Toxoplasma: The Silent Parasite That Can Threaten Babies and Eyesight

It can live inside the body quietly, without a clear fever, alarming pain or obvious warning signs. But its danger becomes serious when it reaches a pregnant woman, a person with a weakened immune system, or an eye vulnerable to inflammation. This parasite is called Toxoplasma gondii, the cause of a disease known as toxoplasmosis.

According to the U.S. Centers for Disease Control and Prevention, many people infected with toxoplasma have no symptoms, especially if their immune system is healthy. In some cases, the infection may feel like a mild flu, with muscle aches, swollen glands or temporary fatigue, and then disappear without the person ever knowing they were infected.

The real concern begins when a woman becomes infected for the first time during pregnancy, or shortly before becoming pregnant. The CDC warns that a mother can pass the infection to her unborn baby even if she does not feel sick. Some babies may be born without visible symptoms, but serious complications can appear later, including vision loss, developmental delays or neurological problems.

Mayo Clinic also notes that toxoplasmosis during pregnancy can lead to miscarriage or birth defects. Pregnant women, newborns and people with weakened immune systems may need medical evaluation and treatment if exposure or infection is suspected.

The danger is not limited to pregnancy. Toxoplasma can also affect the eye, causing inflammation of the retina and choroid, a condition known as retinochoroiditis. The CDC explains that eye disease may result from congenital infection or infection acquired later in life. In some cases, retinal damage may not be detected at birth and may only appear years later.

In severe cases, toxoplasmosis can damage the brain, eyes or other organs, particularly in people whose immune systems are weakened, including cancer patients, people taking immune-suppressing medication or those with conditions that reduce the body’s ability to fight infection.

The parasite is most commonly transmitted through undercooked meat, contaminated food or water, or contact with soil, sand or cat feces containing the parasite. The Public Health Agency of Canada notes that transmission through the placenta can occur if a mother develops an acute infection during pregnancy.

Although the disease is often associated with cats, the medical message is not to fear cats or give them away. The real message is caution. The CDC explains that infected cats can shed the parasite in their feces, which may contaminate litter boxes, soil or water. This makes daily hygiene, handwashing and wearing gloves while cleaning litter boxes or gardening especially important for pregnant women.

Health authorities recommend that pregnant women, or those planning pregnancy, avoid raw or undercooked meat, wash fruits and vegetables carefully, prevent raw meat utensils from touching ready-to-eat foods, and ask someone else to clean the cat litter box when possible. Canadian public health resources also advise changing cat litter daily, because the parasite usually does not become infectious immediately after being shed and often needs one to five days to become infectious.

Health Canada also emphasizes safe food handling during pregnancy, including keeping raw meat, poultry and seafood in sealed containers at the bottom of the refrigerator, washing hands and surfaces thoroughly, and avoiding leaving perishable foods at room temperature for long periods. These steps help reduce the risk of several foodborne infections, including toxoplasma.

The most dangerous thing about toxoplasma is that it does not always announce itself. A mother may feel completely well. A baby may be born without obvious signs. The infection may pass like a minor, forgotten illness. But in certain cases, especially during pregnancy, immune weakness or eye symptoms, medical testing becomes essential.

If there has been possible exposure during pregnancy, such as eating undercooked meat or handling cat litter or contaminated soil, or if symptoms such as blurred vision, eye pain, severe headache or neurological changes appear, medical advice should be sought promptly. Early detection can change the course of the disease, protect an unborn child and help save vision before damage becomes permanent.