African : Conservation in the time of Ebola

The ongoing Ebola epidemic in western Africa underscores the increasingly recognized role of bats as reservoirs for emerging human diseases. But without a better understanding of -to-human disease transmission, culling bats (and other fear-based management responses) could make the problem worse.

Photos: Piotr Naskrecki & Jen Guyton Words: Jen Guyton he last fragile wing finally came free The bat was a dozen feet above us - and I from the threads of my mist net. I sank didn’t have the handle extension sections, t into the sand on the riverbank, took so I quickly duct taped the net to a mist net a deep breath, and tugged off my yellow pole. I raised the net slowly, very slowly, deerskin gloves. Eight cotton bags wiggled sure that the bat would see me coming and as they hung from the line that tethered my take flight. But it continued to munch mer- mist net to a tree. We’d gotten a swell of rily, and it disappeared into the net with banana bats (Neoromicia nana), tiny crea- little more than a metallic peep! of protest. tures, no heavier than a large grasshop- As I collected a faecal sample from it, per, that are thought to roost in the furled Kaitlyn cleaned the urine from her clothes. leaves of banana plants. They had come in low over the river like a pack of tiny, flitte- Stories like these have gotten me into ring wolves, hunting the gnats and mosqui- trouble lately. “I study bat communities in toes that hovered in a veil over the water. Africa,” I’ll say, only to be greeted by wide I’d had to work fast, because the longer the eyes and mouth poised to speak the word bats stayed in the mist net, the more tan- that’s on everyone’s mind: Ebola. gled they became. Some even chewed their Luckily, I work on the other side of the way through the nylon thread, escaping in continent, thousands of miles from where a flurry of teeth and leaving behind a yaw- Ebola has now taken almost 5,000 lives. My ning hole for me to mend, its edges fringed field site in Mozambique, on the southeas- with fragrant urine. Now, I just had to wait tern coast of Africa, is safe from bat-borne for my subjects to leave me a few faecal diseases, as far as we know. But it’s no pellets in the cotton bags so that I could secret that bats have been implicated analyze their diet. frequently in emerging zoonotic diseases I looked with relief at Kaitlyn, my assis- – diseases of origin – that are now tant for the day, as we took swigs of our cropping up among humans: rabies in the beers. I watched the net billow and catch Americas, Marburg virus in Africa, Hendra the moonlight, shining silvery-black like virus in Australia, and Nipah and SARS a benighted spider web, and listened to viruses in Southeast Asia are all harbored the sound of elephants crashing their way they come in low over by bats. through the dense riverine vegetation in the river like tiny the distance. flittering wolves. Out of the corner of my eye, I saw Kaitlyn startle and look down. “I think something A takes a drink on the just peed on me,” she said, sounding per- wing. At the end of the dry season, plexed. I shone my headlamp above her pools like this one are a crucial and was greeted by the glittering eyes and resource for them. bulging cheeks of a large bat, hanging from the branch of the tree above us an happily chomping away on a piece of fruit. From the white patches below its ears and its fawn-colored fur I recognized it as an Epau- Epauletted fruit letted fruit bat, a member of the genus bat (Epomophorus Epomophorus. wahlbergi) I ran to grab my hand net, a long mesh bag on a circular frame with a handle. > > > > > > > > > The recent Ebola outbreak has tenuous evidence that people have become infec- ties to our fluttering friends: scientists have ted through ape carcasses, scavenged and found its antibodies in several species of eaten. People in parts of Africa eat bats West and Central African fruit bats but can’t too, but whether humans can catch the be sure that they are “reservoir” species bug directly from bats is still a mystery. (ones that carry the virus in their bodies Some bat-borne diseases need to pass without showing signs of illness). If this through what’s called an “intermediate” were the case, Ebola could spill over into host – another species that amplifies the humans, but since the live virus hasn’t yet virus, allowing it to multiply and become been isolated from bats, all we know is that more virulent – before humans can catch it. at some point in their lives, they were ex- That is true of Hendra virus, which is found posed to it, and it left its signature on their in Australian flying foxes. Contact with the immune system. bats poses little known threat to humans, So far, there’s no record of a bat transmit- but four people have died after interacting ting Ebola to humans. Humans can get with sick horses. The horses, it seems, fed it from other humans, and we have solid on fruits from trees where bats roosted.

