Daijiworld Media Network – Chennai
Chennai, Dec 12: A new analysis of leprosy surveillance data has revealed that the infection continues to quietly circulate within specific pockets of Chennai—particularly in industrial hubs and border zones that host large migrant worker communities. The findings, published in the Tamil Nadu Journal of Public Health and Medical Research, underline the need for more targeted screening and surveillance in the city.
Leprosy, or Hansen’s disease, caused by Mycobacterium leprae, primarily affects the skin and peripheral nerves. If untreated, it can lead to numbness, muscle weakness and even permanent deformities. India declared leprosy eliminated as a public health problem in 2005, but thousands of new cases are still detected each year, especially in high-density clusters.
The surveillance review, conducted by researchers under the Directorate of Medical and Rural Health Services (Leprosy), analysed secondary data from the National Leprosy Eradication Programme (NLEP) across all 15 administrative zones of Chennai between 2021 and 2025.
Over the five-year period, 515 new leprosy cases were detected in the city. While Chennai’s overall annual new case detection rate stayed steady between 1.0 and 1.3 cases per 100,000 population, the study found several hotspots where rates crossed 2.0, peaking between 2.0 and 4.9 cases per 100,000.
These high-burden clusters were located mainly in:
• Three major industrial zones
• Three border regions with high daily movement of workers and families
One of the most concerning indicators was the consistently elevated child case detection rate, ranging between 3.5 and 11.5 per 100,000 in some zones—far higher than the Tamil Nadu average. Rising child cases point to recent and active transmission, suggesting that the infection is spreading in real time rather than being a leftover from earlier years.
The study noted that more than half of all cases were multibacillary (MB)—the more infectious type of leprosy—while children were more likely to present with paucibacillary (PB) forms.
However, an unusual observation emerged from systematic screenings:
No cases were detected among listed household or neighbourhood contacts.
This indicates that infections may be occurring outside traditional home settings—possibly in:
• Crowded industrial workplaces
• Migrant-worker settlements
• Informal community spaces
• Temporary housing clusters near factories
Experts believe that Chennai’s urban landscape—with its dense population, continuous migrant inflow and high mobility—creates ideal conditions for the disease to linger in unnoticed pockets.
Researchers warn that relying solely on household contact tracing may no longer be sufficient for a fast-growing metro like Chennai.
They recommend:
• Focused screening drives for migrant workers
• Improved surveillance in industrial belts
• Community-level case finding in crowded settlements
• Active monitoring of border zones with high worker movement
While Chennai’s total leprosy numbers appear stable, the presence of persistent hotspots—especially those affecting children—signals that the infection continues to circulate beneath the surface.
Public health officials say that proactive intervention now is essential to prevent these silent clusters from expanding into wider community spread.