Reasonable Rascal
12-26-01, 20:24
CHOLERA
Summary
Signs and Symptoms: Incubation period 4 hours to 5 days; average 2-3 days. Asymptomatic to severe with sudden onset. Vomiting, headache, intestinal cramping with little or no fever followed rapidly by painless, voluminous diarrhea. Fluid losses may exceed 5 to 10 liters per day. Without treatment, death may result from severe dehydration, hypovolemia and shock.
Diagnosis: Clinical diagnosis. Rice water, diarrhea and dehydration. Microscopic exam of stool samples reveals few or no red or white cells. Can be identified by darkfield or phase contrast microscopy, and by direct visualization of darting motile vibrio.
Treatment: Fluid and electrolyte replacement. Antibiotics (tetracycline, ciprofloxacin or erythromycin) may shorten the duration of diarrhea and, more importantly, reduce shedding of the organism.
Prophylaxis: A licensed, killed vaccine is available but provides only about 50 percent protection that lasts for no more than 6 months. Vaccination schedule is at 0 and 4 weeks, with booster doses every 6 months.
Isolation and Decontamination: Standard Precautions for healthcare workers. Personal contact rarely causes infection; however, enteric precautions and careful hand-washing should be employed. Bactericidal solutions (hypochlorite) would provide adequate decontamination.
OVERVIEW
Vibrio cholerae is a short, curved, motile, gram-negative, non-sporulating rod. There are two serogroups, O1 and O139, that have been associated with cholera in humans. The O1 serotype exists as 2 biotypes, classical and El Tor. The organisms are facultative anaerobes, growing best at a pH of 7.0, but able to tolerate an alkaline environment. They do not invade the intestinal mucosa, but rather "adhere" to it. Cholera is the prototype toxigenic diarrhea, which is secretory in nature. All strains elaborate the same enterotoxin, a protein molecule with a molecular weight of 84,000 daltons. The entire clinical syndrome is caused by the action of the toxin on the intestinal epithelial cell. Fluid loss in cholera originates in the small intestine with the colon being relatively insensitive to the toxin. The large volume of fluid produced in the upper intestine overwhelms the capacity of the lower intestine to absorb. Transmission is made through direct or indirect fecal contamination of water or foods, and by heavily soiled hands or utensils. All populations are susceptible, while natural resistance to infection is variable. Recovery from an attack is followed by a temporary immunity which may furnish some protection for years. The organism is easily killed by drying. It is not viable in pure water, but will survive up to 24 hours in sewage, and as long as 6 weeks in certain types of relatively impure water containing organic matter. It can withstand freezing for 3 to 4 days. It is readily killed by dry heat at 117 ° C, by steam and boiling, by short exposure to ordinary disinfectants, and by chlorination of water.
HISTORY AND SIGNIFICANCE
This agent has purportedly been investigated in the past as a biological weapon. Cholera does not easily spread from person-to-person. Therefore, to be an effective biological weapon, major drinking water supplies would need to be heavily contaminated. Recent naturally occurring cholera epidemics in South America have shown the devastating consequences of this disease. Cholera spread quickly in Peru and neighboring countries, despite all attempts to curb the epidemic at an early stage. Over 250,000 symptomatic cases have been reported in Peru alone, and the epidemic has spread to other countries. The rate of symptomatic to asymptomatic cases is 1:400, a factor mitigating against effective use of cholera as a BW agent.
CLINICAL FEATURES
Cholera is an acute infectious disease, characterized by sudden onset with nausea, vomiting, profuse watery diarrhea with 'rice water' appearance, the rapid loss of body fluids, toxemia, and frequent collapse. Mortality can range as high as 50 percent in untreated cases.
DIAGNOSIS
After an incubation period varying from 4 hours to 5 days (average 2-3 days), presumably dependent upon the dose of ingested organisms, onset is usually rather sudden, although the clinical manifestations range from an asymptomatic carrier state to severe illness. Initially the disease presents with intestinal cramping and painless diarrhea. Vomiting, malaise and headache often accompany the diarrhea, especially early in the illness. If fever is present, it is usually low grade. Diarrhea may be mild or profuse and watery, with fluid losses exceeding 5 to 10 liters or more per day. Electrolyte loss can explain almost all clinical signs and symptoms. Without treatment, death may result from severe dehydration, hypovolemia and shock.
