Toxoplasmosis: Prevalence, Latency, and Transplacental Infection

Estimates show that between 30-65% of humans worldwide are carriers of the toxoplasmosis parasite. The disease is caused by a parasite called toxoplasma gondii and is transmitted in several ways. The most common route of infection is via ingestion of raw or undercooked meat, namely pork, lamb, or venison. This form of transmission is prevalent in countries where meat is served raw/ undercooked as part of their custom. In France, steak tartare, raw beef, is a delicacy in fine dining restaurants. Consumption of raw meat such as beef, chicken, and pork is found in many African countries.
Cat feces are known to carry toxoplasma and are commonly found when emptying a cats litter box, while gardening, or playing in a sandbox. The infection is transmitted via hand-to-mouth contact after touching anything contaminated with toxoplasma, so wearing gloves and regular hand washing after working in soil is recommended. A less common way to contract toxoplasmosis is drinking contaminated water. The rarest form of transmission is through contamination via infected organ transplants and blood transfusions.
The worldwide distribution of toxoplasmosis varies by country. France has one of the highest rates of the disease, 88% of its population. Other countries with high prevalence rates of around 80% include Germany, The Netherlands, and Brazil. Toxoplasmosis produces mild flu-like symptoms lasting up to a few weeks, but often goes completely undetected. In humans with healthy immune systems, the infection goes into a latent state, where the person becomes a neutral carrier. Nearly all people with toxoplasmosis have latent toxoplasmosis, and it is generally harmless, never having any subsequent effect on the carrier again in their lifetime. The disease is not communicable via human saliva or blood*. Toxoplasmosis, however, can create fatal complications in patients with weakened immune systems, i.e. HIV and AIDS carriers.
Congenital toxoplasmosis generally does not occur during the pregnancy of a carrier. Women who have already had the disease, and therefore have built up antibodies in their immune system are not at risk of transmitting the disease to their fetus. Mothers that do not have latent toxoplasmosis should take all the necessary precautions to avoid contracting the disease during pregnancy.
Transplacental infection is likely to occur if the mother contracts the infection for the first time shortly before conception, or at any time during pregnancy. Only 30-40% of new cases during pregnancy transmit the disease to the child. Transmission is highest if the disease is contracted during the third trimester. According to a Women’s Health article, ‘Toxoplasmosis infection may lead to miscarriage, stillbirth, or survival with growth problems, blindness, water on the brain (hydrocephalus), brain damage, epilepsy, or deafness.’ There are various prescription medications that can be used to treat toxoplasmosis during pregnancy.

References:
http://www.womens-health.co.uk/infect.asp
http://en.wikipedia.org/wiki/Toxoplasmosis

~Josh Bently

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~ by jdbently on September 5, 2009.

One Response to “Toxoplasmosis: Prevalence, Latency, and Transplacental Infection”

  1. I enjoyed your post! I am sure that this is not something that people even think about when they are pregnant, especially cat owners.
    -Melissa Broderick

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