BATS AND HUMANS: GOOD THINGS, DISEASE, RABIES AND DEATHS

BATS AND HUMANS

From Bats Conservation International

Bats are eaten in a number of places. It has been said that they taste like partridge. In Ivory Coast there is large market for selling hunted bats. People also eat them in the Philippines and Indonesia. In Guam people pay as much as $25 for a single bat.

Bats are often blamed for eating fruit trees in orchards but studies have shown that monkeys are often the culprits not bats. Fruit-eating bats only eaten ripened fruit, which is no skin off a farmer's back because he usually ships off his produce weeks before it is ripe so it will be ripe when it is in the store. Bat apparently don't like unripened fruit any more than humans do.

Bats can be easily killed in places where they roost. A single shotgun blast can kill 20 to 60 roosting bats. Sometimes they are killed by the thousands by covering up their caves so they can’t feed. Because females only have one or two offspring a year it takes a while for a population of bats to recover once members are killed or their cave has been disturbed. Bat deaths can also have a serious on the ecosystem they are part of.

The only other predators that bats have to worry about other than man are snakes and predatory birds like eagles and hawks that sometimes snatch the tree-roosting bats while they are sleeping during the day.

Ways Bats Help Humans

Bats help humans by eating mosquitos and other pests. They are especially useful to farmers eating insects that damage crops. As pollinators and seed dispersers, fruit-eating and nectar-drinking bats play an important role in maintaining forest structure.

lesser-long nosed bat covered in yellow pollen.

Fruit bats serve as seed dispersers and pollinators for forest and agricultural trees, including durian, which produce a high-priced fruit considered a delicacy in southeast Asia. These bats are often the only seed dispersers or pollinators large enough to carry the large fruit they feed upon. They also pollinate canopy trees when searching for nectar. Seed dispersal by large flying foxes are thought to play an important role in the regeneration of cleared forests. [Source: Kelsie Norton, Animal Diversity Web (ADW) /=]

Bats feast on insects each night, adding up to more than $3.7 billion worth of pest control each year in the U.S. When bats are around to eat insects, there are fewer insect pests causing damage to crops, and farmers don't have to invest as much in pesticides. Bats can eat 50 percent or more of their bodyweight in insects each night. Imagine eating 200 quarter-pound burgers—that's how much a bat eats in insects in one night! [Source: National Park Service]

Bats provide inspiration. Some of bats' unique features like membrane wings and echolocation have inspired technological advances in engineering. Drones that have thin and flexible bat-like wings are are in the works as well as tiny, more efficient sonar systems for navigation. The wingsuits used by basejumpers take more than a few cues from bats' aerodynamic bodies.

Ways Bats Help Ecosystems

Several species of bats in tropical and subtropical areas eat nectar. Many types of plants in these regions rely on bats for pollination and seed dispersal. In the southwestern U.S., long-nose and long-tongue bats are perfectly adapted to pollinate blue agave plants, and they provide extensive value to the agricultural industry. [Source: National Park Service]

Fruit-eating bats play important roles in distributing seeds to maintain plants and forests. These species of bats, often called "flying foxes" because of their larger body size and big eyes, live in tropical and subtropical areas of the Old World (Africa, Asia and Australia). Fruit-eating bats are also found in some Pacific islands, Latin America, and the Caribbean and live in national parks in Guam, American Samoa, and the Virgin Islands!

bat catches an adult corn earworm.

Bat guano supports cave communities. Caves are complex and unique ecosystems that provide homes for a diversity of creatures from insects to amphibians and fish as well as mammals like wood rats and bats. Many of these creatures can only survive within the cave, and they rely on nutrients carried into the cave by water or other animals. Bats benefit caves by providing important nutrients in their guano (better fertilizer than cow manure!) that support the growth of communities of cave organisms.

Just as some bats rely on thousands of insects each night for survival, other animals in the ecosystem rely on bats for their calories. Hawks, falcons, and owls eat bats, and mammals like weasels, ringtail cats, and raccoons sometimes attack bats while they roost.

