ARCHIVED - Guidelines for the Prevention and Control of Mumps Outbreaks in Canada

 

6.0 Management

6.1 Spread and Control

Mumps is generally spread by close face-to-face contact. Infection occurs through direct contact with saliva or respiratory droplets from the nose or throat, spread through coughing, sneezing, sharing drinks, or kissing, or from contact with any surface that has been contaminated with the mumps virus(8-11).

The incubation period for mumps ranges from 14 to 25 days(8-11). Once an individual is infected, mumps can be communicable from 7 days before to 5 days after the onset of parotitis (swelling of the parotid gland)(12). A recent review of the scientific evidence suggests that, while the mumps virus can be isolated from saliva or respiratory secretions ≥5 days after parotitis onset, the risk of transmission after 5 days is considered low, due to decreasing viral load(12). Approximately 20% to 30% of mumps infections can be asymptomatic, and these cases can also be infectious(8,11). High childhood immunization rates in Canada have resulted in a dramatic reduction in rates of mumps infection. Under-immunized and unimmunized children and young adults remain the groups at highest risk of infection. Immunity is generally lifelong and develops after either inapparent (asymptomatic) or clinical infections. Mumps immunization is further discussed in Section 7.

The public health response to increased mumps activity includes managing cases, contact identification and management; identifying social networks when individual follow-up is not feasible; and maintaining/enhancing surveillance for further cases and disease outcomes (e.g., hospitalizations, complications). Generally, a mumps outbreak is controlled by the following methods(13-15):

  • defining the at-risk populations and transmission settings;
  • preventing further transmission through isolation of cases and contact education/ awareness;
  • protecting susceptible populations with immunization (where no contraindication to MMR vaccine exists); and
  • good risk communication.

6.2 Case Management

There is no specific or prophylactic treatment for mumps; all confirmed and clinical cases of mumps should be offered supportive care. Cases should be encouraged to practise good hand hygiene, avoid sharing drinking glasses or utensils, and cover coughs and sneezes with a tissue or forearm.

Clinical cases should be advised to stay home from school or post-secondary educational institutions, child care facilities, workplaces, and other group settings for 5 days from symptom onset. Self-isolation will prevent exposure of susceptible individuals to the virus. CDC has revised their recommendation for self-isolation from 9 days to 5 days, citing new information about the period of communicability of mumps(12). Although the mumps virus has been isolated from respiratory secretions >5 days after parotitis onset, the risk of transmission 5 days after parotitis onset is low(12). During recent mumps outbreaks in Nova Scotia (2007), Iowa (2006), and the United Kingdom (2006), local public health authorities found that there were compliance issues with the 9-day self-isolation requests.

Cases in health care facilities should be managed with droplet precautions (in addition to routine practice) until 5 days after symptom onset.

Table 6. Case management recommendations
Case management (clinical cases should be managed as confirmed cases until laboratory evidence suggests otherwise)
  1. Mumps is a reportable disease in all Canadian jurisdictions, and public health authorities should be notified through the usual channels.
  2. In the absence of an epidemiologic link to a confirmed case, an oral swab (buccal specimen is preferred) should be obtained for laboratory confirmation (refer to Section 5.0 and Appendix 4).
  3. Assess risk factors: obtain immunization and/or disease history, assess epidemiologic links to cases or settings, including travel.
  4. There is no specific treatment for mumps, only supportive care.
  5. Advise the case to
    • stay home (self-isolate) for 5 days from symptom onset;
    • perform hand hygiene (wash with soap and water or use an alcohol-based hand rub) frequently;
    • avoid sharing drinking glasses, eating utensils or any object used on the nose or mouth; and
    • cover coughs and sneezes with a tissue or forearm.
  6. Cases admitted to a health care facility should be managed with droplet precautions until 5 days after the onset of symptoms.

6.3 Contact Management (Refer to Section 6.4.3 for management of contacts who are health care workers)

Contacts of mumps cases (as defined in Section 4.3) who are considered susceptible to mumps infection include the following:

  1. those born in Canada in 1970 or later who did not receive two doses of mumpscontaining vaccine (at least 4 weeks apart) after their first birthday;
  2. those who have not had laboratoryconfirmed mumps; and
  3. those who do not have documented immunity to mumps(16).