On microscopic examination of stool samples there are few or no red cells or white cells and almost no protein. The absence of inflammatory cells and erythrocytes reflects the non-invasive character of V. cholerae infection of the intestinal lumen. The organism can be identified in liquid stool or enrichment broths by darkfield or phase contrast microscopy, and by identifying darting motile vibrio. The organism must be transported using Cary-Blair medium and then streaked for isolation onto TCBS (Thiosulfate Citrate Bile Salt Sucrose) medium. Bacteriologic identification is not necessary to treat cholera, as it can be diagnosed clinically.
MEDICAL MANAGEMENT
Treatment of cholera depends primarily on replacement of fluid and electrolyte losses. This is best accomplished using oral rehydration therapy with the World Health Organization solution (3.5 g NaCl, 2.5 g NaHCO3, 1.5 g KCl and 20 g of glucose per liter). Intravenous fluid replacement is occasionally needed in patients with persistent vomiting or high rates of stool loss (>10ml/kg/hr). Antibiotics will shorten the duration of diarrhea and thereby reduce fluid losses. Tetracycline (500 mg every 6 hours for 3 days) or doxycycline (300 mg once or 100 mg every 12 hours for 3 days) is generally adequate. However, due to widespread tetracycline resistance, ciprofloxacin (500 mg every 12 hours for 3 days) or erythromycin (500 mg every 6 hours for 3 days) should be considered. For pediatric treatment, tetracycline (50 mg/kg/d divided into 4 doses x 3 days) can be used, as dental staining has only occurred after > 6 courses of treatment lasting 6 or more days. Alternates are erythromycin (40 mg/kg/d divided into 4 doses x 3 days), trimethoprim 8 mg and sulfamethoxazole 40 mg/kg day divided into 2 doses x 3 days, and furazolidone (5 mg/kg/d divided into 4 doses x 3 days or 7 mg/kg x one dose).
PROPHYLAXIS
Vaccine: A licensed, killed vaccine is available for use in those considered to be at risk of exposure, however, it provides only about 50 percent protection that lasts for no more than 6 months. The vaccination schedule is an initial dose followed by a second dose 4 weeks later, with booster doses every 6 months. An inactivated oral vaccine (WC/rBS), which is licensed in Europe, is safe and provides rapid short-term protection. Licensure in the US is anticipated. WC/rBS requires 2 doses and has approximately 85% efficacy lasting 2-3 years for both El Tor and classical biotypes. Live attenuated oral vaccines show much promise, and one, CVD 103-HgR (classical biotype), will probably be available by 1999. There are no O139 serogroup vaccines close to licensure, and none of the above mentioned vaccines provide cross-protection against O139. Primary infection with V. cholerae O1 serogroup also provides no immunity against O139.
Prevention: Since the major biological threat from this organism appears to be sabotage of food and water supplies, it would seem justified to state that optimal prophylaxis in these circumstances would not be of a
medical nature but would be proper safeguarding of these supplies to prevent the sabotage. The best way to prevent cholera in an endemic environment is to avoid contaminated water, ice, fruits, vegetables and also raw or undercooked seafood. Personal contact rarely causes infection because of the high inoculum required for infection; however, enteric precautions and careful hand-washing should be employed. Bactericidal solutions (hypochlorite) would provide adequate decontamination.
DECONTAMINATION
Contamination is the introduction of microorganisms into tissues or sterile materials. Decontamination is disinfection or sterilization of infected articles to make them suitable for use (the reduction of microorganisms to an acceptable level). Disinfection is the selective elimination of certain undesirable microorganisms in order to prevent their transmission (the reduction of the number of infectious organisms below the level necessary to cause infection). Sterilization is the complete killing of all organisms. BW agents can be decontaminated by mechanical, chemical and physical methods.
