By Linda D. Kozaryn American Forces Press Service [For the full web version (with graphics and related sites), go to www.defenselink.mil/specials/chembio/.] WASHINGTON -- You can't see, smell or taste them, so how do you fight biological agents? The military has geared up defenses against these invisible killers since the threat of biological weapons became a reality during Operation Desert Storm. Since then, the military has fielded new protection equipment and detection systems, and more counter measures are in the works. Still, many people don't understand the nature of biological agents, how they would be deployed or how to protect themselves, according to Col. John V. Wade, an Army medical department officer who has specialized in the chemical-biological warfare field for the past 16 years. During Desert Storm, Wade served as Army Gen. Norman Schwarzkopf's medical chemical-biological warfare adviser. On Oct. 1, 1998, he became deputy for counterproliferation and chemical and biological defense to the director of defense research and engineering and the undersecretary of defense for acquisition and technology. Biological warfare encompasses a mixed bag of bacterial agents, viruses and toxins, Wade explained. Lumping all biological warfare agents together as a class is almost as dangerous as comparing biological and chemical agents directly, because they can be very different, he said. Depending on the situation, some are contagious, others are not. "If you and I in this room are exposed to these agents, unprotected, we're in trouble," Wade said. "But when we leave the room, we may not necessarily 'spread it' in a contagious sense, unless some of the agent remains on our clothing and is physically transferred to someone else." Usually, people think of biological agents as an aerosol threat, according to the Pentagon expert. "Think of that as taking a liquid in an atomizer and putting it out in very, very small microdroplets. Aerosols behave a lot like chemical vapors. There's a lot of water vapor in a room, but we can't see it, or feel it, or taste it, or touch it. That's really what we'd have in a biological event." These deadly "bugs" do have some natural enemies, Wade said. "Most biological agents don't weather well. There are lots of things that make it difficult for these biological agents to exist," he said. "You put them out in ultraviolet light and they die. They don't like drying out. The same environmental factors that keep us from having one cold after another will help us out to some extent in the case of a biological attack." Wade said biological agents can be dispersed either by what's known as a "line source" or by a "point source." Imagine your platoon is dug in at a forward location. Miles away, an enemy boat sailing along a river or coastline, or possibly a train traveling a rail line, releases a spray. The enemy has determined the prevailing wind will carry the disease- laden aerosol in your direction. This "line source," Wade pointed out, can cover a sizable piece of geography. A more commonly envisioned scenario involves a point source, he said. This is where the enemy launches a missile or other munition that detonates and spews biological agent directly on you -- the target. "Either way, what the enemy is trying to do is take the organism or the toxin and disperse it into the atmosphere so that the target troops then inhale it," he said. "That's really the threat of most of these agents. Just like the common cold, we get them via inhalation. "Because the agents are very small particles, they can make it through our nasal passages -- evading all of the normal protective measures we have to filter things out -- and get down to the deep lung area where they then cause disease." Unlike a chemical agent attack, which would cause an almost immediate reaction, a biological attack would not cause a reaction until after an incubation period. "Generally it takes 24, 36, 48 hours before our troops would start showing what oftentimes are nondescript, flu-like symptoms which then progress to whatever symptoms the specific agent would normally cause," Wade said. So, how do you defend yourself against an attack you don't even know has happened? Wade said the best defense comes from using a combination of immunization and physical protective measures. He pointed to the anthrax vaccine as a key countermeasure against a biological warfare attack. Wade, who has already had the entire series of anthrax shots as well as several annual boosters, said DoD is working to develop a number of vaccines to protect against other biological-threat agents. When vaccines are not available as a biological countermeasure, Wade said, the answer is "rapid detection, warning, reporting and masking." He said it is important to note that the protective mask is "effective against every known biological agent, including those for which we don't yet have vaccines." Defense officials are developing and fielding smaller, lighter, and simpler biological detectors, Wade said. "We have a number of systems that can now be deployed on the battlefield." One of these, he said, is the Biological Integrated Detection System, or BIDS. It's a Humvee-mounted mobile lab suite that can detect four different agents simultaneously and is manned by a crew of four. The Army deploys BIDS companies as corps- or theater-level assets to do bio-detection for all forces. BIDS are point detectors, Wade noted. "You have to wait for the cloud to come to the BIDS. We have the same type of system aboard ships called the Interim Biological Agent Detector, or IBAD. After detecting what appears to be an unnatural agent, the systems first provide a warning, then determine specifically what the biological agent is. "The individual doesn't need to know immediately whether it is anthrax or plague," Wade said. "They simply need to put on protective equipment. As a command, we'd need to know what agent it was so that if there are specific medical countermeasures, we can start immediately to protect those who didn't get their masks on soon enough." Biological agents are considered "strategic weapons," Wade noted. "They're not a good tactical weapon. So if someone is going to use them, we want our detection arrayed out in front of, or dispersed throughout, troop locations to give us early warning." Defense officials also have developed (acquired) a long-range biological detector, Wade said. It's a laser-scanning instrument mounted on a Black Hawk helicopter that can look out about 50 kilometers. "It can't identify specific agents, but it's looking for that telltale, cigar-shaped plume that comes from someone laying down a line source," he said. "If we can see it 50 kilometers off, that gives us a tremendous amount of time either to prepare for it coming our way, or to go out and sample that cloud," Wade continued. "In the future, we'll have detectors that are light enough and small enough to go on an unmanned drone vehicle that will fly through the cloud, find out what it is and report back." Wade calls the military's "Portal Shield" device one of its biggest successes since the Gulf War. This system, deployed in the Persian Gulf region in February 1998 during Operation Desert Thunder, is about two-thirds the size of a typical office desk. It's fully modular, self-contained and can detect eight different agents. "The beauty of this device is that it's a network sensor," Wade said. Depending on the geography, as many as 18 sensors may be arrayed around a port or an airfield. The sensors talk to one another, he said, so you're not relying on just one of them sounding an alarm. Using sensor arrays, the false positive rate very quickly gets down to zero, Wade noted. In Bahrain, U.S. forces have run more than 3,000 tests during round-the-clock monitoring by the Portal Shield deployed there. The false positive rate was less than one half of 1 percent, he said. Defense officials are also developing more user- and environment-friendly decontaminates. "We're working on improved technologies which are easier on us, as well as sensitive equipment such as electronics, while still being effective in eliminating the agents," Wade said. "The equipment and materials we have for decontamination right now are pretty sturdy," he continued. "Super tropical bleach is almost as hazardous in terms of being a caustic to human skin as some of the biological agents themselves are. You sure want to have your gloves and all your protective equipment on if you're involved in using it." Defense officials are also evaluating what actually needs to be decontaminated after a biological attack, Wade added. "When we were maneuver-oriented, we always said we'd avoid contamination. We'd go around it, or button up and go through it. We sure weren't going to stop and live there." But if you can't move because you're stationed at a port or airport, Wade said, defense officials need to know what key areas need to be decontaminated. "We're doing studies to see if you take a plane up to 30,000 feet and fly it at 600 to 700 knots, is there anything left to decontaminate?" he said. "Does the flight line have to be decontaminated? What happens when a hazardous material oozes into concrete? We're doing studies now to answer the questions, 'How clean is clean?' and 'What has to be cleaned for us to be able to continue our mission?'"