T-2 Mycotoxins, Bioterrorism

SYMPTOMS

Exposure causes skin pain, pruritus (itchiness), redness, vesicles (fluid-filled blisters), necrosis (tissue death) and sloughing of the epidermis. Effects on the airway include nose and throat pain, nasal discharge, itching and sneezing, cough, dyspnea (difficulty in breathing), wheezing, chest pain and hemoptysis (coughing up of blood). Toxin also produces effects after ingestion or eye contact. Severe intoxication results in prostration, weakness, ataxia (lack of muscle control), collapse, shock, and death.

DIAGNOSIS

Contamination should be suspected if an aerosol attack occurs in the form of "yellow rain" with droplets of variously pigmented oily fluids contaminating clothes and the environment. Confirmation requires testing of blood, tissue and environmental samples.

TREATMENT

There is no specific antidote. Treatment is supportive. Soap and water washing, even 4-6 hours after exposure can significantly reduce dermal toxicity; washing within 1 hour may prevent toxicity entirely. Superactivated charcoal should be given orally if the toxin is swallowed.

PROPHYLAXIS

The only defense is to prevent exposure by wearing a protective mask and clothing (or topical skin protectant) during an attack. No specific immunotherapy or chemotherapy is available for use in the field.

ISOLATION AND DECONTAMINATION

Outer clothing should be removed and exposed skin decontaminated with soap and water. Eye exposure should be treated with copious saline irrigation. Secondary aerosols are not a hazard; however, contact with contaminated skin and clothing can produce secondary dermal exposures. Contact Precautions are warranted until decontamination is accomplished. Then, Standard Precautions are recommended for healthcare workers. Environmental decontamination requires the use of a hypochlorite solution under alkaline conditions such as 1% sodium hypochlorite and 0.1M NaOH with 1 hour contact time.

OVERVIEW

The trichothecene (T-2) mycotoxins are a group of over 40 compounds produced by fungi of the genus Fusarium, a common grain mold. They are small molecular weight compounds, and are extremely stable in the environment. They are the only class of toxin that is dermally active, causing blisters within a relatively short time after exposure (minutes to hours). Dermal, ocular, respiratory, and gastrointestinal exposures would be expected after an attack with mycotoxins.

HISTORY AND SIGNIFICANCE

The potential for use as a BW toxin was demonstrated to the Russian military shortly after World War II when flour contaminated with species of Fusarium was unknowingly baked into bread that was ingested by civilians. Some developed a protracted lethal illness called alimentary toxic aleukia (ATA) characterized by initial symptoms of abdominal pain, diarrhea, vomiting, prostration, and within days fever, chills, myalgias and bone marrow depression with granulocytopenia and secondary sepsis. Survival beyond this point allowed the development of painful pharyngeal/laryngeal ulceration, diffuse bleeding into the skin (petechiae and ecchymoses), melena, bloody diarrhea, hematuria, hematemesis, epistaxis and vaginal bleeding. Pancytopenia, and gastrointestinal ulceration and erosion were secondary to the ability of these toxins to profoundly arrest bone marrow and mucosal protein synthesis and cell cycle progression through DNA replication.

Mycotoxins allegedly were released from aircraft in the "yellow rain" incidents in Laos (1975-81), Kampuchea (1979-81), and Afghanistan (1979-81). It has been estimated that there were more than 6,300 deaths in Laos, 1,000 in Kampuchea, and 3,042 in Afghanistan. The alleged victims were usually unarmed civilians or guerrilla forces. These groups were not protected with masks or chemical protective clothing and had little or no capability of destroying the attacking enemy aircraft. These attacks were alleged to have occurred in remote jungle areas, which made confirmation of attacks and recovery of agent extremely difficult. Some investigators have claimed that the "yellow clouds" were, in fact, bee feces produced by swarms of migrating insects. Much controversy has centered upon the veracity of eyewitness and victim accounts, but there is evidence to make these allegations of BW agent use in these areas possible.