Bats and Human Disease

Bats are blamed for spreading a number of rare, serious diseases to humans such the Lyssa virus which killed people in the Ukraine and Britain; the Nipah virus, which killed hundreds of people in Malaysia, Bangladesh and India; Marburg virus in Africa; the Hendra virus in Australia ; and the ALS-Parkinson dementia complex in Guam. In the later case, the Chamorro on Guam were more 100 times likely to develop ALS-Parkinson dementia complex than other people. It was found that those affected had eaten fruit bats that were full of neurotoxins picked up from feeding on seeds of cyad plants. Bats are also thought to be the natural reservoir for the Ebola virus. They also carry the rabies virus, but in that case the bats are affected by the disease. With other diseases, the show no symptoms and don;t appear to be negatively affected by the viruses.

James Gorman wrote in the New York Times: The tolerance of bats to viruses, “which surpasses that of other mammals, is one of their many distinctive qualities along with being an incredibly diverse group, making up about a quarter of all mammalian species. But their ability to coexist with viruses that can spill over to other animals, in particular humans, can have devastating consequences when we eat them, trade them in livestock markets and invade their territory. [Source: James Gorman, New York Times January 28, 2020]

“Learning how they carry and survive so many viruses has been a deep question for science, and new research suggests that the answer may be how the bats’ evolutionary adaptations to flight changed their immune systems. In a 2018 paper in Cell Host and Microbe, scientists in China and Singapore reported their investigation of how bats handle something called DNA sensing. The energy demands of flight are so great that cells in the body break down and release bits of DNA that are then floating around where they shouldn’t be. Mammals, including bats, have ways to identify and respond to such bits of DNA, which might indicate an invasion of a disease-causing organism. But in bats, they found, evolution has weakened that system, which would normally cause inflammation as it fought the viruses.

fruit bats like can carry the Nipah virus

“Bats have lost some genes involved in that response, which makes sense because the inflammation itself can be very damaging to the body. They have a weakened response but it is still there. Thus, the researchers write, this weakened response may allow them to maintain a “balanced state of ‘effective response’ but not ‘over response’ against viruses.”

“Certainly, rodents, primates and birds also carry diseases that can jump and have jumped to people; bats are far from alone in that regard. But there are reasons they have been implicated in several disease outbreaks and are likely to be implicated in more. They are numerous and widespread. While bats account for a quarter of mammalian species, rodents are 50 percent, and then there’s the rest of us. Bats live on every continent except Antarctica, in proximity to humans and farms. The ability to fly makes them wide-ranging, which helps in spreading viruses, and their feces can spread disease.

“People in many parts of the world eat bats, and sell them in live animal markets, which was the source of SARS, and possibly the latest coronavirus outbreak that began in Wuhan. They also often live in huge colonies in caves, where crowded conditions are ideal for passing viruses to one another.In a 2017 report in Nature, Dr. Daszak, Kevin J. Olival and other colleagues from EcoHealth Alliance, reported that they had created a database of 754 mammal species and 586 viral species, and analyzed which viruses were harbored by which mammals and how they affected their hosts. They confirmed what scientists had thought: “Bats are host to a significantly higher proportion of zoonoses than all other mammalian orders.” Zoonoses are diseases that spill over from animals to humans. And they don’t just survive the viruses they harbor. Bats are remarkably long-lived for small mammals. The big brown bat, a common species in the United States, can live nearly 20 years in the wild. Others live closer to 40. One tiny bat in Siberia lived at least 41 years. Animals like house mice live about two years on average.

Bats and Rabies

People also get rabies from bats. Vampire bats are notorious for that. Many of the human rabies cases in the United States have been caused by the rabies virus from bats. Any bat that is active by day, is found in a place where bats are not usually seen (for example, in a room in your home or on the lawn), or is unable to fly, is far more likely than others to be rabid. Such bats are often the most easily approached. Therefore, it is best never to handle any bat.

vampire bats may carry rabies

If you are bitten by a bat — or if infectious material (such as saliva) from a bat gets into your eyes, nose, mouth, or a wound — wash the affected area thoroughly and get medical advice immediately. Whenever possible, the bat should be captured and sent to a laboratory for rabies testing.People usually know when they have been bitten by a bat. However, because bats have small teeth which may leave marks that are not easily seen, there are situations in which you should seek medical advice even in the absence of an obvious bite wound. For example, if you awaken and find a bat in your room, see a bat in the room of an unattended child, or see a bat near a mentally impaired or intoxicated person, seek medical advice and have the bat tested. People cannot get rabies just from seeing a bat in an attic, in a cave, or at a distance. In addition, people cannot get rabies from having contact with bat guano (feces), blood, or urine, or from touching a bat on its fur (even though bats should never be handled!).

