APPLICATION: Rubella IgM antibodies becomes positive 7 days after the onset of the illness but is usually undetectable after 8 weeks.
INTERPRETATION: A x4 fold rise in IgG titre is evidence of recent infection. Rubella IgM in a neonate is suggestive of congenital infection but false postive and false negative results occur. Viral Culture/Rubella PCR is a definitive method of diagnosing congential infection as the virus is present in throat, conjunctiva, blood and urine. Viral Culture/Rubella PCR is performed at Westmead NSW.