[Left] Some bat-borne diseases are transmitted through a bite or a scratch or from a bat’s saliva coming into contact with the mucous membranes (eyes, mouth or nose). All of this adds to bats’ undeservedly bad reputation. Their mystical association with vampires, nocturnal habits, their seemin- gly erratic flight pattern, a slew of spooky superstitions, and now a misperception that bats are unusually disease-ridden have earned them a less-than-exalted place in so far there’s no the human consciousness. In some cases, this negative image arouses persecution. record of a bat In 2007, hysteria stemming from a Mar- transmitting burg virus outbreak in Uganda led to mass ebola to humans extermination of Egyptian fruit bats, lea- ving heaps of them piled on the floor of the forest. This wasn’t an unprecedented reac- tion – people have been slaughtering vam- [Right] Scientists who pire bats in Peru since the 1960s in an effort research bats are trained to control rabies, and a few years ago, the in how to handle them and four human deaths from Hendra virus in are vaccinated against bat- Australia led to widespread culling of flying borne diseases. foxes. > > > > > > > > > [Left and Below] Bat flies have specialised claws, allowing them to cling tightly to fur and wing membranes.

[Left] Penicillidia bat flies are highly specialised parasites and hardly resemble their winged relatives. This indi- vidual was photographed clinging to the face of a Long- winged bat (Miniopterus natalensis).

Bats play host to two very unusual families It is possible that bat flies play a role in of parasites: the Nycteribiidae and Strebli- the transmission of bat-borne diseases dae, commonly known as ‘bat flies’. Over but there hasn’t been enough research to millions of years of co-evolution with their know for sure. A recent study conducted in mammalian hosts, these parasites have Gorongosa National Park on two bat spe- undergone a remarkable transition. cies (Rhinolophus landeri and Hipposideros Penicillidia, for example, bears little re- caffer) found that tsetse flies - which often semblance to its winged ancestor (which move from one host species to another and probably looked something like a modern occasionally bite people - were vectors of tsetse fly). In the process of becoming a a form of Trypanosoma that is ancestral to highly specialised parasite, all traces of those that cause Chagas disease. Added the wings have disappeared. At the same to this is the fact that one of the first cases time, its body has become flattened and of Marburg disease in Zimbabwe (caused very hard, making it almost impossible to by a virus related to Ebola) was attributed squash against the skin. Large claws at the to a bite from an arthropod. By default all end of each foot grip tightly to the bat’s unidentified bites seem to be classified by is it possible that bat fur, while the head has turned into a small the medical community as “spider bites”, flies could play a role appendage that can be safely tucked away despite the fact that spiders in the area in a protective groove on the back. The were tested, unsuccessfully, for Marburg in transmission of result is a creature that looks more like an disease). It is far more likely that the bite bat-borne diseases? arachnid than a fly. was caused by a parasite that fell off a bat. > > > > > > > > > Fruit bats - which are widely Fruit bats are more consumed by humans - serve as easily captured in reservoir species for the majority of human communities than known bat-borne diseases. in natural , since the loss and hunting could play major former provide access to high roles in the spillover of zoonotic concentrations of cultivated fruit. disease into human populations, This, coupled with habitat loss, highlighting the importance of creates a push-pull dynamic that understanding and mitigating draws potential reservoir these threats. species into human settlements.

> > > > > > > > > it’s not clear whether bats are different from other that could potentially carry diseases, or whether we’re just paying more attention to them now.

