Toxoplasmosis

Overview

Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii, which is commonly contracted from eating undercooked meat or through contact with cat feces. This parasite can also be transmitted to a fetus during pregnancy, potentially causing miscarriage or birth defects. While the parasite primarily reproduces in the intestines of cats, humans can become infected either by direct exposure to cat feces or by consuming infected meat.

Most individuals infected with Toxoplasma gondii do not exhibit any symptoms. However, some may experience flu-like symptoms as their immune system attempts to fight off the infection. In severe cases, particularly among infants, pregnant individuals, and those with compromised immune systems, the disease can be more serious and require drug treatment.

Preventive measures can significantly reduce the risk of toxoplasmosis. These include cooking meat thoroughly and avoiding direct contact with cat feces. For those who are infected, particularly in more severe cases or among high-risk groups, specific drug treatments are available to manage the infection.

Symptoms

Most individuals infected with toxoplasmosis do not exhibit any symptoms and may be unaware of the infection. When symptoms do appear, they are often similar to the flu and can include:

• Fever
• Swollen lymph nodes, persisting for weeks
• Headache
• Muscle aches
• Skin rash

Symptoms of ocular toxoplasmosis
In some cases, toxoplasmosis affects the inner eye tissues, even in people with healthy immune systems. Known as ocular toxoplasmosis, this condition can be more severe in those with compromised immunity. Symptoms include:

• Poor vision
• Eye pain
• Floaters (specks that drift through your field of vision)
• Untreated, this condition can lead to blindness.

Impact on individuals with weakened immune systems
People with weakened immune systems may experience more severe symptoms. This includes those with HIV/AIDS, cancer patients undergoing treatment, and organ transplant recipients. Symptoms can include:

• Confusion
• Breathing difficulties
• Serious lung or brain infections
• Persistent fever
• Cough
• Poor coordination
• Muscle weakness
• Seizures
• Variability in alertness levels

Effects on fetus or infant (congenital toxoplasmosis)
Toxoplasmosis can be transmitted from a pregnant mother to her fetus, with potentially severe consequences, especially if the infection occurs during the first trimester:

• Severe eye infections
• Hydrocephalus (excess fluid in or around the brain)
• Brain tissue abnormalities
• Enlarged liver or spleen
• Jaundice (yellowing of the skin and eyes)
• Rash
• Long-term effects may manifest later in childhood or adolescence, including recurrent eye infections, developmental delays, hearing loss, and early puberty.

If you suspect exposure to toxoplasmosis or are experiencing symptoms such as blurred vision, confusion, or loss of coordination, it is crucial to seek immediate medical attention, especially if your immune system is compromised. Discuss testing options with your healthcare provider if planning a pregnancy or if you are pregnant and concerned about potential exposure.

Causes

Toxoplasma gondii is a parasite capable of infecting most animals and birds. However, it can only complete its full reproductive cycle in domestic and wild cats, which are its primary hosts.

Transmission cycle:

• Immature eggs in cat feces: Cats excrete immature eggs of the parasite, which are part of the middle stage of its reproductive cycle. These can contaminate soil, water, plants, animals, and ultimately, humans.
• Food chain spread: Once the immature eggs are in the environment, they can be transmitted to new hosts, where the parasite can then cause an infection.

Human infection:

• Healthy immune system: In individuals with a robust immune system, the parasites are typically kept dormant, providing lifelong immunity. Any subsequent exposures are usually cleared by the immune system.
• Weakened immune system: If the immune system is compromised later in life, the dormant parasites can become active, potentially leading to severe disease and complications.

Common ways of contracting toxoplasmosis:

• Cat feces: Handling soil or cat litter contaminated with feces can lead to infection. Cats that hunt or are fed raw meat are more likely to carry the parasite.
• Unwashed produce: The surface of fruits and vegetables may harbor the parasite.
• Contaminated food or water: Eating undercooked meats (beef, lamb, pork, venison, chicken) or shellfish, drinking unpasteurized goat milk, or consuming untreated water can pose risks.
• Contaminated kitchen tools: Utensils like cutting boards and knives used for raw meat or unwashed produce can become transmission vectors.
• Medical transmission: Though rare, toxoplasma can also be transmitted through infected organ transplants or blood transfusions.

Risk factors

The parasite can be found anywhere in the world. The infection can spread to anyone. Toxoplasmosis risks for serious disease include conditions that compromise the immune system’s ability to fight infections, such as:

• Cancer patient undergoing chemotherapy treatment.
• HIV/AIDS.
• Medication that keeps donated organs from being rejected.
• Patient receiving high-doses of steroids.