Facts about Wildlife Diseases: Bats and Coronaviruses (2022)

Holly K. Ober and Samantha M. Wisely 2

Some unusual physical adaptations allow bats to harbor viruses that cause no harm to themselves but can cause grave illness in humans. Transmission of these pathogens from bats to humans can occur when humans have close interactions with bats and contact with their bodily fluids. A number of strategies could reduce the likelihood of bat viruses crossing over to humans, such as restricting the harvest of bats for food, curtailing live wildlife markets, enforcing regulations on illegal wildlife trade, and limiting deforestation and cave vandalism to reduce movement of bats into close proximity to humans.

Recently, misguided attempts to preserve human health have led to persecution of bats. In fact, however, what will keep people healthy is to protect bats and their habitat. Enhancing efforts to protect bat roosts can reduce the likelihood of future zoonotic disease pandemics while at the same time increasing the valuable contributions bats provide to natural ecosystems and the benefits they provide to people. Protecting bat roosts can benefit people economically because bats provide valuable natural pest reduction services when they consume insects that cause damage to agronomic crops. Protecting bat roosts can also enhance human health by ensuring bats continue to consume mosquitoes responsible for transmitting diseases such as Zika, dengue fever, malaria, and chikungunya. Finally, protecting bat roosts keeps bats safely distanced from people. Destroying their homes merely forces bats into closer proximity to humans.

Bats Don't Get Ill from Many of the Viruses That Sicken Humans

Bats have highly specialized immune systems that allow them to harbor viruses without showing signs of illness. For many mammals, including humans, it is not the viral infection that kills but the acute inflammatory response mounted by their immune systems. Bats have evolved ways to inhibit the pro-inflammatory response of their immune systems, so though they get infected by viruses, they suffer no visible signs of disease from those viral infections. Their ability to control the inflammatory responses of their immune systems may also explain bats' relatively long lifespans. Scientists are studying the immune systems of bats to develop strategies to better regulate the inflammation response in humans.

How could bats pass viruses to humans?

Wildlife pathogens are considered zoonotic when they are transmitted to humans and cause disease. This transmission is called a spillover event, because the virus "spills over" from animal hosts to human hosts (Figure 1). Some zoonotic viruses simply end their transmission cycle when they infect a human (i.e., the human is unable to pass on the virus to other humans). In this case, the human is called a dead-end host. Sometimes, however, the virus evolves a way to transmit among humans, causing a human epidemic. If an epidemic spreads across continents, it is called a pandemic.

(Video) Bats, rabies and COVID-19: can we stop animal-borne diseases? | The Royal Society

Facts about Wildlife Diseases: Bats and Coronaviruses (1)

Because humans are not typically exposed to wildlife viruses, we are susceptible to infection in those rare instances when we are exposed. Clinical illness can then result. Because viruses can mutate quickly, once transmitted to humans, they can rapidly evolve the ability to jump from one human to another without a wildlife host. Human-to-human transmission can then occur quickly and lead to epidemics or even pandemics.

Unless a virus has already evolved human-to-human transmission abilities, humans can only contract zoonotic viruses when they come into close contact with wildlife. Saliva, urine, feces, and other bodily fluids of an infected animal can transmit viruses to people. Humans could contract viruses by handling infected bats or their bodily fluids. For this reason, protective equipment should be worn when entering structures where bats are known to roost, such as attics or bridges. Professional bat exclusion personnel and researchers who handle bats should consider pre-exposure vaccinations to prevent transmission of rabies from bats to humans.

Wildlife markets, trade in meat from wildlife, called bushmeat, and illegal hunting of wildlife (three instances where humans come into close contact with wildlife) have been implicated in spillover events. Public health and wildlife conservation organizations have called for tightening of restrictions on the bushmeat trade and the closing of all wildlife markets to prevent future spillover of zoonotic diseases into humans.

Close contact between wildlife and humans can also occur when wildlife habitat is destroyed.

Deforestation and suburban sprawl can displace wildlife, including bats. Purposeful vandalism of caves or harvesting of trees used as bat roosts can force bats into closer proximity to humans, which is the phenomenon we want to avoid. Furthermore, displaced bats will be stressed, due to their acute need to find alternative sources of shelter. When stressed, animals produce more virus, increasing the chances of disease transmission to humans. For this reason, people would be far better served if they acted to protect the natural habitats bats need rather than harming those habitats and thereby forcing bats into poor-quality environments. Destroying bats' homes does not eliminate bats. It does make bats more dangerous to people by increasing the bats' viral loads and forcing them to live closer to people.

