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Tracking Ebola: the killer hiding in the jungle

Between outbreaks in humans, the virus stays concealed in the rainforests of Central Africa. Kevin Sieff follows the team hunting it out

Kevin Sieff
Friday 20 March 2015 19:03 GMT
The field team canoes through the National Park
The field team canoes through the National Park (The Washington Post)

More than 3,000 miles from the fading Ebola crisis in West Africa, a team of US-funded researchers is hunting deep in a remote rainforest for the next outbreak.

They aren’t looking for infected people. They’re trying to solve one of science’s great mysteries: where does Ebola hide between human epidemics?

The answer is thought to lie in places like this – vast tracts of African jungle where gorillas, bats and other animals suspected of spreading the virus share a shrinking ecosystem. If scientists can pinpoint the carriers, and how Ebola is transmitted between them, future epidemics will be easier to anticipate – or prevent.

The mission is urgent. Based on the pattern of previous outbreaks, the next one probably isn’t far away.

The world was shocked by the most recent epidemic, which has killed more than 10,000 people in Guinea, Liberia and Sierra Leone. But over the past 40 years, Ebola has exploded sporadically in sub-Saharan Africa, wiping out scores of people – and quietly decimating wildlife populations.

So on this humid Sunday, a 51-year-old wildlife vet from Michigan has loaded his gear into a leaky dugout canoe and headed with his team into the Congo River Basin.

Now they are trekking for miles through the brush. They are seeking one of the animals suspected of harbouring Ebola: the red river hog.

If the researchers capture a wild pig and it tests positive for Ebola, it will confirm decades of hypotheses and help scientists map the disease.

A market in Brazzaville sells red river hog meat (The Washington Post)

Kenneth Cameron, who works for the New York-based Wildlife Conservation Society, has spent much of his life pursuing Ebola through Central Africa.

“The West Africa outbreak was a reminder that it’s out there – and it’s waiting to emerge again,” he says.

There have been 24 recorded outbreaks of Ebola since 1976, when it was first identified. Each began with an interaction between a human and an animal. In West Africa, the recent Ebola outbreak is thought to have begun when a two-year-old Guinean boy touched a droplet of bat faeces in December 2013.

“It’s only a question of how destructive the next one will be,” says Mr Cameron, whose research is funded by the US Fish and Wildlife Service.

Scientists suspect that fruit bats are the “reservoir host” of the Ebola virus, meaning they carry and transmit the disease but don’t suffer from it themselves. But even that hasn’t been proven.

What is known is that in 2002, in a village called Mbomo, more than 200 miles from where Mr Cameron’s team is working, people started getting sick and testing positive for Ebola. Over several weeks, 178 people died. When the epidemiologists traced the disease, they heard the story of hunters who had cooked and eaten the carcass of a gorilla found in the jungle. At the time, dozens of gorillas were dying suddenly. “Soon everyone understood that it came from the forest,” recalled Marco Joel, who was the director of the local Red Cross chapter at the time.

In November 2003, people in Mbomo started getting sick again. The doctors returned. Ebola tests came back positive. Dozens more died. But in trying to trace this outbreak, epidemiologists heard a different story. A group of hunters had killed and eaten a wild pig days before falling ill.

Was this outbreak connected to the last — a pig that had become infected by a gorilla? Or was this a separate transmission chain? No one could tell. No pigs had ever tested positive for Ebola.

Since 2005, as part of his Ebola research, Mr Cameron has tested primate carcasses and faeces. He has captured bats using large translucent nets. He has darted gorillas with a tranquilliser gun. He has loaded blood samples onto jeeps and boats and planes to be taken to labs and tested for Ebola.

There have been successes, such as when his team found Ebola antibodies in the faeces of gorillas, a sign that the animals had been exposed to the disease. But largely, the research has been a slow crawl through the dark.

Now, under a towering ficus tree in the jungle, Mr Cameron and his team hammer the posts of a metal cage into the ground. They set up a trapdoor they hope will be triggered by the weight of a pig, which they will tranquillise and examine for the virus. Mr Cameron watches as the trapdoor is tested. The stakes are high. If he can’t capture a pig, it will be hard to secure funding for a follow-up study. The door goes down with a bang. “Ça marche!” Mr Cameron screams in French with boyish excitement: “It works!”

