In a person with a healthy immune system

When first infected with toxoplasmosis, most people don't get sick. A few people have mild flu-like symptoms, which can last as long as several months. This is why people rarely know whether or when they have had toxoplasmosis. Symptoms can include:

• Swollen glands.
• Muscle aches.
• Fatigue.
• Fever.
• Sore throat.
• Skin rash.

In a newborn

Most infected newborns have no symptoms at birth. But without treatment, some can develop eye or brain damage that ranges from mild to severe. Blindness can develop up to 20 years after birth, but this is rare.

Some infected newborns have severe symptoms at birth, including:

• Eye pain, vision problems, or blindness.
• Brain damage, leading to mental retardation and occasionally seizures.

In a person with a weak immune system

A person who has a very weak immune system (weakened by HIV infection, organ transplant medicines, or lymphoma) can develop life-threatening toxoplasmosis. Antibiotic therapy is often used to prevent this from happening. Severe infection requires aggressive treatment.

In very rare cases, otherwise healthy people who get toxoplasmosis can have severe symptoms related to the brain, eyes, lungs, or heart.³