(Video) Coronaviruses and animals Bats and beyond

What kinds of viruses do bats carry?

Because of their well-adapted immune systems, bats can harbor many types of viruses. Some species of bats are known to carry lyssaviruses including the rabies virus, filiviruses including Ebola and Marburg viruses, and paramyxoviruses, including Nipah and Hendra viruses. In addition, some bats can carry coronaviruses without being afflicted.

There are hundreds of viruses that are classified as coronaviruses, seven of which can cause respiratory infections in humans. Recently, three different types of coronaviruses have caused respiratory disease outbreaks in humans: SARS (Severe acute respiratory syndrome) during 2002–2004, MERS (the Middle East respiratory syndrome) during 2012–present, and COVID-19 during 2019–present. It is believed that the coronaviruses responsible for all three of these disease outbreaks were zoonotic, meaning that the viruses were originally circulating in animals before spilling over to humans. Given the ability of bats to serve as natural reservoirs for coronaviruses, it has been speculated that bats may have been the origin of all three recent widespread respiratory illnesses among people, with other wildlife species likely serving as intermediary hosts (Zhou et al. 2020).

The SARS pandemic of 2003 was a respiratory illness that originated in China and spread to more than 8,000 people in 26 countries over an 8-month period. It is believed to have been caused by a virus that spilled over from horseshoe bats (Rhinolophus spp.) to humans. Horseshoe bats are native to Asia, Europe, Africa, Australia, and Oceania. Several species of horseshoe bats in China can host the virus associated with SARS (SARS-CoV) in their bodies without being adversely affected by it. During the early 2000s, it is believed that the virus moved several times between animals and humans, with the animal hosts including horseshoe bats, palm civets (Paguma larvata, cat-like mammals native to East Asia, Southeast Asia, and Oceania), and pigs. How the virus was first transmitted to humans is still not well understood, but live wildlife markets have been implicated in promoting transmission to humans.

MERS is another widespread respiratory illness with zoonotic origins. Originally reported in Saudi Arabia in 2012, it spread across 27 countries. Dromedary camels (aka Arabian camels, Camelus dromedarius) are now known to be the primary zoonotic reservoir of the virus (MERS-CoV) that periodically facilitates transmission to humans. Scientists believe that bats may have been the original source of MERS as well, years ago before it jumped to camels.

Covid-19 is a third recent zoonotic coronavirus responsible for widespread human mortality. The origin of the virus that causes Covid-19 (SARS-CoV-2) has not yet been definitively identified, but there is speculation that it originated in horseshoe bats living in China, similar to SARS-CoV. We don't yet know whether the virus moved from bats to some other animal species before it was passed to people. There is some speculation that the virus may have passed from bats to pangolins before infecting humans and that live wildlife markets were involved.

Why could persecution of bats lead to greater problems?

The speculation that recent coronaviruses that caused pandemics may have originated in bats is causing persecution of bats worldwide in the name of protecting public health. This response is damagingly counterproductive.

(Video) Why Bats Can Fight Off So Many Viruses

Culling bats creates far more problems for human health than it solves. When left undisturbed in their wild habitats, bats pose little risk to human health. Although dozens of coronaviruses are able to survive within live wild bats, the risk of viruses moving from bats to humans under normal conditions is tiny. Bats have extremely active immune systems that enable them to carry pathogens without succumbing to infection. These viruses become a threat to humans only when the bats are stressed and in close proximity to humans. When left undisturbed, there is limited chance of wild bats transmitting any viruses they harbor to humans.

How does bat conservation improve human health and livelihoods?

Represented by more than 1,400 species, bats are one of the most diverse groups of mammals on the planet. Bats eat a variety of types of food, and in the process, they provide many ecological services to humans (Figure 2). Exterminating bats would result in ramifications harmful to people from an economic and health perspective.

Facts about Wildlife Diseases: Bats and Coronaviruses (2)

Many species of bats eat nectar and fruit, and in the process pollinate or disperse seeds of hundreds of species of fruit consumed by people including mangos, bananas, and guavas. Most bats are insectivorous, and they collectively consume millions of tons of insects a night. Nearly all the bats in the United States eat insects, many of which are considered pests to humans. It is estimated that bats save farmers, ranchers, and gardeners billions of dollars each year by naturally controlling pests of agricultural crops, reducing the cost of expensive pesticide applications while also reducing harm the chemicals could cause.

