Causes
Toxoplasmosis is caused by infection with the microscopic parasite Toxoplasma gondii. This parasite thrives in the bodies of cats, which are its definitive hosts, but it can infect nearly all warm-blooded animals, including humans. People typically contract the infection by accidentally ingesting the parasite through contaminated food, water, or soil, or through contact with cat feces.

Risk Factors
Certain behaviors and environmental exposures increase the likelihood of acquiring the infection:

• Contact with Cats: Handling cat litter boxes or touching soil where cats have defecated poses a significant risk.
• Dietary Habits: Eating raw or undercooked meat (especially pork, lamb, and venison) or shellfish is a primary cause of infection.
• Contaminated Produce: Consuming unwashed fruits and vegetables that have come into contact with contaminated soil.
• Weakened Immunity: Individuals with HIV/AIDS, those undergoing chemotherapy, or organ transplant recipients are at higher risk for severe illness.

Prevention
Preventing toxoplasmosis focuses on hygiene and food safety:

• Food Safety: Cook meat to safe internal temperatures, peel or wash fruits and vegetables thoroughly, and wash hands and kitchen utensils with soap after handling raw meat.
• Garden Safety: Wear gloves while gardening and wash hands afterwards, as soil may be contaminated with cat feces.
• Cat Care: If you have a cat, keep it indoors and feed it commercial dry or canned food rather than raw meat; have someone else change the litter box daily if you are pregnant or immunocompromised.
• Hygiene: Wash hands frequently, especially before eating and after contact with soil or animals.

Signs and Symptoms
Most healthy people who become infected with toxoplasmosis have no symptoms and may not know they are infected. When symptoms do occur, they can vary widely based on the person's immune health:

• Healthy Individuals: May experience mild flu-like symptoms such as swollen lymph nodes (especially in the neck), muscle aches, headache, fever, and fatigue that can last for weeks.
• Immunocompromised Individuals: Can develop severe symptoms including confusion, poor coordination, seizures, and lung problems similar to pneumonia due to inflammation in the brain (encephalitis) or other organs.
• Ocular Toxoplasmosis: The infection can affect the eyes, causing eye pain, sensitivity to light (photophobia), tearing, and blurred vision.
• Congenital Infection: Infants infected in the womb may be born with seizures, an enlarged liver and spleen, yellowing of the skin (jaundice), and severe eye infections.

Diagnosis
Clinicians use several methods to identify the infection:

• Serologic Tests: Blood tests are the most common tool, checking for specific antibodies (IgG and IgM) that the body produces to fight the parasite.
• Molecular Tests: Polymerase chain reaction (PCR) tests can detect the parasite's DNA in blood, amniotic fluid (during pregnancy), or other body fluids.
• Imaging: MRI or CT scans of the brain may be used to look for cysts or lesions in people with neurological symptoms.
• Eye Exams: An ophthalmologist can examine the retina to identify characteristic damage caused by the parasite.

Treatment Options
Treatment depends on the severity of the infection and the patient's immune status. Most healthy people recover without any medical intervention. For those who require treatment, doctors typically prescribe a combination of medications:

• Medications: The standard treatment often involves antiparasitic drugs such as pyrimethamine and sulfadiazine, along with folinic acid to protect bone marrow.
• Pregnancy: Pregnant women may receive spiramycin to reduce the risk of transmitting the infection to the fetus, or other drug combinations if the fetus is already infected.
• Eye Infection: Ocular toxoplasmosis is treated with antiparasitics and sometimes corticosteroids to reduce inflammation.

Management and Monitoring
Management focuses on controlling the infection and preventing reactivation:

• Monitoring: Regular blood tests and imaging may be required for immunocompromised patients to monitor response to therapy.
• Long-term Care: Individuals with HIV/AIDS may need to take preventive medication for life to keep the infection suppressed.

When to See a Doctor
Seek medical attention if you notice concerning signs, especially if you are pregnant or have a weakened immune system:

• Red-flag Symptoms: Blurred vision, confusion, loss of coordination, or seizures require immediate care.
• Exposure Concerns: Pregnant women who believe they may have been exposed to cat feces or raw meat should consult a doctor for testing.
• Persistent Symptoms: See a provider if you have swollen lymph nodes or flu-like symptoms that do not improve.

Severity
The severity of toxoplasmosis ranges from asymptomatic to life-threatening. In the vast majority of healthy adults, the condition is mild and self-limiting. However, it is severe in specific populations:

• High Risk: It is a major cause of death and disability in people with advanced HIV/AIDS and in infants infected before birth.
• Organ Damage: Severe cases can lead to permanent damage to the brain, eyes, and other vital organs.

Prognosis
The long-term outlook varies by group:

• Healthy Adults: The prognosis is excellent; symptoms resolve, and the person usually develops lifelong immunity to future symptomatic infection, though the parasite remains dormant in the body.
• Infants: Early diagnosis and treatment of congenital toxoplasmosis can significantly improve outcomes, though some children may experience vision loss or developmental delays later in life.
• Immunocompromised: Prognosis is guarded and relies on lifelong suppression of the parasite; without treatment, reactivated toxoplasmosis can be fatal.

Complications
Potential complications include blindness, chronic encephalitis, and in congenital cases, hearing loss and intellectual disabilities.

Impact on Daily Activities
For most people, toxoplasmosis does not impact daily life or work once the initial mild symptoms pass. However, for pregnant women and those with compromised immunity, the condition requires lifestyle adjustments to avoid infection sources. This can create anxiety regarding food preparation and pet care. Coping involves staying informed and adhering to strict hygiene practices.

Questions to Ask Your Healthcare Provider
Bring these questions to your appointment to better understand your risk and care plan:

• Am I at risk for this infection based on my medical history?
• If I am pregnant, how can I safely care for my cat?
• Do I need to be tested for toxoplasmosis?
• What specific foods should I avoid to prevent infection?
• If I have tested positive, what are the long-term risks for my vision or brain health?

Q: Can I catch toxoplasmosis from my dog?
A: No, dogs are not definitive hosts for the parasite and do not shed it in their feces like cats do; however, dogs can carry contaminated soil on their fur or paws.

Q: If I had toxoplasmosis before I got pregnant, is my baby safe?
A: Generally, yes; if you were infected months or years before pregnancy, you likely have immunity that protects your unborn baby from infection.

Q: Is toxoplasmosis contagious from person to person?
A: No, you cannot catch it from casual contact with an infected person; it is only spread through mother-to-child transmission, organ transplant, or blood transfusion.

Q: Do I have to give up my cat if I am pregnant?
A: No, you do not need to give up your cat, but you should avoid changing the litter box yourself, keep your cat indoors, and feed it cooked or canned food.

Q: Does cooking meat kill the parasite?
A: Yes, cooking meat to the proper internal temperature (usually 145°F for whole cuts and 160°F for ground meat) kills the parasite and makes the meat safe to eat.