Child with mumps.
Mumps is a contagious viral infection caused by a paramyxovirus that spreads through droplets or saliva, typically entering through the nose or mouth. The virus can be present in saliva before symptoms appear, with the highest transmission just before the development of parotitis (swelling of the salivary glands). Mumps is less contagious than measles and mostly affects unimmunized populations, although outbreaks have occurred even among immunized individuals due to factors such as primary vaccine failure and waning immunity.
In the United States, there was a significant resurgence of mumps in 2006, primarily affecting vaccinated young adults. Since then, sporadic outbreaks have led to fluctuating annual cases, with incidents typically occurring in college campuses and close-knit communities. Mumps cases can be imported and lead to outbreaks within communities, particularly in crowded living conditions.
The peak incidence of mumps is during late winter and early spring, and although the disease can affect individuals of any age, it is uncommon in children younger than 2 years. Approximately a quarter of cases may not present with symptoms. The mumps vaccine, introduced in 1967, is effective in reducing the incidence of the disease, though occasional resurgences have been observed.[1, 2]
See the Centers for Disease Control and Prevention (CDC) recommended immunization schedule for persons aged 0-18 years,[3] the catch-up schedule for persons aged 4 months to 18 years,[4] and the adult immunization schedule for persons older than 18 years.[5]
The mumps virus is transmitted by respiratory droplets, direct contact, or contaminated fomites. It has an incubation period of 12-24 days after initial transmission.[2] After the incubation period, prodromal symptoms occur and last anywhere from 3-5 days. After the prodrome, the symptoms of the virus depend on which organ is affected. The most common presentation is a parotitis, which occurs in 30-40% of patients. Other reported sites of infection are the testes, pancreas, eyes, ovaries, central nervous system, joints, and kidneys. A patient is considered infectious from about 3 days before the onset and up to 4 days after the start of active parotitis. Infections can be asymptomatic in up to 20% of persons.
Mumps occurs worldwide, with a peak incidence during late winter to early spring. Sporadic mumps outbreaks have occurred among susceptible individuals in various settings, including military posts, schools, colleges and universities, and summer camps. During outbreaks, mumps can affect vaccinated individuals, but prior immunization helps to limit the symptoms, duration, and spread of mumps.
United States
Prior to the vaccine about 50% of children contracted mumps. Approximately 200,000 cases were reported in 1964 before the introduction of the vaccine compared with 291 cases in 2005. A resurgence occurred in 1986 and 1987, with almost 13,000 cases reported, and it was associated with a lack of state requirements for immunizations. These cases were mostly in older school-aged children (10-19 y). In the 1990s, 30-40% of cases reported each year were in persons aged 15 years or older as opposed to 90% being younger than 15 years old in earlier years.[6]
An outbreak of mumps occurred in Iowa, with 219 cases reported in 2006. In addition, another 14 cases of people with symptoms consistent with the virus were reported in nearby states (Illinois, Nebraska, and Minnesota). This is the largest number of cases reported in the United States since 1988. The median age of the 219 persons was 21 years, with 30% being college students. In 1991, Iowa mandated that 2 doses of mumps vaccine be required for all people entering public schools. Vaccination history was studied in 133 people from this outbreak: 65% (87) of the patients had received 2 doses, 14% (19) had received only 1 dose, and 6% (8) received no vaccine at all. The source of the Iowa epidemic is unknown.[7]
Among the infected, the most commonly reported symptoms were parotitis (83%), submaxillary/submandibular gland swelling (40%), fever (36%), and sore throat (32%). The average length of illness was 5.1 days. Complications, including encephalitis and orchitis, were reported in 5% of patients.
International
The variations in the number of persons who receive the mumps vaccination worldwide make it difficult to estimate the numbers affected. The incidence varies markedly from region to region.
The United Kingdom reported an epidemic of mumps in 2005, with 56,390 cases reported in persons aged 15-24 years who were not vaccinated.[6]
Sex
For parotitis, males and females are affected equally.