Eradicating bats would also have negative impacts on human health. Bats consume a variety of mosquitoes, which means they ultimately promote human health by reducing the ability of these insects to spread mosquito-borne diseases such as Zika, dengue, malaria, and chikungunya.

Our best strategy for reducing the likelihood of spillover of viruses from bats to humans, while benefitting from the help bats provide in controlling harmful insect pests, is to protect bats and their habitat.

(Video) Here’s How Scientists Think Coronavirus Spreads from Bats to Humans

Additional Information

Bat Conservation International, www.batcon.org

Banerjee, A., M. L. Baker, K. Kulcsar, V. Misra, R. Plowright, and K. Mossman. 2020. "Novel insights into immune systems of bats." Frontiers in Immunology 11: 26. https://www.frontiersin.org/articles/10.3389/fimmu.2020.00026/full

Boyles, J. G., P. M. Cryan, G. F. McCracken, and T. H. Kunz. 2011. "Economic importance of bats in agriculture." Science 332: 41–42. https://doi.org/10.1126/science.1201366

Ge, X., J. Li, X. Yang, et al. 2013. "Isolation and characterization of a bat SARS-like coronavirus that uses the ACE2 receptor." Nature 503: 535–538. https://doi.org/10.1038/nature12711

Ober, H. K. 2008. Insect Pest Management Services Provided by Bats. WEC 245. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/UW289

Ober, H. K., and F. J. Mazzotti. 2008. Conservation of Bats in Florida. WEC247. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/UW291

(Video) Why bats don't get sick - Arinjay Banerjee

Zhou, P., X. Yang, X. Wang, et al. 2020. "A pneumonia outbreak associated with a new coronavirus of probable bat origin." Nature 579: 270–273. https://doi.org/10.1038/s41586-020-2012-7

FAQs

What are the known coronaviruses that can infect people? ›

Human coronaviruses are capable of causing illnesses ranging from the common cold to more severe diseases such as Middle East respiratory syndrome (MERS, fatality rate ~34%). SARS-CoV-2 is the seventh known coronavirus to infect people, after 229E, NL63, OC43, HKU1, MERS-CoV, and the original SARS-CoV.

When was the first case of coronavirus discovered? ›

The first case of the coronavirus (COVID-19) was reported to the World Health Organization (WHO) in December 2019 and was subsequently declared a public health emergency of international concern (PHEIC). This global pandemic is now expected to impact on the economic outlook for some time to come.

What does it mean that coronaviruses are zoonotic? ›

Coronaviruses are zoonotic, meaning they are transmitted between animals and people. Detailed investigations found that SARS-CoV was transmitted from civet cats to humans and MERS-CoV from dromedary camels to humans. Several known coronaviruses are circulating in animals that have not yet infected humans.

What are 'nudgeboxes' and what are they used for? ›

5,000 DNA 'Nudgebox' machines, supplied by DnaNudge, will be rolled out across NHS hospitals in the UK to analyse DNA in nose swabs, providing a positive or negative result for COVID-19 in 90 minutes, at the point of care. The machines will process up to 15 tests on the spot each day without the need for a laboratory.

What is the origin of COVID-19? ›

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel severe acute respiratory syndrome coronavirus. It was first isolated from three people with pneumonia connected to the cluster of acute respiratory illness cases in Wuhan. All structural features of the novel SARS-CoV-2 virus particle occur in related coronaviruses in nature.

When was COVID-19 declared a global pandemic? ›

On 11 March 2020 WHO declared the COVID-19 outbreak a global pandemic due to the rapid spread and severity of cases around the world.

Who issued the official name of COVID-19? ›

The official names COVID-19 and SARS-CoV-2 were issued by the WHO on 11 February 2020.

When was the official name of SARS-CoV-2 announced? ›

On 11 February 2020, the International Committee on Taxonomy of Viruses adopted the official name "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2).

Is COVID-19 caused by a virus or a bacteria? ›

The coronavirus disease (COVID-19) is caused by a virus, NOT by bacteria.

