RUBELLA

Last updated: 06 September 2004

1. Reason for surveillance

• To monitor the epidemiology of the disease to inform the development of better prevention strategies.

2. Case definition

Probable case
A probable case requires:

• Clinical evidence, AND
• Laboratory suggestive evidence (pregnant women only) OR epidemiological evidence.

Laboratory suggestive evidence
(Pregnant women only)
In a pregnant patient detection of rubella specific IgM that has not been confirmed in a reference laboratory, in the absence of recent rubella vaccination.

Clinical evidence

• A generalised maculopapular rash, AND
• Fever, AND
• Arthralgia/arthritis, OR lymphadenopathy, OR conjunctivitis.

• One of them is likely to be infectious (about one week before to at least four days after appearance of rash), AND
• The other has an illness which starts within 14 and 23 days after this contact, AND
• At least one case in the chain of epidemiologically linked cases (which may involve many cases) is laboratory confirmed.

Laboratory definitive evidence

• Isolation of rubella virus, OR
• Detection of rubella virus by NAT, OR
• IgG seroconversion or a significant increase in antibody level or a fourfold, or greater rise in titre to rubella virus in the absence of recent rubella vaccination. The results must be established by the testing of paired sera in parallel, OR
• Detection of rubella-specific IgM, in the absence of recent rubella vaccination.

Clinical evidence
Not applicable.

Epidemiological evidence
Not applicable.

Congenital rubella syndrome
Probable case
A probable case requires:

• Laboratory suggestive evidence (either maternal or infant) AND
• Clinical evidence.

• Isolation of rubella virus, OR
• Detection of rubella virus by nucleic acid testing
• IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to rubella virus. This must be established by the testing of paired sera in parallel, OR
• Detection of rubella-specific IgM, in the absence of recent rubella vaccination AND confirmation of the result in a reference laboratory, OR

Infant evidence

• Detection of rubella-specific IgM in infant blood using capture EIA, OR
• Infant rubella antibody that persists at a higher level and for a longer period than expected from passive transfer of maternal antibody (i.e., rubella titre that does not drop at the expected rate of a two fold dilution per month).

Confirmed case
A confirmed case requires:

• Laboratory definitive evidence, AND
• Clinical evidence.

Laboratory definitive evidence

• Isolation of rubella virus from the infant, OR
• Detection of rubella virus, in the infant, by nucleic acid testing, OR
• Detection of rubella-specific IgM antibody in the serum of the infant AND confirmation of the result in a reference laboratory.

Factors to be considered in case identification
False positive IgM results can occur; results should be confirmed for high risk cases (eg, pregnant women) by testing for IgM fractions after sucrose density centrifugation.
Maternal reinfection with rubella virus has been reported resulting in congenital infection. Its public health significance is unclear.

3. Notification criteria and procedure

Rubella is to be notified by:

• Laboratories on microbiological confirmation (ideal reporting by routine mail)
• School principals and directors of child care facilities (ideal reporting by telephone on same day of notification).

4. The disease

Infectious agent
The rubella virus.

Mode of transmission
Rubella is transmitted by droplet infection and direct contact with nasopharyngeal secretions of infected persons.

Timeline
The typical incubation period is 14 to 23 days, but more commonly 16 to 18 days.

Rubella is communicable for about 7 days before and at least 4 days after rash onset. Infants with congenital rubella syndrome may shed the virus for months after birth.

Clinical presentation
The usual clinical presentation is a mild febrile illness with a diffuse punctate and maculopapular rash. Children usually present with few or no constitutional symptoms, but adolescents and adults may have a prodrome of low-grade fever, headache, malaise, mild coryza and conjunctivitis. Cervical lymphadenopathy is characteristic and precedes the rash by 5 to 10 days.

Congenital rubella syndrome occurs in up to 90 percent of babies born to women who acquired rubella in the first trimester of pregnancy. This syndrome presents with a range of defects including cataracts, congenital glaucoma, congenital heart disease, hearing defects, microcephaly, pigmentary retinopathy, mental retardation, purpura, hepatosplenomegaly, meningoencephalitis and radiolucent bone disease.

5. Managing single notifications

Response time
Investigation
Within 1 working day of notification of a case of congenital rubella syndrome, begin follow-up investigation. Other cases are followed up at the discretion of the PHU Director.

Data entry
Within 5 working days of notification enter probable and confirmed cases on NDD.

Response procedure
The response to a notification will normally be carried out in collaboration with the case's health carers. But regardless of who does the follow-up, PHU staff should ensure that action has been taken to:

• Confirm the onset date and symptoms of the illness
• Confirm results of relevant pathology tests, or recommend the tests be done
• Find out if the case or relevant care-giver has been told what the diagnosis is before beginning the interview
Seek the doctor's permission to contact the case or relevant care-giver
• Review case management.

Education
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission.

Emphasis should be placed on the importance of following the recommended immunisation schedule.

Isolation and restriction
Recommend exclusion from work, school, preschool, child care or other settings where there are susceptible individuals, especially young children, infants and pregnant women, for at least 4 days from the onset of rash.

Only people who are immune to rubella should have contact with congenital rubella syndrome. These children should be presumed infectious at least through to 1 year of age unless nasopharyngeal and urine cultures are negative for rubella virus after 3 months of age.

Environmental evaluation
None.

Contact Management
Identification of contacts
Direct contact with respiratory secretions from the case is generally considered significant. Contacts include people living in the same household, in the same class, at the same social function, or work area as the case.

Investigation and treatment
Passive Immunisation
Post-exposure immunoglobulin has not been demonstrated to be of value.

Active Immunisation
Immunisation will not necessarily prevent infection or illness.

Antibiotic Prophlaxis
None

Education
Susceptible contacts (or parents/guardians) can be alerted to the risk of infection through distribution of a factsheet through the school or workplace of the risk of infection. They should watch for signs or symptoms of rubella occurring within 23 days of exposure. Pregnant contacts should seek medical advice from their clinician for assessment of immunity and further counselling.