Pregnancy and toxoplasmosis. Why eating dry cured ham appear to be safe.

During pregnancy future mums need to follow a suitable diet. This simply means a varied diet including: milk and dairy products, meat, fish, eggs, pulses, cereals and cereal products, fruit and vegetables, and olive oil. A number of precautions have to be taken, such as avoiding the consumption of raw or undercooked meat or fish, as well as salamis, to prevent the risk of acquiring dangerous intestinal infections or toxoplasmosis, an infection which can cause serious harm to the unborn child if acquired by women who are not immune during the early stages of pregnancy.

Toxoplasma gondii is a protozoan which generally lives in the intestines of cats, which become infected by consuming small rodents.

Cats provide a breeding ground for this microorganism, since cats’ intestines are the perfect environment for the sexual reproduction cycle of toxoplasma. The oocysts are expelled in the cat’s faeces and may be ingested by other animals or humans, which act as its intermediate hosts. Toxoplasmosis is a typical syndrome affecting pets.

In man, toxoplasmosis manifests itself in a number of different ways, such as asymptomatic infections and encephalitis. It can produce serious complications in pregnant women, including miscarriage, premature labour and neonatal mortality. Congenital toxoplasmosis (transmitted via the placenta) derives from an acute primary infection of the mother during pregnancy or just before (infection at least six months before becoming pregnant makes it unlikely that the unborn child will be infected). The severity and incidence depend on the trimester of pregnancy.

Toxoplasmosis is one of the commonest infections in the world: it is more common in warm temperate zones at low altitude and less common in cold climates and mountainous regions.

The disease can be acquired in different ways: through the accidental ingestion of oocysts expelled by cats and matured in the external environment (when handling earth and cat litter, contact with anything that has been in contact with cat faeces); eating poorly washed raw vegetables; eating raw or undercooked meats (especially pork, lamb and game), fresh sausages or insufficiently aged salamis and unpasteurised dairy products contaminated by oocysts; accidental ingestion of cysts through contact between the mouth and hands which have handled raw meats. Prolonged refrigeration and freezing, as well as heat (60°C for 20 minutes or 70°C for 10 minutes) remove oocysts from foods. Meat-based products aged for more than 2 months appear to be safe. Dry cured hams, such as Prosciutto di San Daniele, Prosciutto di Parma, Prosciutto di Veneto Berico Euganeo and others should be considered safe since they are salted and matured for over 13 months. Salt, dehydrations (Aw < 0.92) and aging over a long period (more than 13 months) seem to deactivate any oocysts present in the muscles, as demonstrated by numerous international articles.



Bayarri S, Gracia MJ, Pérez-Arquillué C, Lázaro R, Herrera A. (2012) Toxoplasma gondii in commercially available pork meat and cured ham: a contribution to risk assessment for consumers. J. Food Protect. 5(3):597-600.Bayarri S, Gracia MJ, Lázaro R, Pe Rez-Arquillué C, Barberán M, Herrera A. (2010) Determination of the viability of Toxoplasma gondii in cured ham using bioassay: influence of technological processing and food safety implications. J. Food Protect. 73(12):2239-43.


Prof. Giuseppe Comi

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