Thoughts from a Hot Zone: Give Me a New Immune System

The SARS scare in Toronto shows how bad a looming epidemic would be. There's little we can do to prevent it, so bring on the nanobots

Monday, April 07, 2003, 7:01:26 AM CT

I was initially cynical. Yes, thousands of people had SARS. But very few had died. Despite the emails describing the illness in apocalyptic terms, it was still far riskier to drive a car than randomly hug subway riders. I wouldn't take a trip to China, but I wasn't going to alter my life much.

Or so I thought.

That was two weeks ago, before Toronto became a hot zone and Severe Acute Respiratory Syndrome hit home. Hospitals closed. Newspapers started running daily updates. Surgical masks became sought-after fashion accessories and quickly sold out everywhere.

Then my partner, Paula, entered voluntary quarantine after visiting a hospital in which a patient was found to have the illness. The hospital became a SARS-cophagus -- all sealed up, with nobody but healthcare workers allowed in. An aunt and cousin who attended the same hospital also entered isolation.

Now I've gone from cynical to seriously concerned. SARS is the warning shot: An epidemic looms that could kill millions -- or hundreds of millions. And while better than inaction, closing hospitals, stopping air travel, warning tourists, disinfecting counters, wearing masks and quarantining lovers will never prevent an epidemic from wiping out swaths of people.

"Infectious agents will always be present in the natural environment and their evolution into new forms will continue for the foreseeable future," says Robert A. Freitas Jr., a nanotechnology researcher and the author of Nanomedicine, a massive compilation of nanotech solutions to health problems. "So microbes will continue to attempt to colonize human bodies."

What we need is a better immune system.

Fortunately, Freitas has designed one.

Know your enemy

As of Friday, April 4, SARS had infected 18 countries. Worldwide, there were 2,400 cases and 80 deaths from the illness.

About 10% to 20% of SARS sufferers will require mechanical ventilation. About four percent will die -- equivalent to the death rate from the flu. There are no treatment protocols, but antibiotics, antivirals and steroids have shown some benefit.

Doctors believe that SARS is mainly spread through droplet transmission -- coughing and sneezing. Most transmission involves direct contact with an infected person. Healthcare workers are especially vulnerable.

A previously unrecognized coronavirus is likely the culprit. With a crown-like appearance, coronaviruses commonly cause mild respiratory illnesses. This one, apparently, is far more severe.

The next epidemic

Are we on the verge of another disaster, one reminiscent of last century's Spanish Flu? That epidemic swept the globe from 1918 to 1920, left a billion people sick -- more than half of the world's population at the time -- and killed at least 40 million people -- four times the death toll of World War I.

Since the Spanish Flu, two other big pandemics have struck, one in 1957 and one in 1968. Both were responsible for millions of deaths.

There's no way of knowing when we'll have the next.

Environmental changes can benefit microbes that cause infectious diseases. Microbes also typically have high replication rates, allowing them to colonize and mutate quickly. High mutation rates help microbes evade our immune system and such technological defenses as antibiotics.

The flu virus is particularly dangerous. It can live in humans, birds and other animals, and some strains can survive on exposed surfaces. The flu is also highly contagious because it spreads through the air. And its replication method is highly prone to mutations, so it's hard to fight.

Then, of course, there's bioterrorism. With a little help from humans with ill intentions, microbes can become even more virulent and deadly.

Battling microbes

Don't get me wrong, we've come a long way since Dutch merchant Antoni van Leeuwenhoek first looked at a living microbe in the 17th century. (He wanted to examine the quality of cloth, and made a powerful magnifying glass that he eventually used to find "little animals" -- microbes -- in drops of water.)

About 200 years later, Louis Pasteur theorized that microbes involved in wine fermentation might also cause illness.

From there, we developed pasteurization, antibiotics, antivirals, vaccines and other treatments.

Our success has led to expectations that advances in existing treatments will eliminate all infectious agents.

But even with our high technology, dumb packages of harmful, replicating genetic material humble us. Despite all our medical advancements, we're still vulnerable to the ravages of randomly mutated viruses.

Also, war and natural disasters create environments in which infectious agents thrive, changes in human activity expose us to new pathogens and bacteria can develop antibiotic resistance.

So how can we hope to prevent a future epidemic?

Nano defenders

Enter the microbivore.

One of Freitas's many medical nanobot designs, microbivores would patrol your bloodstream to find and digest pathogens such as bacteria, viruses and fungi.

Each microbivore could destroy one pathogen in 30 seconds -- about 100 times faster than a natural leukocyte or macrophage, says Freitas. The robots could eliminate the most severe infections, he says, in minutes to hours.

And if properly designed, says Freitas, microbivores should be able to detect and eliminate virtually any biological pathogen. They could even destroy viruses with high mutation rates, such as the flu, he says, by targeting their genes.

"By the time a molecular manufacturing technology exists that can build medical nanobots, this same technology will make possible the performance of comprehensive microbial assays of tiny blood and tissue samples, with full genomic characterization of all microbes detected, on a timescale of minutes after extraction from the patient," says Freitas.

Even rapidly mutating viruses could be detected through genomics, with microbivores seeking their genetic sequence. "Treatment time should again be on the order of hours or less, even for previously unknown pathogens," says Freitas.

The long wait

Of course, microbivores are nowhere near reality.

Researchers are making steady gains in nanoscale engineering, but have yet to produce programmable nanobots.

Until they do, we'll just have to battle with what's at hand, and quarantine the sick and possibly infected, even when they're close to us.

And we'll just have to hope that nanobots join our arsenal before the next epidemic.