Ricin: Clinical Description

Incubation

Following inhalation or ingestion of ricin, initial manifestation of symptoms is likely to occur within 4 to 12 hours.
After ingestion of ricin it is extremely unlikely that symptom onset would begin more than 10 hours after exposure.
After inhalation exposure to ricin powder, it is very unlikely that symptom onset would begin more than 24 hours after exposure.

Symptoms

Systemic effects of ricin poisoning depend upon route of exposure and exposure dosage.
Dermal and ocular exposure by ricin in powder or mist form can cause erythema and pain of the skin and eyes.
Ingestion Exposure:
- Signs and symptoms from oral exposure to purified ricin are presumed to be similar to reports of illness after castor bean mastication and ingestion.
- Some or all of the following symptoms may be manifest:
  - Profuse vomiting
  - Profuse diarrhea (bloody or nonbloody)
  - Severe dehydration
  - Weakness
  - Influenza-like symptoms: fever, myalgia, and arthralgia
  - Hallucinations
  - Seizures
  - Hematuria
  - Hypotension
  - Hypovolemic shock, and multiple system organ failure may occur, leading to death.
Inhalational Exposure:
- Data on inhalational exposure to ricin in humans are limited.
- Some or all of the following symptoms may be manifest:
  - Cough, respiratory distress, bronchoconstriction
  - Pulmonary edema
  - Cyanosis
  - Nausea
  - Excessive diaphoresis
  - Weakness
  - Influenza-like symptoms: fever, myalgia, and arthralgia
  - Hypotension, respiratory failure and multisystem organ failure may occur, leading to death.
- Persons exposed to castor bean dust in or around castor oil processing plants have been reported to manifest an allergic syndrome. Repeated inhalation exposures to sub-lethal levels of ricin have resulted in:
  - Allergic syndrome with congestion of nose and throat
  - Itchy, watery eyes
  - Hives
  - Chest tightness
  - Wheezing, in severe cases.
Injection Exposure (data are limited):
- In a single human trial of low doses of intravenous ricin, influenza-like symptoms of fatigue and myalgias occurred.
- A case in which a person injected castor bean extract subcutaneously resulted in hospitalization 36 hours after the injection. Clinical manifestations included:
  - Complaints of nausea, weakness, dizziness, and myalgias.
  - Anuria and hypotension developed.
  - Hepatic failure, renal failure, cardiorespiratory failure, and death 18 hours following admission.
- In a case in which a dissident was thought to have been assassinated with a ricin injection, clinical manifestations included:
  - Pain at injection site, which developed immediately.
  - Weakness developed within 5 hours.
  - Fever and vomiting developed within 24 hours, followed by shock and multi-organ failure, and death within 3 days.
- In a case in which a chemist extracted ricin from a caster bean and self-administered injections, symptoms included:
  - Nausea, anorexia, mild elevation of liver function tests, and tissue damage at injection site.
  - Symptoms persisted for 8 to 10 days.
Gastrointestinal System:
- Abdominal pain
- Vomiting
- Diarrhea (bloody or nonbloody)
- Abnormal liver function tests
- Multiple ulcerations and hemorrhages of gastric and small-intestinal mucosa on endoscopy.
Respiratory System:
- Cough
- Bronchoconstriction (chest tightness)
- Dyspnea
- Hypoxemia
- Noncardiogenic pulmonary edema.
Skin and Mucous Membrane:
- Erythema and pain of eyes and skin.
General Systemic:
- Fever
- Fatigue
- Weakness
- Muscle pain
- Dehydration.
Other Organ System:
- Nervous System: Seizures (uncommon)
- Cardiovascular: hypovolemic shock.
Manifestation of aforementioned signs and symptoms does not necessarily mean that a person has been exposed tricin.
Fatal systemic effects from ricin poisoning can occur within 36 to 72 hours of exposure; if death has not occurred in 3 to 5 days, the victim usually recovers.