Did Anthrax Kill More Than 100 Hippos in Namibia?

At least 100 hippos have died in a national park in Namibia from what scientists suspect is an outbreak of anthrax.

The first dead hippo was discovered on Oct. 2 in a remote area of Bwabwata National Park in northeastern Namibia, the New Era newspaper, a Namibian publication, reported on Oct. 9.

In the week following the discovery of the first carcass, additional bloated, dead hippos were found floating in the Okavango River. [11 Famous Places That Are Littered with Dead Bodies]

Pohamba Shifeta, the environment minister of Namibia, told the news organization AFP that state veterinarians have been dispatched to investigate the cause of the mass die-off, as reported by The Guardian. Shifeta said that the actual death toll could be higher than the reported numbers, because crocodiles may have eaten some of the carcasses.

Though officials are waiting on laboratory confirmation of the disease, a diagnosis of anthrax is reasonable given the findings, said Dr. Barbara Byrne, a professor of clinical pathology, microbiology and immunology at the University of California, Davis, School of Veterinary Medicine. Byrne was not involved in studying the Namibian outbreak.

If anthrax is indeed the culprit, then the hippos were likely infected with the bacteria by ingesting a resistant form, called a spore, that was found in their environment, Byrne told Live Science.

She added that she suspects that the area had anthrax spores in the mud that became available to the hippos as water levels in the river decreased. The outbreak may have affected so many hippos because water spread the bacteria to other areas, she said.

In addition, "hippos can also be cannibalistic [and feed] on dead carcasses, so some may be picking up the infection from eating other hippos that died of anthrax," Byrne said.

Flies can also spread the bacteria throughout the environment, by feeding on the infected carcasses and then spreading the bacteria further, Byrne said.

Bacillus anthracis

Anthrax is a bacterial disease that can kill humans and animals by disrupting the water balance of cells in the body, according to the Centers for Disease Control and Prevention (CDC). Animals become infected when they breathe in or ingest spores of anthrax bacteria (Bacillus anthracis), the CDC says.

Once inside a host, Bacillus anthracis disrupts cellular water balance, which causes cells to swell up with water and die. If the bacteria get into the cells that make up blood vessels, those vessels can no longer hold blood or water, resulting in the leaking of fluids, internal bleeding and, eventually, death, Byrne said

But for humans handling the hippo carcasses, there is a "very low risk, if any" of getting anthrax, said Dr. Wolfgang Beyer, the head of the anthrax consulting laboratory at the University of Hohenheim's Institute of Animal Science in Germany.

"Skin anthrax" could happen if the bacteria get into an open cut, Beyer told Live Science. "Of course, the meat or any specimens of the carcasses should not be used for human consumption at all," he added.

A previous anthrax outbreak in Siberia killed more than 2,000 reindeer and sickened 13 people; it was linked to 75-year-old anthrax spores released by melting permafrost. That case highlights the concern that climate change may encourage the spread of certain diseases, experts said.  

Originally published on Live Science.

Contributing Writer