Symptomatic meningitis has a male-to-female ratio of 3:1.
Age
Before the mumps vaccine was introduced, most cases were in children aged 5-9 years, with 90% being younger than 15 years. The resurgence in the late 1980s affected older children aged 10-19 years. In more recent years, up to 30-40% of cases have been in persons older than 15 years.[1]
Uncomplicated mumps generally resolves on its own, with rare cases of relapse occurring around 2 weeks later. The prognosis for patients with mumps-related meningitis is typically good, although some might experience permanent issues like nerve deafness or facial paralysis. Rare complications like postinfectious encephalitis, acute cerebellar ataxia, transverse myelitis, and polyneuritis can also occur. In most cases, children with mumps recover fully within a few weeks, with a good overall prognosis. However, mumps in adults tends to be more severe. The most severe complication is encephalitis, which carries a mortality rate of 1.5%.[8]
Mumps during pregnancy can lead to risks of embryonic or fetal death and spontaneous abortion, although malformations are not commonly reported.[8] Unilateral orchitis rarely causes sterility, but bilateral orchitis poses a higher risk. Unilateral sensorineural hearing loss is considered rare, though subclinical or undiagnosed mumps may contribute to a greater incidence of hearing loss than currently known, with documented cases of bilateral involvement.[2]
Between 1980 and 1999, mumps resulted in an average of one death per year, with most fatalities occurring in individuals older than 19 years. While CNS involvement is common, symptomatic meningitis only affects 1-10% of patients and typically resolves without complications. Encephalitis, a rare occurrence in 0.1% of cases, carries a mortality rate of 1.5%.[9, 10, 11, 12, 13]
Orchitis affects 50% of postpubertal males and may lead to testicular atrophy in up to 50% of cases, particularly in bilateral orchitis where the risk of sterility is higher.[10, 14] Oophoritis is rare but can occur in a small percentage of postpubertal girls.
Pancreatitis manifests in 3% of mumps cases, with resultant transient hyperglycemia and occasional reports of diabetes mellitus.[13] Deafness, reported in 1 in 20,000 cases of mumps, often presents unilaterally.[13, 15, 16] Myocarditis-related deaths have been documented, with an incidence of up to 15%, largely asymptomatic.[17]
In women, mumps during the first trimester of pregnancy increases the risk of spontaneous abortion, although it is not associated with congenital malformations.[18] Additional complications may include chronic arthritis, arthralgias, and nephritis.[17]
Mumps is typically caused by a single-stranded RNA virus belonging to the Paramyxovirus genus. Humans serve as the only natural host for the mumps virus.
Other viruses implicated in recurrent parotitis are influenza, echovirus, parainfluenza (types 1 and 3), and coxsackievirus A. More rare causes of parotitis seen in persons with HIV infection are adenovirus or cytomegalovirus.
Risk factors include lack of immunization or incomplete immunization, international travel, and immune deficiencies.
After a 12- to 24-day incubation period, mumps usually has a prodromal phase, which consists of nonspecific viral symptoms: low-grade fever, malaise, myalgias, and headache.[2]
The prodromal phase is usually followed by unilateral or bilateral parotid gland swelling that peaks on approximately the second day and continues for 5-7 days.[2] This usually occurs within the first 2 days of infection. Parotitis may be unilateral or bilateral. Initial unilateral involvement is followed by contralateral involvement in 90% of cases. Parotid swelling can last up to 10 days.[19]
Infections can be asymptomatic in up to 20% of persons and may be nonspecific or have predominantly respiratory symptoms in up to 50%.
Patients typically complain of worsening pain when eating or drinking acidic foods.[2]
Persons can present with other symptoms without a preceding parotitis. CNS presentations can include headache, neck pain, and fever. Preceding parotitis can be absent in up to 50% of these persons.[15, 9, 11, 12]
Orchitis can occur in up to 50% of postpubertal males, and as many as 30% have bilateral involvement. Sterility is rare.[14, 10] Patients can present with abdominal pain due to oophoritis or pancreatitis. Oophoritis occurs in up to 5% of postpubertal females.
