Rubella and Congenital Rubella Syndrome (CRS)
28 February 2012
- Rubella is a contagious viral disease and occurs worldwide.
- The disease is commonly a mild childhood diseases; however, infection in early pregnancy may cause fetal death, or serious birth defects known as congenital rubella syndromes (CRS).
- CRS is an important cause of hearing, visual impairment and mental retardation in countries where rubella is endemic.
- There is no specific treatment for rubella and CRS, but they can be prevented by immunization.
- The Western Pacific Region has established a goal of accelerating control of rubella and prevention of CRS.
Disease and complications
- Rubella virus, a Togavirus of the genus rubivirus, is an enveloped single-stranded RNA virus with a single serotype. Humans are the only known host.
- In children, rubella is usually mild, characterized by a transient, erythematous rash, conjunctivitis, coryza, postauricular and suboccipital lymphadenopathy, low fever and nausea.
- Complications of rubella are not common, but they tend to occur more often in adults than in children. Up to 70% infected adults may develop arthritis and painful joints.
- The most important and serious consequence of rubella is congenital rubella infection. When primary rubella infection occurs in a pregnant woman, the virus can infect the placenta and fetus.
- The risk of congenital rubella infection is related to gestational age at the time of maternal infection. When pregnant women are infected with rubella during the first 11 weeks of gestation, up to 90% of liveborn infants will have CRS. CRS rate declines thereafter until 17-18 weeks gestation when deafness is rare and the only consequence.
- The outcome of rubella infection during pregnancy includes: spontaneous abortion, stillbirth/fetal death, infant born with CRS.
- The most common defects of CRS are hearing impairment, eye defects (e.g. cataracts) and cardiac defects (e.g. patent ductus arteriosus-PDA). There are other clinical manifestations, such as Microcephaly, developmental delay, or low birth rate.
- Children with CRS may develop late-onset manifestations, such as diabetes mellitus, thyroid dysfunction, visual or neurological abnormalities.
- Natural rubella infection normally confers lifelong immunity.
- Diagnosis of rubella requires laboratory confirmation and serology is the preferred method for routine laboratory diagnosis.
- Rubella affects only humans.
- Rubella virus is transmitted by respiratory routine and virus replicates in nasopharyngeal mucosa and local lymph nodes.
- The incubation period ranges from 12 to 23 days after exposure, with an average of 18 days.
- A person with rubella can infect others from one week before and at least four days after onset of rash.
- Infants with CRS shed large quantities of virus in their pharyngeal secretions and urine for months after birth, and serve as a source of infection to their contacts.
Treatment and case management
- There is no specific treatment for rubella and CRS. Treatment should be symptomatic.
- Suspected rubella infection among a pregnant woman or contacts of a pregnant woman should be laboratory confirmed as a matter of urgency wherever possible, and professional advice from physician should be timely sought.
- A pregnant woman with confirmed or suspected rubella infection or known rubella exposure should be well followed-up to monitor the outcome of pregnancy (e.g. abortion, stillbirth, CRS). Vaccine
- The current licensed rubella vaccines in wide international use are based on the live attenuated RA 27/3 strain of the virus.
- Rubella vaccine can be administered at 9 months or 12-15 months of age, in combination with measles or mumps (MR, MMR, MMRV), or in monovalent form, usually based on appropriate age for measles vaccination.
- One dose schedule is sufficient.
- Primary purpose of rubella vaccination is to prevent the occurrence of congenital rubella infection including CRS.
- Rubella vaccine is very safe.
- Generally, adverse events following rubella vaccination are mild, particularly in children.
- Common transient adverse events include pain, redness and induration at the site of injection, low-grade fever and rash.
- Rubella vaccination should be avoided in pregnancy because of the theoretic, but never demonstrated, teratogenic risk.
- Persons with a history of an anaphylactic reaction after a previous dose of rubella vaccine or anaphylactic reaction to neomycin should not receive the vaccination.
- Rubella vaccines should not be given to persons suffering from advanced immunodeficiency including congenital immunize disorders, malignancies and immunosuppressive therapy.
- The RA27/3 rubella vaccine is highly efficacious.
- Studies prove that 95%-100% of susceptible children aged 12 months and older develop rubella antibodies after vaccination. Vaccination even at 9 months of age still results in seroconversion rates of > 95%.
- Vaccine-induced immunity is generally believed to be lifelong.
Rubella Control Goal in the Western Pacific Region
- Globally, two regions have established rubella and CRS elimination goal, in Region of Americas by 2000 and European Region by 2015.
- In the WPR, accelerating control of rubella and prevention of CRS through integration with measles elimination activities has been emphasized in Regional Committee resolutions (2003, 2010).
- During the 2010 meeting of Technical Advisory Group on Immunization and Vaccination (TAG) for WPR, the TAG endorsed a target of decreasing rubella incidence to < 10 cases per million population and CRS incidence to < 10 cases per million live births, ideally by 2015.
Status of Rubella Control in the Western Pacific Region
- Rubella affects countries unequally in the Western Pacific Region (WPR). Some have likely eliminated rubella or have very high levels of control while others remain highly endemic.
- Based on the WHO/UNICEF Joint Reporting Form on Immunization, reported rubella incidence was 26 per million population in the Region in 2010, down from 40 per million population in 2009; however, because rubella is a mild disease, it is under-recognized and under-reported.
- In 2010, twenty-five countries and areas reported less than 10 rubella cases per 1 million population, but these account for only 15 % of the regional population.
- Based on available data from 2008 – 2010, over 80% of reported rubella cases occurred in the persons under 20 years old Still, more than 30% of female cases were in their childbearing years (15-44 years old).
- Disease burden of CRS is under-recognized and under-reported in most developing countries in the Western Pacific Region.
- Four countries, China, Cambodia, Papua New Guinea and Viet Nam, established sentinel CRS surveillance in 2010-2011.
- The Philippines and the Lao People's Democratic Republic are planning to conduct retrospective studies of CRS in 2012 to determine disease burden.
- By 2011, most countries and areas provide rubella vaccination through either their national immunization programmes or periodic supplementary immunization activities (SIAs), or both, except Cambodia, Papua New Guinea, Solomon Islands, Vanuatu and Vietnam.
- In 2011, the Lao People's Democratic Republic and the Philippines conducted nationwide MR supplementary immunization activities, targeting persons from 9 months up to 19 years old in Lao PDR and 9 months to 7 years old in the Philippines.
- The five remaining countries, Cambodia, Papua New Guinea, Solomon Islands, Vanuatu and Vietnam, are considering introduction of rubella vaccine nationwide in the near future, either through national routine immunization or SIAs, or both.