TOXIN CHARACTERISTICS

The trichothecene mycotoxins are low molecular weight (250-500 daltons) nonvolatile compounds produced by filamentous fungi (molds) of the genera Fusarium, Myrotecium, Trichoderma, Stachybotrys and others. The structures of approximately 150 trichothecene derivatives have been described in the literature. These substances are relatively insoluble in water but are highly soluble in ethanol, methanol and propylene glycol. The trichothecenes are extremely stable to heat and ultraviolet light inactivation. They retain their bioactivity even when autoclaved; heating to 1500o F for 30 minutes is required for inactivation. Hypochlorite solution alone is does not effectively inactivate the toxins. Rather, the addition of 0.1M NAOH to a 1% hypochlorite solution, with 1 hour contact time is required. Soap and water effectively remove this oily toxin from exposed skin or other surfaces.

MECHANISM OF TOXICITY

The mycotoxins appear to have multiple mechanisms of action, many of which are poorly understood. Their most notable effect stems from their ability to rapidly inhibit protein and nucleic acid synthesis. Thus, they are markedly cytotoxic (preventing cell division) to rapidly dividing cells such as in the bone marrow, GI tract (mucosal epithelium), skin, and germ cells. Since this imitates the hematopoietic and lymphoid effects of radiation sickness, the mycotoxins are referred to as "radiomimetic agents." The mycotoxins also alter cell membrane structure and function, inhibit mitochondrial respiration, and inactivate certain enzymes.

CLINICAL FEATURES

In a BW attack with trichothecenes, the toxin(s) can adhere to and penetrate the skin, be inhaled, and can be ingested. In the alleged yellow rain incidents, symptoms of exposure from all 3 routes coexisted. Contaminated clothing can serve as a reservoir for further toxin exposure. Early symptoms beginning within minutes of exposure include burning skin pain, redness, tenderness, blistering, and progression to skin necrosis with leathery blackening and sloughing of large areas of skin. Upper respiratory exposure may result in nasal itching, pain, sneezing, epistaxis, and rhinorrhea. Pulmonary/tracheobronchial toxicity produces dyspnea, wheezing, and cough. Mouth and throat exposure causes pain and blood tinged saliva and sputum. Anorexia, nausea, vomiting and watery or bloody diarrhea with crampy abdominal pain occurs with gastrointestinal toxicity. Eye pain, tearing, redness, foreign body sensation and blurred vision may follow ocular exposure. Skin symptoms occur in minutes to hours and eye symptoms in minutes. Systemic toxicity can occur via any route of exposure, and results in weakness, prostration, dizziness, ataxia, and loss of coordination. Tachycardia, hypothermia, and hypotension follow in fatal cases. Death may occur in minutes, hours or days. The most common symptoms are vomiting, diarrhea, skin involvement with burning pain, redness and pruritus, rash or blisters, bleeding, and dyspnea. A late effect of systemic absorption is pancytopenia, predisposing to bleeding and sepsis.

DIAGNOSIS

Clinical and epidemiological findings provide clues to the diagnosis. High attack rates, dead animals of multiple species, and physical evidence such as yellow, red, green, or other pigmented oily liquid are suggestive of mycotoxins. Rapid onset of symptoms in minutes to hours supports a diagnosis of a chemical or toxin attack. Mustard and other vesicant agents must be considered but they have an odor, are visible, and can be rapidly detected by a field chemical test (M8 paper, M256 kit). Symptoms from mustard toxicity are also delayed for several hours. Inhalation of staphylococcal enterotoxin B or ricin aerosols can cause fever, cough, dyspnea, and wheezing but does not involve the skin.

Specific diagnosis of T-2 mycotoxins in the form of a rapid diagnostic test is not presently available in the field. Serum and urine should be collected and sent to a reference lab for antigen detection. The mycotoxins and metabolites are eliminated in the urine and feces; 50-75% is eliminated within 24 hours, however, metabolites can be detected as late as 28 days after exposure. Pathologic specimens include blood, urine, lung, liver, and stomach contents. Environmental and clinical samples can be tested using a gas liquid chromatography-mass spectrometry technique. This system can detect as little as 0.1-1.0 ppb of T-2, which is sensitive enough to measure T-2 levels in the plasma of toxin victims.

MEDICAL MANAGEMENT

No specific antidote or therapeutic regimen is currently available. All therapy is supportive. If a soldier is unprotected during an attack the outer uniform should be removed within 4 hours and decontaminated by exposure to 5% hypochlorite for 6-10 hours. The skin should be thoroughly washed with soap and uncontaminated water if available. This can reduce dermal toxicity, even if delayed 4-6 hours after exposure. The M291 skin decontamination kit can also be used to remove skin-adherent T-2. Standard burn care is indicated for cutaneous involvement. Standard therapy for poison ingestion, including the use of superactivated charcoal to absorb swallowed T-2, should be administered to victims of an unprotected aerosol attack. Respiratory support may be necessary. The eyes should be irrigated with normal saline or water to remove toxin.

