Volume: 28S4• September 2002

Proceedings of a Meeting of the Expert Advisory Group on Rubella in Canada

Health Canada
Centre for Infectious Disease Prevention and Control
Bureau of Infectious Diseases*

* Now the Health Care Acquired Infections Division, Blood-borne Pathogens Section.

Proceedings of a Meeting of the Expert Advisory Group
on Rubella in Canada
30 Pages - 182 KB in PDF Format

Table of Contents | Summary | Background

Table of Contents

Summary

Rubella and Congenital Rubella Syndrome in Canada
(Dr. Eleni Galanis, Dr. Paul Varughese)

Rubella Overview and the UK/WHO Situation
(Dr. Jenny Best)

Rubella in the U.S. and PAHO
(Dr. Susan Reef)

Rubella Laboratory Diagnostics
(Dr. Graham Tipples)

Waning Immunity to Rubella
(Dr. Sam Ratnam)

Effectiveness of Standard Postpartum Orders for MMR Vaccination
(Dr. Erica Eason)

Review of a “Survey of Late Emerging Manifestations of CRS in Canada”
(Dr. Eleni Galanis)

References

Appendix: List of Participants.

Summary

Background

The Viral Exanthemata Section of the National Microbiology Laboratory, Winnipeg, and the Immunization and Respiratory Infections Division, Centre for Infectious Disease Prevention and Control, hosted a meeting of an Expert Advisory Group on Rubella in Canada on November 22, 2001. The objectives were to review the diagnosis and surveillance of rubella in Canada and to formulate recommendations that would rectify deficiencies in current diagnostic and surveillance methods.

Clinical

Rubella is a viral disease that results in a transient exanthematous rash, lymphadenopathy and low-grade fever. It is generally a mild illness, and serious complications are rare. However, if acquired during the first trimester of pregnancy, there is a 90% risk of congenital malformations in the fetus - congenital rubella syndrome (CRS). Prevention of this syndrome is the main goal of rubella immunization and can be achieved by immunization of children through universal programs as well as immunization of susceptible women of childbearing age.

Epidemiology

Rubella incidence rates in Canada have been approximately two cases per 100,000 in the last 12 years. Fewer than 30 cases of rubella were reported in Canada during the last 2 years, and there were only one to two cases of CRS per year from 1996 to 2000. The elimination of indigenous rubella in Canada should be an achievable goal in the near future. However, Canada has not yet set a national goal for rubella elimination. The U.S. has set a goal to eliminate indigenous rubella and CRS by the year 2010. Importation of rubella cases and immigration of susceptible individuals from regions without rubella vaccination programs are important issues in countries with rubella vaccination programs, such as Canada, the U.S. and the U.K.

Laboratory

Laboratory tests are required to confirm the diagnosis of rubella since the clinical
symptoms are similar to other fever/rash illnesses, such as measles. Thus, rubella and measles laboratory surveillance are integrally linked. The detection of immunoglobulin M (IgM) antibodies is commonly used for diagnosing rubella. Virus isolation, polymerase chain reaction, or IgG serology on paired acute and convalescent sera may also be used for rubella laboratory diagnosis. When the prevalence of rubella is low, as it is in Canada, the positive predictive value of IgM testing decreases such that there can be a significant risk of a false positive result. An alternative laboratory method, such as antibody avidity serologic testing is therefore needed as a confirmatory test, especially for the investigation of rubella in pregnant women, when decisions on termination of pregnancy must be made.

Susceptibility

Studies carried out in Newfoundland indicate that over 20% of women over 14 years of age may be entering the childbearing years without protective antibodies against rubella. It is clear that a significant proportion of those born in the postvaccine era and given a single dose of MMR vaccine are likely to exhibit waning immunity to rubella over time, as the absence of circulating wild virus means that there is no longer a natural booster effect. Whether waning immunity, as defined by the absence of detectable protective rubella antibody, necessarily means susceptibility to rubella infection in previously vaccinated populations has not been established. When a pregnant woman is found to be susceptible to rubella on routine prenatal screening, it is suggested that she seek rubella immunization immediately postpartum. The use of printed, postpartum orders has been shown to increase rubella postpartum immunization rates.

Recommendations

The Expert Advisory Group on Rubella in Canada has made 11 recommendations related to surveillance, immunization, susceptibility screening, and laboratory diagnostics, and has also identified five areas in which more data are required.

Proceedings of a Meeting of the Expert Advisory Group
on Rubella in Canada
30 Pages - 182 KB in PDF Format