Heat-stable toxin 1 of entero-aggregative E.coli (EAST1) is a small toxin. It is not, however, solely associated with entero-aggregative E.coli but also with many other diarrhoaeic E. coli families. Some studies have established the role of EAST1 in some human outbreaks of diarrhoea. Isolates from farm animals have been shown to carry the astA gene coding for EAST1. However, the relation between the presence of EAST1 and disease is not conclusive.