Authorities around the world have been left scratching their heads over what to do with serious outbreaks of bed bugs that have taken hold in multiple countries across Europe and Asia. And there's growing concern here in Hong Kong too, after photos purportedly of a bed bug on the seat of an Airport Express train were widely shared.

But speaking on RTHK's Hong Kong Today programme, Professor Chiu Siu-wai, an honorary senior research fellow of the Chinese University's School of Life Sciences, said bed bugs were already common in Hong Kong.

"A bed bug is a blood-sucking insect. It is quite common in Hong Kong. We have conducted a survey in 2021 and, at that time, one sixth of the respondents said they had found bed bugs at their home," she said. "It is the second most popular blood-sucking insect in Hong Kong. The most popular one is the mosquito."

Professor Chu said, as bed bugs were blood sucking, they could carry a lot of infectious pathogens. But she said, unlike with mosquitoes, there was no scientific evidence available to prove that bed bugs transmit blood-borne diseases and therefore some countries were refusing to take action against them.

On Saturday, the government said it held a briefing to stop the spread of the bugs. In a statement, it said the acting secretary for Environment and Ecology, Diane Wong had met with representatives from the Airport Authority, the MTR Corporation, the hotel sector, the Tourism Commission and several government departments to discuss how to prevent a bedbug infestation.

Professor Chiu said the best way to prevent bed bugs was good personal hygiene, although the bugs themselves were difficult to contain as bred quickly and hid in crevices. She also said many people didn't know they had the bugs in their homes.