Toxoplasma gondii is a parasite that generally uses cats as their host.
Infection from this causes toxoplasmosis
which presents as flu
-like symptoms in normal individuals. This parasite is harmful to pregnant women because it can cross the placenta
and infect the baby. The relationship with gardening is because cats use gardens as litter boxes and the parasite is found/transmitted in their feces
Answer assisted by Michael Erickson, Medical Student