A parasitic disease whose pathogen is Toxoplasma gondii , toxoplasmosis is present all over the world, and it is estimated that one third of the population is infected. This generally harmless pathology, however, presents serious risks in subjects with a weakened immune defense system as well as in HIV-negative pregnant women .
What is toxoplasmosis?
Usually mild infectious disease, toxoplasmosis is transmitted to humans by animals , mainly cats, sheep, goats, as well as pigs among others. This disease often goes unnoticed and can manifest as swelling of the lymph nodes and vague discomfort. The responsible parasite is a sporozoan whose presence in the blood can also be confirmed by an examination in a laboratory for biological analyzes.
Note, however, that this disease is dangerous in pregnant women who can transmit it to their fetus. Fetal malformations are almost always the consequence of this contamination by the placental route.
Parasite cycle
The cat plays an important role because it is the site of sexual reproduction of the protozoan.
Contamination to humans occurs :
- Orally, through contact with an infected cat or through the placenta if the mother is infected
- By eating raw or undercooked meat containing the parasite as a cyst
- In case of immunodeficiency
The cat becomes infected by eating infested meat (mice, birds) which may contain up to 300,000 toxoplasmas in cystic form. It is in the intestine of the cat that sexual reproduction takes place: the eggs produced (oocytes) are found in the feces of the cat where they can live in moist soil for months.
T. gondii is ubiquitous in birds and mammals. This obligate intracellular parasite invades the cytoplasm and multiplies asexually as tachyzoites in any nucleated cell. As the host’s immunity develops, the multiplication of tachyzoites ceases and tissue cysts are formed; cysts persist in a latent state for years, particularly in the brain, eyes and muscles. Dormant forms of Toxoplasma in cysts are thus called “bradyzoites”.
Sexual reproduction of T. gondii takes place in the intestines of cats; the oocysts produced in the stool remain infectious in moist soil for months.
What are the symptoms of toxoplasmosis?
The disease is asymptomatic in 60 to 80% of infected subjects, the parasite living in cystic form.
In the immunocompromised subject:
The parasite reactivates and there is often the appearance of pathologies in the nervous system : encephalitis, paralysis of the cranial nerves, visual abnormalities, mental confusion, convulsions which can go as far as coma. The parasite can spread throughout the body and cause fever, chills, pneumonia, myocarditis, prostration.
Without treatment, the disease can lead to the death of the individual.
In pregnant women (congenital toxoplasmosis):
If the woman is infested before conception , there is, in principle, no transmission to the fetus, except in cases of reactivation during pregnancy.
If the disease is contracted during pregnancy , there may be spontaneous abortions or premature births. The newborn will have an illness that is more serious the earlier the mother has been infected during her pregnancy.
We can find :
- Jaundice
- Hepato-splenomegaly
- Retinochoroiditis
- Cerebral calcifications
- Hydrocephalus
- Psychomotor retardation
These symptoms may appear several months or even years after birth.
Some natural tips to prevent toxoplasmosis
- Cook the meat well
- Wash fruits and vegetables thoroughly to remove all traces of soil
- Avoid the consumption of raw cow’s or goat’s milk, raw smoked or salted cold meats, raw seafood
- Wear gloves when gardening
- Thorough hand washing (hand washing with fingernail brushing) is essential after handling raw meat, gardening or touching objects soiled with dirt, soil or a cat’s litter to prevent toxoplasmosis. Foods that may be contaminated with cat stool should be destroyed. Meat should be cooked to around 74-77 ° C.
- Pregnant women are advised to avoid contact with cats. If contact is unavoidable, pregnant women should at least avoid cleaning cat litter boxes or wear gloves while doing so.
- Thoroughly wash surfaces and utensils used after handling food
- If there is a cat at home, have the litter box washed with boiling water every day, if possible by someone other than the pregnant woman or by wearing gloves. Cleaning with bleach does not provide any additional guarantee for cleaning the litter. Cat scratches are not at risk. Cats residing strictly in apartments and receiving canned food or kibble free from parasites are not however affected by this measure because they are not exposed to danger.
Medical bibliographic sources :
- ANSES Animal Health Laboratory, 2016
- Richard D. Pearson, MD, University of Virginia School of Medicine, MSD, 2020
- CDC: Resources for Health Professionals: Toxoplasmosis AIDSinfo: Guidelines for Prevention of Opportunistic Infections in HIV-Infected Adults and Adolescents
