Toxoplasmosis

Toxoplasmosis is infection by the parasite Toxoplasma gondii, almost always caused by contact with cats.

Incidence; Causes and Development; Contributing Risk Factors

Toxoplasmosis is found worldwide in humans, birds and other animals.  Cats are the primary host.

Toxoplasmosis can be caused by blood transfusions, organ transplants, contact with cat litter, consuming contaminated soil, or eating raw or undercooked meat.  The infection may also be passed from mother to baby through the placenta.

Those with weakened immune systems are especially likely to be affected.

Signs and Symptoms

In about 80% of cases, toxoplasmosis does not cause any symptoms and a person who is infected will not be aware that they are infected.

Symptoms, if the occur, usually appear 1-2 weeks after contact with the parasite.  Affecting the brain, lung, heart, eyes, or liver, symptoms include:

• Enlarged lymph nodes (head, neck, armpits)
• Headaches
• Low fever
• Muscle pain/aches
• Sore throat
• Confusion
• Blurred vision (caused by inflammation of the retina)
• Seizures
• Fatigue
• Malaise (feeling generally unwell)

Diagnosis and Tests

Diagnosis involves looking for toxoplasmosis antibodies in the blood, a CT scan of the brain, an MRI of the head, a slit-lamp examination of the eyes, and/or brain biopsy.

Treatment and Prevention

Antimalarial drugs and antibiotics are the usual treatment.

Ways to prevent toxoplasmosis include not eating undercooked meat, washing hands after handling raw meat, cleaning up dog and cat feces and washing hands after contact, cleaning cat litter boxes very carefully to avoid airborne particles, and not touching anything that may have been in contact with cat feces, including insects.

Prognosis; Complications

A healthy immune system is usually strong enough to prevent the parasite from causing serious illness, and prospects of recovery are excellent.  However, the disease may return and, in those with weakened immune systems, may spread throughout the body: this can be fatal.

Those who have been infected by T. gondii become immune to it, even though it remains in the body for life.

When a pregnant woman is infected, she may pass it along to her unborn child, leading to congenital toxoplasmosis.  This in turn slightly increases risk of miscarriage and stillbirth, and well as serious problems with the child such as water on the brain, brain damage, learning difficulty, epilepsy, jaundice, deafness, eye infection, blindness, deafness, enlarged liver or spleen, growth problems, cerebral palsy.

If toxoplasmosis begins to affect the brain, it can cause encephalitis.  This is one of the main causes of death among those with AIDS.  Known as Toxoplasmosis Encephalitis (TE), symptoms can include headaches, confusion, poor coordination, seizures, chest pain, coughing up blood, difficulty breathing, fever, vision problems such as blurred vision or 'floaters', and brain lesions.