He breathed an audible sigh of relief when the First Antigen Rapid Test came back negative.
“We can rule out hemorrhagic fever,” Byrne said.
“So we can take off these infernal suits?” Warren said. He stood with his back to them, sighting the opposite side of the street through his scope.
“Not yet. There are still hundreds of diseases we need to cross off our list, any one of which could kill us in any number of painful and horrific ways.”
Byrne removed the gelatinous medium from the electrophoresis machine and shined a black light onto it.
Anthony must have read the expression of surprise on his face.
“What is it?”
“There’s no virus.”
“What do you mean?”
“Exactly what I said. There’s no virus.”
“Could it have separated from the blood or could the sample have been contaminated?” Richards asked.
“You don’t understand. A virus works by inserting its DNA directly into the host’s genetic code. That’s its sole biological imperative. It infects the individual cells and uses the host’s RNA to replicate its own DNA. In essence, its genes are incorporated into those of the organism it infects, like adding more teeth to a zipper. The human genome contains the residue of countless historical viruses we’ve been passing down for eons. This blood perfectly matches that of the control sample.”
“Then what the hell killed all of these people?” Richards asked from directly behind him.
Byrne attached the ELISA plate reader to his laptop and launched the software. The application generated a curve that plotted fluorescence against the concentration of interferons, which were signaling proteins released by cells in response to the presence of viruses, bacteria, and parasites. The comparison to the saved control sample excluded Interferon Type I and III reactions, which were produced in response to an aggressive virus. The elevated levels of Interferon Type II indicated an acute immune response, despite the complete absence of any identifiable pathogen. The presence of immunoglobin G and E antibodies further muddied the waters. They were only produced by the immune system in response to specific infections.
And then it hit him.
“That can’t be right,” Byrne said.
“Talk to me,” Richards said.
“The levels of immunoglobins G and E are off the charts.”
“What does that mean?”
“IgG attaches to pathogens designated for elimination and IgE binds to allergens that produce histamine and cause inflammation. The two in conjunction indicate a very specific immune response, one designed to combat the presence of a toxin capable of triggering a violent allergic reaction.”
“In English, Doctor.”
“The human immune system releases these antibodies in response to the presence of biological toxins, like those found in a bee sting or a snake bite, only in nowhere near these concentrations.”
“You’re suggesting—”
“I’m not suggesting anything. I’m telling you that I know without a doubt what killed these people.”
“And what’s that?”
“Venom.”
The building across the street featured a native clothing store and, above it, a two-room apartment, the rear window of which offered an unobstructed view of the grassy slope leading uphill through the pastures to the edge of the forest. From this vantage point, they could clearly see the trampled paths where the bodies had been dragged from the streets. They converged into a single trail that led beneath the dense canopy. In the far distance to the west, Byrne could see the broken fence where the long-horned cattle from the satellite image had once been contained.
The occupants of the apartment had been overcome while they slept. The bed linens lay crumpled to one side and the sheets were spattered with blood, although the combined volume couldn’t have been more than three or four ounces, even taking into account the spatters on the walls and the smears leading across the floor, down the wooden stairs, and through the doors and windows. Whoever claimed their remains had been careful not to leave any traces of their presence. It was as though the attack had come in two phases. The initial siege had been fast and surgical in its precision: the victims had been injected with venom and left to succumb to the eventual paralysis. The second had come some time later, when the bodies could be collected without offering the slightest resistance. That was their working theory, anyway. Unspoken between them was the fact that if their theory was correct, there was the chance the victims could still be alive.
“We should call it in,” Byrne said.
“And say what?” Richards said. “All we have is a single blood test from an unknown victim who, for all we know, could have been stung by a bee before their death.”
“So what do you propose then?”
“We search the remainder of the town. Whoever did this must have left some trace behind. You continue running your tests. If that fails, I can think of one sure way to conclusively determine what we’re up against.”
Byrne stared at the point where the path vanished into the darkness beneath the branches. He recalled his observation that the entire town could have been surrounded without anyone knowing it and had to stifle a shiver.
“What’s over there?” Warren asked from where he knelt by the adjacent window, studying the forest through the scope of his rifle.
“The satellite imagery shows a seamless stretch of forest,” Graves said.
“What about thermal or magnetometric imagery?”
“We didn’t anticipate needing them. We’ll have to wait for the satellite to pass over again.”
“And when’s that?”
“Just under twelve hours from now,” Graves said.
“You’re kidding, right? We should be able to task any satellite and have it here within ninety minutes,” Warren said.
“If you want the same aerial photographs we already have, sure. If you want to see anything below the canopy, we have to coordinate with NASA to get the GEOS 2 satellite overhead. It’s in geosynchronous orbit, so it can only be programmed to pass overhead once every twenty-four hours.”
“By then it could be too late. We need to know what’s out there right now!”
“Then we have no choice but to take matters into our own hands,” Richards said. “Doc, I need to know every possible method of venom dispersal.”
“I’m certainly no authority—”
“An educated guess will suffice.”
“I would imagine the primary method of delivery would have to be subdermal. Our skin acts as a barrier, hence the reason bees have stingers and snakes have fangs.”
“No possible means of aerial envenomation?”
“I’ve never heard of it, but that’s not to say it can’t be done. To the best of my knowledge, no one’s attempted the weaponization of venom, outside of its use on darts and arrows by various indigenous tribes.”
“So if we’re wearing our isolation suits, we should be safe,” Anthony said.
“As long as they remain intact,” Byrne said. “Keep in mind, though, they aren’t designed to stand up to any kind of trauma or sharp penetration.”
“I got news for you, Doc,” Graves said. “Anyone gets that close to us will have a bullet through his brain before he can even think about attacking.”
“This town had a population of nearly two thousand. As far as we know, not one of them escaped their collective fate. We should just report in and wait for backup to arrive.”
“And by doing so we could be consigning our reinforcements to their deaths,” Richards said. “We need to determine the nature of the threat before we do anything else.”