The bad guys have already flown planes into buildings so almost any scenario for spreading pathogens or poisoning water supplies cannot be considered too extreme. Of course, how terrorists might use biological weapons is anyone's guess.

The avian influenza, a natural pathogen, has yet to make the jump to humans (and might not) but preparing for its potential epidemic could be a warm-up for biological attacks. One defense against viral infections, for example, would be to filter the blood of those infected for pathogens and viruses to give their immune system time to respond.

“We've seen products of the Soviet bio-weapons program so it's clear that devising drug-resistant pathogens is not a great challenge,” says Jim Joyce, president of Aethlon Medical Inc., San Diego, (aethlonmedical.com). He suggests that exotic viruses and newer pathogens, such as SARS and Nipah — which are highly mutable RNA viruses similar to HIV and Hepatitis C — might be used in terrorist attacks. These often have no vaccines. “There are no general, broad-spectrum, antiviral agents capable of treating the vast array of potential viral infections,” says Joyce. Even after identifying a particular pathogen, it might be months before a vaccine is available.

But that does not mean there is no defense. There are in fact several ways to at least lessen the viral load (number of pathogens in a person's blood) that give an infected person's immune response system a fighting chance to respond.

More than an air filter

The safest place during an outdoor airborne dispersal of harmful agents will be indoors. So keeping indoor air clean is one way to defeat the pathogens. But ridding indoor air of viruses and toxins will take more than fiber filters. Air & Water Solutions Inc., President Sam Sofer, Nutley, N.J., (cleanairplant.com), may have a filter for the job in what his company calls Clean Air Plants, or CAPs.

Sofer's biological air cleaner looks and works differently than traditional flat-rectangular furnace filters. “First, air enters the center of the spiral wound bio-filter element. The water-washed element captures airborne particles as they bounce around air passages formed by the spiral. Turbulence ensures that airborne particles eventually contact the wet wall of biological filter material. The filter or cartridge is continuously washed so even smoke is removed.” Immobilized enzymes in the filter material transform captured viruses and pathogens ̬ along with formaldehyde, ammonia, xylene, and phenols — into carbon dioxide and water, says Sofer.

The filter material, BioOx, is capable of killing fecal e-coli, adds Sofer. It's a patented bio material that works at room temperature. Pathogens often need higher body temperatures to survive. Once trapped in the CAP, they are overwhelmed by the bacteria on the filter media. “We don't have access to neurotoxins for testing, but we have similar versions in pesticides and have successfully tested BioOx against them. This gives reason to believe it will kill neurotoxins such as the Sarin gas released in the Japanese subway some years ago,” he says. The 1995 release of Sarin killed 12 and affected many more.

The problem with conventional filters is that some particles and vapor are on the order of 0.05 microns. “Even HEPA filters let these pass. And because many odor-causing molecules and particles carry a charge, they are influenced more by electrical fields than by the laws of flow mechanics,” says Sofer. A ventilation system can remove large particles the size of dust from a room, but the ones that stay are small enough so they don't settle. And because such particles are electrically charged, they stick to surfaces. The particles don't vent. Also, charged particles distribute themselves evenly throughout a room. Sofer says the characteristics of charged particles is critical to removing them from air.

He suggests conventional thinking will have to change to better combat airborne problems. “For example, suppose a truck carrying pesticides comes into town, ruptures, and spills its cargo. People would rush indoors where the HVAC — including filters, heaters, and air conditioning — would be turned off because it could pull in the pesticide and spread it. Soon, people would venture outside, into whatever's left of the pesticide. Hence, the best preparation is to use a CAP to create a clean air zone in a building before the attack or accident, which calls for constant air cleaning. Then during an accident, we would not shut down the HVAC, but continue recirculating and cleaning indoor air,” says Sofer.

The CAP improves its efficiency by grounding the air around it, according to Sofer, thereby creating a clean-air zone. Because it is grounded, the unit captures negatively and positively charged particles. The clean-air zone created by the filter reduces the intensity of sudden releases of air emissions and rapidly reduces contaminants.

Sofer says the characteristic of an electric charge works to our advantage. “It is highly likely that biologic agents will be electrically charged so they can be trapped in an active biofilter. Anthrax spores, one example, carry a charge and in tests, did not vent from a test room,” he adds.

Sofer tells of a clean room in which people were using the solvent xylene. The room was vented at 4,000 cfm. “Yet, workers still got sick. We installed two CAP filters, each pulling in 60 cfm, reduced venting to 2,000 cfm which saved on heating and air conditioning, and workers did not get sick again. So even xylene behaves as charged particles,” he says.

What's more, the CAPs work outdoors, according to Sofer. A trash-transfer station originally installed two large air cleaners indoors. But after neighbors complained that the trucks were smelly, the company pulled one CAP into the parking area and alleviated the problem.

A filter for blood

Those infected by pathogens will need a second line of defense — a blood filter. Aethlon Medical has developed a filter that works with portable pumps and dialysis machines. “We just need to pump blood through the Hemopurifier, a cartridge similar to those during plasmapheresis or plasma separation,” says Joyce. “Inside the filter, agents on porous hollow fibers tightly bind and envelope viruses and glycolated proteins on virus surfaces. Proteins there inhibit detection by the immune response. So regardless of the viral mutation, the proteins are still on their surfaces,” says Joyce.

