Blastocystis sp. subtypes (STs 1–9) with various host specificities. Humans can be infected by nine STs, some being mainly found in humans (ST3 and ST9). ST1, 2, 5 and 8 are found both in human and mammalian isolates (primate, pig, human, cattle and pig), while ST4 is also present among rodent isolates, and ST6, 7 and 8 among avian isolates. Some STs are exclusively found in animals (ST10–17). ST10 and 15 are present among Artiodactyla and nonhuman primates, ST11 among Proboscidea, ST12 among Artiodactyla and marsupials, ST13 among nonhuman primates and marsupials, ST14 among Artiodactyla, ST16 among marsupials and ST17 among rodents.