BMJ  2005;331:E363-E364 (9 July), doi:10.1136/bmj.331.7508.E363

BMJ USA: Editorial

Mumps outbreak among young adults in UK

Is the US at risk?

The clinical review by Gupta and colleagues in this issue (p 293) is a timely reminder to clinicians who may have little experience with mumps infection and its complications. Following the United Kingdom's 1988 introduction of routine infant measles-mumps-rubella (MMR) vaccination, and the addition of a second routine dose of MMR vaccine in 1996, mumps became a rare disease in the UK, with a few hundred reports of mumps annually during the 1990s. Reported mumps cases in England and Wales increased to about 4000 in 2003, however, and to over 16 000 reported cases in 2004 (31.1 cases per 100 000 population).¹ Cases have continued to be reported in 2005, predominantly among young adults aged 19 to 23 who were too old to have received two doses of MMR vaccine in the national vaccination program.¹

Is the US at risk for such an outbreak?

The US was one of the first countries to start using the live attenuated mumps vaccine in 1967; mumps vaccine was recommended as a routine childhood vaccine and administered as MMR since 1977.² From over 152 000 reported mumps cases in 1968, mumps incidence in the US declined by over 99.8% during the next 3 decades (figure). Since 1980, the enactment and enforcement of state vaccination laws requiring that students be vaccinated before school entry has contributed significantly to achieving and maintaining high MMR vaccine coverage levels.²

View larger version (35K): [in this window] [in a new window]   Figure Numbers of reported mumps cases, US, 1968-2004. Source of data: National Notifiable Diseases Surveillance System

 

In the mid to late 1980s, American teenagers experienced outbreaks of mumps that were similar to, although less extensive than, those that the UK is currently experiencing.^3,4 In 1987, almost 13 000 mumps cases were reported in America (5.4 cases per 100 000 population), with peak incidence in the 10-19 year old age group. Outbreaks were due to undervaccination, vaccine failure, or both; two doses of MMR vaccine provided better protection than one dose.^3,4 In 1989, to improve measles control, a second dose of MMR vaccine was recommended, and currently all states require children to receive two doses of mumps vaccine prior to school entry.

MMR vaccine coverage has been at or over 90% among preschool age children since 1995, and likely over 95% among school entrants since at least 1990.⁵ Reported mumps cases in the US fell from 5712 in 1989, to 1692 in 1993,² to less than 300 annually since 2001 (CDC unpublished data). This decline in mumps case incidence prompted the declaration of a national health objective to eliminate indigenous transmission of mumps virus by 2010.⁶ The US has already achieved elimination of indigenous measles⁷ and rubella⁸ transmission through the widespread use of MMR vaccine.

Who is most at risk of mumps in the US?

As a result of high MMR vaccination levels in preschool, school, and college age students for the last 10-15 years, US physicians are even less likely than UK physicians to have seen a case of mumps. However, mumps is abundant in the rest of the world, both in developed countries where the mumps vaccination program is less mature, and in less developed settings where mumps vaccine may not yet be included in the routine vaccination program.⁹ Given today's level of globalization, US physicians should be prepared to recognize, confirm, and report cases of mumps suspected in both US- and foreign-born individuals. Physicians should also review the vaccination histories of their patients and provide all indicated vaccines. Imported mumps cases may spread in unvaccinated populations, including infants too young to be vaccinated and persons who are unvaccinated for medical, religious, or philosophical reasons.

What can US providers do in their practices?

In addition to public health personnel, US clinicians play an important role in documenting progress towards national mumps elimination goals. Most reports of mumps originate from clinicians, who usually diagnose mumps based on the presence of acute parotitis. In our current low incidence setting, however, parotitis can be due to many infectious and non-infectious causes, and the positive predictive value of parotitis for mumps is very low (10-16%).^10,11 It is thus important that clinicians attempt to confirm the diagnosis serologically and virologically (by polymerase chain reaction [PCR] and/or culture) and report suspected mumps cases to local health departments to assist in case investigations and specimen processing. Standard serologic testing in the US includes a positive mumps IgM or a significant rise between acute and convalescent phase titers of mumps IgG. Particularly in vaccinated cases, the IgM may not be positive, and thus serial IgGs (collected at least one week apart, and tested in parallel) and virologic specimens (collected within the first five days after parotitis onset) may be necessary to confirm the diagnosis.¹² Viral specimens can be obtained from urine, swabs of the nasopharynx, and perhaps optimally, from oral fluid swabs over the opening of Stensen's duct inside the mouth.

Mumps disease and its complications are rarely seen in the US due to the success of the national vaccination program. Maintaining high vaccine coverage and population immunity are the best protection against mumps in the US and elsewhere.

National Immunization Program
MS E-61
CDC, Atlanta, GA
sbloom{at}cdc.gov

National Immunization Program
MS E-61
CDC, Atlanta, GA

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Clinical review p 293

Competing interests: None declared.

References

1. Savage E, Ramsay M, White J, Beard S, Lawson H, Hunjan R, et al. Mumps outbreaks across England and Wales in 2004: observational study. BMJ 2005;330: 1119-20.[Free Full Text]
2. CDC. Mumps Surveillance, US, 1988-1993. MMWR 1995;44: SS-3.
3. Wharton M, Cochi SL, Hutcheson RH, Bistowish JM, Schaffner W. A large outbreak of mumps in the postvaccine era. J Infect Dis 1988;158: 1253-60.[Medline]
4. Hersh BS, Fine PEM, Kent WK, et al. Mumps outbreak in a highly vaccinated population. J Pediatr 1991;119: 187-93.[CrossRef][Web of Science][Medline]
5. Hutchins S, Bellini WJ, Coronado V, Jiles R, Wooten K, Deladisma A. Population immunity to measles in the United States, 1999. J Infect Dis 2004;189: S91-7.
6. US Department of Health and Human Services. Healthy People 2010. 2nd ed. Washington, DC: U.S. Government Printing Office, 2000. http://www.healthypeople.gov/document/HTML/Volume1/14Immunization.htm#_Toc494510239 (last accessed June 12, 2005).
7. Katz SL, Hinman AR. Summary and conclusions: measles elimination meeting, 16-17 March 2000. J Infect Dis 2004;189: S43-7.
8. CDC. Achievements in Public Health: Elimination of Rubella and Congenital Rubella Syndrome—United States, 1969—2004. MMWR 2005;54:279-82. (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5411a5.htm.)
9. Galazka AM, Robertson SE, Kraigher A. Mumps and mumps vaccine: a global review. Bull World Health Organ 1999;77: 3-14.[Web of Science][Medline]
10. Pelosi J, Meyer PA, Schluter WW. Mumps surveillance results of improved case investigation and serologic testing of suspected cases, Texas, 1995-1996. J Pub Health Manag Pract 2001;7: 69-74.
11. Guy RJ, Andrews RM, Kelly HA, Leydon JA, Riddell MA, Lambert SB, et al. Mumps and rubella: a year of enhanced surveillance and laboratory testing. Epidemiol Infect 2004;132: 391-8.[CrossRef][Medline]
12. Jin Li, Vyse A, Brown DWG. The role of RT-PCR assay of oral fluid for diagnosis and surveillance of measles, mumps and rubella. Bull World Health Organ 2002;80: 77-6.

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Mumps outbreaks across England and Wales in 2004: observational study

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