2nd order laboratory parameters – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification
- Antibodies against measles virus* (IgG, IgM) – IgM often becomes positive in serum with the onset of measles exanthema and is then detectable up to 6 weeks after onset.
- Detection of pathogen RNA* (= NAT method; nucleic acid amplification techniques): measles virus PCR from urine, conjunctiva, dental pocket swabs or cerebrospinal fluid (CSF).
* Direct or indirect detection of the pathogen is reportable by name according to the Infection Protection Act (IfSG), as far as the evidence indicates an acute infection.
Serologic parameters in measles infection
Overview of possible constellations of laboratory diagnostic results and their evaluation:
| Measles serology | Virus genome detection (RT-PCR) | Infection status | |
| Measles IgG | Measles IgM | ||
| negative | negative | negative | susceptible (receptive) |
| negative | negative | positive | acute infection |
| negative | positive | positive | acute infection |
| negative | positive | negative | Acute infection, possibly also nonspecific findings |
| positive | positive | positive | acute infection |
| positive | positive | negative | recent infection, possibly also nonspecific IgM result |
| positive | negative | positive | Reinfection after vaccination |
| positive | negative | negative | past infection/vaccination |
Vaccination status – checking vaccination titers
| Morbilli(measles) | Measles IgG ELISA | <0.15 IU/ml | No sufficient vaccination protection detectable → basic immunization required |
| 0.15-0.20 IU/ml | Questionable vaccination protection → booster recommended | ||
| >0.20 IU/ml | Sufficient vaccination protection |
