Strain-specific assay identifies T gondii during pregnancy

A new serum assay identifies strain-specific antibodies.

The ability to differentiate among T gondii strains can identify those women who would benefit most from treatment.

Research on strains of Toxoplasma gondii that are most strongly associated with prematurity and severe disease at birth has led to a blood test that can determine the specific strain with which a pregnant woman is infected, according to a study published online April 11 in Clinical Infectious Diseases.

Currently available tests can determine only whether a person has ever been infected with any strain of Toxoplasma. The new enzyme-linked immunosorbent assay (ELISA) can detect the presence of strain-specific antibodies that distinguish one strain from another and will allow screening of women to identify which ones could benefit from treatment.

For example, not exclusively type II strains (NE-II) are more likely than type II strains to be associated with premature birth. Infants infected with these strains are more likely to have severe manifestations of disease than those infected by type II parasites. Eye damage, for example, occurred in 67% of infants infected with NE-II strains versus 39% of those infected with type II parasites.

The NE-II serotype was more common in hot, humid regions and was associated with rural areas, lower socioeconomic status, and Hispanic ethnicity. The authors caution that the association is not an absolute one; mild, moderate, and even severe disease can result with any strain, and both types improve equally well with treatment.

Read other articles in this issue of Special Delivery