Case Definition: Ricin Inhalation

Clinical description

Inhalation of ricin typically leads to cough and respiratory distress followed by pulmonary edema, respiratory failure, and multi-system organ dysfunction. Weakness and influenza-like symptoms of fever, myalgia, and arthralgia might also be reported (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 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.

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

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. Garber EAE, O’Brien TW. Detection of Ricin in Food Using Electrochemiluminescence-Based Technology. Journal of AOAC International 2008;91:(2): 376-82.
  8. Cassiday L. Two new methods for ricin detection. Analytical chemistry 2009;3202.
  9. 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.
  10. 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.
  11. Griffiths GD, Understanding ricin from a defensive viewpoint. Toxins 2011;3:1373-1392.
Page last reviewed: April 4, 2018