"The IgM test is still one of the very best tests we have to make us suspicious that the patient may have been infected recently," Remington said. "It does not mean she was but suggests the possibility. What we have attempted through the years is to develop a panel of tests to help clarify whether the patient has indeed been recently infected. We've now developed such a panel."
The tests have been used with a high degree of success at the Palo Alto Medical Foundation, where Remington holds a research appointment in addition to his faculty appointment at Stanford. Because faulty tests and incorrect interpretations persist throughout the country, the U.S. Food and Drug Administration has suggested that other laboratories send serum from IgM-positive tests to the foundation's lab for more accurate testing. The foundation is the only site in the country to offer the battery of new tests. "The majority of the tests were developed in our laboratories and just aren't available elsewhere in the U.S.," Remington said.
The newest test is the avidity test, which measures how strongly IgM antibodies bind to the toxoplasma antigens. A strong bond indicates the infection is not recent. "This applies to women tested within the first three to four months of pregnancy who have a positive IgM test," Remington said. "We can for the first time -- with a very high degree of accuracy -- tell a woman that if she has a high avidity test, there is no risk to her fetus."
Currently, the only certain method of measuring the risk of congenital toxoplasmosis involves screening women for antibodies at the beginning of, and during, pregnancy. Such screenings are a routine part of prenatal care in France but not in the United States where officials are concerned about the cost of widespread screening.
Source: Business Wire
Courtesy of iVillage.com News & Issues
Publication date: 2001-01-25 © 2000, YellowBrix, Inc.