Immunization of mumps-susceptible contacts with MMR vaccine should be considered. However, immunization after exposure may not prevent infection. Passive immunization with immunoglobulin is not effective in preventing mumps. In addition, isolation of mumps-susceptible contacts is not required. On the basis of the epidemiology of the outbreak, susceptible groups should be targeted for immunization, especially those at greatest risk of exposure. Mumps immunization is further discussed in Section 7.0.

Public health capacity during the 2007 outbreak in the Maritimes was quickly overwhelmed by the resources required for individual contact tracing and management. At the start of an outbreak, individual contacts can be managed either directly by public health authorities or indirectly by asking cases to disseminate information to their contacts. Depending on the age groups and settings involved in the outbreak, alternative follow-up mechanisms may be considered to effectively reach large numbers of contacts and other at-risk groups. Examples of alternatives that were used are letters or cards to copy and distribute, the Internet or established e-mail distribution lists, public service announcements, press releases, and a toll-free telephone number.

The logistics of providing immunization to susceptible contacts and at-risk populations should be carefully considered. Some of the issues encountered in managing previous out-breaks included vaccine supply and acquisition costs, low uptake by the college/university-aged cohort, accurate determination of susceptible groups complicated by poor or non-existent immunization records, and vaccine administration and related costs.

To minimize the spread of the virus and the impact on vulnerable groups, contacts with serious mumps-like symptoms should be advised to call ahead before visiting their health care provider. In the event of a large community outbreak where Public Health has set up triage centres, it is appropriate for potential cases to be redirected to one of these centres. For an individual who has developed mild mumps-like symptoms not requiring medical attention, a call to Public Health would ensure that they are included in case counts for the outbreak.

Contacts that are in a health care facility should be managed using droplet precautions for the duration of their period of communicability.

Table 7. Recommendations for contact management
Contact management

Regardless of the mechanism, the dissemination of information to contacts should include

  • information on mumps disease, its symptoms and prevention; and
  • advice to visit one’s health care provider should any symptoms develop, but call before going (if possible).

Offer immunization to susceptible groups as defined by the epidemiology of the outbreak; recognize that immunization may not prevent disease if the individual is already infected. Previous outbreaks have indicated that immunization uptake is low.

6.4 Exposure Settings

The management, prevention, and control of mumps may be specific to the exposure settings affected. Management of mumps cases and contacts in three of the commonly experienced high-risk exposure settings are described below.

6.4.1 Gatherings

Gatherings apply to events of all sizes, in both private and public forums. Gatherings include social or religious functions, sports activities, organized shopping excursions, concerts, conferences, and meetings, as well as public transit. During an outbreak, events need not be cancelled, although jurisdictions may consider postponing gatherings that may pose a risk for transmission or involve vulnerable populations (e.g., well-baby clinics).

It is prudent for organizers to use these opportunities to inform participants about the potential for disease transmission and methods to minimize the spread of the disease, including immunization, practising good hand hygiene, avoiding sharing drinking glasses or utensils, covering coughs and sneezes with a tissue or forearm, and staying home when ill(17). Because of the slight but real risk of infection, exposure settings should be widely communicated to the public. Further details on risk communications are found in Section 8.0.

Table 8. Recommendations regarding gatherings
Gatherings

During an outbreak, events need not be cancelled. Public exposure settings should be communicated to the public, and event organizers should advise participants of the following:

  • the potential for exposure and how to prevent spread of the disease (e.g., checking with their health care provider to ensure that immunization is up to date, practising good hand hygiene, avoiding sharing food/drink/utensils, covering coughs and sneezes with a tissue or forearm, staying home when ill);
  • mumps disease, its symptoms, and prevention; and
  • the need to visit their health care provider should any symptoms develop, but call before going (if possible).

6.4.2 Schools/Educational Institutions

Mumps cases should be excluded from school, day care, child care, or the workplace until 5 days after the onset of symptoms. Caregivers are to be advised to keep the child away from other susceptible children and adults for the period of exclusion. Schools/educational institutions may already have exclusion policies in place; this varies depending on the affected jurisdictions. The risk of exposure should also be communicated to all staff, students, and families.

