Vaccine-Preventable Diseases

Rubella

Rubella is a viral disease that results in a transient erythematous rash, post-auricular or suboccipital lymphadenopathy, arthralgia and low-grade fever. As symptoms are non-specific, it may be mistaken for infection due to parvovirus, adenoviruses or enteroviruses. Adult infection is frequently accompanied by transient polyarthralgia or polyarthritis. Serious complications are rare, and up to 50% of infections are subclinical.

The main goal of immunization is the prevention of rubella infection in pregnancy, which may give rise to congenital rubella syndrome (CRS). This syndrome can result in miscarriage, stillbirth and fetal malformations, including congenital heart disease, cataracts, deafness and mental retardation. Fetal infection can occur at any stage of pregnancy, but the risk of fetal damage following maternal infection is particularly high in the earliest months after conception (85% in the first trimester) with progressive diminution of risk thereafter, and it is very uncommon after the 20th week of pregnancy. Infected infants who appear normal at birth may later show eye, ear or brain damage. Congenital infection may give rise to such problems as diabetes mellitus and panencephalitis later in life. Congenitally infected infants may shed the virus in the urine and in nasopharyngeal secretions for 1 year or more.

Epidemiology

An MMR immunization program for all infants was introduced in Canada in April 1983. The average number of rubella cases reported decreased from approximately 5,300 (1971-1982) to fewer than 30 cases per year (1998-2004). The average annual incidence decreased from 0.08 per 100,000 in 1998 to 0.03 per 100,000 in 2004 (range: 0.02-0.09 per 100,000 per year).

In the two decades following the introduction of routine infant immunization, epidemics of rubella continued to occur every 3 to 10 years with incidence peaking both in the spring and winter months. Many of these outbreaks, including one involving over 3,900 cases in Manitoba in 1997, differentially affected males aged 15-24 years of age who had not been immunized because of previous (before 1983) selective rubella immunization of pre-pubertal girls in some jurisdictions. Since the late 1990s, outbreaks have largely been restricted to isolated clusters of unimmunized people, including those who decline immunization for religious or philosophical reasons.

From 2000 to 2004, fewer than 30 sporadic cases of rubella and 0 to 3 cases of CRS were reported each year in Canada. However, in 2005, in addition to sporadic cases reported in several provinces and territories, there was a rubella outbreak involving over 300 cases in an unimmunized southwestern Ontario community which was philosophically opposed to immunization. These outbreak-related cases accounted for the vast majority of rubella cases in 2005 and primarily involved unimmunized children < 19 years old (median age 11, range 0.3-34 years). Ten cases involved pregnant women, but no cases of CRS have been reported as of March 14, 2006. As a result of immunization rates in excess of 95% in the general population, the outbreak did not spread to the surrounding community.

In Canada, routine infant immunization programs have resulted in sustained high rates of immunity in the general population. In addition, measles elimination strategies since the mid 90s have indirectly resulted in a reduction in the proportion of the susceptible population with the use of rubella-containing vaccines (MR and MMR) for the two-dose routine program and measles elimination catch-up campaigns.

Canada is making progress towards elimination of indigenous rubella infection in pregnancy through routine immunization programs, together with CRS-specific policies to screen 100% of pregnant women for rubella and to offer immunization to all women who are susceptible post-partum. Yet while the rarity of CRS in Canada is a reflection of the impact of these rubella elimination strategies, the risk of cases resulting from importation and limited transmission still exists, both for immigrants arriving from areas of low rubella coverage as well as for Canadian communities and individuals who decline immunization for religious or philosophical reasons. CRS has also been reported in infants of Canadian women who developed rubella infection in pregnancy during travel abroad. Travel-related risk of exposure to rubella may change as more countries initiate childhood rubella immunization programs. By 2003, the majority of Caribbean and South and Central American countries had included rubella in their childhood immunization schedule to comply with the Pan American Health Organization's rubella elimination goals.

Source: Canadian Immunization Guide, 7^th edition, 2006

Links to more information

Guidelines and Recommendations

• For information about Rubella vaccine, see the Canadian Immunization Guide, 7^th edition 2006

Information Sheets

• Childhood Immunization - It's Your Health

Travel Medicine Program

• Rubella