In the mid 2000s, bats in some part of the United States began dying of a strange unknown disease. Many of the victims flew around in winter in the day (in temperate climates bats hibernate in winter and normally bats only fly around at dusk and night) and were found with white fungus on their bodies. In some caves in New York 90 percent of the bats that hibernated there died. No one knew whether the disease was caused by a virus, bacteria, toxin, environmental agent or metabolic disorder produced by fungus. The fungus is believed to have been a secondary symptom.

Rabid Vampire Bats Kill Dozens in Latin America

In November 2005, the BBC reported: Health authorities in northern Brazil are trying to cope with a wave of attacks on humans by vampire bats infected with the deadly rabies virus. Rabies caused by bat bites has killed 23 people in the last two months. It is not the first wave of attacks by vampire bats in the Amazon, but Brazilian authorities say this latest outbreak is unusually serious. Some experts are blaming deforestation in the Amazon region. Sixteen people died of rabies after being bitten by bats in an area of marshlands in the northern state of Maranhao. Seven more died in another part of the state. [Source Tom Gibb, BBC News, Sao Paulo, November 2, 2005]

Health authorities say they have treated more than 1,300 people for rabies after being attacked by vampire bats, almost always at night in their houses. In the affected areas, people have been trying to fill gaps in the walls of their huts with banana leaves to stop the bats getting in. Some experts have blamed the attacks on destruction of the rainforest, denying the bats of their natural habitat. But others have suggested the vampire bat population may have grown rapidly, with the spread of cattle farming in the region providing an ample food supply. Mass attacks on humans have occurred in other cattle regions in Latin America when the cattle are suddenly removed. The bats drink the blood of other mammals while they are asleep. They are the main carriers of rabies in Brazil.

In 2010, more than 500 people were bitten by rabid vampire bats in Peru. The BBC reported: Peru's health ministry has sent emergency teams to a remote Amazon region to battle an outbreak of rabies spread by vampire bats. Four children in the Awajun indigenous tribe died after being bitten by the bloodsucking mammals.Health workers have given rabies vaccine to more than 500 people who have also been attacked. [Source BBC, August 13, 2010

Some experts have linked mass vampire bat attacks on people in the Amazon to deforestation. The rabies outbreak is focused on the community of Urakusa in the north-eastern Peruvian Amazon, close to the border with Ecuador. The indigenous community appealed for help after being unable to explain the illness that had killed the children. The health ministry said it had sent three medical teams to treat and vaccinate people who had been bitten. Most of the affected population had now been vaccinated, it said, although a few had refused treatment.

Vampire bats usually feed on wildlife or livestock, but are sometimes known to turn to humans for food, particularly in areas where their rainforest habitat has been destroyed. Some local people have suggested this latest outbreak of attacks may be linked to the unusually low temperatures the Peruvian Amazon in recent years. In January 2005, Yahoo News reported that 12 young children have been killed by rabid bats in the Condorcanqui province of Peru bordering Ecuador. [Source Yahoo News, January 12, 2005]

In June 1999, Reuters reported: A rash of attacks by vampire bats prompted authorities to declare quarantine alerts in northern Mexico, official news agency Notimex reported. Roxana Avitia Talamantes, head of disease prevention in the border state of Chihuahua, told reporters three small towns had been placed under special watch because of rabies fears after 15 attacks by vampire bats in the first half of 1999. "In the hot season, like now, it's dangerous for inhabitants of the mountainous areas, especially (for) those walking about at night near woods or where there are caves," Avitia Talamantes said. The state official said a 6-year-old child died earlier this year from rabies after being bitten by one of the bats. [Source Reuters, June 7, 1999]

Rabid Bat Bites Michigan Woman in the Neck

In 2011, Michigan resident Ann Clark was bitten in the neck by a rabid bat in the middle of the night. The Daily Mail reported: She desperately tried to fend off the animal when it started attacking her, but it swooped down on her and plunged its fangs into her neck The next day doctors told her the bat was rabid, and started her on an emergency series of vaccinations to stop her developing the terrifying disease. [Source Fiona Roberts, Daily Mail, June 15, 2011]

Mrs Clark said at first she thought a bird had got into her room, but when she turned on the light she realised her winged attacker was actually a bat. She seized an electric fly swat and took three swipes at the animal. It fell to the floor, but then it shot up and bit her on the neck. Mrs Clark said: 'I immediately jump up my feet are going, screaming like crazy.'

