Laboratory parameters of 1st order – obligatory laboratory tests.
- IgM and IgG antibodies – for detection of acute rubella infection [detection of IgM antibodies or a significant IgG antibody titer increase].
- HAH test (hemagglutination inhibition test) > 1:32 – sufficient immunity.
Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.
- Isolation of the virus from pharyngeal lavage fluid or urine.
- Tissue biopsies, blood, or cerebrospinal fluid (CSF) can be used to detect rubella antigens
- Amniotic fluid (amniotic fluid) and fetal blood testing may be performed as prenatal diagnostic tests in cases of questionable or confirmed rubella virus infection.Indications for invasive prenatal diagnostic testing include:
- Primary infection before the 19th week of pregnancy (SSW).
- Confirmed reinfection before the 12th SSW.
- Positive IgM findings that are not explainable by additional tester.
Caution. In case of infection of the mother in the 1st trimester (pregnancy third) is already 5-7 days before the onset of exanthema infectivity (contagiousness)!
The direct or indirect detection of “Rubellavirus” in connatal infections is reportable under the Infection Protection Act (IfSG).
Serological parameters in rubella infection
Overview of possible constellations of laboratory diagnostic results and their evaluation:
| Rubella serology | IgG avidity | anti-E2 IgG | viral genome detection (RT-PCR) | Infection status | |
| Rubella IgG | Rubella IgM | ||||
| negative | negative | – | – | negative | susceptible (receptive) |
| negative | negative | – | – | positive | acute infection serological follow-up |
| negative | positive | – | – | positive | acute infection serological follow-up |
| negative | positive | – | – | negative | (I) acute infection (II) nonspecific rubella IgM (III) persistent rubella IgM serologic follow-up. |
| positive | positive | low | negative | positive | acute infection |
| positive | positive | – | – | negative | (I) acute infection (II) nonspecific rubella IgM (III) persistent rubella IgM Avidity determination and Western blot. |
| Positive | positive | high | positive | negative | (I) past infection (II) persistent rubella IgM no acute infection. |
| Positive | negative borderline positive | low | negative | negative | recent infection |
| positive | negative borderline positive | high | positive | positive | Reinfection |
| positive | negative | high | positive | negative | past infection/vaccination |
Vaccination status – checking vaccination titers
| Vaccination | Laboratory parameters | Value | Rating |
| Rubella (German measles) | anti-rubella virus IgG (ELISA) | > 15 IU/ml | Assume immunity |
| HAHT | HAHT 1: < 8 | No evidence of sufficient vaccination protection → basic immunization required | |
| HAHT 1: 8 | Questionable vaccination protection → booster recommended | ||
| HAHT 1: 16 | |||
| HAHT 1: 32 | Sufficient vaccination protection |
