The Journal of Medical Microbiology, Vol 28, Issue 2 125-128, Copyright © 1989 by Society for General Microbiology
The use of an IgM immunosorbent agglutination assay to diagnose congenital toxoplasmosis
L. J. Skinner, J. M. Chatterton, A. W. Joss, I. L. Moir and D. O. Ho-Yen
Department of Microbiology, Raigmore Hospital, Inverness.
An IgM immunosorbent agglutination assay (ISAGA) was compared with a
standard ELISA IgM test for the diagnosis of congenital toxoplasmosis. It
was more sensitive, detecting all of five mothers of infected babies
whereas the IgM ELISA was positive in two of three mothers tested at
delivery and neither of two mothers referred 10-12 months after delivery.
Five women infected in a previous pregnancy had IgM detectable by ISAGA in
a subsequent pregnancy. The assays were comparable when sera from patients
with past infection were tested or following toxoplasma-associated
miscarriage or abortion. Four cord sera from congenitally-infected babies
were positive by the ISAGA but only three of these were positive by ELISA
for IgM. The ISAGA also detected IgM in another four sera from
congenitally-infected babies referred late (10-18 months old); none were
IgM positive by ELISA. The increased sensitivity of the ISAGA is an
improvement in the diagnosis of congenital toxoplasmosis.