Sudden hearing loss results from a vestibular reaction.[15]
Other rare presenting symptoms can be due to arthralgias, arthritis, mastitis, thyroiditis, thrombocytopenic purpura, or nephritis.
Low-grade fever is common with mumps.
Classic parotid gland swelling typically manifests without warmth or erythema and rapidly progresses over several days. Swelling may be preceded by parotid tenderness and/or earache. Enlargement of the contralateral parotid gland is not uncommon.
The swollen parotid gland may lift the earlobe upward and outward.
The patient may have tenderness over the angle of the mandible, which itself may be obscured by parotid swelling.
Opening of the Stensen duct can be edematous and erythematous.
Trismus may or may not be present.
Submandibular and sublingual glands may also be involved and swollen.
A morbilliform rash may be present.
Potential complications of mumps are as follows[2] :
Mumps traditionally has been considered a clinical diagnosis; however, data from a 2007 outbreak found that only 298 of 2082 cases (14%) of clinically diagnosed mumps were laboratory confirmed.[20]
Laboratory diagnosis of mumps is vital when the disease presents with atypical features such as unilateral swelling, recurrence, or involvement of non-salivary gland tissues. Prolonged parotitis without a clear cause also warrants testing. The preferred diagnostic method is RT-PCR, supported by serological tests and viral culture. In vaccinated individuals, IgM testing may not be reliable, necessitating early RT-PCR on saliva or throat samples.
Additional tests typically are unnecessary, but an elevated serum amylase level in cases of undifferentiated aseptic meningitis can help diagnose mumps, even without typical parotitis. Mild changes in white blood cell count, elevated CSF protein levels, and occasional variations in CSF glucose levels may be observed in meningitis cases. Laboratory evaluations commonly are conducted in the emergency department to rule out other causes or evaluate complications. Mumps-specific tests usually can be done on an outpatient basis.
Mumps virus can be detected in various samples, including nasopharyngeal swabs, urine, blood, and buccal cavity fluid, typically from 7 days before up to 9 days after parotitis onset.[2, 21, 22, 23]
Mumps infection can be confirmed by demonstrating the following:
No specific imaging studies are diagnostic.
Imaging studies may be needed as a further workup with certain complications of mumps.
Testicular ultrasonography may be performed when acute orchitis is suspected, with specific indication to rule out torsion.
Supportive care is the main approach to treating mumps and its complications. Patients should be isolated until glandular swelling diminishes. A soft diet can help alleviate chewing-related pain, and avoiding acidic substances like citrus juices is advisable. IV hydration may be needed for pancreatitis-related vomiting. For orchitis, bed rest, scrotal support using cotton and an adhesive-tape bridge between the thighs, and ice packs can help alleviate pain. Corticosteroids have not been proven to hasten orchitis resolution.[2]
Prehospital Care
Supportive care is usually all that is needed for patients with mumps.
Persons exposed to the virus should be counseled on vaccination and risks.
Emergency Department Care
Supportive care with analgesics and antipyretics as needed. Symptomatic treatment with warm and/or cold compresses over the parotid gland may also be comforting. and outpatient follow up is indicated for straightforward infections.
Complications due to mumps should be treated based on presentation, as follows:
Routine vaccination with the live-attenuated Measles, Mumps, and Rubella (MMR) vaccine is recommended for children in countries with strong healthcare systems, typically administered in 2 doses - the first at ages 12-15 months and the second at ages 4-6 years. Infants immunized before age 1 year require 2 additional doses post their first birthday. The vaccine is known to cause mild, non-communicable infection, with about 5-15% of recipients experiencing a low-grade fever post-inoculation, which may be followed by a rash, whereas central nervous system reactions are exceedingly rare.[25] Notably, multiple studies have debunked the myth of the MMR vaccine causing autism.
