Scientists tracking bats carrying lethal Marburg virus

BY DAY, some of the most dangerous animals in the world lurk deep inside this cave. Come night, the tiny fruit bats whoosh out, tens of thousands of them at a time, filling the air with their high-pitched chirping before disappearing into the black sky.

The bats carry the deadly Marburg virus, as fearsome and mysterious as its cousin Ebola. Scientists know that the virus starts in these animals, and they know that when it spreads to humans it is lethal - Marburg kills up to nine in 10 of its victims, sometimes within a week. But they don’t know much about what happens in between.

That’s where the bats come in. No one is sure where they go each night. So a team of scientists from the US Centers for Disease Control and Prevention travelled here to track their movements in the hopes that spying on their nightly escapades could help prevent the spread of one of the world’s most dreaded diseases. Because there is a close relationship between Marburg and Ebola, the scientists are also hopeful that progress on one virus could help solve the puzzle of the other.

Their task is to glue tiny GPS trackers on the backs of 20 bats so they can follow their movements.

“We want to know where they’re going on a nightly basis,” said Jonathan Towner, 52, who heads a CDC team that specialises in how these deadly viruses are spread. If the animals are feeding on particular fruit trees, that information could identify communities most at risk and help prevent future outbreaks. “It’s much easier to put together a picture and say to local authorities, ‘ Look, this could be potentially how the virus is spread, this is what the bats are doing.’ “

US officials are so concerned about Marburg becoming a global threat that the CDC is asking the Pentagon’s Defence Threat Reduction Agency to pay for the bat trackers, which each cost about US$ 1,000. The CDC is hoping to track more of these Rousettus aegyptiacus bats in several other caves in Uganda.

Marburg’s potential to spread was made clear a decade ago when a pair of tourists on separate trips walked into the cave looking for adventure and walked out with the virus. A Dutch woman died 13 days after her visit. The other visitor, an American woman named Michelle Barnes, survived after a long, painful illness. The cave was closed to tourists in 2008.

Marburg was first identified in 1967 when a shipment of infected African green monkeys from Uganda was sent to laboratories in Marburg and Frankfurt, Germany, and Belgrade, in thenYugoslavia. Seven lab workers died within about a week. Since then, a dozen outbreaks have been reported, killing hundreds of people. Most took place near bat-infested caves or mines, including one last fall along Uganda’s eastern border with Kenya. Of four family members sickened, only one survived.

For the CDC scientists, success hinges on getting the tracking units, which are half the size of a pen cap, to stay on a bat body that is only about six inches long. A practice run in Atlanta with the same device on the same kind of bat in a special CDC laboratory failed. Trackers slipped off or were chewed by the bats.

“I have no idea how well this is going to go because it’s the first time we’ve tried it,” Towner said. “It could end up in total flames.”

Well before you see the bats - about 50,000 live in the cave - you hear their squeaks and chatter and smell the ammonia from their guano, which also covers the cave’s rocky floor. One false step can lead to a fall into a stream underneath. Another could land the scientists on one of the African rock pythons or forest cobras that slither along the ground.

Towner and CDC colleague Brian Amman, 54, discovered a decade ago that this Egyptian fruit bat is a natural reservoir for Marburg. That means the virus can live and grow inside the bats without harming the animal, and be excreted in its urine, feaces or saliva.

By comparison, more than 40 years and over two dozen outbreaks after Ebola emerged in Central Africa, researchers still don’t know what animal or animals carry it, much less how it spreads to people.

The bat team includes CDC scientist Jennifer McQuiston and Luke Nyakarahuka, an epidemiologist at the Uganda Virus Research Institute, a longtime CDC partner. The CDC allowed a Washington Post reporter and photographer to accompany the team.

In a clearing of Maramagambo Forest, scientists’ workstation the the is a table under a tent. Curious baboons perch on nearby tree stumps. Black-and-white colobus monkeys peer from overhead branches. On a drive through the park in search of other bat roosts, the scientists’ Toyota Land Cruiser yields the right of way to a majestic waterbuck, its long, curved horns glinting in the sun.

Their task is to catch and glue trackers on 10 bats the first day, repeat the next day.

The tracking software has already prompted a stream of curses from Amman. To test it again, McQuiston and Nyakarahuka each cup a tiny unit in their palms and jog around the clearing to simulate bats on the move. That’s supposed to trigger readings. But the screen on Amman’s clunky CDC-issued laptop remains blank.

“If it comes back and says zero I don’t know what we’re going to do,” Amman mutters. Several minutes pass in silence. Then, ever so slowly, data points start to show up. Now they can head to the cave. Towner and Amman suit up in special helmets and face shields connected to battery-powered respirators that muffle their voices. Underneath protective gowns they wear Kevlar-lined waist-high pants to guard against snake bites. On their hands are cut-resistant leather gloves, like those worn by law enforcement, over two pairs of medical gloves to protect against bat bites. Towner also had a video mounted on his helmet.

“Hey, Brian, right down there is a bunch of males. You see ‘em?” shouts Towner in the cave, his voice muffled by the head gear.

The bats take flight, which is when they relieve themselves of what Amman calls the “rain of pee and poo.”

Amman, holding a net, heads to where Towner is pointing, veering far away from an enormous python. He returns with two bats, which go into a pillowcase Towner is holding. Each pillowcase will hold about five bats since bats don’t like to be alone. Only males are caught; the scientists don’t want to burden females carrying pups.

Catching the bats is the easy part. Getting the trackers on is trickier.

Amman dreads the prospect of using sutures because they are messy and complicated. But given the failure in Atlanta, he has brought the necessary kit. He hopes a last-minute purchase of different veterinary glue may do the trick. — WP-Bloomberg