What is toxoplasmosis?
Toxoplasmosis is an infection caused by protozoa called Toxoplasma gondii. Many mammals and birds can be infected by toxoplasma, including humans. Infected animals can hold the parasite in cysts within their tissues. Cats, however, are the only definitive host for Toxoplasma gondii. This means that on top of being able to hold the parasite in their meat, they can also pass an oocyte (an environmentally resistant-stage of the parasite) through their faeces to infect other animals.

Toxoplasmosis in cats
Cats get infected by Toxoplasma Gondii by ingesting infected small animals, such as rodents and birds, or from their mother. Therefore, cats with outdoor access have the highest risk of contracting and spreading toxoplasmosis. For indoor cats, the most common source would be any raw meat.

Upon infection, a cat can shed millions of oocytes via their faeces for several days. This is the time where other animals, including humans, can get infected if exposed to an infective stage of the oocyte. An oocyte has to be in the environment for at least 24 hours before becoming infectious. Most infected cats may hold the parasite in their meat throughout their lives but will NOT shed anymore oocytes after the initial stage of shedding.

Many cats appear perfectly healthy although they are infected. Certain immunocompromised cats, like cats with feline leukaemia virus (FeLV) or feline immunodeficiency virus (FIV), are more likely to display clinical signs of Toxoplasmosis. The clinical signs include lethargy, eye lesions, inappetance, diarrhoea, coughing and neurological signs.

Toxoplasmosis in humans
Humans can contract toxoplasma in a few different ways:

1. Handling and ingestion of raw/ uncooked meat is the most common route of infection. The infection is most commonly due to ingestion of tissue cysts in pork, lamb and game. Consumption of raw seafood is also a common route of infection as Toxoplasma gondii can survive in seawater for months. Infection via poultry and beef is less common.
2. Ingestion of unpasteurised milk or milk product
3. Accidental ingestion of faecal matter from cats. This can happen after touching anything that has come in contact with cat faeces. These include: cat litter, vegetables and fruits from the garden, soil from the garden (through gardening) and freshwater.

Signs of toxoplasmosis in humans often include mild, flu-like symptoms which do not require any treatment. In immunocompromised individuals (e.g. individuals undergoing chemotherapy/ pregnant women/ individuals with HIV), this parasite can cause more severe symptoms such as neurological disease, seizures, paralysis, coma and death despite treatment with the appropriate antibiotics.

A woman can also transmit toxoplasma to her foetus during pregnancy. If a woman contracts toxoplasmosis in her first trimester, the result is often more devastating – the foetus will often have eye diseases and neurological diseases that may result in foetal death. Infection that occurs during the second or third trimester is usually less severe. Most babies infected later in the gestation period will show no symptoms at birth but many develop signs later in life. Some clinical signs are vision/ hearing loss, mental disability and if severe, death. A woman that had prior exposure to Toxoplasma before pregnancy will have protection against this parasite and will not transmit it to their foetus. A blood test that tests for toxoplasma antibodies can be taken before pregnancy to check for prior exposure.

How to prevent the transmission of toxoplasmosis
If you are pregnant or immunocompromised, it is definitely still possible to keep your cat(s) around. Here are some basic guidelines to prevent toxoplasmosis infection. For further information, please discuss with your general practitioner or your veterinarian.

1. Daily precautions
   • Avoid consuming any raw/ undercooked meat products or seafood. Avoid tasting food before they are completely cooked. Remember that raw food consumption is the most common cause of toxoplasmosis infection.
   • Wash your hands thoroughly after handling raw meat
   • Wash any kitchen supplies thoroughly after coming in contact with raw food
   • Thorough cleaning of vegetables and fruits from the garden
   • Avoid consuming unpasteurised milk or milk products
   • Boil before drinking any water from ponds or streams during camping
   • Cover sand boxes outdoors to prevent cats from using it as a litter box
2. Cat owners
   • Keep your cats indoor to prevent them from hunting rodents or birds and do NOT feed your cat raw meat
   • Change the litter tray daily before the oocytes become infectious. If you are pregnant/ immunocompromised, please get someone else in the house to clean the litter tray for you. If this is not possible, use a rubber glove and wash your hands thoroughly afterwards.
   • If you are pregnant/ immunocompromised, adopting an older cat is recommended as they are more likely to have been exposed to Toxoplasma and completed the shedding phase. It is NOT recommended to adopt kittens or young cats as infected kittens can shed millions of oocysts.
   • For long haired cats, you can groom the hair at their rear end to reduce faecal material from collecting in the area
   • Thoroughly wash your hands after handling your cat(s), especially before eating or drinking

In summary, humans rarely contract Toxoplasmosis from cats. Therefore, testing healthy cats for Toxoplasma gondii is not indicated. By following the above preventative guidelines, immunocompromised or pregnant individuals that are cat owners/ planning to adopt a cat, can safely prevent toxoplasmosis infection and benefit from animal companionship at the same time.