It's a shocking image.
Lots of hippos, some lying on their sides, others completely belly up, but all mysteriously dead and partially submerged in a lake in Namibia. What confuses locals even more is how quickly it happened.
The first hippo was spotted on October 1, said the acting director of Namibia's Ministry of Environment and Tourism, Johnson Ndokosho. Since then, at least 100 have turned up dead in the western region of Bwabwata National Park, which sits in a northeastern Namibian strip, sandwiched between Angola and Botswana.
"It had not broken out for a while," said Ndokosho. Early theories for the massive die off are centered around previous die offs caused by a lethal bacteria with a household name.
"We suspect that they died because of anthrax but we are yet to confirm this," said the ministry official in a phone interview. He emphasized that, while tests are ongoing, preventing anthrax poisoning is difficult.
"There's not much we can do," said Ndokosho. "We can't move the wildlife."
Several water buffaloes have also reportedly turned up dead. But because the dead hippos are in a remote part of the park, far from livestock operations, there isn't much potential for the disease to spread, Ndokosho said.
In 2004, as many as 200 hippos died from a deadly anthrax outbreak in Uganda. It took researchers months before an official diagnosis was reached, and at least 10 people died after eating contaminated hippo meat.
Where Did It Come From?
Anthrax illness is caused by the bacteria Bacillus anthracis, which is thought to naturally come into contact with wildlife when water recedes. While anthrax is known infamously as a potential biological weapon, the bacteria naturally occur in the soil, where they can lay unnoticed for decades.
According to the Centers for Disease Control, the bacteria produce spores that can become "activated" when they enter a living organism. From there, the bacteria multiply and spread throughout the body, causing severe illness, and, if left untreated, death.
In an interview with regional outlet the New Era, Colgar Sikopo, the director of Namibia's parks and wildlife division, blamed the outbreak on lower than normal river levels that may have exposed the deadly patches of soil.
The ministry is warning locals not to eat meat from dead animals in the region, and hippo carcasses are being burned in an attempt to prevent the disease from spreading.
"We're concerned that animals are dying, but we're not worried about the [overall health of the] population," said Ndokosho. As a species, hippos are listed as "vulnerable" by the International Union for the Conservation of Nature, and an estimated 3,300 live in and around Namibia.
Bwabwata sits just north of the Okavango Delta, the largest freshwater wetland in southern Africa, which supports an abundant array of wildlife. (Learn how National Geographic is helping build long-term sustainability in the Okavango.)
Investigations are still ongoing, and this article will be updated as more details are released.