More than 60 million Americans have it. In some hot humid low-lying places around
the globe, 95% of the people have it. It is the most common cause of food borne illness.
Obviously, it rarely kills people. It’s toxoplasma, a parasite* that lives in humans for years,
almost always kept in check by the body’s natural immunities. In a pregnant woman
(and others), a new infection (toxoplasmosis) might cause some swelling in the lymph nodes
and flu like symptoms that go away without treatment.
But, for a fetus in the womb,toxoplasmosis can be devastating or fatal.
The only time toxoplasmosis is transmitted from one human to another is a new infection
passed from mother to child in the womb. About three to six months after acquiring the
infection, the mothers’ immunities protect the fetus. So if a woman gets toxoplasmosis
shortly before conception or during pregnancy, her fetus is at significant risk for severe
consequences. The greatest risk is from an infection acquired in late pregnancy.
Each year in the U.S. an estimated 500 to 5000 babies are born with toxoplasmosis.
Fewer than half of their mothers have any known history of illness or exposure.
A few infected babies are stillborn or born with serious eye damage, brain damage
or a very large or very small head. Most are born healthy, but months or years later
develop blindness, mental disability or nervous system disorders.
Toxoplasmosis and all the associated personal and societal costs are preventable.
And, when primary prevention fails, if the infection is known, treatment during
gestation may prevent transmission, and failing that, treatment in the first year
of life can significantly improve outcomes.
In Europe, by law, pregnant women are offered a blood test for toxoplasmosis every
month or trimester. If a blood test shows signs of infection, a follow-up test confirms
if the infection is recent and so poses a risk to the baby. In the U.S., screening during
pregnancy is rare and when performed, typically consists of a single test done at
widely varying points during pregnancy. This makes it difficult to tell if the infection is
new and dangerous or if the child is protected from a previous infection by the mothers’
antibodies. Arguments against frequent, routine testing include cost, availability of appropriate
tests,relatively low incidence, and recent controversy about the effectiveness
of treatment during gestation to prevent transmission.
Consequences include difficult-to-interpret test results, perhaps unnecessary
additional testing and treatment for mother and child including amniocentesis and
multiple medications, anxiety, abortions,undetected infections and the devastating
effects on families and healthcare costs.
Here’s the good news: On May 18, 2011 the FDA approved a follow-up test that can
differentiate new infections that require treatment and close monitoring from inconsequential
chronic toxoplasmosis. Experts say the ideal scenario is routine testing in the first trimester,
and in cases where the blood test shows or suggests infection, the follow-up
test to see if it is recent and requires treatment or occurred 12 to 16 weeks earlier
and is of little concern.
It remains to be seen if, how, and when the availability of the new test, called by the
uninformative name VidasToxo IgG Avidity Assay, will change practice and improve prevention,
detection and treatment of toxoplasmosis.
Prevention is still the best defense Meanwhile, home visitors, doulas, and maternity care
providers can help prevent toxoplasmosis. If the family keeps pets, eats meat, or likes to
garden this becomes a priority health topic. Open a conversation as early as possible in
pregnancy about toxoplasmosis. Use the Pregnancy Guide Book 1 page 19, “Partners, please
change the cat litter”.
If needed, offer additional specific prevention information.
Ask questions to assist Mom in naming specific steps she will take to prevent infection.
Put reminders in the record to bring up toxoplasmosis frequently and support the family
in keeping to their prevention plan.
The first step in every plan is to ask the prenatal care provider for the blood test.
Some additional steps to consider:
Montoya, J.T. & Remington, J.S. (2008). Management of Toxoplama gondii
Infection during Pregnancy. Clinical Infectious Diseases 47: 554-566.
Montoya, J.T., Leisenfield,O., Kinney, S., Press, C. & Remington, J.S.(2002).
VIDAS Test for Avidity of Toxoplasm-Specific Immunoglobulin G for Confirmatory
Testing of Pregnant Women. Journal of Clinical Microbiology 40(7): 2504-2508.
FDA News Release May 19, 2011 FDA clears first test for recent
infection with toxoplasmosis parasite.
Consumer Inquiries: 888-INFO-FDA
* Parasite– an organism that lives in and feeds on another organism