Table 9. Recommendations for schools and educational institutions
Schools/educational institutions

Encourage schools/educational institutions to practise good general hygiene to prevent disease spread (e.g., practise good hand hygiene, avoid sharing food/drink/utensils, cover coughs and sneezes with a tissue or forearm, and stay home when ill).

If a case is identified, notify staff, students, and families.

Refer to Section 4.3 for the definitions of contacts of cases.

6.4.3 Health Care Settings

Health care settings include acute care and long- term care facilities, as well as home care. In these settings, a health care worker has the potential to acquire or transmit an infectious agent during the course of his or her work. Examples include nurses, physicians, support staff, home-care workers, emergency responders, students, and volunteers.

There is a small body of literature describing the impact of mumps—both isolated cases and outbreaks—in the health care setting. According to experience with mumps in hospitals during a Tennessee outbreak in 1986–1987, the introduction of mumps by either employees or patients is likely during an epidemic(18).

During the recent Nova Scotia outbreak and as of December 2007, mumps was diagnosed in 37 health care workers (personal communication: S. Clay, Nova Scotia Department of Health Promotion and Protection, Halifax, 2007) It was difficult to distinguish community versus occupational exposure, but, in the region with the majority of cases, most of the health care worker cases were related to community exposures with no clearly documented cross-transmissions to other health care workers or patients (personal communication: L. Johnston, Nova Scotia’s Capital District Health Authority). During the Iowa outbreak, there were no cases of mumps among exposed, non-immune health care workers (unpublished data: D. Diekema, 17th Annual Scientific Meeting of the Society for Healthcare Epidemiology of America, Baltimore, 2007). Evidence that mumps can have an impact in the workplace is presented in a report of a Chicago outbreak that documented 119 cases of mumps among employees and their household contacts in three Chicago workplaces(19).

The clinical diagnosis of mumps can be difficult, even in the outbreak setting (see section 5.0), as up to 30% of mumps infections are sub-clinical(20), and a number of other infectious agents can cause mumps-like illness(21). Additionally, many Canadian physicians in practice today will never have seen a case of mumps. Physicians who are familiar with mumps are a definite asset to an occupational health program. A mumps diagnosis may not be easy to make or to exclude. This difficulty becomes an important one when managing potential mumps cases and exposures in the health care setting.

While mumps is largely a self-limited illness, a small number of affected individuals will experience complications or chronic consequences of acute mumps. There are limited data on whether hospitalized or immunocompromised patients experience increased or more severe complications from mumps.

The available evidence indicates that there is a population of health care workers that is susceptible to mumps. Serologic testing during the 2007 Nova Scotia outbreak found that 83.4% of those born before 1970 and 67.7 % of those born after had laboratory evidence of immunity (unpublished data: S. Clay, 34th Annual Conference of the Association for Professionals in Infection Control and Epidemiology, San Jose, 2007). A community mumps outbreak can have considerable impact on health care settings and health care capacity. Factors contributing to the potential for mumps transmission in health care settings are as follows: the long infectious and incubation periods; a high proportion of sub-clinical and misdiagnosed cases; and a sizable population of susceptible health care workers. During a community outbreak, health care workers may be exposed in workplace settings in addition to their community exposures. In one hospital during the Iowa outbreak, there were 31 exposure events involving more than 600 health care workers (unpublished data: D. Diekema, 17th Annual Scientific Meeting of the Society for Healthcare Epidemiology of America, Baltimore, 2007). In Nova Scotia, one region evaluated 2,400 health care workers for reported contacts and furloughed 261 (personal communication: B. Walker, Nova Scotia’s Capital District Health Authority). A number of the exposures involved co-workers at meetings.

To minimize disruption in the health care setting, both the U.S. Centers for Disease Control and Prevention (CDC) and PHAC have guidelines for mumps management(22,23). In addition, the National Advisory Committee on Immunization (NACI) addresses the immunization of health care workers in some of its statements(1). All authorities emphasize the importance of assessing immunity and providing two-dose MMR vaccine to health care workers where indicated before an outbreak occurs. This strategy will result in minimal disruption to health care facilities during a community outbreak. Exclusion of health care workers who are contacts from work should be balanced with the availability of human resources and should consider the outbreak epidemiology.

