By Deborah Barkin Fromer
Faculty Member, School of Health Sciences, American Military University

Along with ghosts, goblins and zombies, bats are one of the ultimate symbols of Halloween. Negative portrayals in television shows, comic books, horror movies, mythology, folklore and legends have perpetuated fears about bats.

Many people consider bats as creatures to be avoided at all costs. For example, in Bram Stoker’s 1897 novel Dracula, the dreaded vampire transforms into a bat at will.

Bats Have Also Been the Origin for Many Dangerous Diseases

Some of the most deadly viral disease outbreaks in recent years — including SARS, MERS, Ebola, Marburg, Nipah and Hendra — originated in bats. Yet these animals themselves tolerate these viruses without consequences.

Their role as the original source of the SARS-CoV-2 virus that produced the COVID-19 pandemic has intensified their unfortunate public image. It’s unlikely that bats directly infected humans, however, and the spillover of the novel coronavirus to people was through an intermediate host (a variety of species have been suggested, including pangolins).

Facts about Bats

There are many fascinating facts about bats:

• Bats are the only species of mammal capable of powered flight. Some species can reach speeds of up to 100 miles per hour, making them the fastest mammals on earth.
• The first known fossil evidence of bats comes from North America, from about 51 million years ago.
• There are more than 1,400 species of bats that inhabit all continents, except certain oceanic islands, the Arctic and the Antarctic.
• Only three species of these animals are vampires. All of the rest eat insects, fruits, nectar and pollen.
• A majority of bats are active at night. They inhabit “spooky” places such as caves, wells, attics, and hollow trees, causing people to falsely attribute devilish properties to them.
• Bats live in large dense colonies, which creates an ideal ground for transmitting pathogens.
• Bats are important pest controllers, eating billions of insects every year. A single animal can catch and eat over 1,000 insects each night.
• Fruit and nectar eating species are important pollinators. They also disperse seeds from the fruits that they eat.
• These animals have excellent vision. They are not blind.
• They have amazing longevity — their lifespans range from 20 – 40 years.
• Not all bats hibernate, but those that do usually live where insect prey becomes scarce during cold months. Hibernation has been linked to longevity.
• Females give birth to only one young per year.
• The flying fox bat is the largest bat with a wingspan of over six feet.
• Bats do not spread COVID-19. COVID-19 is a human disease and transmitted from person to person.

Related link: There are various ways to celebrate Halloween safely! Here are some tips from the CDC to remain healthy during Halloween activities.

What Biological Mechanisms May Have Caused Bats to Evolve Tolerance to Viruses?

Research has shown that bats’ tolerance for viruses is linked to their ability to fly. When they fly, bats increase their energy expenditure, metabolic rate and body temperature, resulting in body temperatures similar to those seen in other mammals that have a fever (100 to 105 degrees Fahrenheit). This change in a bat’s body suggests that “flight protects bats from infection in the same way that fever protects mammals — by boosting their immune response.”

If the high metabolic rates and high body temperatures that accompany flight activate the immune system, then flight could be the ultimate explanation “for the evolution of viral infections without overt signs of illness in bats,” according to Science Daily.

Science Daily also notes that “Bats are constantly exposed to viruses….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.”

Because these animals are constantly exposed to viruses, their immune systems are in a perpetual arms race with pathogens. A pathogen will enter the bat’s body, its immune system will evolve a mechanism to combat the pathogen, and the pathogen will evolve again. Science Daily observes, “Dealing with all of these viruses may be shaping bats’ immunity and longevity. ”

Studying the Immune System of Bats

Clearly, more studies on bat immune systems are warranted to develop techniques to regulate the inflammatory response in humans to viruses like COVID-19. Studies of bats’ longevity along with other aspects of their bodies may lead to clues about humans and the hallmarks of aging.

Bats don’t normally have much contact with humans. But the more that their habitats are destroyed — by deforestation, agricultural expansion, urban spread and climate change — and the more humans who expose themselves to bats through hunting and consuming bat meat, the more likely it is that these animals will spread viruses to people.

About the Author

Deborah Barkin Fromer received a B.S. in biology at the Sage Colleges in Albany, New York and was certified with the American Society of Clinical Pathologists as a medical technologist in 1976. She worked in the clinical laboratory as a medical technologist specializing in microbiology. In the 1990s, Ms. Fromer became interested in public health, returned to graduate school and completed a Master of Public Health (MPH) degree at Wichita State University in Wichita, Kansas.

Ms. Fromer spent several years at the University of Kansas School of Medicine as a researcher in obstetrics and gynecology, and several years as a researcher and teaching associate in preventive medicine and public health. She has taught online epidemiology and public health courses since 2001.

From 2007-2015, Ms. Fromer was an epidemiologist at the Sedgwick County Health Department in Wichita, Kansas. Her work involved electronic surveillance of reportable disease and medical conditions, investigating outbreaks and illness, solving mysteries, and keeping people in the community educated and healthy.