Serologic Testing for Rubella
Historically, laboratory testing for Rubella has consisted primarily of serology. Rubella IgG is often used as a marker of past infection or response to vaccination. This test is especially important in women of childbearing age and is included in the recommended prenatal blood tests. The presence of IgG typically indicates immunity to acute Rubella infection.
In contrast, testing for IgM class antibodies to Rubella virus has historically been used as a marker of acute phase Rubella infection. IgM antibodies can be detected in serum 2 to 7 days after onset of the rash, but importantly, Rubella IgM levels can persist at low levels for up to 12 months after acute infection, so its presence is not always a marker of recent infection.
Now that we’ve reviewed the conventional laboratory approach for determining immunity and diagnosing acute Rubella infection, I’d like to change gears and discuss a significant change in the epidemiology of the disease that has occurred over the past 40 years. I think this change has a tremendous impact on the approach that we should take when testing for Rubella.
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