the highly infectious fungal pathogen known to target and kill amphibians poses no direct threat to humans; however, its detrimental effects on biodiversity warrant immense concern. bd and similar diseases, like batrachochytrium salamandrivorans (bsal), contribute to a pressing global biodiversity problem. they serve as fuel for additional policy initiatives needed to mitigate these deadly fungi but also target the loss of biodiversity at local, national, and international levels spanning wild, rural, and urban interfaces. there is no “one-size-fits-all” solution to these issues. therefore, several policy changes are needed to prevent the spread of bd and similar infectious diseases and help combat the threat of a loss of biodiversity. 

an unlikely disappearance

according to professor of biology at university of maryland, college park, and self-proclaimed “animal lover,” karen lips, ph.d., “bd infects over 700 species across three orders of vertebrates, causes species extinctions, mass mortality events and precipitous and persistent population declines where it has invaded.” lips has spent her life tracking bd’s impact on frogs throughout central america in countries like costa rica and panama. 

in the 1980s, lips first discovered the disappearance of amphibians in those concentrated areas. it began with the golden toad in costa rica. “when it first disappeared, people didn’t know why,” lips said. the sites she was researching were secured, protected, and remote, so a disappearance like this was strikingly unusual. she first blamed the weather, but the decline in species was too drastic.

when lips returned to central america in the 1990s, frog numbers were abnormal and her research team found “dozens of dead or dying animals,” on their paths of study. they were quickly able to determine that it was bd that was killing off the frog population, or rather, a catalyst for their extinction. bd is an invasive species with zoospores, rounded, water-borne cells that help to move bacteria around the species. according to scholars at global change biology, zoospores spread bd by settling on the frog and entering the cells of the skin, ultimately causing a fatal cardiac arrest. lips calls these zoospores “little balls,” yet despite their benign nickname, they make it especially easy for bd to spread and kill off various amphibian species.

bd ultimately paves the way for an even bigger issue: a catastrophic impact on wildlife biodiversity. “when you remove amphibians from the ecosystem, bugs and tadpoles also disappear, and as a result, entire ecosystems shift,” lips said. during her research, lips also discovered other indirect effects of bd on human health. after the frogs disappeared in costa rica and panama, there was a 10-year increase in the number of malaria cases. 

old laws, new fungi

bd is already in the united states and while there isn’t a definitive way to cure populations with the disease on a global scale, the further spread of bd can be prevented. the u.s. fish and wildlife service (fws) is actively monitoring the spread of bd through many ways such as activating first responders to mitigate the impact, said meghan snow, fws staff member. these efforts are making headway, but only on a small scale. for instance, snow described that biologists are helping frogs fight the deadly fungus, but they’re focused in california. the bd epidemic needs more large-scale change. not only do these mitigation efforts need to continue, but there needs to be an increase in regulating the trade of these infected species. 

enter: the lacey act. introduced by iowa congressman john lacey in 1900 after a noticeable decline in north america’s wild game species, the lacey act prohibits the “trade of any species taken in violation of international or domestic law” and regulates the import of injurious wildlife, according to the wildlife society. while this may seem like a good sign for stopping the spread of bd, the list of animals is small and the sad fact is that most species are unregulated. according to lips, she nearly “had to beg fws to add more animals.” 

in 2013, researchers discovered a new chytrid fungus known as bsal. much like how bd attacks the skin of frogs, bsal attacks the skin of salamanders. because north america is “the global hotspot for salamanders,” noted lips, the fws placed a ban on the import of 201 salamander species under the lacey act in 2016. according to a recent article featuring lips in the atlantic, bsal has not been detected in north america. bd, on the other hand, is already present in many areas of the united states. while the salamander ban under the lacey act acts as a preventative measure to stop the potential spread of bsal, there lies a gap in policy to make effective strides towards mitigating bd, which lips believes to have been pushed to the sidelines.

protecting our biodiversity 

approaches to helping solve this problem span wild, rural, and urban interfaces in which lips outlined many policy initiatives. for instance, on the wild interface front, it’s about placing efforts to reduce deforestation, protect habitats, and increase research on wildlife disease. in the rural interface, it’s increased surveillance on these species and regulating wildlife harvest. for urban interfaces, efforts to create effective vaccines and treatments for amphibians, reduce trade and trafficking, and monitor these invasive diseases are key. 

other approaches stem from a need to quantify the value of nature, lips said. “currently, we don’t have a system in the u.s. to document all the species,” she said. “you need to know how many exist and how good they’re doing before you can measure their value.” there are still a lot of unknown gaps in biodiversity. compiling tangible lists of species is a way to close these gaps, as lists help people visualize the impact of biodiversity crisis. 

under the current administration, a climate and environment division was created to underscore their very commitment to tackling the climate crisis and biodiversity loss. in 2021, the white house office of science and technology policy (ostp), added five new experts in biodiversity to the division, including heather tallis, ph.d. previously, tallis worked with the natural capital project, a platform striving towards quantifying the value of nature. 

