Infectious dose

Infectious dose (ID) is the amount of pathogen (measured in number of microorganisms) required to cause an infection in the host.

Usually it varies according to the pathogenic agent and the consumer's age and overall health.

Infectious doses for some known microorganisms

• Escherichia coli : very large (10⁶ - 10⁸ of organisms)
• Salmonella : quite large ( > 10⁵ of organisms)
• Cholera : relatively large (10⁴ - 10⁶ of organisms)
• Bacillus anthracis : relatively large (10⁴ spores)
• Campylobacter jejuni: low (500 organisms)
• Shigella : very low (10s of organisms)
• C.parvum : very low (10 to 30 oocysts)
• Escherichia coli O157:H7 : very low ( < 10 organisms)
• Entamoeba coli : extremely low (from 1 cyst)