The Resurgence of Mumps

US Pharm. 2019;44(5)18-21.

ABSTRACT: Mumps is a highly contagious viral disease that affects children, adolescents, and adults. There have been outbreaks of mumps recently in close-knit communities such as college campuses. The postulated reasons for the outbreaks, which have occurred among individuals who have received the recommended two-dose vaccination regimen, include the potential waning of the vaccine effect and the lack of long-term boosters. Prevention through vaccination is key in the management of mumps since there is only supportive therapy for infected patients. Pharmacists can play a major role in educating the community and administering the third dose of MMR vaccine during a mumps outbreak.

Mumps is a contagious viral illness characterized by an inflammation of the salivary glands, resulting in painful swelling of one or more parotid glands.^1,2 Mumps may affect children, adolescents, and adults.¹ Although mumps is preventable by vaccination, there has been a surge in cases occurring among vaccinated populations.³ This article will discuss what is currently known about the infection trend, epidemiology, clinical presentation of mumps infection, potential strategies to ensure more complete protection against mumps, and management of the infection.

Epidemiology

There has been a dramatic decline in clinical mumps since the implementation of the two-dose MMR vaccine in 1989, declining from 5,712 cases in 1989 to under 257 cases in 2004.⁴ In 2017, more than 90% of children aged 19 to 35 months received one or more doses of MMR vaccine in the 50 states, the District of Columbia, selected local areas, and U.S. territories.⁵

However, despite vaccination, outbreaks and sharp spikes in reported cases still occur (Figure 1).⁶ Many mumps outbreaks have been found among residents of congregated settings such as college campuses and close-knit communities.^7,8 These outbreaks occurred despite large numbers of infected patients having received the CDC-recommended two-dose schedule of immunization against mumps.⁹

For example, in 2006, there was an outbreak on college campuses across multiple Midwestern states, resulting in over 6,500 reported cases.⁹ In 2016-2017, there was an outbreak in a tight-knit, rural Arkansas community that resulted in nearly 3,000 reported mumps cases within that community alone.⁶ A recent mumps outbreak at Temple University in Philadelphia led to the requirement of the MMR vaccine for all incoming students beginning in fall 2019.¹⁰

It is thought that the slight increase in vaccine-exemption rates in recent years among children may have contributed to the creation of pockets of unvaccinated children.¹¹ During outbreaks among populations with high rates of vaccination, unvaccinated individuals often have a higher mumps-attack rate when compared with those fully vaccinated.¹²

Etiology

Mumps is a single-stranded RNA virus that stems from the Paramyxovirus genus of the Paramyxoviridae family; humans serve as the only host for this virus.¹ Mumps infection is transmitted from an infected person by various routes. The virus can be transmitted person-to-person through coughing, sneezing, or even talking near an infected person. Once the virus enters the respiratory system, it replicates locally and can spread to other organs. It is also spread via fomite exposure from touching surfaces or objects that have previously been touched by a person with mumps. For young children, situations such as these are not uncommon within a daycare or school setting. The virus’ high degree and multiple routes of contagion have also facilitated the outbreaks occurring within college and community settings.³ Therefore, it is vital to take the necessary precautions to decrease a child’s susceptibility to contracting mumps from their peers. 

The recent outbreaks and resurgence of mumps are thought to have occurred for multiple reasons, including declining levels of vaccine-derived immunity and the lack of recommended boosters for the MMR vaccine.¹³

Clinical Manifestations

The classic symptom of mumps is bilateral or (less commonly) unilateral parotitis, occurring 16 to 18 days after exposure, although 15% to 20% of patients affected with mumps are mostly asymptomatic (Figure 2).^7,8,14,15 The swelling and tenderness worsen over 1 to 3 days and can potentially push the earlobe upward and outward, obscuring the angle of the mandible. Patients can experience edema over the sternum and upper chest, or symptoms of a viral illness, including fever, headache, malaise, anorexia, and myalgia (predominantly around the neck).^1,7,8 Mumps is usually self-limiting.²

