Rubella (German measles)

Notification requirement for rubella (German measles)

Rubella and congenital rubella syndrome are ‘routine’ notifiable conditions and must be notified by medical practitioners and pathology services in writing within 5 days of diagnosis.

This is a Victorian statutory requirement.

Primary school and children’s services centres exclusion for rubella (German measles)

Exclude until fully recovered or at least 4 days after the onset of the rash.

Infectious agent for rubella (German measles)

Rubella virus of the Togaviridae family is the infective agent.

Identification of rubella (German measles)

Clinical features

Rubella is a mild febrile viral illness characterised by a diffuse punctate and maculopapular rash. Children usually experience few or no constitutional symptoms, but adults may experience a 1–5-day prodrome of low-grade fever, headache, malaise, mild coryza and conjunctivitis. Post-auricular, occipital and posterior cervical lymphadenopathy is common, and precedes the rash by 5–10 days.

Complications include arthralgia and, less commonly, arthritis, particularly among adult females. Encephalitis is a rare complication.

Congenital rubella syndrome (CRS) occurs in less than 25 per cent of infants born to women who acquire rubella during the first trimester of pregnancy. The risk of a single congenital defect falls to approximately 10–20 per cent by the 16th week of pregnancy. Defects are rare when the maternal infection occurs after the 20th week of gestation.

Differential diagnosis includes measles, human parvovirus (‘slapped cheek’) infection, human herpesvirus 6 (roseola) infection and a large number of other rashes of varied aetiology.

Diagnosis

Clinical diagnosis should be confirmed by one or more of the following:

• demonstration of rubella-specific IgM antibody, except following rubella immunisation
• fourfold or greater rise in rubella antibody titre between acute and convalescent-phase sera obtained at least 2 weeks apart
• isolation of rubella virus from a clinical specimen.

Consider also testing for other similar exanthems, such as measles and human parvovirus.

Incubation period of rubella virus

The incubation period is usually 14–17 days. It ranges from 14 to 21 days.

Public health significance and occurrence of rubella (German measles)

Rubella occurs worldwide and is universally endemic, except in remote and isolated communities. It is most prevalent in winter and spring.

A combined measles–mumps–rubella (MMR) vaccine was first added to the routine childhood immunisation schedule in 1983. This has led to a dramatic reduction in the number of confirmed cases of rubella infection in Australia.

Routine serological testing of suspected clinical cases of rubella in Victoria has revealed that only a small proportion of these cases can be confirmed in the laboratory. The remainder are likely to be due to other causes.

Unimmunised travellers and their unimmunised contacts remain at risk of infection.

CRS was a major cause of congenital abnormalities, including deafness, before the infant immunisation program. Although CRS is now rare, the risk of infection remains for unimmunised pregnant women. Such women have been infected primarily by people who have not been included in rubella vaccine programs.

Reservoir for rubella virus

Humans are the reservoir.

Mode of transmission of rubella virus

Rubella is transmitted by droplet spread or direct contact with infectious patients.

Infants with CRS shed the rubella virus in their nose, pharyngeal secretions and urine for months or even years.

Period of communicability of rubella (German measles)

Rubella is communicable approximately 1 week before and for at least 4 days after the onset of the rash.

CRS infants may shed the virus for months or longer after birth.

Susceptibility and resistance to rubella (German measles)

Immunity after natural disease is usually lifelong. Immunity after vaccination is long term and usually lifelong, although reinfection of vaccine recipients has been observed, including asymptomatic reinfection.

Passive maternal immunity is acquired transplacentally. Infants born to immune mothers are ordinarily protected for 6–9 months, depending on the amount of maternal antibodies transferred.

Control measures for rubella (German measles)

Preventive measures

MMR vaccine is recommended for all infants at the age of 12 and 18 months.

Women of childbearing age should be tested for immunity to rubella before pregnancy, if possible. All nonpregnant seronegative women should be offered rubella vaccine.

Women receiving rubella vaccine should be instructed to avoid pregnancy for 28 days after vaccination. Inadvertent rubella vaccination during pregnancy has not been associated with any CRS-like defects; it is not necessary to consider termination.

Women attending for antenatal care who are unaware of their immune status should be tested for rubella antibodies. If IgG negative or at insufficient titre, they should be vaccinated immediately postpartum.

All health workers should receive rubella vaccine, if not immune.

Control of case

There is no specific treatment.

The case should be excluded from school and childcare for at least 4 days after onset of the rash. Adults should not go to work for the same period of time.

Patients with rubella should avoid contact with other people, particularly pregnant women, while infectious.

If a person with suspected rubella is pregnant, the diagnosis should be confirmed serologically, and the patient referred to a specialist obstetrician for advice, taking care not to expose other pregnant women to possible infection in the process.

Control of contacts

School contacts should not be excluded from school, regardless of immunisation status.

Although immunisation is generally recommended for nonimmune contacts (except pregnant women), it is unlikely to reduce the risk of infection or illness. Immunoglobulin is not generally recommended, except for some pregnant contacts.

Pregnant women in whom immunity to rubella has not been confirmed for the current pregnancy and who may have been exposed to rubella must be investigated serologically. This should occur irrespective of a history of vaccination, clinical rubella or previous positive rubella antibody.

Immunoglobulin should be considered after exposure to rubella in early pregnancy. It may not prevent infection or viraemia, but may prolong the incubation period and therefore slightly reduce the risk to the baby.

Control of environment

Not applicable.

Outbreak measures for rubella (German measles)

All suspected outbreaks should be reported promptly to the department.

Mass immunisation may be recommended during an outbreak of rubella in a school setting, regardless of immune status.