PROPHYLAXIS

Physical protection of the skin, mucous membranes, and airway (use of chemical protective mask and clothing) are the only proven effective methods of protection during an attack. Immunological (vaccines) and chemoprotective pretreatments are being studied in animal models, but are not available for field use by the warfighter. Topical skin protectant may limit dermal exposure. Soap and water washing, even 1 hour after dermal exposure to T-2, effectively prevents dermal toxicity.

DETECTION

Accurate intelligence is required to develop an effective defense against biological warfare. Once an agent has been dispersed, detection of the biological aerosol prior to its arrival over the target, in time for personnel to don protective equipment, is the best way to minimize or prevent casualties. However, interim systems for detecting biological agents are just now being fielded in limited numbers. Until reliable detectors are available in sufficient numbers, usually the first indication of a biological attack in unprotected soldiers will be the ill soldier.

Detector systems are evolving, and represent an area of intense interest with the highest priorities within the research and development community. Several systems are now being fielded. The Biological Integrated Detection System (BIDS) is vehicle- mounted and concentrates aerosol particles from environmental air, then subjects the particle sample to both genetic and antibody-based detection schemes for selected agents. The Long Range Biological Standoff Detection System (LRBSDS) will provide a first time biological standoff detection capability to provide early warning. It will employ infrared laser to detect aerosol clouds at a standoff distance up to 30 kilometers. An improved version is in development to extend the range to 100 km. This system will be available for fixed-site applications or inserted into various transport platforms such as fixed-wing or rotary aircraft. The Short-Range Biological Standoff Detection System (SRBSDS) is in the research and development phase. It will employ ultraviolet and laser-induced fluorescence to detect biological aerosol clouds at distances up to 5 kilometers. The information will be used to provide early warning, enhance contamination avoidance efforts, and cue other detection efforts.

The principal difficulty in detecting biological agent aerosols stems from differentiating the artificially generated BW cloud from the background of organic matter normally present in the atmosphere. Therefore, the aforementioned detection methods must be used in conjunction with intelligence, physical protection, and medical protection (vaccines and other chemoprophylactic measures) to provide layered primary defenses against a biological attack.

PERSONAL PROTECTION

The currently fielded chemical protective equipment, which includes the protective mask, battle dress overgarment (BDO), protective gloves, and overboots will provide protection against a biological agent attack.

The M40 protective mask is available in three sizes, and when worn correctly, will protect the face, eyes, and respiratory tract. The M40 utilizes a single screw-on filter element which involves two separate but complementary mechanisms: 1) impaction and adsorption of agent molecules onto ASC Whetlerite Carbon filtration media, and 2) static electrical attraction of particles initially failing to contact the filtration media. Proper maintenance and periodic replacement of the crucial filter elements are of the utmost priority. The filter MUST be replaced under these circumstances: the elements are immersed in water, crushed, cut, or otherwise damaged; excessive breathing resistance is encountered; the "ALL CLEAR" signal is given after exposure to a biological agent; 30 days have elapsed in the combat theater of operations (the filters must be replaced every 30 days); supply bulletins indicate lot number expiration; or when ordered by the unit commander. The filter element can only be changed in a non-contaminated environment. Two styles of optical inserts for the protective mask are available for soldiers requiring visual correction. The wire frame style is considered to be the safer of the two and is more easily fitted into the mask. A prong-type optical insert is also available. A drinking tube on the mask allows the wearer to drink while in a contaminated environment. Note that the wearer should disinfect the canteen and tube by wiping with a 5 percent hypochlorite solution before use.

The battle dress overgarment suits come in 8 sizes and are currently available in both woodland and desert camouflage patterns. The suit may be worn for 24 continuous hours in a contaminated environment, but once contaminated, it must be replaced by using the MOPP-gear exchange procedure described in the Soldier's Manual of Common Tasks. The discarded BDO must be incinerated or buried. Chemical protective gloves and overboots come in various sizes and are both made from butyl rubber. They may be decontaminated and reissued. The gloves and overboots must be visually inspected and decontaminated as needed after every 12 hours of exposure in a contaminated environment. While the protective equipment will protect against biological agents, it is important to note that even standard uniform clothing of good quality affords a reasonable protection against dermal exposure of surfaces covered.

