What if a deadly new virus jumped from animals to humans?

Nathan Wolfe
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Nathan Wolfe is Visiting Professor in Human Biology at Stanford University and the Chief Executive Officer of Metabiota, a company which specializes in microbial threat detection. He is also a World Economic Forum Young Global Leader. His recent book, The Viral Storm: Dawn of a New Pandemic Age is published by Times Books. We dodged a bullet with bird flu but next time we might not be so lucky, says “virus hunter” Professor Nathan Wolfe. The interview was carried out by the World Economic Forum’s Risk Response Network.

Why is this something that worries you? What warning signs have you seen?

All the greatest hits of modern infectious diseases emerged from wild animals: HIV, SARS, the pandemic influenza outbreaks, Ebola. Although in western countries, most people buy their meat pre-butchered and shrink-wrapped, there are still plenty of areas where humans have a very high level of contact with animals. We have industrial-sized farms and slaughterhouses, and there are still hunters going after game all over the world, whether for vital protein in central Africa or for sport in the United States. What is different now from any other point in human history is that we live in a profoundly interconnected world. We can get anywhere in 24 or 48 hours. The pot keeps getting stirred: any virus that crosses over into humans has the potential to get to any other place amazingly quickly.

How do viruses cross into humans in the first place?

In a variety of ways: through people breathing in the exhaled breath of sick animals, or through skin-to-skin contact, or from blood contact, to which hunters are vulnerable. The most worrying thing is when viruses then mutate so that they can be transmitted directly from human to human.

How do you track the risks posed by new viruses?

My work has taken me from the rain forest hunting camps of central Africa to the wild animal markets of South East Asia. One useful approach has been to get bush meat hunters to act as “sentinels” on the lookout for new viruses. Working in Cameroon, my team gives hunters basic health training and then provides them with little pieces of filter paper to collect blood from the animals they hunt – things like wild pigs, snakes and monkeys. The samples are then analysed in the lab so that we can get a sense of the “viral chatter”, the pinging of viruses into human populations, so that we might be able to catch them early. We have found brand new retroviruses, the class HIV belongs to, and new pox viruses, cousins of smallpox. A number of things we have identified haven’t spread, or have spread but not substantially. The potential is there, though, for them to travel along logging roads to cities and then out into the world. What happens in central Africa doesn’t stay in central Africa.

Another new approach to managing the risk is digital epidemiology, which means monitoring things like blogs, news feeds, twitter and search engine patterns to provide real-time intelligence on new outbreaks. The company I run, Metabiota, works with countries around the world on this sort of biosurveillance.

If a dangerous new virus were to make the jump, how would the situation unfold?

That depends a lot on the nature of the microbe. Some things can spread very rapidly, like H1N1, which caused the so-called “swine flu” pandemic of 2009. Other things move much more slowly, like HIV. Most people do not realize that the majority of the transmission of HIV occurs within the first couple of weeks after an individual has been infected: the virus replicates very extensively, with a high density of particles appearing in the blood and body fluids, but then the immune system controls it and it disappears until you get AIDS. Symptoms appear only years later. These could be very frightening kinds of outbreaks. If a virus that had the same kind of transmission dynamic as HIV entered into human populations six months ago, but was a bit more infectious, it could have already spread around the world and we would not be aware of it.

Who would be impacted the most?

There are many different ways in which these viruses can exist and spread. In general, it goes without saying that places with higher quality medical care and better surveillance will be better off. But there should be no sense of safety, even for people with the best healthcare within the best healthcare systems. These viruses do not respect political boundaries, they do not respect socioeconomic boundaries. There are situations which could affect any different demographic that you wanted to pick. The jet-setter crowd, for example, is more at risk from certain kinds of respiratory viruses, since when you are on a flight,  you are stuck breathing the same air as everybody else.

How well prepared are we for a new pandemic?

We are not very prepared at all. H1N1, or “swine flu”, is an example of how easy it is for the media and the public to get this wrong. The common perception is that public health authorities over-reacted, with people even questioning whether or not it should be called a pandemic. In fact, it was an amazing pandemic, which went from affecting no one to, by some estimates, 10% of the global population within a year. To give some sense of perspective, H1N1 was more successful than Facebook at getting out there. For those who think it wasn’t deadly: it killed a small percentage of those it infected, but because it infected so many, estimates are that over 100,000 people died. When you compare that with other catastrophic events, like 9/11, this is a very significant figure. And in fact, the public health systems which were accused of over-reacting were unable to stop the spread of the virus. Had the mortality rate been even nominally higher, we would have been talking about millions of people dying from the virus. People think it was no big deal, but from my perspective, we dodged a bullet.

How likely is it that we will see something on the scale of the 1918 Spanish flu pandemic this century?

Highly likely, although it would look very different. A number of the over 40 million estimated deaths caused by Spanish flu were associated with secondary microbial infections, which we are now in a better position to treat. But the Spanish flu virus had a mortality rate of 10 to 20% including deaths from subsequent bacterial infections – though estimates are tricky. Something like bird flu, in comparison, kills about 30 to 40%, even by conservative estimates, of those infected. There are plenty of viruses out there that are potentially much more deadly than Spanish flu. Disasters are inevitable, it is just a question of how we prepare for them, how much resilience we put into the system, how well people are able to look beyond a 24- or 48-hour news cycle to recognize phenomena occurring over years or decades.

What can we do about it?

The tools we have are dramatically increasing: in wealthier countries at least, most of us are carrying a networked computer around in our pockets. The capacity to gather and distribute information is higher than it has ever been: the issue is working with governments and other agencies to make sure this information is translated into rapid and appropriate action.

Then there is the matter of addressing poverty in vulnerable parts of the world, so that people do not turn to bush meat for their only available source of protein. It is incredible that, given we know HIV jumped across from monkeys, we are still allowing this situation to exist where people have no choice but to hunt them for food. We also need to cast an incredibly wide net in terms of surveillance to find these new viruses before they make it through to the blood banks, the sexual networks, the airplanes.

Have you ever felt personally at risk from your work?

I have been infected with a number of things over the years, but my closest call was when I caught falciparum malaria, the deadliest form, in Cameroon. I only realized I had it when I got back to the United States, and it was amazing to see that the quality of care in there was actually much worse than in Cameroon. The experience gave me a tremendous respect for people who live without prophylactic drugs in areas where malaria is rife.

Image: A chicken is about to be slaughtered in a market after it was declared an infected area in Hong Kong REUTERS/Bobby Yip


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