Virus killing bats

The researchers then monitored viral spread among cells. While the monkey cells were completely destroyed by the viruses, more of the bat cells survived. The team then re-created their lab experiments using mathematical simulations to calculate how fast the viruses infected other cells and whether antiviral defenses played a role in their spread.

Although the viruses spread more slowly in the monkey cells, the cells were swiftly killed. Pathogens can only spread so fast internally before they kill their host, Brook says. But if the host has an immune system that can defend against rapidly spreading viruses, a virus might evolve to infect new cells even faster than it would in a different environment, in a sort of arms race. And if a quick-spreading virus from bats were to infect another species that lacked batlike defenses?

There are more than 1, bat species in the world, Olival says, and the current study focused on only two. Olival is also curious how the findings might apply to other animals that can carry deadly viruses, such as rodents. They are always flying out and bringing back something new to the cave or nest, and they transfer the virus because they live in such close proximity to each other," said Seluanov.

Because bats are constantly exposed to viruses, their immune systems are in a perpetual arms race with pathogens. Dealing with all of these viruses may be shaping bats' immunity and longevity". However, the study does not suggest humans toss their masks and crowd together in restaurants and movie theatres.

Evolution takes place over thousands of years, rather than a few months. Now, three of the four chambers are empty and quiet, shut down after the last of their bats died last month. Its furry body is no larger than a human thumb. Reeder and her students travel through the rolling Pennsylvania countryside, headed for the limestone mine where bats were caged last fall. The mouth of the mine, tucked into a steep hillside above a two-lane highway, is blocked with a forbidding metal gate, designed to keep out vandals.

But not for the bats in this mine, whose numbers have dropped from an estimated 10, two years ago to roughly today. Reeder and her students zip up their Tyvek suits and pick their way through the fallen rocks on the mine floor, the beams of their headlamps cutting through the cool, misty half-dark. Little brown bats are hanging onto the rocks, alone or in twos and threes, their fur glistening with moisture. Here and there, a dead bat lies on the ground, the bodies hardly more substantial than dried leaves.

The crew counts 35 live bats hanging just inside the mouth of the mine, almost half bearing visible signs of white-nose syndrome. All are far closer to the mine entrance than is normal for this time of year.

Later, a few will flutter out of the mine, pale brown and reeling in the daylight. The crew slips through a narrow horizontal slot on the side of the mine, crawling headfirst down a boulder-filled slope.

There, more bad news awaits: the mesh cages have been vandalized by raccoons, and the treated bats inside have all either escaped or been eaten. An entire season of data lost—to raccoons! Among the researchers, the frustration is palpable, their reactions unprintable. By the time she returns to the mouth of the mine, Reeder is philosophical. Perhaps different compounds, or higher concentrations of the same compounds, might boost survival rates, but those are questions for the next study.

In their search for patterns in the white-nose epidemic, Reeder and her students have found that bats in cooler conditions may have better survival rates. In Tennessee, conservationists are already planning to build an artificial cave that can be kept fungus-free, and in New Hampshire, biologists are studying bats that hibernate in abandoned World War II-era bunkers, hoping that climate conditions inside will help some bats survive.

The National Zoo has attempted to keep endangered Virginia big-eared bats alive in captivity, so far with limited success. Even if such heroic measures can reduce the toll, many bat species will take generations to recover from white-nose syndrome. This past winter, Brooke Slack and her crew conducted their annual survey of nearly Kentucky caves. The early results were good: the bat she had euthanized in Mammoth Cave tested negative for white-nose syndrome, and the rest of their cave surveys came up clean.

It looked as if Kentucky bats had, against the odds, made it through another winter fungus-free. And, with a number of outbreaks having happened in Asia already, it is likely we haven't seen the last of it. There are several reasons the Nipah virus is so sinister. The disease's long incubation period reportedly as long as 45 days, in one case means there is ample opportunity for an infected host, unaware they are even ill, to spread it.

It can infect a wide range of animals, making the possibility of it spreading more likely. And it can be caught either through direct contact or by consuming contaminated food.

Someone with Nipah virus may experience respiratory symptoms including a cough, sore throat, aches and fatigue, and encephalitis, a swelling of the brain which can cause seizures and death.

Safe to say, it's a disease that the WHO would like to prevent from spreading. It's first light in Battambang, a city on the Sangkae River in north-west Cambodia. At the morning market, which starts at , motorbikes weave past shoppers, kicking up dust in their wake.

Carts piled high with goods and covered in colourful sheets are perched next to makeshift stalls selling misshapen fruits. Locals wander in and out of the stands, plastic bags bulging with their purchases. Elderly ladies in wide-brimmed hats crouch over blankets covered with vegetables for sale. In other words, it's a fairly normal morning market. That is, until you crane your neck to the sky. The morning market at Battambang, Cambodia would be an unremarkable affair — except for its fruit bats Credit: Piseth Morais.

Hanging quietly in the trees above are thousands of fruit bats, defecating and urinating on anything that passes below them. On closer inspection the roofs of the market stalls are covered in bat faeces. The Battambang market is one of many locations where Duong has identified fruit bats and other animals coming into contact with humans on a daily basis in Cambodia.

Any opportunity for humans and fruit bats to get near to one another is considered a "high risk interface" by his team, meaning a spillover is highly possible. Despite the dangers, the examples of close proximity are endless. In a normal year, Angkor Wat hosts 2. Fruit bats fly above the Battambang morning market, one of many locations in Cambodia where bats and humans come into close contact daily Credit: Piseth Mora.

From to , Duong and his team launched a GPS tracking programme to understand more about fruit bats and Nipah virus, and to compare the activities of Cambodian bats to bats in other hotspot regions. Two of these are Bangladesh and India. Both countries have experienced Nipah virus outbreaks in the past, both of which are likely linked to drinking date palm juice.

At night, infected bats would fly to date palm plantations and lap up the juice as it poured out of the tree. As they feasted, they would urinate in the collection pot. Innocent locals would pick up a juice the next day from their street vendor, slurp away and become infected with the disease.

Across 11 different outbreaks of Nipah in Bangladesh from to , people were detected to have Nipah — died. Date palm juice is also popular in Cambodia, where Duong and his team have found that fruit bats in Cambodia fly far — up to km each night — to find fruit.

That means humans in these regions need to be concerned not just about being too close to bats, but also about consuming products that bats might have contaminated. Duong and his team identified other high-risk situations, too. Bat faeces called guano make for popular fertiliser in Cambodia and Thailand and in rural areas with few work opportunities, selling bat droppings can be a vital way to make a living.

Duong identified many locations where locals were encouraging the fruit bats, also known as flying foxes, to roost nearby their homes so they could collect and sell their guano. Villagers harvest guano, a popular fertiliser in Cambodia and Thailand but one that comes with risks Credit: Sa Sola. But many guano harvesters have no idea what risks they face in doing so.