乌鸦传媒

Government authorities have confirmed that two suspicious letters, one sent to President Obama and another to Sen. Roger Wicker (R-Miss., shown at right) have tested positive for the toxic substance ricin.

Tuesday, an off-site facility which handles Senate mail notified the U.S. Capitol Police that it had received an envelope containing “a white granular substance.” The next day, the that a similar substance was intercepted at a screening facility for White House mail and was addressed to President Obama. Both envelopes were similar in appearance and had similar markings. The substances in both cases field-tested positive for ricin and have been sent to the laboratory for further testing, the results of which are expected in 24 to 48 hours.

On Wednesday evening, the Paul Kevin Curtis, of Corinth, Miss., the individual believed to be responsible for the mailings.

At the present time, there are no known injuries or exposures from these letters.

This news couldn’t come at a worse time. Tensions in Washington and across the country are already running high due to the deadly bombings on Monday at the Boston Marathon. Three people were killed and more than 170 were injured in the two bomb blasts.

Ricin has been involved in a number of incidents, including the high-profile assassination of Soviet dissident in 1978 using a weapon disguised as an umbrella. He died 4 days later.
<乌鸦传媒>What is ricin?

Ricin is a potent biological toxin derived from part of the “waste” mash when beans from the castor plant (Ricinus communis) are processed during manufacture of castor oil.

Ricin is a toxalbumin, whose mechanism of action is inhibition of protein synthesis; cell death results from the absence of proteins. It is classified as a type 2 ribosome-inactivating protein.

It is a stable substance, affected very little by extreme conditions, such as very hot or very cold temperatures. It can be in the form of a powder, a mist, a pellet. It is water-soluble, odorless, tasteless, and stable under ambient conditions.   

Depending on the route of exposure (such as injection or inhalation), as little as 500 µ of ricin could be enough to kill an adult. A greater amount would be needed to cause death if ricin were ingested.

It  takes a deliberate act to manufacture ricin to poison people. Ricin is one of the most toxic biological agents known — a Category B bioterrorism agent and a Schedule Number 1 chemical warfare agent.

<乌鸦传媒>What are the symptoms of ricin poisoning?

Clinicians should be alert to illness patterns and diagnostic clues that might indicate an intentional release of ricin.

The extent of manifestations of ricin poisoning in humans depends on the amount of ricin to which a person was exposed, route of exposure, and extent of organ involvement.

Significant exposure to ricin would result in a relatively rapid, progressive worsening of symptoms over approximately 4 to 36 hours. Death may occur within 36 hours of exposure. If death has not occurred by 5 days from exposure, the victim usually recovers.

Symptoms

Ingestion Exposure:
Some or all of the following symptoms may be manifest:

• Profuse vomiting
• Profuse diarrhea (bloody or non-bloody)
• 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:

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.

Dermal and ocular exposure by ricin in powder or mist form can cause erythema and pain of the skin and eyes.  

Laboratory Findings:

Nonspecific laboratory findings in ricin poisoning:

• Metabolic acidosis
• Abnormal liver function tests
• Abnormal renal function tests
• Hematuria
• Leukocytosis (two- to five-fold higher than normal value)

At the present time, there are no specific clinically validated assays for detection of ricin that can be performed by a hospital/healthcare facility clinical laboratory.
   
Laboratory tests performed on ricin-suspicious samples include:

• Time-resolved fluorescence immunoassay: antibody binds to ricin
• Polymerase chain reaction: locates and makes copies of parts of the DNA contained in the castor bean plant. The search specifically identifies the DNA of the gene that produces the ricin protein.

<乌鸦传媒>How is ricin poisoning treated?

There is no antidote for ricin poisoning.Treatment consists of supportive measures:

Inhalation

• Place in half-upright position.
• Perform pulmonary toilet, if needed.
• Provide oxygen, and/or mechanical ventilation with positive end expiratory pressure to maintain oxygenation, if needed.
• Perform cardiopulmonary resuscitation if necessary.

Ingestion

• Do not induce vomiting.
• Administer a single dose of activated charcoal as soon as possible if the patient has suspected/known ricin ingestion, if vomiting has not begun and airway is secure.
• Do not give anything by mouth.
• Gastric lavage may be considered if ingestion has occurred in ≤1 hour.
• Provide early and aggressive intravenous fluid and electrolyte replacement.
• Administer blood pressure support through the use of intravenous vasopressors, if needed.
  

Ocular Exposure
Flush eyes with large amounts of tepid water for at least 15 minutes.
   
Dermal Exposure

• Remove clothing.
• Decontaminate skin by showering or washing, using soap and water, and rinsing skin with plenty of water.

One of the most important considerations in diagnosing and treating ricin poisoning is maintaining a high index of suspicion.

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