18 Rubella

18.2 Clinical features

Clinical features include a transient erythematous rash and lymphadenopathy without respiratory symptoms. Arthritis or arthralgia is relatively common and a classic feature of infection in adults. While usually a mild childhood illness, rubella may also present as a more severe illness, clinically indistinguishable from measles. Encephalitis occurs with a prevalence of approximately 1 in 6000 cases and may result in residual neurological damage or, occasionally, death. Thrombocytopenia rarely occurs.

Clinical diagnosis is unreliable because the symptoms are often fleeting and can be mimicked by other viruses. In particular, the rash is not diagnostic of rubella. A history of rubella should never be accepted as proof of immunity without laboratory confirmation.

Transmission of rubella is through direct or droplet contact with infected nasopharyngeal secretions. The incubation period is usually 16 to 18 days (range 14 to 23 days) and infectivity is between seven days before and seven days after the onset of the rash. Infants with congenital rubella shed rubella virus in their pharyngeal secretions and urine for months after birth and should be considered infectious until they are aged 12 months.

Although the vaccine virus is excreted after vaccination, mostly from the pharynx, transmission to susceptible contacts has not been demonstrated (see section 11.7.2). Therefore, a recently immunised contact is not a risk to a pregnant woman.

Maternal rubella in the first eight weeks of pregnancy results in fetal damage in up to 85 percent of infants, and multiple defects are common. The risk of damage declines to 10–20 percent by about 16 weeks’ gestation, and after this stage of pregnancy fetal abnormalities are rare.

Infants born with the congenital rubella syndrome (CRS) may have cataracts, nerve deafness, cardiac malformations, microcephaly, mental retardation and behavioural problems. Inflammatory changes may also be found in the liver, lungs and bone marrow. Some infected infants may appear normal at birth, but have nerve deafness detected later.

The frequency of complications and consequences of rubella infection are best described from the 1963/64 US outbreak, involving 12.5 million cases of rubella and 30,000 infants damaged by intrauterine rubella, an incidence rate of 100 per 10,000 pregnancies (see Table 18.1 below and Table 11.1).

Table 18.1: Estimated morbidity and mortality associated with the 1963/64 US rubella epidemic

Total number of cases of rubella: 12,500,000  
Complications of rubella Risk per case
Arthritis or arthralgia 1.3%
Encephalitis 17 per 100,000
Neonatal deaths 17 per 100,000
Complications caused by congenital rubella syndrome (CRS) Numbers of cases
(% of CRS cases)
Total number with CRS 20,000
Deaf children 8055 (40%)
Deaf–blind children 3580 (18%)
Intellectually handicapped children 1790 (9%)

Source: Adapted from Reef S, Plotkin SA. 2013. Rubella vaccine. In: Plotkin SA, Orenstein WA, Offit PA (eds). Vaccines (6th edition). Elsevier Saunders, Table 31.7.

Rubella infection can occur (very rarely) in individuals with either naturally acquired or vaccine-induced antibody. Rare cases of CRS have been reported after reinfection during pregnancy.

As with measles, public health measures of accurately diagnosing potential cases of rubella with notification and contact tracing are critical (see section 18.8).