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 infectious diseases harmless (e.g., toxic chemical sterilization) in order to not hurt people or damage materials which are to be freed from contamination.
Mechanical decontamination involves measures to remove but not necessarily neutralize an agent. An example is the filtering of drinking water to remove certain agents (e.g., Vibrio cholera or Clostridium
botulinum) that may have been used to purposefully contaminate a water supply. Chemical decontamination renders BW agents harmless by the use of disinfectants which are usually in the form of a liquid, gas or aerosol. One has to remember that some disinfectants are harmful to humans, animals, the environment, and/or materials.
Dermal exposure with a suspected BW agent should be immediately treated by soap and water decontamination. Careful washing with soap and water removes a very large amount of the agent from the skin surface. It is important to use a brush to ensure mechanical loosening from the skin surface structures, and then rinse with copious amounts of water. This method is often sufficient to avert contact infection. The contaminated areas should then 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 also 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 one part Clorox and nine 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 patients with (1) open abdominal 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 radiation (UV radiation) has a certain disinfectant effect, often in combination with drying. This is effective in certain environmental conditions but hard to standardize for practical usage for decontamination purposes.
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. Environmental decontamination of terrain is costly and difficult and should be avoided, if possible. If contaminated terrain, streets, or roads must be passed, spray with a dust-binding spray to minimize reaerosolization. If it is necessary to decontaminate these surfaces, chlorine-calcium or lye may be used. Otherwise, rely on the natural processes which, especially outdoors, leads to the decontamination of agent by means of drying and solar UV radiation.
DETECTION
Adequate and accurate intelligence is required in order 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 of 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 generic and antibody-based detection schemes for selected agents. The Long Range Standoff Detection System (LRSDS) 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. In the research and development phase is the Short-Range Biological Standoff Detection System (SRBSDS). It will employ an uiltraviolet 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 medical protection (vaccines and other chemoprophylactic measures), intelligence, and physical protection to provide layered primary defenses against a biological attack.
Summary
Signs and Symptoms: Incubation period 4 hours to 5 days; average 2-3 days. Asymptomatic to severe with sudden onset. Vomiting, headache, intestinal cramping with little or no fever followed rapidly by painless, voluminous diarrhea. Fluid losses may exceed 5 to 10 liters per day. Without treatment, death may result from severe dehydration, hypovolemia and shock.
Diagnosis: Clinical diagnosis. Rice water, diarrhea and dehydration. Microscopic exam of stool samples reveals few or no red or white cells. Can be identified by darkfield or phase contrast microscopy, and by direct visualization of darting motile vibrio.
Treatment: Fluid and electrolyte replacement. Antibiotics (tetracycline, ciprofloxacin or erythromycin) may shorten the duration of diarrhea and, more importantly, reduce shedding of the organism.
Prophylaxis: A licensed, killed vaccine is available but provides only about 50 percent protection that lasts for no more than 6 months. Vaccination schedule is at 0 and 4 weeks, with booster doses every 6 months.
Isolation and Decontamination: Standard Precautions for healthcare workers. Personal contact rarely causes infection; however, enteric precautions and careful hand-washing should be employed. Bactericidal solutions (hypochlorite) would provide adequate decontamination.
OVERVIEW
Vibrio cholerae is a short, curved, motile, gram-negative, non-sporulating rod. There are two serogroups, O1 and O139, that have been associated with cholera in humans. The O1 serotype exists as 2 biotypes, classical and El Tor. The organisms are facultative anaerobes, growing best at a pH of 7.0, but able to tolerate an alkaline environment. They do not invade the intestinal mucosa, but rather "adhere" to it. Cholera is the prototype toxigenic diarrhea, which is secretory in nature. All strains elaborate the same enterotoxin, a protein molecule with a molecular weight of 84,000 daltons. The entire clinical syndrome is caused by the action of the toxin on the intestinal epithelial cell. Fluid loss in cholera originates in the small intestine with the colon being relatively insensitive to the toxin. The large volume of fluid produced in the upper intestine overwhelms the capacity of the lower intestine to absorb. Transmission is made through direct or indirect fecal contamination of water or foods, and by heavily soiled hands or utensils. All populations are susceptible, while natural resistance to infection is variable. Recovery from an attack is followed by a temporary immunity which may furnish some protection for years. The organism is easily killed by drying. It is not viable in pure water, but will survive up to 24 hours in sewage, and as long as 6 weeks in certain types of relatively impure water containing organic matter. It can withstand freezing for 3 to 4 days. It is readily killed by dry heat at 117 ° C, by steam and boiling, by short exposure to ordinary disinfectants, and by chlorination of water.
