In the light of the current panic over the potential for an H5N1 pandemic, a report from the Bulletin of the Atomic Scientists is bleak and worrisome. In it, the authors worry that the next deadly pandemic will be man-made - released, like so much science fiction, from a laboratory. They also say that, by a conservative estimate, a pandemic unleashed by one of these diseases could infect 15 percent of the world's population - infecting a total of 1 billion. As many as 100 million people could die as a result.

Study authors Lynn C. Klotz and Edward J. Sylvester, from the Center of Arms Control and Non-Proliferation and Arizona State University, respectively, state that there are four diseases currently in existence that have the capacity to become global pandemics. The first is smallpox, which has killed and maimed millions of people. The second is the 1918 influenza virus, which killed 50 million people over just two years. The third is severe acute respiratory syndrome, or SARS for those who turned on the news at least once in 2003 - newer than the other two diseases, but potentially much more deadly. The last, while not yet transmittable between humans, is Bird Flu.

The four diseases, or potential pandemic pathogens (PPPs), are currently kept alive in various laboratories. Smallpox seems to be the PPP that is least likely to become a pandemic, simply because it is only kept alive in two laboratories: Russia's Vector and the United States' Centers for Disease Control and Prevention. At both of those locations, all the workers there have been vaccinated to eliminate the threat of their spreading the disease to outsiders.

Meanwhile, SARS, the flu virus of 1918, and possibly human-contagious H5N1 are studied in laboratories across the world, using less than the highest possible biocontainment known as BSL-4. Furthermore, for the three viruses, there is no approved vaccine. If you count the two laboratories that created bird flu that was contagious in ferrets (simulating human models), the study authors estimate that there are at least 42 laboratories worldwide studying PPPs.

That may not sound like a huge number. But Klotz and Sylvester say that, for every single laboratory, there is a 0.3 percent chance that the virus will escape from the lab. That comes out to and 80 percent chance of one of the PPPs escaping every 536 years. But, with 42 labs, that number jumps up to a possible 80 percent chance of escaping every 12.8 years. For comparison, that time period is shorter than the amount of intervals between flu epidemics in the twentieth century.

In this global world, the likelihood of a pandemic is high. If your memory of SARS in the Americas in 2003 is foggy, a patient who was infected with SARS in Hong Kong flew to an airport in Toronto. The city of Toronto has great public health capabilities. By the end of the scare, 438 people in Canada had been infected and 44 had died. The 1918 flu virus has a fatality rate of 2.5 percent of people infected. SARS, in comparison, has a fatality rate of 9.6 percent. SARS has already escaped from the lab three times, resulting in "several secondary infections and one death."

Klotz and Sylvester make recommendations to minimize the threat of such an outbreak, like forcing lab staffers into a quarantine period after a working shift and making sure that all labs handling the viruses were at BSL-4 level.

The study authors admit that, while the risk of escape is high, the risk of a pandemic-level outbreak is quite low.

The entire report, published in the Bulletin of Atomic Scientists, can be found here.