Assessing the evidence of immunity can be challenging. NACI suggests cautious application of the natural immunity assumption to high-risk adults like health care workers and military personnel(16). This is further supported by Nova Scotia’s serologic results, which suggest that approximately 15% of those born before 1970 may not be immune to mumps. It is therefore recommended that birth in Canada before 1970 not be taken as evidence of immunity for health care workers and that even birth before 1957 offers only presumptive evidence of immunity(22). Furthermore, a self-reported history of mumps is not acceptable as proof of immunity. A positive IgG result may not necessarily indicate immunity, although a negative result may indicate that antibody levels are simply too low to be detected by commercially available assays. See Section 5.0 and Appendix 4 for further details on IgG tests and interpretation of test results.

In addition to the recommendations for health care settings (Table 10), algorithms to assist with the management of health care workers who are close contacts of a case of mumps and the assessment of health care workers for susceptibility to mumps are outlined in Appendix 5 (figures A and B). Management strategies in health care settings should take into account the epidemiology of the outbreak and the composition of the patient population.

Table 10. Recommendations for management of health care workers in health care settings
Health care settings

Health care settings include those related to acute care, long-term care, and home care. Some health care settings may not have occupational health and infection prevention and control departments. When these are mentioned, they refer to the individual(s) responsible for occupational health and infection prevention and control for that health care setting.

A health care worker (HCW) is an individual who may have the potential to acquire or transmit an infectious agent during the course of his or her work in the health care setting (e.g., nurses, physicians, students, volunteers, home-care workers, emergency responders, and support staff ).

Pre-placement of HCWs

  • Occupational Health should document HCW immune status at the pre-placement examination. A HCW is considered immune if there is
    1. documentation of two doses of a mumps-containing vaccine;
    2. documentation of laboratory-confirmed mumps; or
    3. positive mumps IgG (refer to Section 5.0 and Appendix 4 for interpretation
      of IgG results).

Existing HCWs

  • Occupational Health should provide MMR vaccine to all HCWs unless the individual has
    1. documentation of two doses of a mumps-containing vaccine;
    2. documentation of laboratory-confirmed mumps;
    3. positive measles, mumps, and rubella IgG; or
    4. a valid contraindication to measles, mumps, and rubella (MMR) vaccine.

HCWs who are cases

  • Clinical cases are managed as confirmed cases until laboratory evidence suggests otherwise.
  • Advise cases to immediately notify Occupational Health and/or Infection Control for the facility in which they work.
  • Advise case to stay home for 5 days from symptom onset and until symptoms have resolved.
  • Cases are to report to Occupational Health and/or Infection Control for their facility to determine fitness to return to work.

HCWs who are contacts

For contact in the community (see Section 4.3) and contact in the health care setting (if unprotected face-to-face interaction within 1 metre of an infectious mumps case)

  • Advise HCWs to immediately notify Occupational Health and/or Infection Control for the facility in which they work.
  • Provide information on mumps disease and its symptoms.
  • Assess immunity to mumps if not assessed at pre-placement:
    • documented two doses of mumps-containing vaccine, can return to work immediately;
    • documented laboratory-confirmed mumps infection, can return to work immediately;
    • documented one dose of mumps-containing vaccine, provide a dose of MMR vaccine and return to work immediately; or
    • undocumented immunization history:
      • draw blood for MMR IgG serology;
      • provide a dose of MMR vaccine (after specimen taken);
      • while waiting for serology results, exclude HCW from work for the period of communicability, which starts on day 10 after exposure when exposure is day 1;
      • refer to Section 5.0 and Appendix 4 for interpretation of IgG results:
        1. if IgG positive, then consider immune and can return to work, but consider a second dose of MMR vaccine for adequate measles protection;
        2. if IgG negative, then consider susceptible, provide a second dose of MMR vaccine 28 days after the first and exclude from work on day 10 after first exposure until day 26 after last exposure.

6.5 Travellers

When a case of mumps is being investigated, the travel history as a potential risk factor should be considered both within and outside of Canada. The provincial/territorial health authority that identifies an infectious traveller should advise the provincial/territorial health authority of the area of residence of the case and of any known contacts, so that the authorities may follow up accordingly. The identifying health authority should also report the information to PHAC.

