Genome sequencing reveals rare cow-linked tuberculosis case amid Singapore’s ongoing TB surveillance efforts
A rare medical finding in Singapore has highlighted how modern disease surveillance can uncover infections linked to exposures decades in the past, reinforcing the importance of food safety and public health vigilance.
Singapore’s First Human Bovine TB Case
Singapore recorded its first and only known human case of bovine tuberculosis in 2021, involving a 73-year-old man who had previously worked as a dairy farmer for 28 years. The Communicable Diseases Agency (CDA) confirmed that the patient was infected with Mycobacterium bovis, a bacterium commonly found in cattle and rarely seen in humans in developed urban settings.
Link to Unpasteurized Milk Exposure
Medical investigations revealed that the man regularly consumed raw, unpasteurized cow’s milk during his farming years, which ended in 1990. According to Associate Professor Lim Poh Lian, group director for CDA’s communicable diseases programs, M. bovis can be transmitted through unpasteurized milk and dairy products. Such cases are now uncommon in Singapore due to strict pasteurization requirements for dairy imports and local consumption.
Diagnosis and Treatment Outcome
The patient presented with symptoms including poor appetite and weight loss, consistent with pulmonary tuberculosis. Chest X-rays and laboratory tests initially indicated TB, but whole genome sequencing later confirmed M. bovis as the cause. He completed standard TB treatment successfully, and none of his close contacts tested positive following contact tracing.
Understanding Bovine Tuberculosis Risks
Tuberculosis is caused by the Mycobacterium tuberculosis complex, which includes several related bacteria affecting humans and animals. While M. tuberculosis causes most human TB cases, M. bovis primarily affects cattle, bison, elk, and deer, according to the US Centers for Disease Control and Prevention. A 2013 Stellenbosch University study estimated bovine TB accounts for less than 1.4 percent of human TB cases outside Africa.
TB Trends and Surveillance in Singapore
TB remains endemic in Singapore. Ministry of Health data showed 1,156 new active TB cases among residents in 2024, slightly down from 1,201 cases in 2023. Since 2020, Singapore has used whole genome sequencing to precisely identify TB strains and detect clusters, including a notable Bukit Merah cluster identified between 2022 and 2023.
Strengthening Public Health Preparedness
CDA reported that more than 7,000 TB-positive samples have been analyzed using genome sequencing since November 2020. This rare bovine TB case underscores the robustness of Singapore’s surveillance, diagnosis, and treatment systems. As Prof Lim noted, detecting such uncommon infections demonstrates the country’s preparedness to manage both routine and rare communicable diseases effectively.
This singular bovine tuberculosis case serves as a reminder that past occupational and dietary exposures can have long-term health implications. It also highlights the critical role of pasteurization, advanced diagnostics, and cross-border public health standards, offering valuable lessons for both Indonesians and Singaporeans as regional mobility and food trade continue to expand.
Sources: Malay Mail (2025) , Straits Times (2025)
Keywords: Bovine Tuberculosis, Raw Milk Consumption, Mycobacterium Bovis, Tuberculosis Singapore, Genome Sequencing