Is COVID-19 still a pandemic? ›

With over 1 million deaths this year alone, the pandemic remains an emergency globally and within most countries. "The COVID-19 summer wave, driven by Omicron BA.4 and BA.5, showed that the pandemic is not yet over as the virus continues to circulate in Europe and beyond," a European Commission spokesperson said.

Can the coronavirus disease be transmitted through the consumption of cooked foods, including animal products? ›

There is currently no evidence that people can catch COVID-19 from food. The virus that causes COVID-19 can be killed at temperatures similar to that of other known viruses and bacteria found in food.

How is the COVID-19 disease transmitted? ›

COVID-19 transmits when people breathe in air contaminated by droplets and small airborne particles containing the virus. The risk of breathing these in is highest when people are in close proximity, but they can be inhaled over longer distances, particularly indoors. Transmission can also occur if splashed or sprayed with contaminated fluids in the eyes, nose or mouth, and, rarely, via contaminated surfaces.

Can you take ibuprofen if you have the coronavirus disease? ›

Patients can take paracetamol or ibuprofen when self-medicating for symptoms of COVID-19, such as fever and headache, and should follow NHS advice if they have any questions or if symptoms get worse.

Does the NHS COVID-19 app track my location? ›

It does not record or track where you or other app users are (for example, at home or in a public space). The app does not identify you or your location to other app users (or, as noted above, the government).

What is the natural reservoir for SARS-CoV-2? ›

The most likely ecological reservoirs for SARS-CoV-2 are bats, but it is believed that the virus jumped the species barrier to humans from another intermediate animal host. This intermediate animal host could be a domestic food animal, a wild animal, or a domesticated wild animal which has not yet been identified.

Is COVID-19 still a global threat? ›

With over 1 million deaths this year alone, the pandemic remains an emergency globally and within most countries. "The COVID-19 summer wave, driven by Omicron BA.4 and BA.5, showed that the pandemic is not yet over as the virus continues to circulate in Europe and beyond," a European Commission spokesperson said.

When was the Coronavirus Yellow Card reporting site launched? ›

The dedicated Coronavirus Yellow Card reporting site was launched in May 2020 specifically for medicines and medical devices used in COVID-19, as well as COVID-19 vaccines when authorised.

Which company designed the NHS COVID-19 app to protect the privacy and identity of the users? ›

This system is designed by Apple and Google to protect the privacy and identity of app users, making their use of the app anonymous.

What is the new COVID-19 vaccine booster called? ›

The bivalent vaccines, which we will also refer to as “updated boosters,” contain two messenger RNA (mRNA) components of SARS-CoV-2 virus, one of the original strain of SARS-CoV-2 and the other one in common between the BA.4 and BA.5 lineages of the omicron variant of SARS-CoV-2.

What is the COVID-19 Law Lab? ›

The COVID-19 Law Lab is a database of laws that countries have implemented in response to the pandemic. It includes state of emergency declarations, quarantine measures, disease surveillance, legal measures relating to mask-wearing, social distancing, and access to medication and vaccines.

Are COVID-19 tests 100% reliable? ›

No test is 100% reliable, even those who meet regulatory standards for performance and safety. The results are also only relevant to that sample at that point in time.

What is the coronavirus procurement policy note? ›

This Procurement Policy Note (PPN) sets out information and guidance for public bodies on payment of their suppliers to ensure service continuity during and after the current coronavirus, COVID-19, outbreak. Contracting authorities must act now to ensure suppliers at risk are in a position to resume normal contract delivery once the outbreak is over.

When was the first case of coronavirus discovered? ›

The first case of the coronavirus (COVID-19) was reported to the World Health Organization (WHO) in December 2019 and was subsequently declared a public health emergency of international concern (PHEIC). This global pandemic is now expected to impact on the economic outlook for some time to come.

Do smokers suffer from worse COVID-19 symptoms? ›

Early research indicates that, compared to non-smokers, having a history of smoking may substantially increase the chance of adverse health outcomes for COVID-19 patients, including being admitted to intensive care, requiring mechanical ventilation and suffering severe health consequences.

When was COVID-19 declared a global pandemic? ›

On 11 March 2020 WHO declared the COVID-19 outbreak a global pandemic due to the rapid spread and severity of cases around the world.

Has Canada dropped all COVID-19 restrictions? ›

Canada announced on Monday that it would remove all remaining coronavirus entry restrictions, including testing and quarantine requirements, effective Oct. 1, ending some of the worlds longest and most stringent rules.

