Disease factsheet about rubella

factsheet

Rubella (German measles) is a worldwide, mild, exanthematous and highly infectious viral disease of children in unvaccinated populations. Its prominence and the rational for immunising against rubella is the high risk of congenital malformations associated with rubella infection during pregnancy, something first observed by Dr Norman McAlister Gregg during the rubella epidemic in Australia 1940-41. Congenital Rubella Syndrome (CRS) is characterised by a constellation of ophthalmologic, neurologic, cardiac and auditory anomalies. Immunisation with the safe and highly effective attenuated live vaccine started in Europe in 1970s and has had a profound impact on the epidemiology of rubella and CRS.Elimination of rubella requires sustained overall immunisation coverage of more than 95% and maintenance of low levels of susceptibility across all subgroups of a population.

Pathogen

The rubella virus is a RNA virus and belongs to the genus Rubivirus and the family Togaviridae. It is of a single serotype divided into two clades and within these two clades there are at least seven genotypes. The genetic variation does not translate into antigenic differences. Humans are the sole reservoir of rubella virus.

Clinical features and sequelae

Rubella is typically a mild disease with few complications, and infections go unrecognised or are asymptomatic. Children usually have few or no constitutional symptoms but adults may experience a 1–5 days prodrome of fever, malaise, headache and arthralgia. The typical presentation of rubella is a transient, erythematous maculo-papular rash that starts in the face, becomes generalised over 24 hours and lasts for about three days. Enlarged post-auricular and sub-occipital lymph nodes, which precede the rash, are characteristic of rubella and last for 5–8 days.
 
Clinically, rubella is indistinguishable from febrile rash illnesses caused by measles, parvovirus B19, human herpes virus 6 (HHV6), Coxsackie virus, ECHO virus, adenovirus and dengue virus, and laboratory confirmation is required for diagnosis unless there is an epidemiological link to a confirmed case. There are three standard tests for laboratory confirmation of a suspect rubella case: (1) isolation of rubella virus from a clinical specimen; (2) detection of rubella virus nucleic acid in a clinical specimen; or (3) rubella virus specific IgG antibody response in serum or saliva. A specific IgM antibody response indicates a probable acute infection1.
 
Complications of acute rubella are rare, with the exception of rubella infection during pregnancy (see below). Encephalitis occurs in 1 out of 5000–6000 cases of rubella -the presentation can be dramatic but fatalities are rare and most patients recover completely without sequelae-; thrombocytopenia develops in 1 out of 3000 cases; transient polyarthralgia and polyarthritis are common complications in adolescents and adults, but rare in children.
 

Congenital Rubella Syndrome

The clinical presentation of acute rubella in pregnancy is identical to that in non-pregnant women and adults, and asymptomatic and undiagnosed infections are common. Infection during pregnancy carries a considerable risk of the constellation of foetal malformations referred to as Congenital Rubella Syndrome (CRS), foetal death and abortion.  Women who plan to become pregnant should be tested for rubella and immunised if found to be susceptible. Pregnant women should have rubella immunity tested early in pregnancy. The EU case definitions for rubella and for CRS (2002/253/EC) for the purpose of reporting communicable diseases to the community network can be found here.

Epidemiology

Rubella was endemic in Europe before widespread immunisation, with the exception of small and isolated populations, and there were regular epidemics at 6–9 year intervals on top of background transmission. The transmission pattern of rubella is similar to that of measles and rubella was a childhood disease in the pre-vaccine era, with the highest incidence in the 4–9 years age group. Routine immunisation has dramatically changed the epidemiology of rubella in Europe. The vaccine is highly effective, with seroconversion rates of 95–100% and the induced immunity is likely to be lifelong in most recipients. Rubella is a notifiable disease and European surveillance data indicate that the overall incidence of rubella has fallen from about 35 per 100 000 in 2000 to <10 per 100 000 population in 2008.
 
The 27 EU/EEA countries reported 38 847 rubella cases in 2013; Poland accounted for 99% of all reported rubella cases.  In 2012, Romania had the most cases of Rubella in the EU, and notably, Italy had a large outbreak of Rubella in 2008. In 14 countries the rubella notification rate was rate less than one case per million population. Annual updates on rubella incidence are published in ECDC’s Annual epidemiological report on communicable diseases in Europe. The 2013 report is available here.
 
The clinical criteria for rubella surveillance include:
• Maculopapular rash; and
• Cervical, suboccipital or post-auricular lympadenopathy or arthralgia/arthritis.
The laboratory criteria for rubella surveillance case confirmation in non-pregnant cases include:
• Rubella IgM antibody detection;
• Rubella virus isolation; or
• Rubella viral RNA detection by reverse transcriptase PCR; or
• A significant rise in rubella IgG antibody in paired sera.
 
Surveillance guidelines for measles, rubella and CRS can be found here.

Transmission

Rubella is transmitted by direct contact or droplet spread similar to the transmission of measles. Humans are the only known hosts and children born with CRS, who may be infectious for several years, are the only reservoir. The risk of transmission is 10–30%, but varies with the immunisation rate of the population, and infectivity is high in those susceptible. The period of infectivity is seven days before to six days after the onset of rash and the incubation period is 13–20 days.

Prevention

Rubella and measles are targeted for elimination in the WHO European region. The definition of elimination is interruption of indigenous transmission. Small outbreaks due to imported index cases are likely to still occur but circulation should end naturally after a limited number of generations, and the incidence should be below 1 case per 100 000 population. The rubella vaccine is a live attenuated vaccine. The most commonly used strain is Wistar RA 27/3 which has a seroconversion rate of 98% and induces secretory IgA antibodies, a quality that makes vaccination similar to natural infection and prevents reinfection with wild virus. All countries in Europe immunise against rubella with measles-mumps-rubella (MMR) vaccine, a combination vaccine with three live attenuated vaccines against measles, mumps and rubella respectively. Vaccination schedules by country can be found on ECDC’s Vaccine Scheduler. There are two licensed MMR vaccines in Europe: Priorix (GSK) and MMR II (Sanofi Pasteur), both of which contain the Wistar RA 27/3 attenuated rubella strain.
 
Seronegative women of child-bearing age and healthcare workers who need to be protected against rubella should continue to be offered rubella vaccine, usually as combined MMR vaccine.
In most of Europe, rubella antibody testing is offered to all pregnant women as part of their antenatal care. For practical reasons, the test is usually performed irrespective of immunisation history or previous laboratory reports of rubella specific IgG. If a pregnant woman is rubella antibody negative then MMR vaccine should be given post-delivery.

Management and treatment

There is no specific treatment for rubella. Treatment should be symptomatic. Suspected rubella infection among contacts of a pregnant woman should be laboratory confirmed as a matter of urgency wherever possible. If a pregnant woman who has been in contact with a confirmed rubella case has had two documented doses of rubella containing vaccine, at least two previous positive rubella antibody screening tests, or one dose of vaccine followed by a documented positive rubella antibody test, then she should be reassured that the likelihood of her developing rubella is remote. Investigation is not required but she should return if a rash develops. Decisions on the management of a susceptible woman developing a non-vesicular rash or rubella in the first 20 weeks of pregnancy should be taken in partnership with a specialist foetal medicine unit and laboratory services.
 
Note: The information contained in this fact sheet is intended for the purpose of general information and should not be used as a substitute for the individual expertise and judgement of healthcare professionals.
 

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