Case Definition: Ricin Ingestion

Clinical description

Ingestion of ricin typically leads to profuse vomiting and diarrhea, which might be bloody, followed by hypovolemic shock and multisystem organ dysfunction. (1-5)
Laboratory criteria for diagnosis

  • Biologic: CDC can assess selected specimens on a provisional basis for urinary ricinine, an alkaloid in the castor bean plant. Only urinary ricinine testing is available at CDC or the Laboratory Response Network.

– OR-

  • Environmental: Detection of ricin in environmental samples, as determined by CDC. Ricin can be detected qualitatively by time-resolved fluoroimmunoassay (TRF) in environmental specimens (e.g., filters, swabs, or wipes).

Case classification

  • Suspected: A case in which a potentially exposed person is being evaluated by health-care workers or public health officials for poisoning by a particular chemical agent, but no specific credible threat exists.
  • Probable: A clinically compatible case in which a high index of suspicion (credible threat or patient history regarding location and time) exists for ricin exposure, or an epidemiologic link exists between this case and a laboratory-confirmed case.
  • Confirmed: A clinically compatible case in which laboratory tests have confirmed exposure.

The case can be confirmed if laboratory testing was not performed because either a predominant amount of clinical and nonspecific laboratory evidence of a particular chemical was present or the etiology of the agent is known with 100% certainty.

Additional resources

  1. Audi JA, Belson M, Patel MM, Schier JG, Osterloh J. Ricin poisoning – A comprehensive review. JAMA 2005;294(18):2342-51.
  2. Ellenhorn MJ, Barceloux DG, eds. Ornamental beans. In: Medical toxicology: diagnosis and treatment of human poisonings. New York, NY: Elsevier; 1997:1225-7.
  3. Kortepeter MG, Parker GW. Potential biological weapons threats. Emerg Infect Dis 1999;5:523–7. Available from URL:
  4. US Army Medical Research Institute of Infectious Diseases. Ricin. In: Eitzen E, Pavlin J, Cieslak T, Christopher G, Culpepper R, eds. Medical management of biological casualties [Handbook]. 4th ed. Fort Detrick: MD: US Army Medical Research Institute of Infectious Diseases, Operational Medical Division; 2001:101-6.
  5. Franz DR, Jaax NK. Ricin toxin. In: Zajtchuk R, Bellamy RF, eds. Textbook of military medicine: medical aspects of chemical and biological warfare. Washington, DC: US Department of the Army; 1997:631-42.
  6. Knight B. Ricin—a potent homicidal poison. BMJ 1979;1:350-1.
  7. Cassiday L. Two new methods for ricin detection. Analytical chemistry 2009;3202.
  8. Johnson RC, Lemire SW, Woolfitt AR, et al. Quantification of ricinine in rat and human urine: A biomarker for ricin exposure. Journal of Analytical Toxicology 2005; 29:149-55.
  9. Puri P and Kumar O. Integrating immunobased detection and identification methods for ricin analysis: an overview. Journal of Bioterrorism and Biodefense 2011;S2:1-7.

Note: A case should not be considered ricin poisoning if another confirmed diagnosis exists to explain the signs and symptoms.

Page last reviewed: April 4, 2018