et al. Mumps and the UK epidemic 2005. BMJ. 2005;330(7500):1132–1135
(3) Department of health 2006. Immunisation against infectious disease - "The Green Book". Chapter 23 – mumps
Clinical features
In approximately a third of individuals exposed to infection there is no apparent clinical illness despite positive serology.
(asymptomatic infection is common in children) (1).
Clinical symptoms are much more severe in adults & adolescents than in children (2).
There is an incubation period of 14 to 25 days.
A prodrome of non specific symptoms like fever, malaise myalgias, and anorexia
may be followed by enlargement of one or both parotid glands,
developing over a period of 1 to 3 days.
Older children may complain of tenderness over the parotid gland and occasionally ear ache
before actual swelling becomes evident (2)
The parotid enlargement may displace the ear lobe upwards
and obliterate the space between the mandible and the sternomastoid muscle
the swelling may even impede chewing or pronunciation of words (3)
Other salivary glands,
namely the submandibular and sublingual salivary glands,
may also become inflamed.
Upon looking in the mouth, the tonsils may be displaced towards the midline.
The swellings settle in 7 to 10 days and there is no specific treatment.
Salivary gland swelling is not apparent in about 30% of cases.
Other causes of unilateral or bilateral parotitis
can be divided into infectious
& non infectious causes
Infectious causes - include other viral agents like parainfluenza, coxsackievirus, influenza A, Epstein-Barr virus, adenovirus, and suppurative bacterial infection.
Non infectious causes - include salivary calculi, tumors, sarcoid, and Sjögren’s syndrome, ingestion of starch or thiazides, and iodine sensitivity (2).
Reference
(1) Department of health 2006. Immunisation against infectious disease - "The Green Book". Chapter 23 – mumps
(2) Gupta R.K et al. Mumps and the UK epidemic 2005. BMJ. 2005;330(7500):1132–1135
(3) Senanayake S.N. Mumps: a resurgent disease with protean manifestations. MJA 2008; 189 (8): 456-459
MUMPS: INFECTIVITY PERIOD
3 days before salivary gland swelling to 7 days after.
Investigations
The diagnosis is usually clinical.
1. Antibody titres,
Serum IgM can be detected as early 11 days after exposure
the optimal time for detection is around 7–10 days after the development symptoms (1).
Saliva IgM
The salivary IgM test has
Specificity is high (98%), and its
Sensitivity increases from 75% in the first week after symptoms appear to 100% thereafter. (1).
2. detection of viral RNA by reverse transcriptase-polymerase chain reaction (RT-PCR) techniques
Can use both IgM and RT-PCR tests (if salivary IgM is negative) to detect mumps in saliva
Urine viral culture and RNA detection in urine can be done during the first 2 weeks of illness (2).
3. or viral culture from saliva, urine or CSF is diagnostic.
The excretion of virus persists longer in the urine than in the saliva;
it can be cultured from urine in 70% of cases.
CSF
CSF shows
lymphocytosis,
an elevated protein
and a normal opening pressure,
serum glucose ratio (< 50%) in up to a quarter of cases
mumps RNA (up to 96% of cases)
and specific antibody tests – IgG (in half of cases )
and IgM (in one third of cases)
can be used to detect mumps in CSF (1).
Complications
Possible complications of mumps include:
meningo-encephalitis
most frequent complication of infection in children.
symptomatic viral meningeal irritation occurs in about 15% of cases of mumps infection
may precede or follow parotitis or may even occur without salivary gland enlargement (1)
encephalitis is much less common, occuring about once in a thousand patients (2,3)
bilateral or unilateral sensorineural deafness
occurs with frequency varying from one in 3400 cases to one in 20,000 (1)orchitis
- in up to 25% of adult male patients (1),unilaterally in 80% of these;
the predominance of unilateral orchitis means that infertility is relatively rare
but 13% of patients with bilateral disease may have hypofertility (2)
oophoritis - occurs in about 5% of female patients (1)
pancreatitis - this is a rare complication of childhood infection. It may be seen in up to 7% of infections (1)
other possible complications include (1) (2):
- episcleritis
- uveitis
- optic neuritis
- arthritis
- nephritis
- thyroiditis
- myocarditis
- idiopathic thrombocytopenic purpura
- increased risk of a miscarriage in the 1st 12 weeks of pregnancy (1)
Treatment
There is no specific treatment for mumps
and management is, in general, supportive and based in the primary care setting.
Management of orchitis
Testicular atrophy and, irreversible infertility, may develop in 40-70% of cases of severe bilateral mumps orchitis
Consult urological advice - especially if bilateral orchitis
ice packs to the scrotum can help relieve the pain associated with orchitis
scrotal support (e.g. an adhesive bridge)
and nonsteroidal anti-inflammatory agents may provide symptomatic benefit (1)
corticosteroids may decrease the pain and oedema -
however corticosteroid use has been found to cause testosterone levels to decrease
and FSH and LH levels to increase (2)
Early incision of the tunica vaginalis and drainage of the hydrocoele
may avoid the development of testicular atrophy in most patients
However infertility may still occur in 12% to 30% (3)
There is evidence that systematic treatment with interferon-alpha-2B
does reduce the incidence of testicular atrophy
however this treatment modality
does not seem completely effective in preventing testicular atrophy after mumps orchitis (3)
Other significant complications
such as meningitis, encephalitis, nephritis and pancreatitis
require specialist review.
Effective post exposure prophylaxis for mumps is not available.
In individuals exposed to mumps virus,
vaccination will not prevent progression to infection (4).