Those casualties unable to continue wearing protective equipment should be held and/or transported within casualty wraps designed to protect the patient against further chemical-biological agent exposure. Addition of a filter blower unit to provide overpressure enhances protection and provides cooling.

Collective protection by the use of either a hardened or unhardened shelter equipped with an air filtration unit providing overpressure can offer protection for personnel in the biologically contaminated environment. An airlock ensures that no contamination will be brought into the shelter. In the absence of a dedicated structure, enhanced protection can be afforded within most buildings by sealing cracks and entry ports, and providing air filtration with high efficiency particulate air (HEPA) filters within existing ventilation systems. The key problem is that these shelters can be very limited in military situations, very costly to produce and maintain, and difficult to deploy. Personnel must be decontaminated prior to entering the collective protection unit.

The most important route of exposure to biological agents is through inhalation. Biological warfare (BW) agents are dispersed as aerosols by one of two basic mechanisms: point or line source dissemination. Unlike some chemical threats, aerosols of agents disseminated by line source munitions (e.g., sprayed by low-flying aircraft or speedboats along the coast) do not leave hazardous environmental residua (although anthrax spores may persist and could pose a hazard near the dissemination line). On the other hand, aerosols generated by point-source munitions (i.e., stationary aerosol generator, bomblets, etc.) are more apt to produce ground contamination, but only in the immediate vicinity of dissemination. Point-source munitions leave an obvious signature that alerts the field commander that a biological warfare attack has occurred. Because point-source munitions always leave an agent residue, this evidence can be exploited for detection and identification purposes.

Aerosol delivery systems for biological warfare agents most commonly generate invisible clouds with particles or droplets of < 10 micrometers (mm). They can remain suspended for extensive periods. The major risk is pulmonary retention of inhaled particles. To a much lesser extent, particles may adhere to an individual or his clothing, thus the need for individual decontamination. The effective area covered varies with many factors, including wind speed, humidity, and sunlight. In the absence of an effective real-time alarm system or direct observation of an attack, the first clue would be mass casualties fitting a clinical pattern compatible with one of the biological agents. This may occur hours or days after the attack.

Toxins may cause direct pulmonary toxicity or be absorbed and cause systemic toxicity. Toxins are frequently as potent or are more potent by inhalation than by any other route. A unique clinical picture may sometimes be seen which is not observed by other routes (e.g., pulmonary edema after staphylococcal enterotoxin B (SEB) exposure). Mucous membranes, including conjunctivae, are also vulnerable to many biological warfare agents. Physical protection is then quite important and the use of full-face masks equipped with small-particle filters, like the chemical protective masks, assumes a high degree of importance.

Other routes for delivery of biological agents are thought to be less important than inhalation, but are nonetheless potentially significant. Contamination of food and water supplies, either purposefully or incidentally after an aerosol biological warfare attack, represents a hazard for infection or intoxication by ingestion. Assurance that food and water supplies are free from contamination should be provided by appropriate preventive medicine authorities in the event of an attack.

Intact skin provides an excellent barrier for most biological agents. T-2 mycotoxins would be an exception because of their dermal activity. However, mucous membranes and abraded, or otherwise damaged, integument can allow for passage of some bacteria and toxins, and should be protected in the event of an attack.

DECONTAMINATION

Contamination is the introduction of an infectious agent on a body surface, food or water, or other inanimate objects. Decontamination involves either disinfection or sterilization to reduce microorganisms to an acceptable level on contaminated articles, thus rendering them suitable for use. Disinfection is the selective reduction of undesirable microbes to a level below that required for transmission. Sterilization is the killing of all organisms.

Decontamination methods have always played an important role in the control of infectious diseases. However, we are often unable use the most efficient means of rendering microbes harmless (e.g., toxic chemical sterilization), as these methods may injure people and damage materials which are to be decontaminated. BW agents can be decontaminated by mechanical, chemical and physical methods:

  • Mechanical decontamination involves measures to remove but not necessarily neutralize an agent. An example is the filtering of drinking water to remove certain water-borne pathogens (e.g. Dracunculus medinensis), or in a BW context, the use of an air filter to remove aerosolized anthrax spores, or water to wash agent from the skin.

