2nd order laboratory parameters – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification
- Parvovirus B19 antibodies (IgM and IgG; if IgG antibodies are detectable but no IgM antibodies, there is immune protection; IgM antibodies are detectable seven to ten days after infection and remain positive for up to three months).
- Small blood count [signs of acute anemia/anemia; occasionally, persistent thrombocytopenia and neutropenia/platelet and neutrophil leukocyte/white blood cell deficiency]
- Toxoplasmosis antibodies (IgG, IgM).
- TPHA search test
- Measles antibodies (IgG, IgM)
- Rubella antibodies (IgG. IgM)
Note!Infection with parvovirus in the second trimester (third trimester) may cause an increase in the concentration of alpha-1 fetoprotein!
Serologic parameters in erythema infectiosum infection
Illustration of B19V-specific diagnostic markers, their possible combinations, and inferable infection status:
| Diagnostic marker* (detection method). | Infection status | |||
| B19V DNA (PCR) | Anti-VP1/VP2 (ELISA) | IgG against epitopes in denatured VP2,-VP/C* * (Western blot/line). | ||
| IgM | IgG | IgG | ||
| positive | negative | negative | negative | acute infection |
| positive | positive | negative | negative | acute infection |
| positive | negative | positive | positive | acute/ recent infection |
| positive | positive | positive | positive | acute/ recent infection |
| negative | negative | positive | positive | recent infection |
| negative | positive | positive | positive | recent infection |
| negative | negative | positive | negative | expired infection |
| positive in follow-up samples | negative | positive | negative | persistent infection |
* All constellations of markers refer to their detectability in immunocompetent, nonpregnant individuals. * * IgG antibodies against epitopes in denatured capsid proteins (VP2, VP/C) are detectable only up to six months after acute infection and indicate recent infection. The production of the different antibodies/antibody classes may differ, especially in acute infections of pregnant women, due to the altered immune response.
Caution.
- If a pregnant woman has no immune protection against ringworm, a new blood test after 2 weeks is absolutely necessary to exclude a possible ringworm infection.
- To detect infection in a pregnant woman, amniocentesis can be performed from the 16th week of pregnancy.
