Gastroenterology clinic

Blastocystis infection: to treat or not to treat?

Robyn Nagel



Symptomatic patients with Blastocystis hominis should be given a trial of antibiotic therapy if no other cause can be found for their symptoms.

Article Extract

  • Blastocystis hominis is one of the most common enteric parasites encountered worldwide. It is commonly referred to as a protozoan parasite, but the latest taxonomic classification suggests that it is more closely linked with brown algae and water moulds in the Chromista group.
  • Blastocystis species have been identified in many animals, including earthworms, birds, dogs, possums and monkeys. Blastocystis may also have zoonotic potential in dogs, possums and primates.
  • Blastocystis species that infect humans are conventionally named B. hominis although the group is genetically diverse and not species specific. Children appear to be less likely to be infected than adults.
  • Polymerase chain reaction (PCR) techniques have shown that many different subspecies exist (at least seven), even within a host range.