Toxoplasmosis

Toxoplasmosis is an infection caused by the organism Toxoplasma gondii which is one of the world's most common parasites. It is relatively common and most adults have been infected at sometime in their lives and have since developed an immunity to it. Typically it produces "flu-like symptoms such as low fever, malaise, sweats, and swollen glands(lymph nodes). In healthy adults the infection is easily contained and the body's immune system overcomes the organism. The main concerns are infection in pregnancy, infection in immunocompromised states, and differentiating toxoplasmosis from other conditions such as lymphoma that cause similar signs and symptoms .

Life-cycle of the organism

You won't want to hear this, but the host for toxoplasma is the cat and the organism lives in the wall of the cat's gut. Cats get infected by eating uncooked meat of infected animals and that includes not just what you feed them, but also what rodents they catch themselves. The parasite releases eggs which come out in the cat's faeces...so you can imagine how we get infected! Soil gets contaminated and toxoplasma can exist for a year in this state- so wash your hands after gardening and wash fruit and vegetables before eating. Also, while your cat is rather clean he/she still manages to get dirty paws and then walk on your kitchen bench. We are infected by ingesting the eggs. Other animals such as pigs, cows, rodents are infected in the same way. The eggs become small cysts in the muscle of these animals and when that muscle is eaten by cats the cycle repeats itself.

Signs and symptoms

Typically it is manifest as a flu-like illness that is just considered just another bout of flu. Sometimes the swollen lymph nodes are all that is noted and these frequently present as a cluster of nodes in one region of the neck although they can be present on both sides. They are generally only 1-2cm in size and non-tender or only mildy so. Nodes may persist for weeks.

Pregnancy

There is about a 50% chance of a pregnant woman transferring the organism to her foetus during an acute infection. This poses a risk to foetal brain, heart, eye and ear development. It is therefore important for pregnant women to avoid infection (see above life-cycle) and to seek medical advice if infected.

Immunodeficiency

Patients with compromised immune systems (eg. AIDS, organ transplant recipients) are at increased risk from toxoplasmosis which can cause serious brain, eye, lung problems. These patients require specific therapy against the organism.

Diagnosis

Toxoplasmosis is diagnosed by a blood test which detects a high level of antibodies to the organism. Typically specific IgM antibodies to toxoplasma are raised for months before returning to low levels. Once the infection is contained the specific IgG antibodies remain elevated for life thus conatining the organism and indicating immunity.

Treatment

Specific treatment against toxoplasmosis is rarely required. Only in pregnant women and in immunocompromised patients is medication advised.

Can you pass toxoplamosis on to others?

The only human to human transmission that is possible is from mother to foetus. It is not possible for an infected man or a friend to pass it on to a pregnant woman. The cat is the sole host of the organism and infection of humans occurs through ingestion of contaminated food or drink, or contaminated hands transferring it to the mouth.

 

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