Mumps: an Update on Outbreaks, Vaccine Efficacy, and Genomic Diversity

Abstract

SUMMARY Mumps is an acute viral infection characterized by inflammation of the parotid and other salivary glands. Persons with mumps are infectious from 2 days before through 5 days after parotitis onset, and transmission is through respiratory droplets. Despite the success of mumps vaccination programs in the United States and parts of Europe, a recent increase in outbreaks of mumps virus infections among fully vaccinated populations has been reported. Although the effectiveness of the mumps virus component of the measles-mumps-rubella (MMR) vaccine is suboptimal, a range of contributing factors has led to these outbreaks occurring in high-vaccination-coverage settings, including the intensity of exposure, the possibility of vaccine strain mismatch, delayed implementation of control measures due to the timeliness of reporting, a lack of use of appropriate laboratory tests (such as reverse transcription-PCR), and time since last vaccination. The resurgence of mumps virus infections among previously vaccinated individuals over the past decade has prompted discussions about new strategies to mitigate the risk of future outbreaks. The decision to implement a third dose of the MMR vaccine in response to an outbreak should be considered in discussions with local public health agencies. Traditional public health measures, including the isolation of infectious persons, timely contact tracing, and effective communication and awareness education for the public and medical community, should remain key interventions for outbreak control. Maintaining high mumps vaccination coverage remains key to U.S. and global efforts to reduce disease incidence and rates of complications.

Mumps Outbreaks in Vaccinated Populations—Is It Time to Re-assess the Clinical Efficacy of Vaccines?

“…Several reviews, both observational and systematic have demonstrated the clinical benefit of a mumps vaccine ( 107 , 108 ), the pathogenesis and genomic diversity of the MuV ( 10 , 107 , 108 ) and the epidemiology surrounding the outbreak ( 1 , 10 , 82 ). It is not clear why these mumps outbreaks occur, although it has been alluded to be due to a number of interrelated factors, such as sub-optimal vaccine uptake ( 1 , 109 , 110 ), primary or secondary vaccine failure or failure of the mumps vaccine to protect individuals from infection (vaccine efficacy) ( 107 ) ( Figure 1 ).…”

Bilateral Optic Neuritis: A Rare Complication of Mumps

“…The most common clinical features include fever, bilateral parotid gland swelling, headache, nausea, vomiting, and sometimes seizures. The neurological complications linked with mumps include sudden-onset sensorineural hearing loss, aseptic meningitis, which is usually benign and encephalitis, which is associated with grave consequences, including death [6]. Ocular involvement may lead to follicular conjunctivitis, episcleritis, dacryoadenitis, keratitis, scleritis, anterior uveitis, choroiditis, and paralysis of extraocular muscles (abducens nerve palsy), although rare, there can also be bilateral optic neuritis after an encounter with mumps virus [7].…”

“…Ocular involvement may lead to follicular conjunctivitis, episcleritis, dacryoadenitis, keratitis, scleritis, anterior uveitis, choroiditis, and paralysis of extraocular muscles (abducens nerve palsy), although rare, there can also be bilateral optic neuritis after an encounter with mumps virus [7]. Mumps is preventable with the administration of the measles-mumps-rubella (MMR) vaccine, with effectiveness after a single dose ranging from 49-92% (median: 78%), and to 66-95% (median:88%), after administration of the second dose [6].…”

Epidemiology of laboratory-confirmed mumps infections in South Africa, 2012–2017: a cross-sectional study

“…A booster dose of the mumps vaccination is currently recommended only in the setting of an outbreak [9,10,[26][27][28]. Although the level of protective antibodies and correlates of protection against mumps infection are not well-defined, suggested causes of the resurgence of infections have included waning immunity over time due to a lack of a durable T-cell mediated response, as well as antigenic differences between vaccine and circulating mumps strains, [1,4,[7][8][9][10][26][27][28][29][30][31]. As such, the mismatch between vaccine and circulating mumps strains has also prompted the consideration of a polyvalent vaccine [1,32].…”

“…Firstly, missing data could not be accounted for and information on risk factors was not available since the secondary data that was analysed did not include information about clinical and medical history. Secondly, 50% of mumps infections present non-specifically or with respiratory symptoms, while 20-40% of infections are reportedly asymptomatic or have mild symptoms [1,27,40]. These cases may not present at health facilities and would therefore not have been accounted for in the data that we reviewed.…”