HISTORY AND SIGNIFICANCE
This agent has purportedly been investigated in the past as a biological weapon. Cholera does not easily spread from person-to-person. Therefore, to be an effective biological weapon, major drinking water supplies would need to be heavily contaminated. Recent naturally occurring cholera epidemics in South America have shown the devastating consequences of this disease. Cholera spread quickly in Peru and neighboring countries, despite all attempts to curb the epidemic at an early stage. Over 250,000 symptomatic cases have been reported in Peru alone, and the epidemic has spread to other countries. The rate of symptomatic to asymptomatic cases is 1:400, a factor mitigating against effective use of cholera as a BW agent.
CLINICAL FEATURES
Cholera is an acute infectious disease, characterized by sudden onset with nausea, vomiting, profuse watery diarrhea with 'rice water' appearance, the rapid loss of body fluids, toxemia, and frequent collapse. Mortality can range as high as 50 percent in untreated cases.
DIAGNOSIS
After an incubation period varying from 4 hours to 5 days (average 2-3 days), presumably dependent upon the dose of ingested organisms, onset is usually rather sudden, although the clinical manifestations range from an asymptomatic carrier state to severe illness. Initially the disease presents with intestinal cramping and painless diarrhea. Vomiting, malaise and headache often accompany the diarrhea, especially early in the illness. If fever is present, it is usually low grade. Diarrhea may be mild or profuse and watery, with fluid losses exceeding 5 to 10 liters or more per day. Electrolyte loss can explain almost all clinical signs and symptoms. Without treatment, death may result from severe dehydration, hypovolemia and shock.
On microscopic examination of stool samples there are few or no red cells or white cells and almost no protein. The absence of inflammatory cells and erythrocytes reflects the non-invasive character of V. cholerae infection of the intestinal lumen. The organism can be identified in liquid stool or enrichment broths by darkfield or phase contrast microscopy, and by identifying darting motile vibrio. The organism must be transported using Cary-Blair medium and then streaked for isolation onto TCBS (Thiosulfate Citrate Bile Salt Sucrose) medium. Bacteriologic identification is not necessary to treat cholera, as it can be diagnosed clinically.
MEDICAL MANAGEMENT
Treatment of cholera depends primarily on replacement of fluid and electrolyte losses. This is best accomplished using oral rehydration therapy with the World Health Organization solution (3.5 g NaCl, 2.5 g NaHCO3, 1.5 g KCl and 20 g of glucose per liter). Intravenous fluid replacement is occasionally needed in patients with persistent vomiting or high rates of stool loss (>10ml/kg/hr). Antibiotics will shorten the duration of diarrhea and thereby reduce fluid losses. Tetracycline (500 mg every 6 hours for 3 days) or doxycycline (300 mg once or 100 mg every 12 hours for 3 days) is generally adequate. However, due to widespread tetracycline resistance, ciprofloxacin (500 mg every 12 hours for 3 days) or erythromycin (500 mg every 6 hours for 3 days) should be considered. For pediatric treatment, tetracycline (50 mg/kg/d divided into 4 doses x 3 days) can be used, as dental staining has only occurred after > 6 courses of treatment lasting 6 or more days. Alternates are erythromycin (40 mg/kg/d divided into 4 doses x 3 days), trimethoprim 8 mg and sulfamethoxazole 40 mg/kg day divided into 2 doses x 3 days, and furazolidone (5 mg/kg/d divided into 4 doses x 3 days or 7 mg/kg x one dose).
