Pythium insidiosum
Pythium insidiosum is a species of Pythium and a member of the class oomycota. Pythium insidiosum is mainly found in standing water and occasionally soil. Unlike most Pythium species, which are generally pathogens of terrestrial plants, Pythium insidiosum is a pathogen of mammals. It causes pythiosis, mainly in horses, dogs, and humans. It can also cause disease in cats. It is a non-transmissible disease and occurs mainly in tropical climate, endemic to Thailand, affecting mainly humans and horses and in Brazil. Infection can occur in healthy mammals. The pathogen is well-adapted to mammalian body temperature, with an optimum temperature for growth of.
The cell walls of Pythium insidiosum are composed of β-glucans and cellulose, and their cytoplasmic membranes lack sterols, molecules that are targets of antifungals. For this reason, infection caused by Pythium insidiosum is often difficult to treat.