Expert warns mystery elephant killer could leave Botswana herd "decimated"

Johannesburg — A mass elephant die-off in Botswana remains a mystery, but officials and conservationists hope to have some answers in the coming week. Elephants don't just drop dead for no reason, which is why the unexplained deaths of more than 350 elephants in the Okavango Delta has caused global concern.  

It appears the elephants started dying as early as March, but the deaths only really came to the attention of conservationists about two months ago, when carcasses were spotted during flights over the area.

In May, 169 elephant carcasses had been found. By June the number had risen to over 350, drawing global attention.  

"It's a catastrophe!" says Dr. Niall McCann, Conservation Director for the National Park Rescue organization. "Until we know that this is no longer a danger to the herd, there is the prospect of Botswana's entire herd being decimated."

McCann is also worried that whatever is killing the elephants could also affect people, and even could become a public health crisis.

"If it's a poison or if it's a disease, the possibility of it spilling over into the human population is very real," he told CBS News.

Experts have found very few clues as whether the cause of the deaths is something sinister like poisoning, or a naturally occurring elephant-specific disease.

McCann says whatever it is, it appears to strike the elephants' nervous system, "because you're seeing them dying very quickly, dropping onto their front, or moving around in a confused manner with some form of neuro-impairment."

Some conservationists believe the Botswana government has been dragging its feet in investigating the deaths. Officials collected samples from the elephants in May, but there are still no results.

Botswana's Acting Director of Wildlife and National Parks Cyril Taolo concedes there has been a delay, but says it's because they needed to be thorough in their investigation. "We did not want to create undue alarm. We were also concerned that we needed to ensure that this was not something that was spreading in the population."

Samples have been sent to labs in South Africa, the U.S., Canada and Zimbabwe. 

The Botswana government has ruled out poaching as no tusks have been removed from the dead animals, and officials believe the deaths have not spread to any other elephant populations elsewhere in the country.   

The government hopes lab test results will be made available within a week. While officials are concerned about the deaths, they don't believe they're dealing with an environmental disaster at this stage, given that the country is home to a third of the world's elephants, with a 130,000-strong population.