Mumps overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Lakshmi Gopalakrishnan, M.B.B.S. [2]; Nate Michalak, B.A.
Overview
Mumps is a highly contagious viral disease that leads to painful swelling of the salivary glands and is caused by the mumps virus. Mumps is spread through direct contact with an infected person. Symptoms include fever, glandular swelling, headache, sore throat, and orchitis. Mumps is a self-limiting disease, and the prognosis is generally good, even if other organs are involved.
Historical Perspective
Mumps may have first been described by Hippocrates as a disease causing parotitis and orchitis in the 5th century. Prior to the vaccination program, which started in the United States in 1967, approximately 186,000 cases occurred each year. Implementation of the vaccination program resulted in an approximate 99% decrease in mumps cases. Outbreaks in 2006 and 2009 in the United States resulted in 6,584 and over 3,000 affected people, respectively.
Pathophysiology
Mumps is spread by droplets of saliva or mucus from the mouth, nose, or throat of an infected person, usually when the person coughs or sneezes. Most mumps transmission occurs before the enlargement of the salivary glands and within the 5 days after the swelling begins. Therefore, CDC recommends isolating mumps patients for 5 days after their glands begin to swell.
Causes
Mumps is caused by a paramyxovirus, and transmission of the virus occurs via respiratory secretions such as infected saliva, air droplets or via direct contact with articles that have been contaminated with infected saliva. The incubation period is usually 18 to 21 days. Infected patients remain contagious from approximately 6 days before the onset of symptoms until about 9 days after the onset of symptoms.
Differential Diagnosis
Mumps must be differentiated from other diseases or pathogens that cause upper respiratory infection, prodromal symptoms, swelling of salivary glands (sialadenitis), particularly parotitis. Etiologic agents that cause similar symptoms include: parainfluenza virus, adenovirus, Epstein-Barr virus, coxsackievirus, influenza A, parvovirus B19, human herpesvirus 6. Non-infectious causes include: salivary calculi, tumor, sarcoid, Sjögren’s syndrome, thiazide drug reaction, iodine sensitivity.
Epidemiology and Demographics
Since the initiation of the MMR vaccination program in the United States, the incidence of mumps has declined by 99%. Currently, the number of cases per year ranges from a couple hundred to a couple thousand. Mumps predominantly occurs in school-age children (5-14 years) but outbreaks have occurred in adolescents and adults. There is currently no significant difference in mumps incidence between sexes and races. Mumps is uncommon in the United States and other developed countries. However sporadic outbreaks have occurred, predominantly in environments that involve close contact or high level of social interaction. Only 57% of countries belonging to the World Health Organization use a mumps vaccine. Most of these countries are developing and mumps remains endemic in these regions.
Risk Factors
Risk factors for mumps include: unvaccinated individuals who do not have evidence of immunity, belonging to the age group 2-12 years, international travel, especially to countries without mumps vaccination programs, working or living in close proximity to individual(s) infected with Rubulavirus, and being in states of immunodeficiency.
Natural History, Complications and Prognosis
The average incubation period for Rubulavirus is 16-18 days. Nonspecific prodromal symptoms develop and last 3-4 days. Several days after onset of prodrome, one or both of the parotid salivary glands begin to swell (parotitis). One parotid may swell before the other, and in 25% of patients, only one side swells. Other salivary glands (submandibular and sublingual) under the floor of the mouth also may swell but do so less frequently (10%). Parotitis, lasts at least 2 days, but may persist longer than 10 days. Complications include: orchitis in post-pubertal males, Oophoritis and/or mastitis in post-pubertal females, transient sensorineural hearing loss, Meningitis, Encephalitis, Pancreatitis, and Spontaneous abortion during the first trimester of pregnancy. Mumps is self-limiting and prognosis is excellent for uncomplicated mumps. Adolescents and adults are more likely than children to develop complications but these are rare, and prognosis is still favorable.
Diagnosis
Diagnostic Criteria
Suspected mumps involves parotitis, orchitis, or oophoritis unexplained by another diagnosis OR a positive lab result with no mumps clinical symptoms. Probable mumps involves parotitis or other salivary gland swelling lasting at least 2 days, or orchitis or oophoritis unexplained by another more likely diagnosis, in a person with a positive test for serum anti-mumps immunoglobulin M (IgM) antibody OR person with epidemiologic linkage to another probable or confirmed case or linkage to a group/community defined by public health during an outbreak of mumps. Confirmed mumps involves positive mumps laboratory confirmation for mumps virus with reverse transcription polymerase chain reaction (RT-PCR) or culture in a patient any of the following symptoms: acute parotitis or other salivary gland swelling, lasting at least 2 days, aseptic meningitis, encephalitis, hearing loss, orchitis, oophoritis, mastitis, pancreatitis.
History and Symptoms
The most common symptoms of mumps are a prodrome with low grade fever, myalgia, anorexia, malaise, and headache, followed by painful, bilateral parotitis. Less common symptoms include orchitis in post-pubertal males, oophoritis or mastitis in post-pubertal females, encephalitis, and transient sensorineural hearing loss. Approximately 15-20% of patients may be asymptomatic.
Physical Examination
The characteristic presentation of mumps is tender, swollen parotid glands. Inflammation of submandibular and sublingual salivary glands is palpable in 10% of patients. Sialoadenitits is usually preceded by a low-grade fever. The jawbone is often not palpable and swelling pushes the angle of the ear out and up. 25% of patients present with unilateral swelling. Stensen's duct orifice may be inflamed and erythematous. Lymph node swelling can be differentiated by the well-defined borders of the lymph nodes, location behind the angle of the jawbone, and lack of the ear protrusion or obscuring of the jaw angle.
Laboratory Findings
Laboratory findings for the mumps virus can be useful, and may include virus isolation from swabs of affected salivary ducts, urine, or serum samples. Serologic testing for IgM antibody or detecting a significant rise in IgG antibody confirms a mumps diagnosis. However, there are many important caveats to be aware of when interpreting the results. Antigen detection by polymerase chain reaction (PCR) is an efficient and rapid method to determine mumps as a diagosis. It may be necessary to test for antibodies for other infections causing parotitis including: Epstein-Barr Virus, parainfluenza virus, parvovirus B19, adenovirus, and enterovirus.
CT
Mumps is a clinical diagnosis. Imaging studies do not play a role in the initial diagnosis of mumps. However, imaging studies, such as a CT scan, may be helpful in patients with secondary complications.
Ultrasound
Mumps is a clinical diagnosis. Imaging studies do not play a role in the initial diagnosis of mumps. However, imaging studies, such as an ultrasound, may be helpful in patients with secondary complications.
Other Diagnostic Studies
Mumps is a clinical diagnosis. Further testing may be required in patients with secondary complications.
Treatment
Medical Therapy
No antiviral agent currently exists and therefore supportive care is indicated for patients with mumps. Supportive care includes prescribing analgesics, application of warm or cold packs to swollen areas, warm salt water gargles, and fluid intake. Patients should avoid acidic foods or juices.