Where did COVID-19 origin? ›

The first known infections from SARS‑CoV‑2 were discovered in Wuhan, China.[17] The original source of viral transmission to humans remains unclear, as does whether the virus became pathogenic before or after the spillover event.[19][75][9] Because many of the early infectees were workers at the Huanan Seafood Market,[76][77] it has been suggested that the virus might have originated from the market.[9][78] However, other research indicates that visitors may have introduced the virus to the market, which then facilitated rapid expansion of the infections.

Can I get COVID-19 from my pet? ›

COVID-19 in the UK is spread between humans. There is limited evidence that some animals, including pets, can become infected with SARS-CoV-2 (the virus that causes COVID-19) following close contact with infected humans.

Can I delete the NHS COVID-19 app? ›

You can delete the app at any time and/or turn off notifications. If you choose to delete the app, you will not receive any notifications (alerts) from the app about coronavirus (COVID-19) and the data stored by the app on your phone will be deleted. If you decide to install the app again, you will need to provide the requested information again.

Is COVID-19 still a pandemic? ›

With over 1 million deaths this year alone, the pandemic remains an emergency globally and within most countries. "The COVID-19 summer wave, driven by Omicron BA.4 and BA.5, showed that the pandemic is not yet over as the virus continues to circulate in Europe and beyond," a European Commission spokesperson said.

Where did COVID-19 origin? ›

The first known infections from SARS‑CoV‑2 were discovered in Wuhan, China.[17] The original source of viral transmission to humans remains unclear, as does whether the virus became pathogenic before or after the spillover event.[19][75][9] Because many of the early infectees were workers at the Huanan Seafood Market,[76][77] it has been suggested that the virus might have originated from the market.[9][78] However, other research indicates that visitors may have introduced the virus to the market, which then facilitated rapid expansion of the infections.

Is COVID-19 caused by a virus or a bacteria? ›

The coronavirus disease (COVID-19) is caused by a virus, NOT by bacteria.

When was COVID-19 declared a global pandemic? ›

On 11 March 2020 WHO declared the COVID-19 outbreak a global pandemic due to the rapid spread and severity of cases around the world.

Is COVID-19 still a global threat? ›

With over 1 million deaths this year alone, the pandemic remains an emergency globally and within most countries. "The COVID-19 summer wave, driven by Omicron BA.4 and BA.5, showed that the pandemic is not yet over as the virus continues to circulate in Europe and beyond," a European Commission spokesperson said.

Has Canada dropped all COVID-19 restrictions? ›

Canada announced on Monday that it would remove all remaining coronavirus entry restrictions, including testing and quarantine requirements, effective Oct. 1, ending some of the worlds longest and most stringent rules.

Who issued the official name of COVID-19? ›

The official names COVID-19 and SARS-CoV-2 were issued by the WHO on 11 February 2020.

Can I get COVID-19 from my pet? ›

COVID-19 in the UK is spread between humans. There is limited evidence that some animals, including pets, can become infected with SARS-CoV-2 (the virus that causes COVID-19) following close contact with infected humans.

How is the COVID-19 disease transmitted? ›

COVID-19 transmits when people breathe in air contaminated by droplets and small airborne particles containing the virus. The risk of breathing these in is highest when people are in close proximity, but they can be inhaled over longer distances, particularly indoors. Transmission can also occur if splashed or sprayed with contaminated fluids in the eyes, nose or mouth, and, rarely, via contaminated surfaces.

Do smokers suffer from worse COVID-19 symptoms? ›

Early research indicates that, compared to non-smokers, having a history of smoking may substantially increase the chance of adverse health outcomes for COVID-19 patients, including being admitted to intensive care, requiring mechanical ventilation and suffering severe health consequences.

Videos

1. Studies point to bats as likely hosts of novel coronavirus: Experts
(CNA)
2. Why Do Bats Carry So Many Dangerous Diseases?
(SciShow)
3. Why Do Bats Carry So Many Diseases? (like Coronavirus)
(MinuteEarth)
4. Bats and COVID 19: Live Q&A
(Youth4Nature)
5. How Bats Can Transmit Viruses | Virus Hunters
(National Geographic)
6. Scientists find coronaviruses in bats, pangolins across Asia
(CNA)

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