Anthrax: A hidden threat to wildlife in the tropics

August 2, 2017, Max Planck Society
In National Park the anthrax pathogen Bacillus cereus biovar anthracis is posing a serious threat to wildlife, including chimpanzees. Credit: MPI f. Evolutionary Anthropology/ L. Samuni

Anthrax, a disease so far not associated with tropical rain forests, is common in the Ivory Coast's Taï National Park and is posing a serious threat to wildlife there. The bacterium could soon even cause the extinction of local chimpanzee populations. This is revealed in a study by scientists from the Robert Koch Institute (RKI), the Max-Planck Institute for Evolutionary Anthropology, the University of Glasgow, and the Ivorian National Animal Health Institute.

"The results demonstrate the importance of long-term studies of infectious diseases and their effects on wildlife", says RKI's Fabian Leendertz, the veterinary scientist leading the study. "They help us to better protect endangered species. But at the same time, infections in great apes are often indicators of diseases that can also affect humans". Lothar H. Wieler, president of the RKI and co-author, adds: "The work really highlights the One Health approach that sees human and animal health as intimately connected and stresses the need for considering them jointly."

Anthrax is caused by spore-forming bacteria, typically Bacillus anthracis. Especially in the arid regions of Africa, outbreaks are common and can also affect people and their livestock. In 2004, Leendertz' team at RKI discovered a previously unknown type of the in dead chimpanzees in the rainforests of Taï National Park: Bacillus cereus biovar anthracis. Studies conducted since have shown that the same type has also caused mortality in isolated cases in chimpanzees, gorillas, and elephants in Cameroon and the Central African Republic.

In their current work, the researchers focused on the distribution of the pathogen within Taï National Park and its effect on wildlife populations. They analysed bone and tissue samples which had been collected over the last 28 years from mammal carcasses found in the park. They also looked at the stomach content of carrion flies: these flies constantly encounter carcasses, pick up the anthrax pathogen, and can thus provide clues about the areas and species it circulates in. Bones and flies from 16 other regions in sub-Saharan Africa were also tested. Sequencing and analysing the pathogen's genome, which also involved scientists at the University of Glasgow, enabled establishment of how animal cases were linked.

"To our surprise, almost 40 percent of all animal deaths in Taï National Park we investigated were attributable to anthrax," reports Emmanuel Couacy-Hymann from the Ivorian Animal Health Institute. The researchers found the pathogen in several monkey species, duikers, mongoose, and a porcupine. Most seriously affected were the chimpanzees: 31 of the 55 individuals whose carcasses were examined had died from the disease. "According to our projections, anthrax could over time contribute to drive chimpanzees in Taï National Park to extinction," says Roman Wittig, who leads the Taï Chimpanzee project at the Max-Planck Institute for Evolutionary Anthropology. The scientists are now trying to find out why the pathogen is particularly active in Taï National Park; they also still don't know where and how animals become infected. In addition, the researchers are searching for ways to protect the chimpanzees, including the possibility of vaccination.

Human infections with the atypical type of the bacterium have so far not been reported. But the probability that it also poses a threat to humans, just like Bacillus anthracis, is high, since both types are highly related. Collaborative studies between RKI and research institutes and agencies in Ivory Coast to investigate this are currently under way. Anthrax in humans can cause death but if recognised early can usually be treated successfully with antibiotics.

Explore further: A new pathogen in Africa causes anthrax-like disease in wild and domestic animals

More information: Constanze Hoffmann et al, Persistent anthrax as a major driver of wildlife mortality in a tropical rainforest, Nature (2017). DOI: 10.1038/nature23309

Related Stories

Anthrax spores use RNA coat to mislead immune system

April 11, 2017

Researchers from Harvard Medical School have discovered that the body's immune system initially detects the presence of anthrax spores by recognizing RNA molecules that coat the spores' surface. But this prompts an unfavorable ...

Scientists describe how anthrax toxins cause illness, death

August 28, 2013

Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) and the National Heart, Lung, and Blood Institute, both part of the National Institutes of Health, have identified the cells in two distinct ...

New, unusually large virus kills anthrax agent

January 27, 2014

From a zebra carcass on the plains of Namibia in Southern Africa, an international team of researchers has discovered a new, unusually large virus (or bacteriophage) that infects the bacterium that causes anthrax. The novel ...

Recommended for you

Researchers isolate parvovirus from ancient human remains

July 13, 2018

Airborne and bloodborne human parvovirus B19 causes a number of illnesses, including the childhood rash known as fifth disease, chronic anemia in AIDS patients, arthritis in elderly people, aplastic crisis in people with ...

Finding the proteins that unpack DNA

July 12, 2018

A new method allows researchers to systematically identify specialized proteins that unpack DNA inside the nucleus of a cell, making the usually dense DNA more accessible for gene expression and other functions. The method, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.