The outbreak stopper

Shalin Hai-Jew

By A Contributor

“Only about one out of every ten cells between your hat and shoes is human-the other nine belong to the masses of bacteria that coat our skin, live in our guts, and thrive in our mouths.
When we consider the diversity of genetic information on board, only one out of every thousand bits of genetic information on and in us can properly be called human.
The bacteria and viruses represented by thousands of species will outnumber the human genes every time.” — Nathan Wolfe

Think about every way you interact with your environment. You breathe the air. You touch surfaces and often unconsciously touch your face. You consume food and water. You hunt and eat wild game. You interact with your pets. You form physical intimacies with the people around you.

According to Nathan Wolfe, author of “The Viral Storm” and a Professor of Epidemiology at the UCLA School of Public Health, those mundane interactions may be channels for the exchange of disease-causing microbes.

The invisible microbial world exists far outside the realm of direct human knowledge. Even when people see electron scanning micrographs of the images of various microbial agents-bacteria, fungi, protista (algae), archaea, viruses, and prions-how prevalent these biological and chemical agents is not very clear.

“The dominant forms of life on our planet, when measured in terms of diversity, are unambiguously microscopic,” the author notes.

He puts his own students through a thought experiment in which they are wearing magical glasses that would allow them to see the microbial life all around: “The floor would seethe, the walls would throb, and everything would swarm with formerly invisible life. Tiny bugs would blanket every surface-your coffee cup, the pages of the book on your lap, your actual lap. The larger bacteria would themselves teem with still smaller bugs…They are everywhere, unavoidable, infecting every species of bacterium, every plant, fungus, and animal that makes up our world.”

Further, these microbes enable life on the planet. However, there are also disease-causing microbes which have pandemic-potential. Wolfe has made it his life’s mission to identify “the first moments at the birth of a new pandemic” and to strive to stop that before it reaches a global stage. He is part of the new field of pandemic prevention and a designer of systems to accurately predict pandemics early.

The author credits Don Burke, a retired medical colonel and virologist from the Walter Reed Army Institute of Research and professor at the Bloomberg School of Public Health at Johns Hopkins University with discussing this idea a decade ago. Predicting a beginning pandemic and not just responding to it once it has broken out widely would theoretically enable people to lessen the human, animal, and environmental toll of a novel microbe, mosaic virus, or a re-emerging disease.

Technological advances-such as the storehouses of genetic data-could be used to understand these as-yet undiscovered life forms. If health professionals could create listening posts in microbial hot spots for “chatter” that might indicate that a large pandemic event might be in the offing, humanity may have a fighting chance at heading off mass human (and animal) die-off.

What if H5N1 (“bird flu”) with a 60% human mortality rate were to mutate with H1N1 (“swine flu”) with a high human-to-human contagion rate through airborne means? What if a virus projected to infect over a third of the human population has a 60% mortality rate? What if this virus has a high “basic reproductive number” (R0) or “super-spreading” capabilities from infected individuals to others with no prior immunity or compromised immune systems? What could such a scalable epidemic look like especially if there are no or ill-informed interventions? (The 1918 influenza pandemic in which 50 million people died had an estimated fatality rate of only 2.5 - 20%, depending on expert estimates.)

Viruses evolve, reassort, and mutate; they swap genes. Within host humans or animals which serve as “mixing vessels,” they will acquire new features that may enable these strings of genetic code to better survive. “If H5N1, the deadly bird flu, gains the right combination of genetic mutations it needs to spread effectively, the results will be destructive in a way that, however less visually dramatic, will make even the most deadly earthquakes seem like a walk in the park. And if H1N1, the rapidly spreading swine flu, were to increase in virulence even minimally, its potential to kill would be striking. Neither scenario is implausible,” Wolfe writes.

While Wolfe is highly aware of the dread human costs of pathogenic viruses, he marvels at the elegance of their genetic code. Humanity has some three billion base pairs of genetic information, but viruses have a comparably small number-some 10,000 base pairs of genetic information. They maximize the coding of this information by using what Wolfe calls “overlapping reading frames” to be able to have its code read in multiple ways and directions to extract meaning for how to behave in a host cell.

Humanity, writ large, may develop drugs and vaccines to combat possible pandemics. They may strive to modify behaviors. They may put people under quarantine. They may engage in varieties of educational campaigns. Even in combination, such endeavors are not the most effective.

For example, HIV/AIDS affects some 33 million people today, and many tens of millions have already died of this human immune-deficiency virus even in the face of public health education campaigns, drug regimens, condom sales, and other efforts. But what if people had been able to catch this virus before it spread widely? After all, this virus lingered in humans for some 50 years before it spread widely and before it was discovered by French scientists Francoise Barré-Sinoussi and Luc Montagnier.

Wolfe describes the natural selection strategies of various microbes in the world and their evolutionary deviousness in striving to ensure their own survival. He shows how Toxoplama gondii, if they end up in rodents instead of their preferred host of cats, will spread to the nervous systems of infected rodents and hijack their brains to make sure that the rodents find cats “positively enticing,” which ensures that when the cats eat the mice, the parasites can transfer to the cat.