The MMR vaccine provides lasting immunity, with effectiveness rates of 72% to 86% in preventing mumps in children aged 9 months to 15 years.[26] However, the MMR vaccine is contraindicated during pregnancy and post-exposure vaccination doesn't safeguard against contracting mumps. The Centers for Disease Control and Prevention (CDC) recommends isolating infected individuals and vaccinating susceptible contacts, with a suggested third dose during outbreaks.[27]
The vaccine's main adverse reactions are typically minor, including pain, redness, and swelling at the injection site, and occasionally joint or muscle aches, fevers, or parotitis – with more severe complications like CNS effects being astronomically rare.[25] It is crucial to note that there is no credible scientific link between the MMR vaccine and autism. The American Academy of Pediatrics confirms the vaccine's safety and efficacy, emphasizing the necessity of vaccination in disease prevention.[28]
For further information on the MMR vaccine, including indications, contraindications, dosing, and potential adverse effects, refer to the CDC's MMR Vaccine page, including indications, contraindications and precautions, dosing and administration, and adverse effects.. Additionally, the latest immunization schedules, including guidance on childhood vaccinations, can be found on the CDC's Childhood Vaccination Schedule.
It is essential for all children over 1 year and adults to receive the two-dose MMR vaccine unless medically contraindicated. Should there be any uncertainty regarding prior infection or vaccination status, a blood test may help verify antibody levels or the vaccine could be administered as a precaution. In January 2018, the Advisory Committee on Immunization Practices (ACIP) recommended that individuals previously vaccinated with 2 doses of a mumps virus-containing vaccine receive a third dose during outbreaks to bolster protection against mumps.[29]
Live vaccines, including the MMR vaccine, are prepared within a chicken embryo and should not be given to individuals with severe egg allergies, pregnant women, those experiencing high fevers or severe illness, or in immunocompromised individuals. Central nervous system (CNS) effects post-MMR are rare and should not deter vaccination.
Acute mumps cases could result from various factors like incomplete vaccination or waning immunity over time, marking the significance of adhering to immunization schedules.[30] As the MMR vaccine continues to demonstrate safety and effectiveness, it remains a critical tool in global efforts to prevent infectious diseases.
Evidence suggests that patients diagnosed with mumps should be isolated with standard and droplet precautions in a hospital setting for 5 days from the onset of parotitis, including the exclusion of healthcare personnel from work during this period. Transmissibility is greatest immediately after onset of parotitis and decreases rapidly over the subsequent 5 days. Transmission may also occur from patients prior to development of parotitis or with subclinical mumps.[27]
In a retrospective cohort study involving over 95,000 children, researchers examined the potential connection between MMR vaccination and autism spectrum disorder (ASD) risk. Among the children with older siblings diagnosed with ASD, those who received the MMR vaccine did not show an increased risk of developing ASD at age 2 year or age 5 years. Specifically, the study found that MMR vaccination rates were 84% at age 2 years and 92% at age 5 years for children with unaffected older siblings, while rates were slightly lower at 73% at age 2 and 86% at age 5 for children with affected siblings. The adjusted relative risk (RR) for developing ASD following MMR vaccination compared to no vaccination at age 2 was 0.76, and at age 5, it was 0.56 for children with older siblings with ASD. Conversely, for children whose older siblings did not have ASD, the adjusted RR at age 2 was 0.91 for 1 dose and 1.09 at age 5 for 2 doses. Overall, the study concluded that both 1 and 2 doses of the MMR vaccine were not associated with an increased risk of ASD, even in children with a familial history of the disorder.[31]
Patients with specific complications may require further inpatient care.
Persons with encephalitis, meningitis, nephritis, myocarditis, or severe pancreatitis require inpatient management and monitoring.
Classic mumps with no major complications can be managed on an outpatient basis with supportive care and good follow up.
Current evidence suggests that patients diagnosed with mumps should be isolated for 5 days from the onset of symptoms.[27]
Scrotal support, ice, and analgesia are indicated.
Hearing testing is performed upon resolution of symptoms.
Transfer is rarely needed. Indication to transfer would be if major complications are present and current hospital does not have appropriate services to treat the patient appropriately.
Child with mumps.
