Salmonella typhi is the causative agent of typhoid fever. The infective does of S.typhi: (A) One bacillus, (B) 108-1010 bacilli, (C) 102-105 bacilli, (D) 1-10 bacilli
Answer is C. Ans. is 'c' i.e., 102-105 bacilli In human volunteer experiments, the infective dose was found to be 103-106 bacilli. Organism Infective dose . ETEC . EIEC . EHEC . Shigella . Campylobactor jejuni . Yersinia enterocolitica . Vibrio 106-101deg 108-10m 10-100( 104 108-109 1010 (if source of infection is water) 102-104 (if source of infection is food)