She managed to rip the bat out of her neck, but it was badly injured from the fly swat so she put it into a glass jar and tried to get back to sleep. But the bat kept crying, she said, and she felt so guilty for electrocuting it she got up and put some air holes in the jar.She said: 'I hear him crying in the jar and I feel really bad for the bat because he was just doing his job chasing mosquitoes, he goes in a house and this old lady bashed him.'

The next morning she went to the doctor and showed him the two vivid staple-shaped fang marks in her neck. He immediately ordered her to take the bat to an animal control centre, and the next day tests confirmed it was rabid. The next day doctors told her the bat was rabid, and started her on an emergency series of vaccinations to stop her developing the terrifying disease.

Dr Brian Petroelje told the Grand Rapids Press bites to the neck are particularly serious.He said: 'Because the virus travels up the nerves from the site of the bite to the brain, bites closer to the head and neck are more likely to result in rabies and commonly progress more quickly than bites from the hands or feet.'

She was given several shots of vaccine and immunoglobulin straight into her neck, and must still have at least one more painful injection to make sure her system is clear. Doctors cannot guarantee she has escaped rabies, which takes between one and three months to develop, but say they are optimistic. Mrs Clark told the Press the injections are exhausting. She said: 'It is a miserable treatment so I am just dealing with this the best that I can and pretending it didn’t happen. 'There’s not a way to test if they were able to kill the virus without chopping my head off and looking in my brain.'

Studying Bats

Yale University's Alvin Novick has spent the better part of his life studying bats in locations around the globe: tall trees in the Philippines, rain forests in Africa and caves in Jamaica. He has studied vampires bats, flying foxes, and moustache bats. His favorite places to find bats are attics, which unfortunately become very flimsy after termites or dry rot sets in: "I've fallen through ceilings around the world," he boasts.

Novick catches bats in caves with fishing net; in the rain forest with a net draped in between trees. Captured bats are studied in echo-absorbing chambers were scientists sometimes hook up electrodes to bat brains to listen in. During the 1970s Novick was working on "bat dictionary" that classified bat species by the sounds they admitted.

Catching bats can be dirty, nasty work. Describing an effort to snag some spear-nosed bats in an abandoned gold mine Panama, Novick wrote in National Geographic: "I was standing there naked. I wanted to capture several bats...Every morning for half a century hundred of bats have flown back to this roost bearing morsels of fruit, which they often dropped into the water along with their guano. All this brewed into a pungent mix the color and consistency of thin chocolate pudding...Stripped except of my flashlight I wadded in...My light shone on the hanging bats...they became disoriented and crashed into the walls, the pudding and me...a rain of dozens of bats smashing wild into my face...I ducked. I found myself chin deep in the soup and verging on nausea...I downed by emotions, rose dripping from the gumbo, capturing my quarry, and moving out swiftly.”

Flying foxes that are studied by scientists are caught with nets and outfit with radio collars.

Anna White wrote in Smithsonian magazine: In a 2017 issue of Journal Mammalogy, U.S. Forest Service scientist Sybil Amelon and colleagues at the University of Missouri outline a solution to an issue that has stumped scientists for decades: how to non-invasively tag individual bats. Until then, scientists have been almost entirely dependent on bands for tagging the 44 species of bats in U.S. and Canada, but Amelon and her team have found a better way. By examining patterns of collagen-elastin bundles on the bats’ fibrous wings, scientists can differentiate between individuals without having to capture and tag the animals. The researchers were successful using wing collagen as an identifier in multiple species of bats, analyzing wings of little brown bats, northern long ear bats, big brown bats and tricolor bats. The system is highly effective, with a 96 percent success rate even when identifying bats with wings damaged by fungus. [Source: Anna White, Smithsonian magazine, April 2019]

Image Sources: Wikimedia Commons, Bats Conservation International, National Park Service

Text Sources: Mostly National Geographic articles. Also David Attenborough books, Live Science, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated January 2025