Levels > 15 IU/L of rubella IgG are consistent with immunity.
Uncertainty of Measurement: 6%
| Age Range | Either Sex |
|---|---|
| All | >= 15 |
Test performed on weekdays.
Rubella virus is a ss RNA virus classified as a rubivirus in the family Togaviridae.
Rubella is usually asymptomatic or a mild disease characterised by an erythematous maculopapular discrete rash, generalised lymphadenopathy (suboccipital, postauricular and cervical) and slight fever. Transient polyarthralgia is more commonly seen in adults especially females. Rare complications include encephalitis and thrombocytopenia. However, infection during pregnancy (in particular the 1 st trimester) frequently results in the newborn having features (one or several) of the congenital rubella syndrome [CRS] (see below):
* Opthalmologic abnormalities (cataracts and retinopathy)
* Cardiac abnormalities (patent ductus arteriosus, pulmonary artery stenosis)
* Auditory abnormalities (sensorineural deafness)
* Neurologic abnormalities (behavioural disorders, meningoencephalitis, mental retardation).
In addition, infants with CRS are frequently growth retarded, have radiolucent bone disease, hepatosplenomegaly, thrombocytopenia and purpuric skin lesions. Severity of disease lessens with increasing gestational age at time of infection. CRS is a direct result of rubella virus interfering with the timing of developmental processes in the foetus.
Postnatal rubella is transmitted through direct or droplet contact from nasopharyngeal secretions. Peak incidence of infections occur in late winter and early spring.
The average incubation period of rubella is 16-18 days (range 14-21 days), with the risk of communicability occurring from a few days before to 7 days after rash onset.
Detection of rubella specific IgG at a level greater than 15 IU/mL is consistent with immunity. Despite this, re-infection can rarely occur in situations of prolonged close contact where antibody levels are low.
Generally, immunity gained from exposure to wild type virus is more prolonged than that gained through vaccination. Also, there have been reports of individuals unable to be successfully immunised who then become infected with the wild type virus and mount a strong response.
References
1. Abbott Laboratories Axsym Rubella IgG product insert.
2. 1997 Red Book. Report of the Committee on Infectious Diseases. 24 th Edition. American Association of Paediatrics p ixxvi, 1-764. 1997.
For further information contact the laboratory (contact via Lablink: 22000 or (09) 307-8995 or 0800 522 7587) ,or:
the Virology team
virology@adhb.govt.nz