looking ahead

the bd epidemic is just one of the many catalysts for a loss in biodiversity. the hard truth is that the world is facing a huge biodiversity crisis. bd and bsal are just contributors, so any efforts to mitigate the spread of these deadly fungi can help immensely in moving the needle towards a brighter future for the environment. “it’s not just about the frogs,” lips said, “it’s also about the importance of protecting biodiversity.”

it can be especially hard to grasp the personal impact of a loss of biodiversity as a result of these species-destroying fungi. if there’s anything that the covid-19 pandemic has proven, it’s that understanding a global spread of disease is important and that the management of emerging infectious diseases at national and international scales requires close attention. but, it’s not just about covid-19, it’s also about the epidemics that are silently killing amphibians and ultimately biodiversity.

lips was camped out in the costa rica rainforest, alone, for a year and a half. her shack was nestled in a remote village atop a mountain bordering panama. each night, she plucked every frog she spotted up from the jungle’s tapestry of flora and swabbed them. 

“you’re walking down this beautiful trail, and you hear the birds and see a hummingbird sleeping on the branches. and you look up and there’s a frog sitting on a leaf, and you walk over there, and you pluck it off the leaf,” lips says.

that was in 1993. when lips returned just three years later, she couldn’t hear the croaking of toads or frogs splashing in streams. their environment was “dead silent.” lips noticed that the number of frogs in the region was  down 90% by 1996. initially, lips blamed everything, from her headlamp to the weather. but when she spotted dead frogs everywhere, she sensed she was front-row to the world’s next environmental calamity.

lips shipped 50 lifeless frogs back to a veterinary pathologist in maryland who confirmed her greatest fear… thousands of frogs were dying at the hands of a mysterious killer. 

a viral villain

it wasn’t until the late 1990s when researchers like lips discovered that frogs in australia and panama were dying by the masses. the silent killer wasn’t an elusive predator or a toxic food source. rather, a virulent fungus was swiftly eradicating species in one fell swoop. amphibians were dying at the hand of batrachochytrium dendrobatidis.

the fungus—called bd for short—is so lethal because it invades amphibians’ porous skin, which the animals use to breathe and drink water. the viral villain destroys the skin’s proteins and devours the remaining amino acids. infected animals become lethargic and experience organ failure in a matter of weeks.  

like the most vicious of diseases, bd doesn’t play favorites: it annihilates frogs young and old, wiping out amphibians across the globe. some amphibians can resist or tolerate bd, but 695 species are vulnerable. and 90 species already have disappeared, while 500 others have sunk into a steep decline, with few projected to recover.

“it’s so widespread. it’s not specialized or anything. it’s huge, it’s just a terrible generalist disease. and that’s what makes it terribly lethal,” lips says.

stopping bd’s killing spree

after her bombshell discovery, lips dove headfirst into understanding and advocating for “one of the largest losses of biodiversity.” in the 25 years since, bd’s killing spree hasn’t slowed down, and neither has lips. 

“there’s so many ways to think about karen and all the different things she’s done. i think one is her curiosity, and her ability to just persist, that she cared so much about this,” says margaret krebs, who led a leadership academy with lips.

lips tracked the global spread across six continents to find that human activity is pushing an amphibian death wish to all corners of the earth. the amphibian meat and pet industries allow bd to travel, leaping off of the back of one frog to the next.

though the virus poses no direct health threat to humans, the global destruction of frogs has devastating consequences. a decrease in the frog population causes an uptick in insects like flies and mosquitoes, who spread deadly diseases including malaria and pose a danger to human health. 

“there are indirect effects on human health… as soon as the frogs disappeared, there’s about a 10-year increase in the number of malaria cases in costa rica and panama,” lips says.

currently, wild populations raging with bd cannot be cured on a global scale. for now, researchers say that the best step is to prevent the fungi’s further spread. in 2009, lips left the south american rainforest for the bureaucratic jungle to promote policy that would prevent the further spread of bd.

“because she saw her study and research sites destroyed by this disease, she realized she was going to have to jump in and get her hands dirty in the policy world to try to deal with it,” says peter jenkins, an environmental lawyer who petitioned government agencies alongside lips for preventing the import of infected amphibians who might bring bd. 

bd is already present in the united states, and the u.s. fish and wildlife service is actively monitoring its spread. yet, in march 2017, the agency ceased consideration of a 2009 petition to ban all amphibian imports unless they were bd-free. 

lips argues that although bd is already in the united states, other harmful variants could make their way into the country without the proper testing that is not presently in place. studies show that the even deadlier african and brazilian strains of bd could hybridize with the original bd strain. 

in 2013, researchers identified b. salamandrivorans, known as bsal. its name aptly translates to “salamander-devouring,” as from 2009 to 2012 the fungus eliminated dutch fire salamander populations by more than 99%. a 2016 ruling banned the import of 201 salamander species. however, if the bsal-infected species were already in the u.s. before the ban went into effect, interstate transport of the species is legal. 

salamanders are indicator species, the frontline voice to determine if an environmental catastrophe is looming. often referred to as a “canary in a coal mine,” they serve as an early warning system for an ecological decline that will inevitably impact humans. spotting a two-lined salamander living under a rock at a stream is a sign of good water quality. the absence of woodland salamanders in a forest is an ill omen.

