Wildlife authorities are still baffled by what could have been killing elephants in the west of Zimbabwe, with the number of dead animals now at 22, an official said Thursday.
Over the weekend, 12 elephants were found dead in Pandamasue Forest, between Hwange national park and Victoria Falls, and another 10 were discovered this week.
"We are still waiting for laboratory results to ascertain what really these 22 elephants have succumbed to," Tinashe Farawo, spokesman for the Zimbabwe Parks and Wildlife Management Authority, said.
"We are continuing our serial surveillance of the park with drones to monitor the situation," he added.
Tests so far have ruled out what authorities initially suspected to be the bacterial infection anthrax, Zimbabwe's Environment Minister Mangaliso Ndlovu told journalists earlier this week.
"It will take us time to have conclusive results on the real cause of [the] deaths," Ndlovu said, adding that scientists suspected "a bacterial plant" might be the culprit.
Poaching has been ruled out because all the elephants still had their tusks when found.
Last month, neighbouring Botswana also found hundreds of dead elephants and is still investigating the cause. It has ruled out poaching or pesticides but said the mass deaths might be due to a natural toxin.
Zimbabwe has one of the biggest elephant populations in the world. Hwange national park alone is home to about 45,000 elephants.