Typhoid Graphic (IMAGE) University of California - San Diego Caption Due to a single oxygen atom difference in sialic acids, typhoid toxin affects humans while other mammals are resistant. Credit UC San Diego School of Medicine Usage Restrictions Use caption and credit as indicated above. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.