“(north america) has more families, more species of salamanders than anywhere else in the world. we safeguard the salamanders of the planet,” lips says. “and so if this salamander chytrid gets here, we’re going to expect to see massive infections, die-offs, and impacts just like we saw with bd.”

for almost thirty years, karen lips has been studying and advocating for policies to stop one mysterious fungal disease that has irreparably damaged international amphibian populations.

at the first world congress of herpetology in 1989, scientists compared extinctions of amphibian species in different environments since the 1970s, but they had no idea what was causing these declines. 

lips noticed this same decline as a graduate student in 1992, when she spent a year and a half recording the reproductive season of spiky tree frogs, called isthmohyla calypsa, in a cloud forest between costa rica and panama. 

lips remembers seeing “from like 200 [frogs] in an hour to two all day.” it was a massacre but without any dead frogs left behind. now, if you look up the isthmohyla calypsa frogs, they are considered critically endangered in panama and extinct in costa rica. 

lips remained undeterred by the subject of her studies disappearing over her winter break. she finished her doctorate in tropical biology and began writing about the decline of amphibians in a seemingly pristine habitat. 

like she would prove to be for most of her career, lips was ahead of the curve. comparing the earlier extinctions in north costa rica to the disappearance of species in the southern cloud forests she’d seen, she noticed that there was a wave of extinction traveling down into panama. in 1996, she brought a team of grad students with her to western panama and started recording the amphibian populations, hoping to catch the mysterious disappearance of frogs in its tracks. 

lips and her students finally had a breakthrough when they found 50 dead frogs in one area, all of different species. the researchers sent the frogs to a lab that found something in their skin; a chytrid fungus, called batrachochytrium dendrobatidis (bd).

amphibians “breathe” and drink through their skin, it’s how they absorb water and oxygen and dispose of carbon dioxide. when an amphibian’s skin is blocked by bd, it alters their blood chemistry. slowly all the organs in a frog’s body will shut down as bd spreads, and according to lips, “eventually their heart just gives out.” 

amphibians tested in australia and at the smithsonian national zoo all had the same skin infection. lips had helped prove that an epidemic was killing amphibians worldwide, not climate change.

for many scientists this discovery would be the end of their work, but as lips watched bd directly cause the extinction of 90 species of amphibians and the decline of 500 species, she realized her work must go beyond traditional academic institutions.

“because she saw her study and research sites destroyed by this disease, she realized she was going to have to jump in and get her hands dirty in the policy world to try to deal with it,” says peter jenkins, an environmental lawyer. 

jenkins first partnered with lips in 2008 to use her bd research to petition the u.s. fish and wildlife service to restrict the importing of infected amphibians. 

“fish and wildlife basically said after a lengthy review, what do you want us to do? bd is already here,” lips summarized. “and so they just sort of put it on the shelf.”

in 2014, a new chytrid fungus that affected salamanders and other amphibians was discovered, called bsal. the u.s. fish and wildlife service reached out to jenkins and lips again, and this time they partnered with advocacy groups, journalists, and even the pet industry to help make their case. lips, with her wide smile and willingness to break down any scientific process into simple terms, spoke at congressional hearings and met one-on-one with senators.

“she’s a really great resource in that way,” jenkins said. “and is, you know, not only fantastic on the science, but can communicate about the policy.”

lips partly gained these communication and collaboration skills during her fellowship at the aldo leopold leadership program, now called the earth leadership program, where program designer margaret krebs remembers “her curiosity and her ability to just persist.”

“there is nothing about her that was pompous or ‘listen to me.’ you know, she really was humble,” krebs said. “she really recognized that it was going to take a whole network of people to move this forward.”

lips and jenkins’ collaborative work helped to halt the spread of bsal coming from asia and europe. the u.s. fish and wildlife service blacklisted the international trade of 200 species of salamanders, leading to canada and the eu banning imports of all salamanders.

lips has shown a willingness throughout her career to develop new skills when her research leads to novel fields of ecology and calls for urgent policy change.

“i got into all this because i really wanted to sort of go to the jungle, be the explorer, live in my shack and do what i was doing,” lips said. “and then when the frogs started dying, i basically changed. and i ended up as a disease ecologist for you know, a couple decades.”

when lips was finishing her doctorate, disease ecology wasn’t an established field, and scientists weren’t working with lawyers to successfully petition the government to protect amphibians, but lips carved out the skills and connections to pursue both paths.

lips is continuing to re-define her role as a biologist and policy advocate. now, she’s raising awareness of how human encroachment on wildlife is causing diseases like bd and covid-19 to appear. 

lips explained that “it’s not so much about the frogs and salamanders per se. it’s about the broader problem of infectious diseases of wildlife that are completely unregulated.” while covid-19 can be traced back to human interactions with diseased animals, the spread and variants of bd are connected to the international trade of amphibians.

“if we can prevent the next covid, we can also save the frogs at the same time, right?” lips asked.