The preferred method of diagnosis is by PCR or culture (see Appendix 8), which can be performed in LabPlus (Auckland) and Canterbury Health Laboratories (Christchurch). Serology may be useful but can be hard to interpret if the person has received rubella vaccine in the past.
The local medical officer of health will arrange contact tracing and alert the contacts or the public of potential exposure, particularly of pregnant women.
Parents/guardians should be advised that children with suspected rubella should be excluded from early childhood services or school until fully recovered and for seven days after the appearance of the rash. Children with congenital rubella should be considered infectious until they are aged 12 months. Adults should be excluded from work until fully recovered and for seven days after the appearance of the rash.
Exclusion should be considered for unimmunised contacts from early childhood services, school or work. MMR should be given. Female staff should ensure they are immune to rubella.
Rubella-containing vaccine does not provide protection if given after exposure to rubella. However, if the exposure did not result in infection, the vaccine would induce protection against subsequent infection. Normal human immunoglobulin (NHIG) does not prevent rubella infection after exposure and should not be used for that purpose.9
The local medical officer of health will advise on contact management.
It is critical to accurately document the rubella status of all people who may have rubella and potentially exposed a pregnant woman (see above). Rubella infection in the first half of pregnancy is potentially devastating, and every possible exposure of a pregnant woman should be discussed with the local medical officer of health, obstetrician and microbiologist or infectious diseases physician.
All women should have been routinely tested for the presence of rubella antibodies before or early in every pregnancy (see sections 18.5.2 and 18.5.4). If this result is available and the woman is known to be immune, she may be reassured.
An exposed pregnant woman with low anti-rubella antibody levels should have her serology repeated if she comes into contact with a probable or confirmed case of rubella; almost always this is someone who has recently arrived or returned from overseas.
Women whose immunity to rubella has not been conﬁrmed for the current pregnancy, and who have been exposed to rubella in the first half of pregnancy, must be investigated serologically and virologically, irrespective of immunisation history or history of previous clinical rubella. Serum should be obtained as soon as possible, with the clinical details included on the request form. The laboratory should be asked to store an aliquot of serum for later testing in tandem with a follow-up sample. These results must be interpreted in conjunction with the time period since exposure, to determine whether or not acute infection has occurred.
It is essential that all requests to laboratories state the:
An obstetrician (or a maternal fetal medicine specialist) and an infectious diseases specialist/microbiologist should be consulted when the diagnosis of possible rubella infection in a pregnant woman is ﬁrst considered. The clinical picture and all test results should be discussed by all involved in the care of the woman, to enable an accurate interpretation of the serological results before advising the woman about the risk to her fetus and options regarding the continuation of pregnancy.
Coordinated care and management are essential (Table 18.2). Ideally this will be done by the woman’s GP, who will liaise with the medical officer of health, an obstetrician and/or infectious diseases (ID) specialist and the LMC.
The routine use of immunoglobulin (IG) for post-exposure prophylaxis of rubella in early pregnancy is not recommended. It may be considered if termination of the pregnancy is not an option, but termination must be discussed when maternal infection is confirmed. Although IG has been shown to reduce clinically apparent infection in the mother, there is no guarantee that fetal infection will be prevented.
|LMC||Medical officer of health||GP||Obstetrician/ |
maternal fetal medicine specialist
|Check rubella status in every pregnancy and vaccinate any woman who is not immune AFTER delivery||✓|
|Investigate initial suspected rubella case and trace contacts||✓|
|Coordinate care of exposed non-immune pregnant woman and arrange serology testing||✓|
|Review clinical and laboratory results, and discuss options with the pregnant woman if rubella is confirmed||✓|