Rubella

Synonym: German measles

Rubella is a viral infection once seen mainly in spring and early summer. Epidemics occur every six to nine years in populations with no vaccination programme^[1]. Before introduction of vaccination it was endemic in virtually all countries.

It is now quite rare in developed nations since the introduction of immunisation (see the separate article Measles, Mumps and Rubella (MMR) Vaccination). The vaccine is safe and vaccination is a very successful health intervention.

In the absence of mass vaccination, approximately 10-20% of women reaching child-bearing age are susceptible to rubella^[2].

Pathophysiology

• An RNA virus (genus Rubivirus, family Togaviridae) with man as the only known host:
  • There is only one major antigenic type.
  • It is transmitted as airborne droplets between close contacts (unlike most togaviruses which are arthropod-borne).
  • The incubation period is 14-21 days with patients being infectious for up to seven days before and four days after symptoms appear.
  • Infectivity is greatest just before and on the day of symptoms appearing.
• Its major complication of maternal infection in early pregnancy is congenital rubella syndrome (CRS) - see the separate article Rubella and Pregnancy:
  • This causes a wide variety of malformations affecting the cardiac, ocular, central nervous and skeletal systems when a pregnant mother is infected.
  • This is still a problem in many developing countries.

Epidemiology

• Since 1991, only around one third of CRS infants have been born to UK-born women who acquired the infection in the UK.
• There were 12 confirmed cases of rubella in England and Wales^[3].
• It should be remembered that rubella remains endemic in many developing countries and that over 100,000 children worldwide every year are born with CRS.

Presentation

Symptoms

• Prodromal phase of lassitude, low-grade fever, headache, mild conjunctivitis and anorexia with rhinorrhoea very similar to a cold. The prodrome may be absent in children and tends to be more noticeable in adults.
• The rash then develops (it may be absent, especially in young children) - initially, pink discrete macules that coalesce, starting behind the ears and on the face, spreading to the trunk and then the extremities.
• Cervical, suboccipital and postauricular lymphadenopathy are characteristic and may precede the rash.
• Constitutional symptoms are usually mild (can be more prominent in adults).
• In older patients, arthralgia is common.

Signs

• There may be petechiae on the soft palate (Forchheimer's sign) but this is not diagnostic for rubella.
• The rash is shown in close-up but it should be remembered that clinical diagnosis is unreliable.
• The rash usually develops 14-17 days after exposure to the virus.

Rubella rash

Differential diagnosis

• Contact dermatitis.
• Erythema multiforme/drug allergy.
• Measles.
• Cutaneous manifestations of syphilis.
• Scarlet fever.
• Kawasaki disease.
• Arthropod-borne infections (eg, Rocky Mountain spotted fever).

Investigations

Clinical diagnosis is unreliable since symptoms are often fleeting and mimicked by other viruses. In particular, the rash is not diagnostic.

• Serological and/or polymerase chain reaction (PCR) testing is the gold standard investigation and the local Health Protection Unit (HPU) can provide a testing kit^[4].
• FBC may show a low WBC count with an increased proportion of lymphocytes and thrombocytopenia (usually resolves in a month).

Management

• There is no specific treatment.
• Keep the child away from school for four days after the rash appears.
• Use antipyretics for fever - avoid aspirin in children, due to the danger of Reye's syndrome.
• Ask about any contact with pregnant women.
• Where suspected infection occurs in a pregnant woman, it should be confirmed by investigation, in liaison with a virologist, and counselling should be given about the dangers to the fetus. Management requires referral and expert support.

Complications

Complications occur rarely.

• Rubella encephalopathy may occur about six days after the rash (usually there is full recovery in a few days without sequelae).
• Arthritis and arthralgia can occur in adults.
• Thrombocytopenia occurs in around 1 in 3,000 cases.
• Guillain-Barré syndrome/neuritis.
• Panencephalitis.

Prevention

• The advice is that children should be excluded from school for four days after onset of the rash^[5].
• Vaccination via MMR in the second year of life plus a preschool booster, with antenatal screening for rubella susceptibility.
• Where non-immunity to rubella is discovered during pregnancy, immunisation after delivery offers protection for future pregnancies.
• The vaccine has been proven to be safe, immunogenic and effective^[6].
• The overall decline in rubella incidence and increase in the number of countries conducting rubella surveillance through a mandatory notification system are notable achievements toward the goal of rubella elimination in Europe^[7].

Rubella in pregnancy

See the separate Rubella and Pregnancy article.