<prompt> A person returns to Delhi from Bangladesh after 2 days and has diarrhoea. Stool examination shows RBCs in Stool. The likely organism causing is ?Enteropathogenic E. ColiEnterotoxigenic E. ColiSalmonella typhiShigella dysentriae  <response>: Ans. is d i.e., Shigella Dysentriae . The person is suspected to have travellers diarrhoea. . The most common cause of travellers diarrhoea is E.coli , but the strains of the E.coli Enterotoxigenic Enteropathogenic given in the choice do not produce invasive illness i.e presence of blood in stool. . It is a feature of Enterohemorrhagic E.coli . Now the choice is between Salmonella Shigella diarrhoea are . Both these organisms produce invasive disease i.e dysentery or inflammatory diarrhoea . But Shigella Salmonella can be differentiated on the basis of incubation period. i Shigella 1-2days ii Salmonella --0. 10-14 days 