The filter would reduce viral loads by pulling toxins out of the blood. Then a person's natural immune response of cells and organs can take over. But timing is everything. During an infection, the immune system over-responds by producing an abundance of proteins, called cytokines, to control itself. “Once this so-called cytokine storm occurs, there is no hope of using an antiviral drug, even if one exists.”

“The goal is to circulate the patient's blood through the filter as long as required for the patient to recover,” says Joyce. At present, humans have been treated for up to four hours at a time. “Front-line practitioners would like an 8 to 12-hr. cartridge,” he adds.

The Hemopurifier can augment other therapies, according to Joyce, because “It recognizes a variety of pathogens and provides a defense even against those that are genetically engineered,” he says.

Joyce tells of one study of 24 people done in India. “It showed that the filter could work without adverse events. Two people in the group reported only chills and a brief period of nausea. These people had kidney failures and were infected with hepatitis C, a virus that replicates rapidly. Any reduction of hepatitis C is good. The filter captured up to 52% of the viruses in a in four-hour treatment.”

Few drug therapies work against hepatitis C, he adds. “One tactic is to use the filter to reduce the viral load before a new drug treatment so the drugs and immune system are not overloaded and respond positively,” says Joyce.

Filters for water

Viresolve membranes from Millipore Inc, Billerica, Mass, (millipore.com) are intended more for laboratory use but show one way to purify water. The membranes detect and capture proteins, antibiotics, and acids that are on the order of 0.001 to 0.1 micron.

“Filtration speed depends on the pressure driving the fluid through the filter,” says product manager Shawn Gaskell. “But the filter can trap mammalian and polio viruses.” It consists of a substrate of nonwoven polyester or polypropylene coated with regenerated cellulose or poly ethersulfron. The chemistry of the coating attracts or repels particles, depending on application. It could be a charged membrane to attract certain ions or viruses. “Attaching certain proteins to it would hold back other viruses. So you could tune the filter to a particular virus,” he says.

To remove large particles from water, another filter would be used first, and other filters in succession. This setup lets the filters work longer. But for biodefense, the membranes would be used to sample water or air to capture what's in it for identification.

Trained nanospheres could hunt blood-borne toxins

Nano-sized particles made partially of iron and covered with proteins that bind to specific toxic agents provide a novel way to trap blood-borne toxins and pathogens. The spheres are coated with a type of polyethylene glycol that prevents white blood cells from attacking them. The technology to clean blood of biological, chemical, and radiological attacks is being developed jointly by Argonne National Laboratory, the Armed Forces Radio-biology Research Institute, and The University of Chicago Hospitals. The development also shows promise for delivering therapeutic drugs to targeted cells and organs.

“The key is biodegradable spheres 100 to 5,000-nanometers diameter,” says Argonne's Michael Kaminski. “They are small enough to pass through tiny blood vessels, yet large enough to avoid being filtered from the bloodstream by the kidneys.” Developers say the system also lends itself to drug and medication overdose emergencies, for example, or treatment of various chronic or acute illnesses.

Current medical procedures to detoxify human blood are restricted to a few types of toxins and are mainly limited to dialysis and filtration. Current treatments can take several hours, requiring the turnover and filtration of large volumes of blood. Treatments such as antibodies and chelators, substances that combine and neutralize specific toxins, are inefficient and can cause serious side effects, such as allergic reactions and organ failure.

Four-cent inhaler could speed mass vaccinations

A recently developed disposable inhaler may change the way some drugs are administered. One advantage: It delivers 40% more active drug than many other inhalers. Cambridge Consultants Cambridge, Mass, (cambridgeconsultants.com), say they have developed the Conix One for vaccinating against chronic and global diseases. The device is said to deliver the performance of high-end inhalers at a lower cost than a syringe. Inhalation is a better drug delivery mechanism for many chronic diseases.

The inhaler is based on a reverse-flow cyclone and contains no moving parts or propellants. It is made from a single piece of plastic and costs just four cents to manufacture at volumes of five million per year. Syringes cost between four and eight cents. An asthma inhaler, about a 20-part device, costs at least $0.40 even in volume.

The company says the inhaler is comfortable and easy for patients to use. They simply remove a foil seal that protects the drug, fold the device shut, inhale, and discard. This eliminates the risk of needle-stick injuries and infection, which poses a threat to health workers.

How preparedness pays for itself

Most plant managers don't daily measure the indoor air quality of their facilities, suggests Air&Water Solutions' Sam Sofer. “But they do care about the cost to heat and cool their plants. The law tells them to burn highly polluted air or run it through carbon, both of which are expensive.”

But one plant manager, says Sofer, found that CAP biological air filters worked so well that they allowed lower ventilation rates for a new building. And that reduced the size of air conditioners and heaters because they would need to heat and cool less replacement air, which leads to smaller ducts and fewer structural roof reinforcements, and even smaller wiring for the unit. “So protecting buildings against foul air and possible bioterrorist attacks can save on operating costs because the filter trims energy use,” he says.

Time to Settle

A research team lead by Linda Utrup found that sufficiently small particles can linger in indoor air almost indefinitely.

Particle size, microns	Time to settle eight
100	8 sec
10	13 min.
1	19 hrs
0.1	9 days
0.01	infinite