SINGAPORE - At least three patrons who attended a concert at the Esplanade on Sunday (May 15) said that they have bites on their bodies which may be from bedbugs, but the performance venue said that it does not have such an infestation.

Ms Ana Dhoraisingam, a sales director in an investment management firm, told The Straits Times that she started feeling itchy almost as soon as the Blue Note Tokyo All-Star Jazz Orchestra concert that she was attending with her friend in the Esplanade's Concert Hall had started.

"When the conductor came on, I thought to myself, why is my skin starting to itch? It was in my lower back and under my thighs," said Ms Dhoraisingam, who is in her 40s. The pair had sat in the stall seats E21 and E22, which are near the stage.

By Monday, there was a raised welt on Ms Dhoraisingam's back which caused her some pain. A doctor she saw on Wednesday told her that the bite seemed consistent with that of a bedbug.

Her friend, healthcare professional Evelyn Lee, 32, also had bites on her back, which had developed into angry, red splotches.

They both sent complaints to the Esplanade via e-mail, along with photos of the bites.

According to the reply to Ms Dhoraisingam which was obtained by The Straits Times, a spokesman from the Esplanade says that its pest control company, Aardwolf Pestkare, had been immediately activated on Wednesday to search their seats and those in the immediate area for signs of bedbugs, but had not found any.

Another audience member who attended the same concert on Sunday and who does not wish to be named, told ST that he had sat at the circle seats on the second level of the Concert Hall for the same show and had been bitten at the back of his thighs.

Two friends who attended the concert with him did not get bitten.

Bedbugs are four to five millimetre-long parasitic insects which feed on human blood, and they are attracted to body heat and carbon dioxide. Bedbug nymphs are translucent or light in colour and they become darker in colour as they grow. Bedbug bites can lead to skin rashes and even allergic reactions.

Responding to queries sent by ST, Mr Ravi Sivalingam, the Esplanade's head of hospitality and services, said that the performance venue conducts ultra-low volume spraying treatments on the seats in its venues once every two months.

This treatment involves the spraying of a form of pesticide over a large area. The last such treatment of the seats in the Concert Hall was on May 9.

Mr Sivalingam said: "We also conduct regular steam cleaning of the seats in our venues. All this is in addition to the cleaning of our venues before and after performances, as well as daily cleaning even when there are no performances in the venues."

Stressing that the Esplanade takes these issues seriously and that it has never had any past infestations of bedbugs, he adds that even with regular cleaning "there is a possibility of transference, and insects which may not have been inherent in the venues can be brought in too".

A pest management professional told ST that bedbugs present a great challenge for venues such as The Esplanade and cinemas, which have thousands of seats, as any patron can possibly bring them in and it is not necessarily because the venue is unsanitary or unclean.

"Bedbugs are great hitchhikers. Once brought in through a patron's clothes or bags, it's a matter of how soon you are able to detect them and carry out the necessary treatment before it gets out of hand," said Mr Eugene Surendra, technical and client services director of PestBusters, a 25-year-old pest management company.

He added that up to 50 per cent of people do not have reactions to bed bug bites, and those that do may only feel the bites days or even weeks after.

Mr Peer Mohamad Abbas, director of 50-year-old cleaning company Naina Mohamed Cleaning Services, said that the cleaning regime for his cinema clients usually consists of thorough cleaning of the upholstery every two to three months, which involves using chemicals to remove dirt, as well as steam cleaning every half yearly.

"Steam cleaning is the best way to remove bed bugs. But you can't do it too often because the high temperature of the steam might damage the fabric," said Mr Abbas.

Further queries to the Esplanade, which were re-directed to its appointed pest management company, Aardwolf Pestkare, revealed that it is aware that the ultra-low volume treatment is not used to control bedbugs, but "is a treatment to control exposed crawling and flying insects".

Mr Patrick Chong, managing director of the pest management company, clarified that the company relies on steam cleaning as well as "direct spray treatment" to control bed bugs. Steam cleaning involves the use of vaporised heat, above 60 deg C, to kill insects and eliminate their eggs.