The most common complication of mumps in children is meningitis, sometimes associated with encephalitis.¹⁶ Encephalitis is the most dangerous complication and can result in seizures, paralysis, or other neurologic conditions. It is the most frequent cause of the very rare deaths attributed to mumps.^17,18 The mortality rate for patients presenting with meningoencephalitis has been reported to be up to 1.4%.¹⁸ Other rare complications include, but are not limited to, nephritis, arthritis, thrombocytopenia purpura, mastitis, thyroiditis, and keratouveitis.^17-19 Postpubertal males can also develop orchitis in approximately 20% of the cases. Oophoritis in females can also occur, but with significantly less frequency.^1,2

Although hearing loss is a rare (1%) complication of mumps, it is usually unilateral and temporary.^19,20 However, the hearing loss can be permanent, and mumps is the most frequent cause of one-sided sensorineural deafness in children.

Prevention

Mumps can be prevented with the MMR vaccine. This vaccine protects the individual against three viral diseases including measles, mumps, and rubella. The CDC recommends all children receive a two-dose schedule of MMR vaccine, starting with the first dose at age 12 through 15 months, and the second dose at age 4 through 6 years.²¹ The CDC also recommends all adolescents and adults be up-to-date on their MMR vaccinations.⁴ Generally, the MMR vaccine is approximately 88% effective when the individual receives two doses and is about 78% effective with a single dose.²² It is estimated that the immunity against mumps infection wanes an average of 27 years (95% CI, age 16 to 51 years) postimmunization.²³

Prompted by the multiple outbreaks and increased incidence of mumps cases in the U.S., the CDC, working collaboratively with several leading health organizations, including the American Academy of Pediatrics, reviewed reports of mumps outbreaks and examined the characteristics of patients affected. The group looked at epidemiology, duration of immunity after the recommended two-dose schedules, and the impact of an additional dose of vaccine on outbreak control and public health resources.²⁴

The effect of a third dose was examined in retrospective observational studies.^25,26 One such study was carried out in 2015 during the mumps outbreak at the University of Iowa.²⁶ The university required all students to show proof of a two-dose scheduled MMR vaccination before registration in the spring semester. During the outbreak, the university arranged vaccination clinics to provide a third dose of MMR vaccine. The study demonstrated that during the outbreak, the students who received a third dose of MMR vaccine had less risk of contracting mumps compared with those who received only two doses. The findings suggest that administering the third dose of MMR vaccine helped improve mumps outbreak control and that this strategy might be beneficial among individuals living in the outbreak area.^23,26

In January 2018, the CDC’s Advisory Committee on Immunization Practices (ACIP) recommended that individuals who were identified by public health authorities as having an increased risk of mumps infection during an outbreak and who were previously vaccinated with two doses of MMR vaccines receive a third dose of MMR vaccine. However, ACIP did not specifically recommend a third dose of MMR vaccine outside of a mumps outbreak.²⁷

Mumps remains a common infectious disease worldwide, especially in some parts of Europe, Asia, and Africa. Therefore, individuals preparing for travel outside of the U.S. to endemic areas without evidence of immunization or adequate immunity should be vaccinated with two doses of MMR vaccine.²⁸ Despite the FDA-approved age range, the CDC recommends that infants aged 6 to 11 months receive one dose prior to international travel and be revaccinated with the two-dose series at age 12 to 15 months.^21,29

Clinical Management

There are no curative treatments for mumps; it generally resolves in a few weeks. Supportive care, including analgesics such as acetaminophen or ibuprofen, may relieve associated pain and fever.³⁰ Additionally, patients should be advised to use warm or cold compresses for the pain and swelling; to rest; to avoid hard foods that demand chewing; and to avoid contact with others to reduce risk of viral transmission.

Pharmacist’s Role

Since therapy is limited to supportive care in the treatment of diagnosed mumps, prevention is key to reducing mumps development in children and mumps incidence during outbreaks. Pharmacists currently play a critical role in the immunization of the U.S. population due to their accessibility in the local community pharmacy.²⁹ This appropriately positions pharmacists to vaccinate patients with the MMR vaccine, as well as educate parents on the importance of the MMR vaccination for their children and on mumps symptoms to facilitate early recognition and minimize community outbreaks.³⁰ Thus, pharmacists can be champions in the community to empower and educate on the role of prevention in management of mumps outbreaks.

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