IT WAS in October last year that the red flags were raised.
Cynthia Chee, a senior consultant at Tan Tock Seng Hospital’s TB Control Unit, and her team realised that a patient diagnosed that month lived in a block of flats where several other people had been diagnosed before with the same strain of multi-drug resistant tuberculosis.
When another case surfaced last month, she knew it was time to act.
“The significance was not clear to us at that time,” said Dr Chee about that discovery in October last year.
“Then another case surfaced, and I just felt that it was something that MOH should know about.”
After more digging, it came to light that altogether six people in Block 203, Ang Mo Kio Avenue 3 had fallen prey to that particular strain of bacteria over a four-year period.
How this happened is still puzzling doctors, as the patients came from four different households. Aside from three who were from the same household, the patients said that they did not know or interact with one another.
The TB bacteria typically requires close contact over a long period of time to spread.
Koh Poh Koon, an MP for Ang Mo Kio GRC and a medical doctor himself, told reporters yesterday that Dr Chee was “very astute” to have noticed the pattern.
“All of us see many patients on a daily basis, and the amazing thing is how she connected six patients over a four-year period,” he said.
Doctors were able to ascertain the cases were linked, as the DNA fingerprints of TB cases in Singapore are recorded.
If the strains of two people match up – as they did in the Ang Mo Kio case – then it is likely that they have been in close contact.
DNA fingerprinting makes it easier to track the spread of TB than the traditional method of contact tracing, or asking an infected person who he has been in contact with.
“It’s very, very challenging,” Dr Chee said. “People don’t want to tell us about where they have been because there is a fear of stigmatisation from family or friends. Some are afraid they will lose their jobs.”
The Health Ministry is currently providing free screening for residents of the affected block as a precautionary measure, in order to pick up any undiagnosed TB cases.
As of 5pm yesterday, about 70 residents and former residents of Block 203 Ang Mo Kio Avenue 3 had been screened on-site for TB. They will get their screening results within two weeks, said the ministry in a statement.
linettel@sph.com.sg
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