Types of Parasite Infections. There are four common types of parasite infections in the U.S. Like any illness, early detection and treatment makes a difference in recovery. It can also help prevent the spread of the disease to others. Most parasitic infections lead to dehydration and chronic digestive problems. For some, the infections can be life-threatening. Cryptosporidiosis (crypto) can be severe for individuals with a weakened immune system. Giardiasis infections cause gastrointestinal diseases. The organism’s protective shell also makes it more difficult to eradicate. Toxoplasmosis infections are the leading cause of fatalities of foodborne parasites the U.S. Trichomoniasis is a sexually transmitted disease (STD) infection that exists in over three million people in the U.S.