Nine monkeys who died over two days at a zoo in Hong Kong had caught a bacterial disease, possibly as a result of recent digging work near their enclosure.
On Sunday 13 October, eight monkeys were found dead, with another dying a day later, after they all displayed unusual behaviour and appetite.
Officials launched an investigation at the Hong Kong Zoological and Botanical Gardens, sealing off and disinfecting areas amid fears of a zoonotic disease.
They have now said the animals died after being infected with melioidosis, which caused them to develop sepsis.
This may have been as a result of recent digging near their enclosure, an official said.
Secretary for culture, sports and tourism Kevin Yeung said that infections of this type often occur through contact with contaminated soil and water.
"We're saddened by the passing of the nine monkeys," Mr Yeung said, adding there was thought to be no danger to humans of contracting it.
The deceased animals were a De Brazza's monkey, a common squirrel monkey, four white-faced sakis and three cotton-top tamarins - a species listed as critically endangered by the International Union for Conservation of Nature.
The park had previously conducted work to repair irrigation pipes under a flower bed near the monkey enclosure earlier this month, and the deaths may be related to that, Mr Yeung said.
"The incubation period for melioidosis in primates is about a week and this matched with the period after the soil digging work," he said.
Another explanation could be that some infected monkeys had close contact with other monkeys, he continued.
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Or, he added, the monkeys might have been exposed to the bacteria after park staff had walked into the cages with possibly contaminated shoes.
Another De Brazza's monkey also displayed unusual behaviour and appetite but officials said that, as of Friday, its condition remained stable.
Edwin Tsui, the controller of the centre, said the incident only took place in a single zone of Hong Kong's oldest zoo.
(c) Sky News 2024: Officials uncover cause of death of nine monkeys who died in two days at Hong Kong zoo
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