Cluster of multi-drug resistant TB cases discovered in a single block in Ang Mo Kio

The Ministry of Health (MOH) is investigating a cluster of drug resistant tuberculosis (TB) cases residing at Blk 203 Ang Mo Kio Ave 3.
TB can be spread through fine respiratory droplets containing the TB bacteria when a person with infectious TB coughs or sneezes. Persons with close or prolonged contact with persons with TB may be at risk of becoming infected. Drug resistant TB takes longer to treat.
The cluster of infections in Ang Mo Kio was detected by a vigilant doctor from the Tuberculosis Control Unit at Tan Tock Seng Hospital.  The doctor reported his findings to MOH in May 2016, leading to an investigation that established in June 2016 that the six individuals were infected with the same MDRTB strain, with the last case confirmed on 10 June.
The route of transmission for the unrelated individuals not living in the same unit has yet to be determined. And MOH has assured residents of the block that the risk of transmission to persons who are not in close contact is very low.
MOH however is offering free TB screening as a precautionary measure to the residents of Block 203 Ang Mo Kio Ave 3.
The following is MOH’s press statement on the matter.
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The Ministry of Health (MOH) will offer on-site Tuberculosis (TB) screening to residents of Block 203 Ang Mo Kio Avenue 3. This is a precautionary measure following the detection of an unusual cluster of six multi-drug resistant TB (MDRTB) individuals across four unrelated units at the block. These tests are conducted free of charge.  Residents can be screened at the void deck of Block 203 from 9am to 9pm, 16 to 19 June 2016. Those who are unable to attend TB screening during this period may be screened at any SATA CommHealth clinic until 30 June 2016.
2.            Former residents who had lived in the block from July 2011 who wish to be screened can go to any SATA CommHealth Clinic from now till 30 June 2016. After 30 June, residents and former residents may make an appointment to be screened at the Tuberculosis Control Unit at Moulmein Road. Screening is free.
Unusual Cluster of 6 Multi-Drug Resistant TB
3.            Six MDRTB individuals across four unrelated units at Block 203 Ang Mo Kio Avenue 3 have been detected. Three of the individuals, including the index case, were from the same unit. The other three individuals lived in different units of Block 203. None of the cases involved children.
4.            Among the six individuals, three have already completed treatment, while the other three are currently undergoing treatment.  All six individuals are no longer infectious and cannot transmit MDRTB. They are therefore not an ongoing public health risk.
5.            TB transmission typically requires close and prolonged contact with an infectious individual. It is unusual for TB to be spread by casual, brief exposure. Hence persons who are contacted and screened around an infectious TB individual typically comprise family members, flat-mates, close workplace colleagues and acquaintances from common social activities with close and regular interaction. This approach is recommended by the World Health Organization (WHO) and is practised in Singapore.
6.            The MDRTB cluster at Block 203 Ang Mo Kio Avenue 3 is thus highly unusual and does not fit the usual pattern of TB spread. Our investigations did not uncover any common links among the cases, other than the three cases from the same unit and that they live in the same block. They did not know or interact with one another, or congregate at the same common areas. While the lift is a common facility which residents would have used, the probability that TB could be transmitted via this mode is low.
7.            A vigilant doctor from the Tuberculosis Control Unit at Tan Tock Seng Hospital had first observed the cluster of MDRTB cases residing at Block 203. The matter was reported to MOH in May 2016, leading to an investigation that established in June 2016 that the six individuals were infected with the same MDRTB strain, with the last case confirmed on 10 June. The route of transmission for the unrelated individuals not living in the same unit has yet to be determined.
Precautionary TB Screening
8.            The TB screening offered by MOH is a precautionary measure to assure and protect residents. The exercise can help detect any undiagnosed TB cases.  Those with positive screening results will be offered appropriate advice and follow-up. Those with active TB can then be treated immediately. Individuals with latent non-infectious TB can be monitored and treated if necessary.
9.            While screening is not compulsory, MOH strongly encourages residents to be screened. The whole screening process, comprising of a blood test and chest x-ray, will take about 15 minutes. Officers from MOH will work with grassroots volunteers to go door-to-door to share details of the screening with the residents.  Residents may also call the MOH hotline at 6325 9220.
10.         The risk of transmission to persons who are not close contacts of a TB case is very low. Screening is thus not necessary for individuals who had visited the block or its vicinity.
Health Advisory
11.         TB is common in Asia.  While Singapore has the second lowest incidence of TB in Asia, our TB incidence is moderate. Latent TB infection is not uncommon in our population as TB had been prevalent in Singapore until the 1970s, and older Singaporeans could have been exposed to TB and acquired latent TB infection when they were younger. 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.