SINGAPORE: Residents and former residents of a single block in Hougang will be offered free and voluntary tuberculosis (TB) screening by the Ministry of Health (MOH) as a precautionary measure after four people from the block were found to have contracted the disease.
“MOH was notified on 10 October 2020 of four TB cases involving residents of the same HDB block at 174D Hougang Avenue 1, who were diagnosed between January 2018 (and) June 2020,” said the ministry in a news release on Saturday (Oct 24).
“All four individuals live in different units of Block 174D. The cases had immediately started treatment following diagnosis. Among them, two have completed treatment, while the remaining two are currently undergoing treatment and are no longer infectious.
“As individuals diagnosed with TB will rapidly become non-infectious once treatment starts, the cases are not an ongoing public health risk,” MOH added.
The screening will be conducted at the Tuberculosis Control Unit (TBCU) located at Moulmein Road from Oct 26.
Between Sunday and Tuesday, officers from the unit and the National Centre for Infectious Diseases (NCID) will be conducting house visits to all units at Block 174D Hougang Avenue 1 to “engage affected residents and encourage them to go for the screening”.
Residents will be able to make appointments for the screening at TBCU during the house visits or call the unit to make an appointment. Former residents who had lived in the block from February 2020 and want to be screened can call the TBCU hotline.
MOH said the Singapore TB Elimination Programme (STEP) had initiated contact investigations upon notification of the four cases. Close contacts of the cases were identified and contacted by STEP for screening.
“Investigations for each of the four cases at the time of their diagnosis did not identify each other as close contacts,” said the ministry.
It added that the expanded tuberculosis screening beyond close contacts of the cases was a “precautionary measure to assure and protect residents living in the same block”.
“The exercise could help detect any undiagnosed TB cases,” MOH said.
Those with positive screening results will be offered appropriate advice and follow-up. Those with active TB will be “treated immediately” while those with latent non-infectious TB will be monitored and treated if necessary, said the ministry.
HOW THE HOUGANG CLUSTER WAS DETERMINED
MOH said the cluster at the Hougang block was “determined due to the results of the genetic sequencing performed in October 2020 as part of retrospective testing of TB cases to determine possible linkages”.
“This revealed that all four cases have similar genetic make-up.
“Investigations into the cases did not reveal any common links, other than that they live in the same block. They did not know or interact with one another, or congregate at the same common areas, and had also not identified each other as close contacts.
“The TB cluster therefore does not fit the usual pattern of TB spread,” the ministry said.
TB is typically spread through close and prolonged contact with an infectious individual and not by contact with items or surfaces touched by a person with tuberculosis.
According to MOH, tuberculosis is an endemic in Singapore and latent tuberculosis infection is not uncommon in the population because the disease had been prevalent in the country until the 1970s. Older Singaporeans could have been exposed to it and acquired latent tuberculosis infection when they were younger.
Those with latent tuberculosis do not experience symptoms of tuberculosis and are not infectious, it added.
“TB is curable and the spread of TB is preventable. Early detection and prompt treatment of cases remain important in helping those infected and rendering them non-infectious. For individuals diagnosed with active TB, adherence to treatment is important,” said MOH.