Case Closed–No further action needed.
Subsequent stories about bats have been greatly improved, mostly positive. Thank you Bat Fans for your participation. May 24, 2016
Rebuttal of Exaggerated Disease Claims Published in New Scientist
By Merlin Tuttle
Sensationalized media reports of diseases in bats pose immediate threats worldwide. Regardless of what is said about bat values, no one wants to conserve animals they fear. Recent newspaper and popular science magazine stories speculating that bats are dangerous harbingers of dread diseases fly in the face of a well-established track record of people living safely near bats.
Disease transmission from bats to humans is exceedingly rare and could be virtually eliminated by people simply not handling them, as the people of Austin, Texas have learned. When 1.5 million bats began moving into newly created crevices beneath a downtown bridge, health officials warned that many were rabid and dangerous, and the bats were nearly eradicated by panicked public demand. However, by simply educating people not to handle them, no one has contracted any disease from a bat in Austin in over 30 years, despite exceptionally close contact with hundreds of thousands of tourists who come to enjoy the bats’ spectacular emergences.
In fact, based on long experience, the people of Austin now greatly appreciate bats as safe and valuable neighbors. These bats consume roughly 15 tons of insects nightly, a large proportion of which are yard and crop pests, and they attract 12 million tourist dollars each summer. Without exception, a wide variety of major bat-watching tourism sites from America and Australia to Asia and Africa have similarly positive records.
On seeing scary speculation you can be of great assistance to bats by simply letting editors know you do not approve. Here are some talking points that may be useful in setting the record straight.
This New Scientist, Contagion, story provides an excellent example of the grossly exaggerated claims of disease in bats.
Bat Disease Counterpoints
Merlin Tuttle1, Luis Viquez-R2, Bernal Rodriguez-Herrera3, Rodrigo Medellin2
Viral taxonomy is in its infancy. Of the millions of viruses believed to exist, only a few thousand have been identified and described. New ones can be found wherever they are looked for, even on our own bodies. In fact it has been estimated that a single teaspoon of seawater likely contains a million viruses (Bergh et al. 1989; Suttle 2005). Many are benign or beneficial, probably essential to the very survival of life on earth. On the other hand, bats suffer from an unfounded, seriously bad reputation. Not only are bats essential for many ecological processes and for various aspects of human well-being, they have also not been proven to be the maligned carriers of as many diseases as recent articles have implied. The points below will provide the basis for a better understanding of bats and the infectious diseases they have been accused of spreading:
- We are currently finding more viruses in bats because millions of dollars are being spent disproportionally looking for them in bats. Though much has been said about coronaviruses being discovered in bats worldwide, these often benign entities are also widely distributed in other animals, from birds to whales. Furthermore, contrary to repeated assertions, Olival and associates (2012) demonstrated that bats host only 4.5 percent of known Emerging Infectious Diseases (EIDs). Rodents, ungulates, primates and even horses hosted more human EIDs than bats.
- Available evidence indicates that “emerging” viruses are not new. They have been here for millions of years, but are only now being discovered. Describing them as EIDs simply adds an unnecessary level of fear. Their diversity is high in bats because 20 percent of the world’s mammals are bats, and because they are the most ecologically diverse of all mammals. These viruses have long, co-evolved histories of reliance on specific host species or groups, reducing the probability of spillover to humans.
- Much of what has been implied simply cannot be justified by current knowledge. There is no scientific basis for claims that “hoards of deadly diseases lurking in bats,” are ready to spill over to humans. There is also no evidence that humans are living in closer association with bats today than in the past. Bat literature contains numerous examples of major decline of bats, and modern humans increasingly live in homes that are less suitable for bat colonization. Reports that newly discovered viruses are closely related to others that are known to be human pathogens seem meaningless when we consider both the infancy of viral knowledge and the fact that compared nucleotide for nucleotide, the human genome differs from that of chimpanzees by only 1.23 percent. We may be closer relatives to chimpanzees than some of these so-called “closely related” viruses are to each other. We also do not yet know that some of these bat-associated viruses are not weak varieties that could help convey immunity to more virulent versions. Finally, all 1,300 bat species are frequently discussed as though they were one apparently universal species, implying that rare, but scary viruses from some of earth’s most remote regions might be found in anyone’s back yard.
- Empty warnings of potentially devastating pathogen outbreaks aside, bats have an outstanding safety record. Throughout the Old World tropics, where the most feared pathogens reside, many thousands of humans hunt and eat bats, and extract guano from bat caves. While these are all likely unsustainable practices, they are not triggering any of the pandemics now hypothesized. This is additionally true for the thousands of bat researchers who have handled and closely observed bats over decades of time before so-called EIDs were even discovered.
- It is appropriate to study potential pathogens and to warn people not to handle unfamiliar animals, but there appears to be no justification for singling out bats as especially dangerous while ignoring the fact that our own pet dogs account for more human mortality annually than EIDs have in all recorded history.
Bergh, Ø., Børsheim, K.Y., Bratbak., G., Heldal, M. 1989. High abundance of viruses found in aquatic environments. Nature 340:467-468
Suttle, C.A. 2005. Viruses in the sea. Nature 437:356-361.
Olival, K.J., J.H. Epstein, L.F. Wang and H.E. Field. 2012. Are bats exceptional viral reservoirs? Pp. 195-212in New Directions in Conservation Medicine: Applied cases of ecological health. Oxford Univ. Press, USA, Oxford, ISBN 9780199909056.
- University of Texas
- Institute of Ecology, UNAM
- University of Costa Rica