Meet the man who has dedicated his life to hunting for Ebola in Africa's rainforests

Bob Swanepoel is a virologist at South Africa's University of Pretoria. Over the last 40 years, he has hunted in the rainforests of Africa for microscopic pathogens, including the hemorrhagic-fever viruses Marburg and its sister Ebola. Knowing which animals can live with Ebola could help scientists better understand and predict outbreaks, and identify an Ebola vaccine. It could also help researchers figure out which behaviors or activities might put humans at risk for Ebola. But the work is painstaking, involving trapping animals at all hours of the night and testing them for a deadly virus, while trying not to get infected yourself. So, despite four decades of trying, Bob and his colleagues still haven't solved the mystery of Ebola's natural reservoir. Their best guess is that the virus lives in fruit bats when it's not ravaging humans — a theory they haven't been able to prove. Here he explains why the work of virus hunting is "no Sunday school picnic" and how the answer to the question at the center of this Ebola epidemic has eluded him all these years.

I got involved in this work during the second outbreak of Marburg ever, which happened in 1975, when two Australians who had hitch-hiked in Zimbabwe became sick in South Africa. But then Marburg disappeared and Ebola hadn't even been of heard of. The first known outbreaks of Ebola only happened in the following year, 1976.



Hunting for viruses is no Sunday school picnic. You've got to go out at night, into forests. Say you have to take a leak. So you walk 10 minutes away from the others on your team. You've got a headlight on, but suddenly the others are gone, and you're totally disoriented.

You start shouting or running in the wrong direction. They're gone. You've walked hours to get to this place in the forest to catch these bats. Then you're lost.

The bats will come out just after sunset, and they will fly until about 9:30 or 10 pm. Then they will go back home and they'll only come out again as the sun comes up. They fly in the evening and the morning. In the depth of the night, they are not flying. So you can either hang around or put up your nets and go home and come back the next day.

The trouble is, these bats — despite being big and strong — can't take the cold. They die. So the next morning they're stiff and you can't bleed them.

You've got to make sure you're catching the right bats, too. When I worked on the 1995 Ebola outbreak in Kikwit in the Democratic Republic of the Congo, I had discovered that the really big fruit bats they were selling for food, the Africans were catching them high in the trees. They would climb up the trees and put their nets 40 meters up. If we put up nets the ordinary way, we'd put them 10 meters up, so we would catch the wrong kind of bats.

People say, "Kill all the bats." That's nonsense. You'll make the situation worse.

This whole game is far more complex than you would think. It's a very tricky business.

When you catch the bats, funnily enough, these things are huge and strong. Their wingspan is very wide. They have teeth like you won't believe. On top of that, you think, not only can they bite you, they might have Marburg or Ebola. You have to be careful of all of that, but despite your best efforts, you will get bitten.

While in the forest, we tested thousands of other animals, not just bats: rodents of every kind, birds, insects, snakes, slugs, snails, frogs, anything we could catch. Therefore, before you put your bat nets out in the evening, you put out rodent traps. If you put those out in daylight, the baboons or monkeys will take them.

Late at night you return to base with the bats you have caught and work until the early hours of the morning dissecting them. Then you have time for a quick wash and to rest for an hour or two before you have to go out and collect the rodent traps before dawn. You have time for a hasty breakfast and then you have to dissect the rodents.



Now it's 10 or 11 in the morning and you've got to wash all your traps and nets. And by three o'clock, you've got to be on the road to do the next day's trapping.

That's day after day after day.

By the end of the week, you may give your team a day off. But you'll be exhausted. You're not eating too well. You've been bitten to hell by mosquitos. If you brush against a leaf they'll be 50 fire ants biting your arm. You'll be on fire. The next branch, you turn around, you knock into thorns six inches long. Little flies cover your skin. They love going into your ears. If you put cotton into your ear, they'll go up your nose.

You have to be tough. The toilet arrangements and facilities leave much to be desired. Sanitary conditions are unbelievable, and privacy doesn't exist.

Doing this work, I got malaria in 1995 and again in 1999. I nearly died.

So why did you do it?

The same reason, when George Mallory was asked why do you want to climb Everest, he famously said, "Because it's there." It's curiosity. For this game, you've to have the curiosity of a child.

Besides the difficulty of the work, the reason Ebola's host has been so hard to find has to do with the fact that, in the past, outbreaks were rare. It was very difficult to get permission to go in and look for the virus when there wasn't an outbreak. There was also an element of "let sleeping dogs lie. We don't have Ebola now, so please don't find it." There's lots of downsides to having this virus in your country. People really didn't want to know about it.

And when you asked your boss for funds to go out and do research on Ebola, and an outbreak wasn't happening, they'd say, "This disease has killed less than 1,000 people in the whole of history. Why are you bothered about it?"

While an outbreak is happening, we also found if you want to go there and hunt for viruses, the international response teams and the locals will tell you to get lost. They've got more important things to do like stopping the outbreak.

I'm hopeful. I think we'll confirm the source of Ebola quite soon.

In any case, getting into these countries at the right time is always difficult. First of all, almost invariably in every Ebola outbreak, there is a long interval before the outside world picks up that an outbreak is happening. By the time investigators get there, the original source of infection is no longer relevant since it's been almost a year now that this thing has been spreading from human to human. So where it came from originally is not going to affect how it's controlled right now. If it was a bat, the season might have changed, so the type of bat that caused the outbreak may have gone elsewhere.

We have some consensus that Ebola lives in bats. In the very first outbreaks that happened simultaneously, in Sudan and Zaire in 1976, the first six people to get Ebola in Sudan, the very first people in history known to get Ebola, worked in the same room. There were holes in the ceiling above them and there were bats in that hole.

Then subsequent to that, if you go to every outbreak in history you find something that suggests there could have been a bat connection. So the indications are strong that it is bats that are involved.

I inoculated bats and snakes and frogs and spiders with Ebola virus. I inoculated tortoises, geckos, everything with the virus, to see what would happen. What happened was — in most of these animals, the virus didn't multiply — except in bats.

In bats, the virus multiplied like crazy, but it didn't do them any harm, which suggests that they're the natural host of Ebola virus.

But we don't have the second-step proof, though. If the virus is in bats, you can do a 'PCR' test that picks up the genetic material to say the virus is there. But you have to get the virus to grow in the lab. If you've got genetic material in a bat, and you can't grow that virus, you haven't proved that this is live virus. The Marburg virus has been grown on several occasions and there is little doubt that bats harbor it. But we haven't been able to do that with Ebola virus.

I'm hopeful. I think we'll confirm the source of Ebola quite soon. I think it'll happen in the not-too-distant future. But the problem is: what do you do about it then? You can't stop everybody, you can't reach down into the primeval forest, get the word into every nook and cranny and say, "Don't eat bats." You can try but it'll probably still happen.

Other people say, "Kill all the bats." That's nonsense. You won't succeed, and you'll make the situation worse. If you upset the ecology of these things, suddenly the virus is everywhere.