  • Chemical decontamination renders BW agents harmless by the use of disinfectants that are usually in the form of a liquid, gas or aerosol. Some disinfectants are harmful to humans, animals, the environment, and materials.

  • Physical means (heat, radiation) are other methods that can be employed for decontamination of objects.

Dermal exposure to a suspected BW aerosol should be immediately treated by soap and water decontamination. Careful washing with soap and water removes nearly all of the agent from the skin surface. Hypochlorite solution or other disinfectants are reserved for gross contamination (i.e. following the spill of solid or liquid agent from a munition directly onto the skin). In the absence of chemical or gross biological contamination, these will confer no additional benefit, may be caustic, and may predispose to colonization and resistant superinfection by reducing the normal skin flora. Grossly contaminated skin surfaces should be washed with a 0.5% sodium hypochlorite solution, if available, with a contact time of 10 to 15 minutes.

Ampules of calcium hypochlorite (HTH) are currently fielded in the Chemical Agent Decon Set for mixing hypochlorite solutions. The 0.5% solution can be made by adding one 6-ounce container of calcium hypochlorite to five gallons of water. The 5% solution can be made by adding eight 6-ounce ampules of calcium hypochlorite to five gallons of water. These solutions evaporate quickly at high temperatures so if they are made in advance they should be stored in closed containers. Also the chlorine solutions should be placed in distinctly marked containers because it is very difficult to tell the difference between the 5% chlorine solution and the 0.5% solution.

To mix a 0.5% sodium hypochlorite solution, take 1 part Clorox and 9 parts water (1:9) since standard stock Clorox is a 5.25% sodium hypochlorite solution. The solution is then applied with a cloth or swab. The solution should be made fresh daily with the pH in the alkaline range.

Chlorine solution must NOT be used in (1) open body cavity wounds, as it may lead to the formation of adhesions, or (2) brain and spinal cord injuries. However, this solution may be instilled into non-cavity wounds and then removed by suction to an appropriate disposal container. Within about 5 minutes, this contaminated solution will be neutralized and nonhazardous. Subsequent irrigation with saline or other surgical solutions should be performed. Prevent the chlorine solution from being sprayed into the eyes, as corneal opacities may result.

For decontamination of fabric clothing or equipment, a 5% hypochlorite solution should be used. For decontamination of equipment, a contact time of 30 minutes prior to normal cleaning is required. This is corrosive to most metals and injurious to most fabrics, so rinse thoroughly and oil metal surfaces after completion.

BW agents can be rendered harmless through such physical means as heat and radiation. To render agents completely harmless, sterilize with dry heat for two hours at 160 degrees centigrade. If autoclaving with steam at 121 degrees centigrade and 1 atmosphere of overpressure (15 pounds per square inch), the time may be reduced to 20 minutes, depending on volume. Solar ultraviolet (UV) radiation has a disinfectant effect, often in combination with drying. This is effective in certain environmental conditions but hard to standardize for practical usage for decontamination purposes.

The health hazards posed by environmental contamination by biological agents differ from those posed by persistent or volatile chemical agents. Aerosolized particles in the 1-5 µm size range will remain suspended due to brownian motion; suspended BW agents would be eventually inactivated by solar ultraviolet light, desiccation, and oxidation. Little, if any, environmental residues would occur. Possible exceptions include residua near the dissemination line, or in the immediate area surrounding a point-source munition. BW agents deposited on the soil would be subject to degradation by environmental stressors, and competing soil microflora. Simulant studies at Dugway Proving Ground suggest that secondary reaerosolization would be difficult, and would probably not pose a human health hazard. Environmental decontamination of terrain is costly and difficult and should be avoided, if possible. If grossly contaminated terrain, streets, or roads must be passed, the use of dust-binding spray to minimize reaerosolization may be considered. If it is necessary to decontaminate these surfaces, chlorine-calcium or lye may be used. Otherwise, rely on natural process which, especially outdoors, leads to the decontamination of agent by drying and solar UV radiation. Rooms in fixed spaces are best decontaminated with gases or liquids in aerosol form (e.g., formaldehyde). This is usually combined with surface disinfectants to ensure complete decontamination.

Most of this information is courtesy of US Government CDC. In times of an emergency much of this material may not apply when it comes to specialized care and testing. These are guidelines to help you when that care is not available. Some of this information is very technical and difficult to understand, but hopefully someone will be available for help in treatment and understanding.