Scientists aren’t sure which species are immune to Ebola, but Mr Cameron uses the example of a tree he once filmed in the Republic of Congo to explain the challenge they face . Pigs, gorillas and chimpanzees were all seen eating from it, often consuming different pieces of the same fruit. “You watch that film and you see just how quickly this thing could spread,” Mr Cameron says.

In a place like this country’s north, where bushmeat is still consumed as a rare source of protein, the chain would almost inevitably lead to humans, as Mr Cameron’s team members know well. They are from local villages, and while they no longer consume wildlife, they still extol its virtues.

Bushmeat is still a major source of protein in the Congo (AFP/Getty) (AFP/Getty Images)

“Elephant is delicious,” says Makoti Marcelin, one of the wildlife trackers. “It tastes just like gorilla.”

But while most people in the Republic of Congo stopped eating great apes in the wake of the 2002 Ebola outbreak, pigs are still sold in markets around the country. If an infected pig made its way near a town or village, it would probably be eaten.

Mr Cameron’s team returns to the trap the next morning.

“There were pigs here last night,” says another vet, Alain Ondzie, pointing to hoof marks nearby. But the metal cage is empty.

“It’s frustrating,” Mr Cameron says. “There’s still just so much we don’t know.” He returns to his office in Brazzaville empty-handed, but he is hopeful about the next site visit in a few weeks.

A few miles away, at one of the city’s largest markets, a frenzy of people is selling chicken, antelope and other meat. In one area, the tables are piled with wild pig, brought from the northern Republic of Congo, near Mr Cameron’s research site. The salesman says he has heard about Ebola – the epidemic 3,000 miles away. But there has been no impact on local people’s taste for wild pig.

“We all know that pigs can’t get Ebola,” he says confidently.

© The Washington Post

Knock-on: Crisis disrupted immunisation work

The World Health Organisation warned yesterday of a risk of outbreaks of measles, whooping cough and other diseases in West African countries hit by Ebola. It said this must be countered with rapid intensification of routine immunisations.

The Ebola epidemic, which has infected 24,000 people – killing more than 10,000, mostly in Guinea, Liberia and Sierra Leone – has reduced vaccination coverage as healthcare workers focused on fighting the outbreak.

A study published last week by Johns Hopkins Bloomberg School of Public Health in the US warned that measles cases could double in countries hardest hit by Ebola.

It calculated that for every month healthcare systems were disrupted, up to 20,000 children aged between nine months and five years were put at risk. The Ebola epidemic has also disrupted delivery of routine childhood vaccines against tuberculosis and polio, and of a combined shot against meningitis, pneumonia, whooping cough, tetanus, hepatitis B and diphtheria.

The outbreak has hampered treatment of other conditions (Getty) (Getty Images)

The WHO warned affected countries: “Any disruption of immunisation services will increase the likelihood of vaccine-preventable disease outbreaks.”

Jean-Marie Okwo-Bele, the WHO’s vaccines director, told a briefing in Geneva it wanted intensification of routine immunisation services, and mass measles vaccination campaigns in all areas, where feasible.

“Campaigns will only be conducted in areas free of Ebola virus transmission,” he said, stressing that clinics and health workers giving vaccines would have to adhere to strict infection- control measures.

Measles is a viral disease that killed around 146,000 people globally in 2013, mostly children under five – about 16 deaths every hour. The WHO faced criticism for its handling of the Ebola crisis yesterday. Internal emails and documents obtained by the Associated Press showed that it resisted sounding the international alarm over West Africa’s Ebola epidemic for two months.

The WHO acknowledges being slow but has blamed its response partly on the surprising characteristics of the outbreak. Documents show officials were informed of the dire situation early on and received an urgent plea for help. Senior staff privately floated the idea of declaring an international health emergency in early June, two months before the declaration was finally made.

But directors discouraged making the move earlier, saying the declaration could be seen as “a hostile act” and endanger economies.


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