retina of the right eye (Fig 2). At this the time, the IgM was negative and the IgG positive
for toxoplasmosis (88 UI/ml). Computerized axial tomography of the brain showed a
calcified granuloma. Serologies for the lymphochoriomeningitis virus herpes and syphilis
were negative.
This case report raises some important questions regarding the possible causes of
the transmission of toxoplasmosis from an imunnocompetent mother to her fetus. This
transmission could possibly be related to reinfection or to a new infection with a different
strain. The problem with similar cases has always been the difficulty in definitely
establishing that a previously infected mother gave birth to a baby with congenital
toxoplasmosis with the currently available serological tests. Much of the evidence to
support this hypothesis is of an indirect nature.
Current serological tests do not tell us which strain of toxoplasmosis caused the
antibody response and whether or not the response is due to the same strain of the parasite.
During acute primary maternal toxoplasmosis, fetal infection occurs as a result of
maternal parasitemia and infection of the placenta. One theory that may account for
reinfections from mothers to the fetus is the presence of a local infectious nidus of
toxoplasmosis in the maternal uterus.
This is a case that describes the congenital transmission of Toxoplasma gondii from
a mother who was immunocompetent and who had documented infection caused by
toxoplasmosis 20 years before the conception. Vogel et al, 1996 described 3 similar cases
of imunnocompetent mothers with preconceptually acquired infection who transmited the
T. gondii to their fetuses (
7
).
This case suggests that women with old retinal scar due to toxoplasmosis who also
have longstanding circulating IgG antibodies to toxoplasmosis could transmit the disease to
the fetus. This is an important issue, because it raises the possibility that reinfections can
occur and it is still not determined if humans or animals could be reinfected with the same
or with different strains of Toxoplasma gondii.
