Point-of-Care Test Can Increase Access to Toxoplasma Testing

A novel fingerstick test may improve access to Toxoplasma gondii testing for pregnant women, according to a study published Aug. 16 in PLoS Neglected Tropical Diseases. The study demonstrates that the point-of-care test has comparable performance to whole-blood and reference testing and may have other potential, multiplex applications.

Toxoplasmosis is a parasitic infection transmitted from eating undercooked meat, from infected mothers to fetuses, or from exposure from soil or cat feces. While the majority who are exposed are asymptomatic, newborns and those with compromised immune systems are at risk for death, brain damage, and vision problems. However, with timely detection and intervention, the infection is treatable, even before birth.

Pregnant women who are at risk of infection should be tested once a month during pregnancy. Current practice involves serological testing. But, point-of-care testing may improve access to testing, both domestically and internationally in developing nations, where infection is more prevalent.

The lateral flow immunochromatography Toxoplasma ICT IgG-IgM point-of-care test was developed by LDBIO Diagnostic (France). Researchers compared its performance to serum-based testing and reference testing in obstetrical patients in Chicago, Ill. and in Morocco (with genetically distinct patients and parasites). The point-of-care test takes less than two minutes of operator time with results available for visual interpretation within 20 to 30 minutes. The test costs $4 to $5 per test.

There was 100 percent concordance between fingerstick and venipuncture point-of-care testing and reference testing. For the fingerstick, point-of-care testing, sensitivity was 100 percent and specificity was 100 percent. Point-of-care testing was even able to diagnose individuals with lower levels of anti-Toxoplasma antibodies in the range detected by gold-standard tests.

While point-of-care testing is less invasive and can be conducted at a clinical site without laboratory equipment, it cannot distinguish seropositivity for IgG and IgM and, therefore, cannot differentiate between acute from chronic infection. A positive point-of-care test prior to 12 weeks of gestation, the authors say, requires further confirmatory testing.

“Our demonstration of the high performance of this whole-blood point-of-care test and the test’s strong functionality at the point of care, which has not been previously demonstrated, provide the proof of principle of its potential utility and widespread applicability in clinical settings” write the authors led by Joseph Lykins, from University of Chicago in Illinois. “This new test also fulfills the World Health Organization criteria for the ideal point-of-care test (affordable, sensitive, specific, user friendly, rapid/robust, equipment-free, and deliverable to users).”

Takeaway: This point-of-care test has high reliability for toxoplasmosis screening and has the potential to improve access to testing for pregnant women globally.