 |
| Photo Credit: Charl Durand |
Scientific Frontline: Extended "At a Glance" Summary: Elephant Deaths Linked to Bisgaard Taxon 45
The Core Concept: Scientists have discovered that a little-known bacterium, provisionally named Bisgaard taxon 45, caused the fatal septicemic infections responsible for the mysterious deaths of endangered African savanna elephants.
Key Distinction/Mechanism: Unlike initially suspected causes such as anthrax, cyanide poisoning, or poaching, the mortalities were definitively traced to an unclassified member of the Pasteurella bacterial family. This marks the first time this specific pathogen has been associated with elephant deaths, and researchers believe the infection is exacerbated by physiological stress from extreme weather events (like severe drought) and transmitted through the highly sociable behavior of the herds.
Origin/History: The investigation focused on the sudden deaths of thirty-five elephants in a 40-by-25-kilometer radius of northwestern Zimbabwe between August and September 2020. This incident closely followed a massive die-off of approximately 350 elephants in neighboring Botswana from May to June 2020.
Major Frameworks/Components:
- Postmortem examinations and field sampling of wildlife carcasses.
- Toxicological analyses to effectively rule out anthropogenic poisons, including cyanide.
- Bacterial isolation and genetic analysis to classify the unknown pathogen.
- Epidemiological assessment of the link between environmental stress factors, animal sociability, and disease transmission.
Branch of Science: Veterinary Medicine, Veterinary Microbiology, Wildlife Biology, and Epidemiology.
Future Application: These findings will drive enhanced disease surveillance protocols for wildlife conservation, targeted research on Pasteurella bacteria in free-ranging animals, and the integration of climate-stress indicators into proactive wildlife management strategies.
Why It Matters: African savanna elephants are a severely endangered species, with only 350,000 remaining in the wild and an estimated population decline of 8 percent annually. Identifying specific pathogenic threats like Bisgaard taxon 45 is critical for mitigating outbreaks and sustaining the future of the species.
During this unique study, scientists from the Victoria Falls Wildlife Trust, the Animal and Plant Health Agency UK, the University of Surrey and laboratories in South Africa investigated the mysterious deaths of 35 elephants mostly between August and September 2020, in a 40 x 25 km radius of North-Western Zimbabwe. This incident followed the death of approximately 350 elephants in neighboring northern Botswana from May to June 2020, which triggered much international concern.
African savanna elephants are an endangered species with only 350,000 remaining in the wild and ongoing losses estimated at eight percent annually. This finding is very worrying since elephants are on the International Union for Conservation of Nature red list already. Investigating the deaths of these elephants is crucial to sustaining the future of this majestic species.
Lead Investigator, Dr Chris Foggin a Wildlife Veterinarian at the Victoria Falls Wildlife Trust, said;
“Investigating this mortality in the wildlife areas in north-west Zimbabwe proved challenging. Identifying and then reaching the carcasses in time to obtain useful samples is one problem we often face in this type of work.
“However, we also didn’t know what disease we may be dealing with, although we initially suspected that it could be anthrax, which is known to occur in the area; or possibly some other disease that might pose a risk to human health. We therefore had to be cautious when undertaking the post-mortem examinations on elephant which, in itself, is a difficult task with such a big animal, especially working in field conditions.”
A number of such postmortem examinations were carried out. Poaching was quickly ruled out, mainly because all the dead elephants had their tusks intact. Toxicology analyses, including immediate testing for cyanide, which is sometimes used to kill elephant in Zimbabwe, as well as more sophisticated analyses done in UK, found no traces of poisons in the carcasses or at a waterhole close to many of the carcasses.
Further examination by veterinarians and scientists identified a septicemic infection caused by a by a little-known bacteria provisionally named Bisgaard taxon 45, an unclassified member the of Pasteurella bacterial family, in six elephants. This was confirmed by bacterial isolation and genetic analysis. Only a limited number of samples were suitable to carry out such examinations. Pasteurella bacteria have previously been implicated in sudden deaths of wild animals such as antelopes, but a role in elephant deaths was not suspected prior to this study.
APHA Head of Virology Professor Falko Steinbach said:
“The identification of this bacterium is a significant step forward in learning more about why these elephants died, and I was pleased to be part of the team at APHA that could corroborate these important findings.
“Transmission of the bacteria is possible, especially given the highly sociable nature of elephants and the link between this infection and the stress associated with extreme weather events such as drought, which may make outbreaks more likely.
“Further research is needed to learn more about the bacteria and its long-term implications for the African elephant population and other wildlife.”
Dr Arnoud van Vliet, Senior Lecturer in Veterinary Microbiology from the School of Veterinary Medicine at the University of Surrey, said:
“The international composition of our research team highlights the opportunities arising for conservation investigations into the disease and death of free-ranging animals. Bisgaard taxon 45 has never before been associated with bacterial septicemia and it adds to the growing list of disease related threats to elephant conservation.”
Published in journal: Nature Communications
Title: Pasteurella sp. associated with fatal septicaemia in six African elephants
Authors: Chris M. Foggin, Laura E. Rosen, Marijke M. Henton, Angela Buys, Toby Floyd, Andrew D. Turner, Jonathan Tarbin, Antony S. Lloyd, Columbas Chaitezvi, Richard J. Ellis, Helen C. Roberts, Akbar Dastjerdi, Alejandro Nunez, Arnoud H. M. van Vliet, and Falko Steinbach
Source/Credit: University of Surrey
Edited by: Scientific Frontline
Reference Number: vet102523_01
