Toxoplasmosis is an infectious disease found in people and animals such as cats, dogs, pigs, mice…etc. Toxoplasmosis is caused by a parasite called "Toxoplasma gondii".
The infection is mainly transmitted via fecal-oral transmission which means that the parasite must migrate from the animal’s stool to somehow reach the human mouth. Toxoplasmosis infection can be also transmitted through damaged skin that has been in contact with animal secretions.
In most cases an infection with toxoplasma gondii passes without symptoms. In rare cases it can manifest with a fever, rash, bad general condition, cardiac, respiratory and nerve symptoms that usually end with death.
A special form of toxoplasmosis is the congenital form. Congenital toxoplasmosis occurs when pregnant woman get infected with Toxoplasma gondii. In these cases the mother is not affected but the fetus is damaged. Prognosis of congenital toxoplasmosis is quite bad. Most of babies infected with congenital toxoplasmosis die before birth (miscarriage) or soon after birth. Those that will survive have severe neurological and psychical disorders: epilepsy, cerebral paralysis, mental retardation etc.
There is no efficient prevention of toxoplasmosis except to avoid contacts with animals especially for pregnant women. In your case, you might consider asking somebody else to take care of your dog.