Elephant Mass Death Could Be Caused by New Pathogen—with Small Risk of It Passing to Humans

What caused the mass death of hundreds of elephants in Botswana is still a mystery. While poisoning is one possibility, it has also been suggested that a new pathogen may be responsible—and the idea it could be passed to humans has been raised.

A statement from the Botswana government dated July 12 said 281 elephant carcasses had so far been found around Seronga. It said investigations into these "unexplained deaths" were ongoing. Diagnostic samples were sent to other countries for analysis. While results from Zimbabwe had been returned, the government was waiting for other countries' results before making any further announcements.

Locals reported elephants walking in circles before falling face-first to the ground. It has been suggested this is a sign of neurological impairment, potentially from a new disease.

Niall McCann, from U.K.-based conservation charity National Park Rescue, told Newsweek that until test results come back, what caused the mass death is speculation. As of yet, there is no evidence to say this is a new disease. "It's all unknown," he said in an email. "What we do know is that affected elephants appear to be suffering from compromised motor function, suggesting that this thing, whatever it is, affects the central nervous system in some way.

"The government of Botswana is sampling multiple carcasses and the surrounding environment. These samples are being sent for analysis to multiple laboratories both regionally and internationally. If this was something simple we'd already know what it was; if it's something novel, complex or that degrades rapidly, then it could take months to find out what is killing all these elephants."

If the deaths are the result of a new disease, there is a risk it could spread further among different populations. McCann said that because elephants travel great distances, it should be assumed it will not be contained to the region.

He also suggested that whatever is causing the elephants to die could pose a risk to humans. "If this is a toxin or a poison then the risk to human populations is obvious, as the water or soil is likely to be contaminated," he said. "If this is a disease then it is worth being very prudent and assuming that zoonosis is a possibility until ruled out. We are all living with the consequences of a zoonotic event, and to assume that this couldn't happen here would be cavalier."

Zoonosis is where a disease can be passed from animals to humans. It is believed this is how the current COVID-19 pandemic began. Elephants have been known to pass tuberculosis to humans in the past, but whether any new disease could also be transmitted is not known. Experts also say the risk of this is very low.

Stephen M. Rich, Director of the Laboratory of Medical Zoology at the University of Massachusetts Amherst, told Newsweek in an email that viruses "don't follow rules." He said a virus that could be deadly to elephants could be harmless to humans, and vice versa.

"First, the universe of viruses is very large and so we will be uncovering 'novel' viruses for a long time to come," he said. "Some of those will be pathogenic, i.e. disease-causing. And a subset of those will be pathogens of animals that can spillover into humans."

Daniel Streicker, a Senior Research Fellow at the U.K.-based research charity the Wellcome Trust who studies infectious diseases, said without knowing what virus is killing the elephants—if it even is a virus—it it is impossible to tell whether it poses a risk to humans. "The sudden onset and geographic restriction of deaths suggest that if it is a pathogen—and not for example a toxin—it may be newly introduced to elephants, perhaps from another species," he told Newsweek via email.

Eric Fèvre, Chair of Veterinary Infectious Diseases at the U.K.'s University of Liverpool, said he believes zoonotic transmission "is a pretty remote possibility, but [I] agree that it makes sense to investigate to be sure.

"In the absence of better diagnostic information it is difficult to be more certain, though the human risk here is likely to be low—there is no reason for now to imagine that this is zoonotic," he told Newsweek in an email.

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An elephant in Botswana in 2015. Almost 300 elephants have died in one region in the country since March. CHRIS JEK/AFP via Getty Images