When cases or contacts are from a different country, the identifying provincial/territorial health authority should notify PHAC, which will contact the appropriate authority of the affected country. When international travellers associated with mumps cases or contacts are identified by the Quarantine Service or Duty Officers at an international port of entry, PHAC will notify the appropriate provincial/territorial or international public health authority.

When multiple jurisdictions are involved, it is not always clear who should report a case. Case reporting is important for describing and monitoring the epidemiology, impact, and spread of an outbreak. Therefore, during outbreaks, the jurisdiction that initially identifies and primarily handles the case is asked to report it. This decision rule is flexible and should be evaluated for each case, considering place of residence, travel itinerary, and the public health response or intervention that was implemented.

6.5.1 Airplanes

PHAC, the CDC, the World Health Organization (WHO), and the International Air Transport Association have guidelines on when and how to notify passengers and flight crew after they have been exposed to certain infectious diseases aboard international commercial aircraft(24-27). These guidelines apply mainly to highly communicable or virulent diseases such as tuberculosis, measles, or meningococcal disease, as well as other conditions listed in the Quarantine Act(28).

The appropriate public health response to exposure and transmission of mumps during commercial air travel varies. During the 2006 mumps outbreak in Iowa, the CDC initiated contact tracing of passengers sitting near an infectious passenger for flights of 5 hours or longer. The U.K. and Canada, on the other hand, generally do not follow up on the reported exposure of mumps on aircraft. In Canada, if a traveller infected with mumps has travelled by air during the infectious period (7 days before onset of symptoms to 5 days after the onset of symptoms), the local public health authorities and PHAC should be consulted. However, contact tracing through a passenger manifest is not necessary since the guidelines for tuberculosis, measles, and meningococcal disease may not apply to less infectious and self-limited diseases like mumps. In addition, follow-up is not performed, as there is no treatment or prophylactic intervention for mumps, and the passenger manifests are difficult to obtain and/or are often incomplete.

Communication of the traveller’s itinerary should be considered by the overseeing public health authority so that other jurisdictions are aware of the potential exposure, as they may have different protocols or be assessing changes in their own mumps activity. Non-nominal travel details can be shared with public health professionals across the country through the Canadian Integrated Outbreak Surveillance Centre, a secure, Webbased, alerting application.

In Canada, airlines can refuse permission to board to individuals who appear to have an infectious disease.

6.5.2 Cruise Ships

Respiratory tract infections are frequent in cruise ship settings. In the event of an identified mumps outbreak, the cruise ship’s health services would have responsibility for the traveller’s health during the cruise and would follow up with contacts according to the conveyance operator’s policy.

Ninety-six hours before port arrival, ships are to report to Canadian port authorities as to the presence and status of anyone aboard with certain communicable diseases. If a condition of quarantine or public health concern is suspected, the port authority will notify National Quarantine Services (PHAC) to meet the ship upon arrival; PHAC will then alert the provinces and territories if an outbreak is confirmed. In Canada, cruise lines can refuse permission to board to individuals who appear to have an infectious disease.

In Canada, cruise lines can refuse permission to board to individuals who appear to have an infectious disease.

Table 11. Recommendations for travellers
Travellers

Travellers should ensure that their routine immunizations are up to date. As mumps is transmitted through infected oral/nasal secretions, travellers should protect themselves and others by practising good hand hygiene, coughing or sneezing into a tissue or forearm, and avoiding sharing food, drinks, or utensils.

In Canada, individuals can be refused permission to board an aircraft or cruise ship if they appear to have an infectious disease. Travellers with symptoms of mumps, including fever, should postpone travel until they are better.

When provincial/territorial borders are crossed, the province or territory where the case was diagnosed should alert other provinces/territories and the Public Health Agency of Canada (Centre for Immunization and Respiratory Infectious Diseases). When international borders are crossed, the province or territory where the case was diagnosed should alert the Public Health Agency of Canada (Centre for Immunization and Respiratory Infectious Diseases) which will, in turn, notify the appropriate international authorities.

 


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