Does reducing bat populations actually It’s not clear whether bats really are dif- help reduce the risk of bat-borne diseases ferent from other animals that could poten- jumping to humans? Surprisingly, the ans- tially carry diseases, or whether we’re just wer is: probably not. In fact, there’s evi- paying more attention to them now; there’s dence that it could make things worse. In currently a debate raging among scientists Uganda, the fruit bat extermination led to about whether bats are special as disease [Right] Lander’s Horseshoe Bat a much larger outbreak of Marburg, which reservoirs. Some say yes. This may be (Rhinolophus landeri) is closely related to Ebola, among humans. because many bat species are very social, roosting in a cave in As it turned out, fruit bats recolonized the which would allow pathogens to spread Gorongosa. Our caves from which they’d been extermina- easily. Or, it could be that bats have a long knowledge of colony ted, and the new population had a much evolutionary relationship with some virus and population sizes higher prevalence of Marburg infection families. Some scientists hypothesize that and dynamics is poor for than the exterminated one. We’re seeing a it’s linked to bat physiology: an unusual im- many species. similar effect in the Peruvian vampire bats mune system, or the remarkably high body – rabies prevalence is higher in populations temperatures that bats experience during that are subjected to culling by a poison flight, could play a role in their ability to [Left] A common and nume- called “vampiricide”, which preferentially survive infections and, in the end, become rous species. Sundevall’s kills adult bats. That’s probably because reservoirs of pathogens. roundleaf bats killing adults removes individuals that Others argue that the numbers just don’t (Hipposideros caffer) are have already been exposed to the disease, add up and that bats aren’t any more di- extremely gregarious making them immune. That allows “sus- sease-ridden than other groups. and capable of forming ceptible” juveniles, with no immunity, to Given that bat research is on the increase huge colonies where proliferate, and the infection spreads like it could be the simple result of a twisted there is adequate wildfire. treasure hunt: the harder we look, the more roosting space. we find. > > > > > > > > > Every year, a team of scientists visits You can see the evidence of this in their Gorongosa National Park to survey its faces; bats echolocate, or use reflected incredible diversity. I’ve been participating sound, to find their food. But not all echo- in the surveys since they began in 2013, as a location is the same -- different bats make small mammal / bat specialist. Bats are the different types of sounds, and process the second most diverse group of in reflected sound differently, depending on the world, and the number of ways they’ve their environment and their evolutionary come up with to cope with life as a history. That’s why we see such a diversity nocturnal, flying mammal is astounding. in ear shape and facial structure. > > > > > > > > > Solutions can be devised to reduce human In an effort to minimize wildlife-human sing, given that deeply entrenched cultural hunting bats could also reduce exposure to contact with bats without resorting to contact and combat Ebola, the govern- practices can be difficult to change, and the riskiest situations. Encouraging safer population control measures. For example, ments of Guinea and Sierra Leone have people often rely on bushmeat for nutrients slaughter and handling practices of wildlife exclusion netting over crops can reduce recently banned all harvesting and sale that are difficult to attain elsewhere. One and domestic stock may also help. damage by fruit bats while simultaneously of bushmeat. These laws, however, are potential compromise might be to impose Ultimately, however, development efforts reducing provisions that attract bats to poorly enforced, and the sale of bushmeat a hunting season accompanied by aware- should aim to provide communities with human communities in the first place. continues in the region. This is unsurpri- ness campaigns. Discouraging people from safe, sustainable sources of animal protein. > > > > > > > > > While ongoing research into the internal interventions may have. However, as bat- structure of emerging pathogens such as borne diseases are increasing in frequency Ebola virus and efforts to develop treat- and severity, it is paramount that we under- ments are of undeniable importance, qua- take further studies. rantine of infected humans and prevention Bat natural history research was once of disease transmission from wild reservoir limited by how difficult bats are to observe, species may be the most effective public but modern technology is changing that. health measures in controlling epidemics In particular, much-needed assessments in regions, like Africa, with limited medical of population size and connectivity for bat services. species across the globe are becoming in- We should aim to understand bats and their creasingly possible with the help of modern pathogens sufficiently to know at which technologies. point to intervene in the cycle of disease Population assessments for bats will be par- transmission. Our current knowledge of the ticularly important in understudied regions, basic natural history of bats, especially in such as Africa, where human-bat contact Africa, is woefully inadequate to attempt rates are high and risk for disease transmis- any accurate prediction of what impact any sion is substantial. Bats are special in a lot of ways, and they as dispersing the seeds of rainforest trees deserve a boost in popular image. They’re or pollinating flowers, including the agave the only mammals that have evolved true used to make tequila. flight. They’re also one of the few groups, We don’t yet know as much about bats and along with some whales, shrews, and birds, their diseases as we should, but the little that use echolocation – the ability to “see” evidence we do have suggests that killing a landscape using reflected sound waves. bats will actually worsen the problem. It The combination of flight and echolocation also suggests that the same things that are allows them to fill a special role as noc- driving some bats toward extinction are turnal predators of aerial insects, with the also driving spillover events. Deforestation, potential to suppress insects like mosqui- for example, forces bats to find new homes toes or some agricultural pests that aren’t in cities and increases the probability of active during the day. This does humans their contact with humans. And eating bats an important service, and scientists have gives their pathogens even easier access to estimated that bats save U.S. agriculture people. We can reduce those risks if we pro- $53 billion dollars in pest control every year. tect bat habitats, halt culling efforts, and The high diversity of bats – they’re the convince people to stop hunting and eating second most diverse mammal group after bats. None of these are trivial endeavors, rodents – allows them to fill a number of but we need to try. In the time of Ebola, bat other important roles in ecosystems, such conservation is more important than ever.

Climbing into aban- doned wells and creeping around at night isn’t for the faint of heart, but for scientists who study bats, it’s all in a day’s work. Contact: [email protected] +44(0)117 911 4675