Differential Diagnosis and fetal diagnosis.
At the beginning of pregnancy among the routine serological screening of
the pregnant woman, the anti-toxoplasma IgM and IgG antibodies are
usually checked (3). In case both anti-toxoplasma (anti-toxo) IgM and
IgG antibodies results are negative there is a follow up serological
examination of them every 1, 2 or 3 months. Since on follow up, they
remain negative while fetal ultrasounds have no detectable
abnormalities, no more actions are required. In case anti-toxo IgM
antibodies are negative and IgG antibodies are positive, most probably
the pregnant woman was infected in the distant past and before
conception, which means no treatment is required (unless the pregnant
woman is immunosuppressed). If anti-toxo IgM are positive, while
anti-toxo IgG antibodies are negative, additional serological tests
should be repeated in 1-3 weeks. In this case, since the after coming
results are the same, the outcome is considered to be clinically
insignificant, which means no treatment is required and a routine
serological testing follow up is enough. However in case both anti-toxo
IgM and IgG are positive after the follow up or even both of them are
positive in the first test, an early infection of toxoplasma gondii is
more likely to have occurred. In this case more serological tests should
be performed in order to differentiate an early from a past infection
and to find out whether the fetus has been infected too (11). To detect
an early infection the main additional serological tests used are IgG
avidity, anti-toxo IgA and IgE antibodies detection by the ELISA method.
Avidity is called the binding force of an antigen to its antibody. In
the initial stages of antigenicity avidity is low, while after a few
months it is increased by creating B cell antigens (12). The antigenic
contact causes B cell maturation, while antibodies and antigens are
binding stronger. In this way avidity will rise. High avidity can reject
the possibility of acute infection. However, It seems that the
combination of IgM and IgE anti-toxo antibody detection by ELISA is the
most reliable method for acute infection diagnosis (13).
The main benefits of the anti toxo IgE antibody detection by ELISA,
which make it an excellent supplementary method to diagnose acute
toxoplasmosis, are its high specificity and positive predictive value
with a sufficient sensitivity (14).
Finally, Toxoplasma gondii IgA antibody detection has been used in
screening of pregnant women since they significantly increase the
possibility of acute T. gondii infection in contrast to patients without
them (15-17). However, some authors have found IgA either too
insensitive or reactive for too long suggesting that, IgA testing is
controversial and not a dependable marker for T. gondii acute infection
detection (18).
For fetal toxoplasmosis infection, it is the amniotic fluid PCR analysis
rather than the umbilical cord blood sample, the leading method for
prenatal diagnosis. Despite the fact that this method provides fast
results for parasite detection, it is also independent of a patient’s
immunological status and it has a broad spectrum of application in
different biological samples. In addition, the protocol provides
qualitative results (19).
Moreover, amniotic fluid PCR analysis should be done when primary
infection is detected in pregnant women or even when serological tests
are inconclusive whether an acute infection has occurred. Finally, PCR
analysis is used in case of abnormal fetal ultrasound features have been
detected, such as microcephaly, ascites, hepatosplenomegaly,
hydrocephalus and severe IUGR (intrauterine growth restriction).
Furthermore, in order to reduce the false negative results, amniotic
fluid PCR should be performed 4 weeks after the suspected primary
infection of the pregnant, but never before the 18th week of gestation.
In case primary infection of the mother is confirmed while embryo
infection is not, spiramycin has to be used for embryo protection, in
order to avoid T.gondii transmission to the fetus across the placenta.
Finally, when embryo infection is confirmed or highly suspected (in most
cases by a positive amniotic fluid PCR analysis) pregnant women should
receive pyrimethamine sulfadiazine and folic acid as a treatment (20).
Overall, this is one of the few cases reported based on the literature
of a 19-year-old girl detected with toxoplasmosis during her pregnancy,
managed successfully leading to a successful pregnancy. Early detection
and medical intervention are necessary either to prevent embryo
infection or treat embryos when infection is confirmed or suspected. Not
only her young age but also her successful pregnancy as well,
contributes to its interest for publication.