Learn about toxoplasmosis, a worldwide and common parasitic disease responsible for serious problems in pregnant women and those with weakened immune system.
By Ricardo Ribas
Toxoplasmosis is a world distributed disease affecting warm-blood species such as birds, mammals and humans. The agent is a single-celled protozoa parasite named Toxoplasma gondii. Whilst studies suggest that the Toxoplasma can be found in approximately 30% of the human population, the disease is rarely a reason of concern in healthy individuals, but can lead to serious consequences in those with weak immune system, such as AIDS sufferers or those undergoing chemotherapy. Pregnant women are also vulnerable and the disease can lead to miscarriage, stillbirth and devastated neurological problems to the foetus.
How is Toxoplasma transmitted?
Most of human and animal infections occur during the consumption of uncooked meat containing toxoplasma cysts or by ingestion of food/water contaminated with eggs. Other less common routes of transmission include blood transfusions, organ transplantation and vertical transmission from the mother to foetus. The World Health Organisation suspects that, just in Europe, there are over a million toxoplasma infections happening each year.
The Toxoplasma’s life cycle
Cats and other felines have a crucial role in the life cycle of the Toxoplasma’s given that they are the only species able to provide the right environment for the parasite to mature sexually and complete its life cycle. The process starts when the felines consume meat (often rodents, birds, and other small animals) carrying the parasite cysts. The cysts will travel to the animal’s stomach where they lose the protective envelop, triggering the start of the process of maturation and replication. Once reach the intestines, the toxoplasma produce eggs that are subsequently released into the environment with the animal’s faeces.
The eggs can remain in the environment for several years and are been able to contaminate food and water. Once ingested by animals or humans, the eggs have the potential to migrate through their bodies and lodge in the form of cysts in many tissues, such as brain, muscles, liver, heart, lungs, eye, etc, generating a new route for transmission to other species that will consume these tissues. Infection during pregnancy is of particular concern both in animals and humans, because the parasite has the potential to trespass the placenta and to lead to the development of neurological problems in the foetus, stillbirth and miscarriage.
What are the symptoms?
While most of the infections by Toxoplasma do not cause any symptoms in healthy animals and humans, complications often occur in pregnant females or individuals with weaken immunity. This is because the toxoplasma is an opportunist parasite that takes advantage of hosts with weakened immunity to spread. In the majority of the cases, people show flu-like symptoms such as fever, tiredness, muscles-ache, lack of appetite and weight loss. However, complication can happen depending of the organs affected. These can include diarrhoea, vomiting, jaundice, coughing, difficulty breathing, pancreatitis, headaches as well as problems in the nervous system and with the eye (reduced or blurred vision, eye pain, redness or tearing) and occasionally death. Recent studies have also suggested a link between Toxoplasmosis and schizophrenia and suicide. Finally, particular care should be given during pregnancy because it can bring catastrophic consequences to the foetus and lead to stillbirths or birth defects such as mental retardation, blindness, hydrocephalus – presence of water in the brain, seizures, etc.
And how can we treat?
Whilst most animals and humans often recover without any specific treatment, in some cases this is required. A combination of antibiotics and antimalaria drugs are usually recommended in animals and humans to prevent serious complications. Depending on the specific symptoms, a selection of other treatments may be required, such as the use of corticosteroids for those suffering from eye problems.
• Ensure meats are well cooked, fresh vegetables are washed thoroughly and avoid consuming unpasteurized milk or any products made from it.
• Avoid handling raw meats without gloves.
• Wash utensils and surfaces that may have been in contact with raw meats to avoid contamination with other foods.
• Clean the garbage daily using disposable gloves.
• Wear gloves and wash your hands thoroughly after handling or cleaning cat faeces. Disinfect the places where the cat may have defecated.
• Prevent cats from eating raw meat or any animals such as mice or birds.
• Avoid touching or handling pregnant sheep or lambs.
• If you intend to become pregnant, it is advisable to take a toxoplasmosis test. If the test is positive, it means that you are already immune. If the test is negative, take extra precautions to prevent infection during pregnancy.
By Ricardo Ribas, Veterinary Doctor, doctorate in veterinary sciences and scientific researcher.
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The subjects and ideas discussed on this article are for informational purposes only. For more information consult a doctor, a vet or a professional in the area. Whilst every effort is made to make sure the article is accurate at the time of publication, I take no liability for any new developments on the subject as well as any errors or omissions.