An invisible spore captured the attention of an overflowing lecture hall Tuesday afternoon, when former U.S. Army combat medic and biological warfare expert Kenneth Van Horn gave a presentation titled “Anthrax: Pathology of a Biological Weapon.”

After detailing anthrax’s potential horrors, Van Horn, a UW-Madison senior who is a National Guard member and life sciences communication major, said it was pointless for the average Madison citizen to worry about the biological agent.

“The chances of getting anthrax are less than getting hit by lightning,” he said. “There’s not much an individual can do to protect themselves. But don’t go out and buy a gas mask; unless you wear it 24 hours a day, it can’t protect you.”

However, Van Horn made it clear anthrax and other forms of biological warfare are serious hazards. Anthrax, he said, is at the top of the U.S. list of main biological weapons.

“If Mother Nature designed something that should be used for a weapon, anthrax is it,” Van Horn said. “75 to 95 percent of exposed humans are likely to die from concentrated aerosol exposure. And it’s 75 percent lethal even if immediately after exposure you get antibiotics.”

Dr. Thomas Inglesby, of the Center for Civilian Biodefense Studies, said time will only increase the likelihood of a bioterrorism attack.

“Bioweapons and bioterrorism are a serious national security concern that will only deepen with time,” he said. “It’s not the case that biological weapons do not work.”

Anthrax is an infection caused by the bacterium Bacillus anthracis. Bacillus anthracis is an endospore-forming bacteria, meaning it forms spores to survive unfavorable conditions. Spores are essentially dormant cells with the capability to come back to life, or germinate back into bacteria. These bacteria are called vegetative cells, which only form spores again when their nutrient supply is exhausted.
These spores, unlike the vegetative cells, can withstand sunlight, heat and time. This distinction has often led to confusion, even within the national media.

Van Horn said he wanted to set the record straight.

“I was watching a national news broadcast and they said something that was the exact opposite of the truth,” he said. “They said the sun kills anthrax ? that’s just not true. The sun kills the vegetative type, not the spores, which is the weapons kind.”

In humans, anthrax spores cause three types of infection by germinating and then generating toxins within the human body. Although two of these forms are highly lethal, none are contagious.

“If I have anthrax right now and I was in this room, I couldn’t give it to you,” Van Horn said. “Once the organism is in you, it doesn’t present itself in a form you can cough out. Once it’s in you, it’s in you.”

Cutaneous anthrax, the least serious and most common form, occurs when spores touch open cuts and begin to germinate. Characteristic black lesions begin to grow, but cutaneous anthrax is most often successfully treated with antibiotics.

The second type, gastrointestinal anthrax, is “essentially the cutaneous form of anthrax inside your body,” Van Horn said. It can be treated with antibiotics, but can have mortality rates up to 50 percent.

The most fatal form of anthrax is inhalation anthrax. Without previous antibiotic treatment, it is lethal in 75 to 90 percent of cases, Van Horn said. Inhalation anthrax infection begins with minor flu-like symptoms, which go away and then return with a vengeance and include respiratory distress.

“If you delay [antibiotic treatment] after the first set of symptoms, it’s just too late,” Van Horn said. “It’s virtually impossible to stop ? by this time, no amount of antibiotic can get rid of the toxins.”

In terms of biological warfare and bioterrorism, inhalation anthrax is the killer.

“If 50 kilograms are used against a city of one million people, it would kill 36,000 people and incapacitate 54,000,” Van Horn said. “To give you an idea of how bad anthrax is, over a square mile you would need 1,763 pounds of sarin nerve gas and only .02 pounds of anthrax spores to get the same effect. It’s easier to deliver, so less of it goes further.”

However, Van Horn said fears of crop dusters dispersing anthrax are unfounded. Crop dusters are meant to distribute particles up to 10 times the size of anthrax spores.

“It would be a large feat to scale down a crop duster to disperse things this small,” he said.

Other encouraging news about anthrax is it is hard to concentrate lethal doses, even over a small area, and it is difficult to keep spores in the air. Also, a vaccine does exist.

“There is a vaccine, and the vaccine works well,” Van Horn said. “I have it and I feel pretty good now that I have it.”

Although Van Horn is vaccinated, he said the general public does not need vaccination.

“The chances of getting a side effect [from the vaccine] is higher than getting anthrax,” he said. “It wouldn’t make sense to vaccinate the general public.”