Viruses have to balance the likelihood of causing death in its victim once the victim is infected, and their efficacy in allowing the victim to spread the infection to others. It is in the interests of a pathogen to keep its carrier alive sufficiently long to transmit the virus.

All living creatures have various “microbial repertoires” that are unique to them-or a list of viruses, bacteria, and parasites that may be found in that species. Most major diseases of humans emerged from warm-blooded vertebrates-like primates, bats, and rodents.

Human habits of global and regional travel may spread pathogens. Human intimacies and the exchange of bodily fluids have also been identified as a major risk factor. Human cultural practices of circumcision, ritual scarring, acupuncture, and tattooing may spread pathogens if sufficient care is not used to ensure that fully sterile equipment is used.

While blood donations have saved many lives, prior to the high levels of screening donors and testing the blood, HIV ended up in pooled blood-derived clotting factors for hemophiliacs. There are fears that if a new virus entered into humans quietly that the blood supply would be tainted before sufficient screening could be put into place. Xenotransplantation (the uses of genetically engineered, animal-grown organs for human use) is still some years away from actual use. However, many scientists are asking: “Is one life saved worth a species potentially plagued?”

Vaccines administered to thousands, unless they are carefully created, may carry viruses.

The domestication of animals for human companionship and needs may also transmit diseases from wild animals that may infect domesticated ones (who serve as zoonotic bridges), who may then transfer infectious pathogens to humans.

Various terror groups and religious cults have experimented with various types of bioterror agents.

One of the central bioterror agents of concern involves “smallpox,” which while it has been eradicated, is thought to exist in the world beyond the two high-security labs in the US and Russian federation. There is speculation that there may be animal reservoirs with smallpox. Because people have not been immunized against smallpox in recent generations and because of how contagious and virulent smallpox is, there is worry that a release of this “Category Five” (high-risk) biological agent could be devastating.

For all the advancements in genetic research and bioinformatics, people themselves are at much higher risks of pandemics now than in the past.

Humanity is projected to concentrate in big cities, with 70% of humanity living in big cities by 2050. Such human concentrations may lead to exponential (and potentially uncontrollable) spread of a highly contagious pathogen. An estimated 1 percent of humanity is immunodeficient due to prior health conditions, and many more suffer malnutrition.

The demands for wood have meant that loggers encroach into forests and interact with greater diversities of wildlife. The demands for animal proteins push subsistence hunters into the woods. In developed countries, livestock production now has become much more concentrated in industrial settings. There are over a billion cattle, a billion pigs, and 20 billion chickens on Earth.

People eat processed meats that may consist of meat from multiple species and “derived from hundreds of animals.” An average meat eater today will “consume bits of millions of animals during their lifetimes,” he notes. This food processing reality raises the specter of potential infection of people by prions, folded proteins found to cause bovine spongiform encephalopathy (BSE) (or “mad cow disease”). “Sheep have long been known to have a prion disease called scrapie, and it appears that processing their carcasses as cattle feed permitted the agent to jump over and adapt,” he notes.

The demands for exotic pets have meant that live animals are transported from around the world. In 2003, imported African rodents infected some 93 humans in the US with monkeypox.

Historically, people have poor “risk literacy.” Formalizing methods of assessing pandemic risk (of viruses and pathogens that could “go viral” vs. burning out) for virologists, epidemiologists, public health professionals, policy makers, and the general public is a central part of Wolfe’s book. His Global Viral Forecasting maintains a number of program sites and labs and partners sites around the world to enable viral situational awareness.

In “The Viral Storm”, Wolfe demonstrates media savvy both in writing to a generalist audience and political savvy in giving credit to his many professional colleagues. He writes with empathy of subsistence hunters and points to rural poverty as the real enemy for public health professionals, who need to help identify viable solutions for the nutritional needs of the poor. He alludes to the potential of using viruses to potentially fight cancer or other diseases.

Dr. Nathan Wolfe worked for the Army Institute of Research and was a guest researcher with the CDC , National Center for Infectious Diseases, HIV and Retrovirology Branch. He is the recipient of a Fulbright Fellowship. He was awarded a $2.5 million NIH Director’s Pioneer Award in 2005. He earned a doctorate in Immunology and Infectious Diseases from Harvard University’s School of Public Health in 1998; he has an M.A. in Biological Anthropology from Harvard.

He has traveled to the “wet markets” of East Asia and remote towns of central Africa.

He has gone into remote forests to set up sentinel networks of hunters to collect the blood of their animal prey-given that such mammal-to-human viral transmissions may emerge from these spaces.

In “The Viral Storm”, he proposes a control room that monitors the world for natural infectious disease outbreaks, with genetic and spatial data, to protect human lives. While he portrays human life as not particularly biologically special, he still does see it as precious.

Shalin Hai-Jew works for Kansas State University. She lives in Manhattan.

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