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Mumps

Mumps is an acute infectious disease caused by the mumps (paramyxovirus) virus. The National Advisory Committee on Immunization (NACI) recommends immunization against mumps.

About Mumps

Agent of disease

Mumps virus is a member of the Paramyxoviridae family.

Symptoms

About 40% of those infected develop unilateral or bilateral parotitis, 16-18 days after exposure. Subclinical infection is common. Nonspecific or primarily respiratory symptoms can occur in about half of those who acquire infection. Approximately 20% of infections are asymptomatic.

Although complications are relatively frequent, permanent sequelae are rare. Before the widespread use of mumps vaccine, mumps was a major cause of viral meningitis and is associated with hearing loss and pancreatitis. Mumps meningoencephalitis can, rarely, result in permanent neurologic sequelae.

Orchitis occurs in 20% to 30% of post-pubertal male with infection and oophoritis occurs in 5% of post-pubertal female with infection, although sterility is a very rare complication of mumps. While mumps infection in pregnancy is not associated with congenital malformations, infection during the first trimester may increase the rate of spontaneous abortion.

Period of communicability

Those infected with mumps are infectious from 7 days prior to 9 days after onset of parotitis, while maximum infectiousness occurs 1-2 days prior until 5 days after parotitis onset.

How it is transmitted

Mumps virus is transmitted by airborne transmission or droplet spread as well as direct contact with saliva of an infected person.

Worldwide distribution

Mumps occurs worldwide with cases reported throughout the year and epidemics occurring every two to five years. Mumps remains endemic in many countries, and mumps vaccine is used in only 59% of World Health Organization (WHO) member states.

In the United Kingdom (UK), a large outbreak with occurred between 2004 to 2006 with the number of reported cases peaking in 2005 with over 43 000 laboratory-confirmed cases reported primarily in young adults who were either not immunized against mumps or had received only one dose of mumps-containing vaccine. In 2009, another outbreak occurred in England and Wales with over 7 400 cases of mumps confirmed. Most of the cases occurred among unvaccinated young adults (Source: Health Protection Agency).

In 2006 and 2009, the United States experienced multi-state outbreaks involving approximately 6500 and 1500 reported cases respectively. This resurgence has been has been associated with populations of youth and young adults in congregate settings (e.g. summer camps and college dormitories), where prolonged, close contact among persons may facilitate transmission. In the 2009 outbreak in New York and New Jersey, 88% of cases had received at least 1 dose of mumps-containing vaccine while 75% had received 2 doses. This outbreak was considered unique in terms exposure risks, since the outbreak occurred in a school where students had very close contact with one another (Source: Centres for Disease Control & Prevention).

In both the US and UK outbreaks, the circulating genotype has been identified as genotype G. The G genotype is not an unusual or rare genotype and, like the rest of known genotypes of mumps, it has been circulating globally for decades or longer.

Prevention & control

Mumps can be prevented by immunization and it is recommended by the National Advisory Committee on Immunization (NACI).

Mumps Epidemiology in Canada

Since the approval of mumps vaccine in 1969, the number of reported mumps cases has decreased by more than 99% from an average of 34,000 cases reported per year in the early 1950s to fewer than 400 cases per year in the early 1990s. A further reduction in incidence was observed following the introduction of MMR vaccine in 1996 to 1997. The annual number of cases has continued to decrease; during the period 2000 to 2006, an average of 81 cases were reported annually, ranging from 28 (2003) to 201 cases (2002). In 2007 and 2008, the annual number of reported cases increased to 1,120 and 748, respectively, mainly as a result of outbreaks in several provinces.

The age distribution of mumps in Canada has changed after the introduction of routine second dose of MMR vaccine (Figure 1). While the overall incidence of mumps decreased, the proportion of reported cases aged 20 years and older increased from an average of 16% in 1990-1995 to 51% in 1998-2008. Conversely, the proportion of reported cases aged 1 to 9 years decreased from an average of 59% to 25% during the same period (Figure 1).

Figure 1. Reported mumps incidence (per 100,000) by year and age group in Canada, 1986 to 2008.