PROPHYLAXIS
Vaccine: A licensed, killed vaccine is available for use in those considered to be at risk of exposure, however, it provides only about 50 percent protection that lasts for no more than 6 months. The vaccination schedule is an initial dose followed by a second dose 4 weeks later, with booster doses every 6 months. An inactivated oral vaccine (WC/rBS), which is licensed in Europe, is safe and provides rapid short-term protection. Licensure in the US is anticipated. WC/rBS requires 2 doses and has approximately 85% efficacy lasting 2-3 years for both El Tor and classical biotypes. Live attenuated oral vaccines show much promise, and one, CVD 103-HgR (classical biotype), will probably be available by 1999. There are no O139 serogroup vaccines close to licensure, and none of the above mentioned vaccines provide cross-protection against O139. Primary infection with V. cholerae O1 serogroup also provides no immunity against O139.
Prevention: Since the major biological threat from this organism appears to be sabotage of food and water supplies, it would seem justified to state that optimal prophylaxis in these circumstances would not be of a
medical nature but would be proper safeguarding of these supplies to prevent the sabotage. The best way to prevent cholera in an endemic environment is to avoid contaminated water, ice, fruits, vegetables and also raw or undercooked seafood. Personal contact rarely causes infection because of the high inoculum required for infection; however, enteric precautions and careful hand-washing should be employed. Bactericidal solutions (hypochlorite) would provide adequate decontamination.
DECONTAMINATION
Contamination is the introduction of microorganisms into tissues or sterile materials. Decontamination is disinfection or sterilization of infected articles to make them suitable for use (the reduction of microorganisms to an acceptable level). Disinfection is the selective elimination of certain undesirable microorganisms in order to prevent their transmission (the reduction of the number of infectious organisms below the level necessary to cause infection). Sterilization is the complete killing of all organisms. BW agents can be decontaminated by mechanical, chemical and physical methods.
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 infectious diseases harmless (e.g., toxic chemical sterilization) in order to not hurt people or damage materials which are to be freed from contamination.
Mechanical decontamination involves measures to remove but not necessarily neutralize an agent. An example is the filtering of drinking water to remove certain agents (e.g., Vibrio cholera or Clostridium
botulinum) that may have been used to purposefully contaminate a water supply. Chemical decontamination renders BW agents harmless by the use of disinfectants which are usually in the form of a liquid, gas or aerosol. One has to remember that some disinfectants are harmful to humans, animals, the environment, and/or materials.
Dermal exposure with a suspected BW agent should be immediately treated by soap and water decontamination. Careful washing with soap and water removes a very large amount of the agent from the skin surface. It is important to use a brush to ensure mechanical loosening from the skin surface structures, and then rinse with copious amounts of water. This method is often sufficient to avert contact infection. The contaminated areas should then 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 also 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 one part Clorox and nine 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 patients with (1) open abdominal 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 radiation (UV radiation) has a certain disinfectant effect, often in combination with drying. This is effective in certain environmental conditions but hard to standardize for practical usage for decontamination purposes.
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. Environmental decontamination of terrain is costly and difficult and should be avoided, if possible. If contaminated terrain, streets, or roads must be passed, spray with a dust-binding spray to minimize reaerosolization. If it is necessary to decontaminate these surfaces, chlorine-calcium or lye may be used. Otherwise, rely on the natural processes which, especially outdoors, leads to the decontamination of agent by means of drying and solar UV radiation.
DETECTION
Adequate and accurate intelligence is required in order 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 of 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 generic and antibody-based detection schemes for selected agents. The Long Range Standoff Detection System (LRSDS) 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. In the research and development phase is the Short-Range Biological Standoff Detection System (SRBSDS). It will employ an uiltraviolet 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 medical protection (vaccines and other chemoprophylactic measures), intelligence, and physical protection to provide layered primary defenses against a biological attack.