Whereas most amoebozoans are free-living, those that belong to the genus Entamoeba are parasites. They infect all classes of vertebrates as well as some invertebrates. Humans are host to at least six species of Entamoeba, but only one, E. histolytica, is known to be pathogenic. E. histolytica causes amebic dysentery and is spread via contaminated drinking water, food, or eating utensils. Responsible for up to 100,000 deaths worldwide every year, the disease is the third-leading cause of death due to eukaryotic parasites, after malaria and schistosomiasis.