Rubella

Overview

Rubella, also known as German measles, is usually mild and characterised by febrile illness with a diffuse punctate and maculopapular rash sometimes resembling that of measles or scarlet fever.

Disease epidemiology

Majority of countries worldwide have included rubella vaccination as part of their national immunisation programme. Countries with good vaccination coverage have seen a significant decline in the incidence of rubella and congenital rubella syndrome (CRS). Incidence of CRS is highest in areas of Africa and Southeast Asia where vaccine coverage is low. Humans are the only reservoir of rubella.

Rubella immunisation in Singapore was introduced in 1976 and included as part of the trivalent measles, mumps, rubella (MMR) vaccine in 1990. A two-dose MMR vaccine regime was introduced in 1998 under the National Childhood Immunisation Schedule, in which the first dose is given at 12 months, and the second dose at 15 to 18 months.

Pathogen(s)

Rubella virus

Transmission

Rubella primarily transmits through inhalation or direct deposition of infectious respiratory particles (IRPs) such as when an infected person coughs or sneezes. It can also spread via contact with contaminated surfaces such as when IRPs settle on surfaces or transfer through contact (e.g. handshake) before reaching the mouth, nose or eyes.

Maternal-foetal transmission may occur, with the highest risk of CRS ensuing if infection occurs in the first trimester.

Incubation period: Typically 14 to 17 days; ranging from 14 to 21 days.

Infectious period: From 7 days before and up to 7 days after rash onset. Infants with CRS may shed the virus up to 1 year after birth.

Clinical features

Many cases are subclinical. Rubella is a mild self-limiting viral illness. Infection usually starts with a prodrome that lasts 1-5 days with symptoms that include low grade fever, headache, malaise, anorexia, coryza and conjunctivitis. Tender occipital, postauricular and cervical lymphadenopathy is a characteristic feature, and precedes the appearance of rash. These symptoms subside rapidly after the rash appears. The rash progresses in a cephalo-caudal direction and usually subsides in 3 days. By the end of the first day of rash, the body is covered with red, discrete maculopapules. By the third day, the rash disappears without any staining or desquamation.

Complications such as arthralgia and arthritis, which are more common in adults, clear in about 5-10 days. Encephalitis and thrombocytopenia are rare. The risk of foetal infection and congenital anomalies depends on the stage of pregnancy at which infection occurs (risk is highest in the first trimester). Differentials for rubella rash include roseola infantum, drug rash, infectious mononucleosis, enteroviral infections, mild measles and scarlet fever.

Risk factors

All persons who are unvaccinated or partially vaccinated.

Diagnosis

Positive results for polymerase chain reaction (PCR), virus isolation or serology (IgM or four-fold rise in antibody titre).

Treatment and management

Management is symptomatic.

If infection occurs in early pregnancy, the patient should be referred to a gynaecologist or an Infectious Diseases physician who can provide advice and counselling on the possible risks of CRS and appropriate management at that point in pregnancy.

Precaution, prevention, and control

Isolation measures

All cases should be isolated and managed under airborne precautions.

Contact management

Pregnant contacts should be identified and those who do not have adequate proof of immunity should be offered serological testing for rubella-specific IgM and IgG antibodies.

Vaccination

Vaccination with the MMR vaccine is the main preventive measure against rubella.

The National Childhood Immunisation Schedule recommends that all children should receive 2 doses from age 12 months onwards, at least 4 weeks apart.

The National Adult Immunisation Schedule recommends that adults (18 years or older) who have not been vaccinated, or lack evidence of past infection or immunity should receive 2 doses (the first dose, and the second dose 4 weeks after the first dose).

Notification

Rubella is a legally notifiable disease in Singapore.

Who should notify:

• Medical practitioners

• Laboratories

When to notify:

• On clinical suspicion or laboratory confirmation

How to notify:

• Please refer to the Infectious Disease Notification for more information.

Notification timeline:

• As soon as possible. No later than 24 hours.

Resources

Please refer to the Weekly Infectious Diseases Bulletin for the number of rubella cases in Singapore.

For more information on rubella, please refer to the World Health Organization website.

For general travel advisory, please refer to Health Advice for Travellers.