400 Elephants Dropped Dead. Now, a 'Very Worrying' Find

In a first, researchers link 'Pasteurella' Bisgaard taxon 45 to blood poisoning
By Arden Dier,  Newser Staff
Posted Oct 25, 2023 11:15 AM CDT
Updated Oct 28, 2023 12:10 PM CDT
400 Elephants Dropped Dead. Now, a 'Very Worrying' Find
Wildlife vets take samples from dead elephants found in Hwange National Park in Zimbabwe on Aug. 29, 2020.   (AP Photo)

Experts believe they've gotten to the bottom of a "conservation disaster" that killed hundreds of endangered African savanna elephants across Botswana and Zimbabwe, and the explanation isn't likely to soothe those hoping to save the beautiful beasts. Nearly 400 elephants of all ages were found dead in 2020 alongside live elephants who were observed walking in circles. At the time, government officials in Botswana blamed an unspecified cyanobacterial toxin, having ruled out anthrax and malicious poisoning, per the Guardian. An international team of researchers is now offering a different explanation based on tests of samples taken from elephant carcasses in Zimbabwe, which "fail to find evidence of cyanobacterial or other intoxication," per the study published Wednesday in Nature Communications.

The tests indicate the animals died of blood poisoning as a result of a bacterium closely related to one linked to a mass die-off of antelopes, which experts describe as "very worrying," per the BBC. Researchers confirmed 13 elephants had blood poisoning, or septicemia, at the time of death. They found Bisgaard taxon 45, "an unnamed close relative of Pasteurella multocida," in six of those animals. "It was known to exist, but it had not been associated with [septicemia] and never been found in the African elephants," Falko Steinbach of the UK's Animal and Plant Health Agency tells the BBC. Researchers believe the bacterium wreaked havoc as the elephants' immune defenses were weakened due to the severe stress they suffered amid drought and a food shortage. It's thought to have spread between the highly social animals.

It may also have been responsible for elephant deaths in Botswana, though samples from those animals weren't analyzed. The closely related Pasteurella multocida type B, was previously linked to the deaths of 200,000 saiga antelopes in Kazakhstan. In that case, researchers found the usually harmless bacterium was altered by unusually high temperatures, allowing it to reach the bloodstream, where it also caused septicemia. The elephant findings "suggest a bacterial [septicemia] similar to haemorrhagic [septicemia] caused by P. multocida," according to the study, which describes the Pasteurella species as "an important conservation concern for elephants." (More elephants stories.)

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