Melioidosis killed over 10 monkeys at a Hong Kong zoo, likely due to contaminated soil from pipe repairs. Photo: Sam TsangHealth authorities confirmed that melioidosis caused the death of more than 10 monkeys last month at the Hong Kong Zoological and Botanical Gardens.
Secretary for Culture, Sports and Tourism Kevin Yeung Yun-hung said the cause of the infection might have been due to digging during pipe-repair work in early October in a nearby flower-bed area, causing contaminated soil to be exposed to the environment.
“The contaminated soil might have been brought into the cages by staff wearing shoes with the soil,” he said.
What is melioidosis?
Melioidosis is an infectious disease caused by the bacterium Burkholderia pseudomallei (see graphic).
The disease can manifest as conditions such as a localised infection, pneumonia, meningoencephalitis and sepsis, which is an extreme response to infections where the immune system starts to attack healthy tissue.
Depending on the location of infection, symptoms can also include fever, headache, cough, chest pain, ulceration and localised pain or swelling.
The incubation period commonly ranges from two to four weeks. The fatality rate is between 40 and 75 per cent. It can be treated with antibiotics, but there is no vaccine targeting the bacteria.
How common is the disease in Hong Kong?
Melioidosis is an endemic disease in Hong Kong and cases have been recorded in the city every year, according to the Department of Health’s Centre for Health Protection. Health authorities have said they recorded 19 cases this year, and documented 17 the year before.
The government announced a human infection of the disease late last month, which involved a 59-year-old woman with underlying medical conditions living in Sham Shui Po. She developed a fever and abdominal pain on October 5 and was subsequently admitted to Caritas Medical Centre on October 7. She is currently in a stable condition.
Centre for Health Protection controller Dr Edwin Tsui Lok-kin said the cases recorded this year were sporadic and not clustered, suggesting no escalating trend. None of the cases were related to the Hong Kong Zoological and Botanical Gardens, he added.
Hong Kong previously experienced a widespread outbreak of melioidosis in 2022, with dozens of cases recorded in Sham Shui Po.
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Can animals pass the disease to humans?
Tsui said melioidosis infections between humans and from animals were rare occurrences. He added that authorities understood that staff at the garden were still in good health and not experiencing any abnormal conditions.
Tsui also said he believed the monkey infections were an isolated case and would pose a minimal risk to residents.
Culture minister Yeung said current measures were already enough to protect visitors, with the whole mammal section closed off to the public, and cleaning and disinfection of animal cages carried out.
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How can you protect yourself?
Tsui suggested residents handling soil or dirty water should wear protective equipment.
People who have suffered wounds must deal with them immediately, use waterproof coverings, and avoid any outdoor activities.
He added that residents should also refrain from eating undercooked food or consuming water that had not been boiled and adequately treated.
Professor Vanessa Barrs, dean of the Jockey Club College of Veterinary Medicine and Life Sciences at City University, said that while human-to-human or animal-to-human infection did not generally occur, the public should not take the disease too lightly.
“The highest risk of human infection occurs after heavy monsoon rains and winds, when the bacteria is more widely dispersed in aerosols from disturbed soil and can be inhaled,” she said.
“In general, healthy humans are resistant to the disease, but in people in poor health such as those with medical conditions like diabetes, cancer or kidney disease, the infection can be fatal in 10 per cent to 40 per cent of cases.”
She added that pet owners should also stop their dogs from digging but said there was no cause for panic as their animals were not a source of the infection.