Infected water and foods. Organisms are carried by some animals. Acute gastroenteritis lasting 1 to 7 days. Incubation time ranges from 12 to 36 hours. Organism can be excreted for weeks after illness, making food handlers potent reservoirs for contamination.
Humans are reservoirs, but cases of food borne shigellosis have been documented.
Varies from flu like gastric upset to severe dysentery. Secondary infections prevalent with infants. Requires as little as 200 organisms for disease. Human carriers excrete organisms for weeks after illness. Toxins are heat stabile.