The shock and heartbreak of a baby being born with a swollen brain, blindness, and debilitating seizures is unimaginable. These devastating conditions could have been prevented if a simple test for the common parasite Toxoplasma gondii was taken during pregnancy. Toxoplasma can be contracted anywhere an infected cat has defecated, including in litter boxes, sandboxes, gardens, and yards. Other routes of infection include consuming contaminated water, undercooked meat, or shellfish.
Most people who are infected with Toxoplasma experience only mild illness and are able to get the infection under control. However, if a pregnant person contracts Toxoplasma for the first time during pregnancy, the parasite can cross the placenta and lead to spontaneous abortion or serious birth abnormalities. This transmission during pregnancy is known as congenital toxoplasmosis, and up to 4,400 babies may be born with this condition in the US each year.
As a professor of microbiology at the Indiana University School of Medicine, I study the biology of Toxoplasma in my lab. Blood tests can monitor the level of Toxoplasma antibodies in parents, with increases indicating an acute infection that could put the fetus at risk of congenital toxoplasmosis. Promptly administering anti-parasitic drugs to pregnant individuals who develop toxoplasmosis is crucial in protecting the fetus from the severe outcomes of the infection.
Countries like France and Austria have been conducting prenatal testing and treatment for toxoplasmosis for years, with Brazil recently starting a similar program. However, it is concerning that Toxoplasma testing is not included in prenatal screening in the US. Despite over 40 million American adults being infected with the parasite, the widespread nature of the infection makes it alarming that routine screening is not a standard practice.
The Benefits of Screening
Numerous studies have shown the benefits of detecting and treating toxoplasmosis during pregnancy. The Toxogest clinical trial, which aimed to reduce toxoplasmosis transmission prenatally, found that treatment not only decreased infection transmission but also lessened disease severity for breakthrough infections. Additionally, a meta-analysis from 2017 to 2021 revealed that pregnant women given the antibiotic spiramycin had significantly lower rates of parasite transmission to their unborn child compared to untreated mothers.
Dr. Jose Montoya, a researcher and clinician at the Remington Laboratory at Sutter Health, strongly advocates for screening, noting that countries with prenatal screening programs for toxoplasmosis experience far less severe cases of congenital toxoplasmosis compared to the US. The argument that congenital toxoplasmosis is too rare to warrant testing is refuted by the fact that even rarer conditions are screened in the US, such as phenylketonuria.
One of the major challenges in combating congenital toxoplasmosis is the lack of national surveillance data on the infection in the US. Since the infection is not nationally notifiable, researchers do not have a clear picture of how many miscarriages are caused by Toxoplasma or how many children suffer from the infection. Routine, standardized testing during pregnancy is essential in providing crucial data to evaluate the prevalence of the threat to babies.
Researchers also warn that Toxoplasma prevalence may rise with the popularity of free-range, organically raised foods and climate change. Free-range animals have a higher risk of picking up infectious Toxoplasma oocysts in outdoor environments, with warmer temperatures and powerful storms due to climate change promoting oocyst persistence and dissemination. Reports of virulent Toxoplasma strains from South America migrating to the US could exacerbate the severity of congenital toxoplasmosis infections.
The Economic and Emotional Costs
Dr. Rima McLeod, director of the Toxoplasmosis Center at the University of Chicago, highlights the significant economic impact of congenital toxoplasmosis. Studies have shown that following the prenatal screening and treatment model implemented in France could save US taxpayers $620 per child or $2.5 billion annually. McLeod’s team has developed inexpensive tests that detect Toxoplasma within minutes, offering a cost-effective solution for screening.
The physical, emotional, and economic toll of congenital toxoplasmosis is profound. Without systematic prenatal testing for the infection, pregnant individuals in the US are left without simple, low-cost procedures that could protect their children from birth defects. Vigilance to risk factors, such as avoiding cleaning litter boxes and ensuring proper food hygiene, is currently the best approach for pregnant individuals until routine testing becomes a standard practice.
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