I research toxoplasmosis from an animal health and food safety perspective

Maria Vang Johansen

Interview with Maria Vang Johansen, a professor in parasitic zoonoses at the University of Copenhagen, Denmark

Our current knowledge on the prevalence of toxoplasmosis is very fragmented, and most official reports can only estimate the burden of disease. We currently have no systematic way of determining the prevalence of Toxoplasma in the food chain. Sheep, goats, pigs and wild game tend to be more easily infected than indoor poultry and cattle. Food animals become infected if a cat is in the area shedding oocysts into the environment. Toxoplasma can be picked up from contaminated soil, surface water, feed or infected rodents.

Food trends are always evolving and changing, from how we raise our food, to how we prepare it. The risk is constantly changing. There are no standard guidelines across Europe for how to prepare meat, and lowering the temperature in pork cooking guidelines in some countries poses a risk to consumers. Cooking meat until all potential pathogens have been eliminated is essential in preventing foodborne disease. First and foremost, people should know the risks of handling and consuming raw and undercooked meat products.

Zoonotic diseases cannot be fixed with one method alone: they need to be tackled through an integrated and one health (animal and human) approach. We must inform the public, secure our agriculture and food practices, conduct active and passive surveillance, and attack the parasite at many places in its life cycle. However, it is certainly clear that we must do better at educating women of childbearing age about the risks of toxoplasmosis.

Cat’s role in human toxoplasmosis exaggerated

There is no doubt that the general public has an exaggerated assumption of a cat’s role in human toxoplasmosis. The main way to become infected is by ingesting raw or undercooked meat and vegetables, or infected soil and water. Cats mostly become infected when they are young. Following infection, cats shed the oocysts for a maximum of 3 weeks, after which they usually hold lifelong immunity.

Medical doctors can educate women better about the foodborne risk during pregnancy. Veterinarians have a duty to inform their clients about zoonotic transmission from cats. However, if this is the only message people receive about toxoplasmosis, the information about how somebody becomes infected is unclear and improperly weighted toward the zoonotic route.

Education on toxoplasmosis and transmission should be part of doctors’ training, guiding them on what to tell women. However, risk communication is not solely the responsibility of medical doctors or veterinarians. We all must work together to increase awareness about toxoplasmosis and how to prevent the disease in mothers, their children and the population at large.