MOH to offer tuberculosis screening to Block 174D Hougang Ave 1 residents after cluster detected

A cluster of four individuals diagnosed with tuberculosis residing in four different units at the block was detected. PHOTO: SCREENGRAB FROM GOOGLE MAPS

SINGAPORE - Current and former residents of Block 174D on Hougang Avenue 1 will be offered voluntary screening for tuberculosis after a cluster was detected, said the Ministry of Health (MOH) on Saturday (Oct 24).

This is a precautionary measure following the detection of a cluster of four individuals diagnosed with tuberculosis residing in four different units at the block, MOH said.

The screening will be conducted free of charge at the Tuberculosis Control Unit in Moulmein Road from Oct 26.

MOH was notified on Oct 10 of four tuberculosis cases involving residents of the same Housing Board block, who were diagnosed between January 2018 and June this year. All four individuals live in different units of Block 174D.

MOH noted that the cases had immediately started on treatment following diagnosis. Two have completed treatment, while the other two are currently undergoing treatment and are no longer infectious.

"As individuals diagnosed with tuberculosis will rapidly become non-infectious once treatment starts, the cases are not an ongoing public health risk," MOH said.

In line with its prevention strategy, contact investigations were initiated upon notification of the four cases.

Close contacts of the cases had already been identified and contacted for screening. Investigations for each of four cases at the time of their diagnosis did not identify each other as close contacts, MOH said.

"The cluster was subsequently determined due to the results of the genetic sequencing performed in October as part of retrospective testing of tuberculosis cases to determine possible linkages," MOH added.

"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 cluster therefore does not fit the usual pattern of tuberculosis spread."

MOH noted that tuberculosis 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.

Therefore, persons who are contacted and screened following the detection of an infected individual typically comprise family members, close workplace colleagues and acquaintances from common social activities with close and regular interaction.

"The expanded tuberculosis screening offered by MOH is a precautionary measure to assure and protect residents living in the same block. The exercise could help detect any undiagnosed cases," MOH said.

"While screening is not compulsory, MOH strongly encourages residents to be screened. Those with positive screening results will be offered appropriate advice and follow-up. Those with active tuberculosis will be treated immediately while those with latent non-infectious tuberculosis will be monitored and treated if necessary."

MOH also noted that the risk of transmission to persons who are not close contacts of a case is very low, which means screening is also not necessary for individuals who had occasionally visited the block or vicinity.

Officers from the Tuberculosis Control Unit and the National Centre for Infectious Diseases will also be conducting house visits to all units at the affected block between Oct 25 and 27 to engage affected residents and encourage them to go for the screening.

Residents will be able to make appointments for the screening during the house visits. Residents who are not at home at the time of the visit can call the Tuberculosis Control Unit to make an appointment for screening.

Former residents who had lived in the block from February this year and wish to be screened may call the Tuberculosis Control Unit hotline at 6248-4430.

MOH noted that tuberculosis is endemic in Singapore and latent infection is not uncommon in the population, as the condition had been prevalent in Singapore until the 1970s and older Singaporeans could have been exposed and acquired latent tuberculosis infection when they were younger.

Those with latent tuberculosis do not experience symptoms and are not infectious.

Tuberculosis is also curable.

"Early detection and prompt treatment of cases remain important in helping those infected and rendering them noninfectious. For individuals diagnosed with active tuberculosis, adherence to treatment is important," MOH said.

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