Subtitles section Play video Print subtitles On the hunt, for deadly viruses. Yes, we are the bat hunters. Their aim is to prevent the next catastrophe. Bats carry a lot of viruses that could trigger pandemics. Pandemics, of which we humans are the cause. Because of our destruction of the environment, humans are moving ever closer to wild animals. We can cut down half the rainforest and there'll still be enough left. People who are campaigning to protect the rain forest ? ?and for biodiversity? ?are helping to prevent new pandemics. How can we humans destroy a living forest, hundreds of years old, with a chain saw? We are in the Brazilian Amazon region with a group of virus hunters. They are tracking down invisible killer pathogens in the jungle. Our first trip takes us deep into the hinterland of São Paulo state. It's the region of sugar cane plantations. Trucks pass us by, carrying the sweet harvest. In the dusk we spot a ring-tailed coati. We are out with biologist Cristiano Carvalho and his team. In the few remaining strips of the Atlantic rain forest, he is looking for the hiding places of bats. He thinks he has located some in these water pipes, where he heard the sound of wings flapping inside. Indeed, there is a colony of bats. Dozens of them are living here in the cracks and crevices of the pipes. I'm specialised in seeking out bat hideaways in regions like this, close to agricultural land. Mostly I find them in trees, or like here, in water pipes. The bat expert's work begins shortly before dusk. He spans a net over the entrance and the bat hunt is on. We are working with these animals to find out how far the various viruses have spread. It is part of our scientific work to find out which bats are carrying which viruses. Now — in times of the coronavirus — everyone needs to wear protective clothing to prevent a transmission of the virus. Chiroptera — the scientific name for bats — have been Cristiano's passion for 26 years. He wants to lure them from the back of the pipe into the net. It's amazing how quickly he succeeds. Cristiano has to painstakingly untangle the animal from the net. For him, it's a routine procedure after his many bat hunts. He hands over the bats he has caught to virologist Angelica Campos, who neatly hangs them up in fabric sacks. It's only since this year that people worldwide have been noticing that bats carry numerous viruses which can be transmitted to humans and trigger pandemics. That's why researchers are now looking more closely and precisely to find out which viruses are being carried in each individual animal. They need thick gloves to do the job. The bats are not afraid to bite. Angelica takes samples out of the throats and digestive tracts of the bats, places where the coronavirus likes to settle. We've been expecting a coronavirus pandemic for years, but hoping that we would be wrong. They keep finding new previously unknown viruses in the faeces of the bats. With our work we want to prevent another pandemic from breaking out. We are hunting for new, dangerous types of virus or trying at least to limit them. According to estimates, there are more than 300,000 unknown pathogens in the world's jungles — mostly hidden in the bodies of mammals such as bats or rodents. As long as the rain forest stays intact, the viruses and bacteria pose no threat to humans. When humans and their livestock get too close to wild animals, the viruses can be transmitted to cattle, pigs, or humans, and become deadly. The virus hunters want to find out which pathogens are a threat to humans. The bat samples have to be kept frozen at -80°C on their way to the laboratory to keep the virus code intact. It's important to get as many samples from the bats as possible, so we can identify the many types of virus circulating in the population. Bats are more interesting for researchers than other mammals, as they carry an unusually high number of viruses. We can think of bats as a kind of virus storage. The pathogens stay in their bodies, far away from us humans. Pandemics arise when humans encroach on the natural territory of the bats and upset the balance of nature where the viruses exist. The researchers show us what they mean on the way to their São Paulo laboratory with their freezer box. Due to the sugar cane monoculture here the hanta virus has spread rapidly. It is transmitted by rat droppings. The hanta virus is not dangerous for the rodents. But for humans, every second case of infection leads to death. According to researchers, the hanta virus started spreading rapidly after the jungle was cleared for the monoculutre. In the 1970s, Brazil began building roads through the impenetrable Amazon rain forest. With their Trans-Amazonian Highway, the military dictatorship laid the foundation for the massive deforestation we see today. Agriculture has bestowed prosperity upon many regions, at the cost of the rain forest. More and more railway lines and highways cut through the Amazon. Every year fires ravage more swathes of the rain forest. They are usually started by farmers wanting to increase the size of their fields. We are on the Trans-Amazonian Highway on our way to an indigenous reserve. We see traces of slash and burn farming on all sides. Now in dry season, smoke lingers over vast stretches of the countryside. President Jair Bolsonaro won 60% of the votes in this region of the Brazilian state of Pará. In his election campaign, he promised to free up the reserves of the indigenous peoples for deforestation and to support the many local cattle breeders. When we reach the reserve, we see an illegal settlement. The collection of huts is called 'Vila Renascer', 'the place of rebirth'. It looks like a piece of the wild west, and indeed it is. Vila Renascer stands on a piece of indigenous land protected by the constitution. This fact was confirmed by civil servants, who also told us that they're powerless against illegal squatters. They're not allowed to give interviews but one person agrees to speak to us: Antoneta Araujo, a cook from an entirely different region who moved to Vila Renascer a year ago. Our restaurant will do well. This place is growing. Are there many workers here? Yes. Many Brazilians come from far away and stake out a piece of land to work on. I think it must be worthwhile. Antoneta and her husband Berto are frustrated. Neither of them has ever learned to read and write, and they do not understand why the state sees them as illegal squatters. We have no nurse here who could take care of us. She is not allowed to come here, because our settlement is illegal. The politicians come here to get our votes but so far no one has helped us to get a legal title as landowners. Berto shows us his building site next door, where a new, larger restaurant is planned. They have just laid the foundation for the floor tiles. Antoneta is hoping for good business, in spite of everything. The authorities say this is indigenous territory. But the old people say there have never been any indigenous people here. Still, the state won't give us this land. Are they right? I'm not sure. We hope that we can soon be the legal owners of this land. Then we can work here with a clear conscience. You don't see yourselves as illegal? We persevere. Buildings are going up everywhere. The craft workers are just putting up walls for an Evangelical free church. It is the sixth in the settlement. In just two years, the settlement has grown to around 2,000 people. For years, the squatters' spokesman has been fighting for legalization in court. In his view, the indigenous reserve is too big. He demands that it be reduced in size. Traditionally, the indigenous people have never lived on this land. That's why we demand that the reports justifying the reserve should be checked again. We just want everything to be done truthfully. The squatters' lawyers have managed to get the status of the reserve re-evaluated. You have to understand that the people living here in the Amazon want to survive. That has to be possible on this land. That's also how Joca Costa sees it. He runs the corner shop in Vila Renascer. He too is hoping that the size of the reserve will be cut. If they legalise our place then everything will be fine. There is so much wealth in this earth, raw materials. Which ones? A lot of gold and more. So, we're hanging in there to see what happens. Shortly afterwards, Leandro Aires arrives. He lives near the gold mines and complains about the latest raid by the state controllers. I have no idea whether the raid was legal or not.