Figure 1 Reported mumps incidence (per 100,000) by year and age group in Canada, 1986 to 2008.

Figure 1 - Text Equivalent

Recent Outbreaks

In Canada, three localized outbreaks occurred between 2001 and 2005. The first outbreak, totaling 193 cases, occurred between September 2001 and March 2002 and involved an under-vaccinated community in northern Alberta following importation of the disease from Bolivia. Most members of the community were philosophically opposed to vaccination. The majority of cases (80%) occurred in unimmunized individuals.

In 2007, large outbreaks occurred in Nova Scotia, New Brunswick and Alberta with a total of 1159 confirmed cases, accounting for 90% of the total cases in Canada that year. The majority (58%) of cases occurred in persons aged 20 to 29 years (Figure 1), many of who were college or university students. Immunization history was known for less than one-half of the mumps cases. Of those known, 8% had received two or more doses, 73% had received one dose, and 19% had received no mumps immunization.

The viral strain in the 2007 outbreaks was identical to the strain (genotype G) detected in the previous Nova Scotia outbreaks, the 2006 US multi-state outbreak, and the UK epidemic.

Beginning in October 2009, an outbreak of mumps occurred among a religious community in Quebec with 23 confirmed cases. The outbreak was linked to a large mumps outbreak in New York and New Jersey in the US. All cases were male and aged 8 to 47 years.

An outbreak in Ontario in 2009-10 involved 134 confirmed cases, the majority of which were males (72%) and between 15 and 24 years of age. Among cases, 83% had received at least one dose of mumps-containing vaccine, while 28% had received 2 doses.

Mumps Surveillance in Canada

In Canada, national surveillance data on mumps are collected through the Canadian Notifiable Disease Surveillance System (CNDSS).

Mumps Data

The following two tables contain recent data on the number of reported cases and incidence of mumps in Canada from 2005 to 2011. Data from 2009 to 2011 are preliminary. For further surveillance data, please see the Notifiable Diseases On-Line webpage as well as the Publications section below.

Table 1. Reported cases of mumps in Canada by year and age group, 2005 to 2011.
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 years or Greater Age Unspecified

*Data obtained from the Canadian Notifiable Diseases Surveillance System.
†An additional 175 cases were reported through an enhanced mumps surveillance system in place in 2007.
‡Based on preliminary data.

2005* 79 1 1 6 12 5 19 10 10 14 1 0
2006* 42 1 1 2 2 5 5 5 10 6 5 0
2007* 1110 3 8 16 18 118 509 177 161 78 21 1
2008* 748 2 46 113 128 143 96 71 91 50 7 1
2009 214 1 5 10 13 44 38 34 40 21 8 0
2010 799 0 12 42 79 142 127 86 180 114 15 2
2011 282 2 4 5 20 24 66 49 57 50 5 0
Table 2. Reported incidence per 100,000 population of mumps in Canada by year and age group, 2005 to 2011.
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 years or Greater

*Data obtained from the Canadian Notifiable Diseases Surveillance System.
†An excess 0.53 per 100, 000 were reported through an enhanced mumps surveillance system in place in 2007.
‡Based on preliminary data.

2005* 0.24 0.29 0.07 0.32 0.56 0.23 0.85 0.47 0.22 0.14 0.02
2006* 0.13 0.29 0.07 0.11 0.10 0.23 0.22 0.23 0.22 0.06 0.08
2007* 3.37 0.83 0.57 0.89 0.88 5.27 22.41 7.93 3.58 0.79 0.34
2008* 2.25 0.54 3.21 6.30 6.36 6.34 4.20 3.10 2.01 0.50 0.11
2009 0.63 0.27 0.34 0.56 0.66 1.95 1.64 1.45 0.88 0.21 0.12
2010 2.34 0.00 0.80 2.33 4.08 6.38 5.37 3.59 3.92 1.13 0.22
2011 0.82 0.52 0.26 0.27 1.05 1.09 2.75 2.03 1.23 0.49 0.07

Mumps Resources

Case Definitions

Publications

Guidelines and Recommendations

Other Resources