Chapter last reviewed and updated in May 2012.

Epidemiology

New Zealand Epidemiology

There have been no reported cases of congenital rubella in New Zealand since 1998. Internationally, the number of rubella and congenital rubella cases remains high in developing countries, including many Pacific Islands, where routine childhood vaccination is not available or has only recently become available.

More detailed epidemiological information is available on the Institute of Environmental Science and Research (ESR) surveillance website.

Case definition

Clinical description

In general, the younger the fetus when infected, the more severe the illness. Severe cases may spontaneously abort, or have multiple manifestations in infancy; mild cases may have only a single manifestation. The most common anomalies are deafness, cataract or glaucoma, congenital heart disease and mental retardation. In addition, infants with congenital rubella syndrome are often growth retarded and may have radiolucent bone disease, hepatosplenomegaly, thrombocytopenia and purpuric skin lesions.

Laboratory criteria for diagnosis

Laboratory confirmation requires at least one of the following:

  • demonstration of rubella-specific IgM antibody
  • infant rubella antibody level that persists at a higher level and for a longer period than expected from passive transfer of maternal antibody (that is, rubella titre that does not drop at the expected rate of a twofold dilution per month)
  • isolation of rubella virus by culture
  • detection of rubella virus nucleic acid.

Case classification

  • Under investigation: A case that has been notified, but information is not yet available to classify it as probable or confirmed.
  • Probable: A clinically compatible illness.
  • Confirmed: A clinically compatible illness that is laboratory confirmed.
  • Not a case: A case that has been investigated and subsequently found not to meet the case definition.

Spread of infection

Incubation period

14–23 days, commonly 16–18 days.

Mode of transmission

Infants with congenital rubella shed rubella virus in their pharyngeal secretions and urine.

Period of communicability

Infants with congenital rubella may shed the virus for months after birth and should be considered infectious until they are 1 year of age.

Notification

Notification procedure

Attending medical practitioners or laboratories must immediately notify the local medical officer of health of suspected cases. Notification should not await confirmation.

Management of case

Investigation

Ascertain relevant history of maternal vaccination, any maternal symptoms, possible contacts and travel.

Ensure laboratory confirmation by serology or detection of virus in clinical specimens has been attempted. Nasal, throat, urine, blood and cerebrospinal fluid specimens can yield the virus, especially in congenitally infected infants.

Restriction

In health care facilities, infants with congenital rubella syndrome should be managed under contact and droplet isolation precautions until urine and pharyngeal cultures are negative or until approximately 1 year of age. Non-immune pregnant women, in particular, and also non-immune women of childbearing age should not have contact with an infectious case.

Treatment

Nil specific.

Counselling

Advise caregivers of the nature of the infection and its mode of transmission.

Management of contacts

Definition

All people with close unprotected contact (for example, household, workplace, school, military camp) with the case during the week before onset of illness or during the subsequent period of communicability.

Other control measures

Identification of source

Refer to ‘Other control measures’ in the separate chapter on rubella.

Reporting

National reporting

Ensure complete case information is entered into EpiSurv.

If a cluster of cases occurs, contact 0800GETMOH - CD option, and outbreak liaison staff at ESR, and complete the Outbreak Report Form.