Risk-Group Surveillance for Leishmaniasis
Effective prevention and control of leishmaniasis in Sri Lanka requires targeted surveillance of populations at highest risk of exposure. Risk-group surveillance helps identify early infections, detect transmission hotspots, and guide public health action before disease spreads further. This forms a key component of the national strategy for surveillance and early detection outlined in the NSP 2024–2028.
Who Are the High-Risk Groups?
Based on epidemiological patterns, behaviour, and environmental exposure, the following groups are considered at higher risk:
1. Outdoor and Agricultural Workers
- Farmers, cultivators, chena workers
- Cattle herders and persons working in paddy fields
- Workers involved in forestry, land clearing, irrigation schemes
These groups are frequently exposed to sandfly habitats, especially during dawn and dusk.
2. Military Personnel and Security Forces
Historically, soldiers stationed in scrubland and jungle areas were the earliest affected group in Sri Lanka. Many are stationed in highly endemic districts with active sandfly breeding sites.
3. Residents in Endemic Areas
Communities living in districts such as:
- Anuradhapura
- Polonnaruwa
- Hambantota
- Matara
- Kurunegala
- Matale
- Monaragala, Ratnapura, Gampaha and Badulla (emerging high-reporting areas)
are at sustained risk because of environmental factors favouring vector breeding.
4. People Living Near High-Risk Environments
- Houses with cracks, damp walls, and poor plastering
- Residences close to cattle sheds, banana groves, thick vegetation
- Poorly maintained gardens with decaying organic matter
These settings provide ideal sandfly breeding sites.
5. Immunocompromised Individuals
Patients with:
- HIV/AIDS
- Chronic illnesses
- Long-term steroid use
may experience more severe disease forms and require close monitoring.
What Does Risk-Group Surveillance Involve?
Risk-group surveillance focuses on systematically screening, monitoring, and investigating populations who are at increased risk. A Structured parasitological and entomological surveillance in these groups are needed to be strengthened.
1. Active Case Detection (ACD)
- Field-based screening in high-risk communities
- Mobile dermatology clinics for point-of-care diagnosis
- Household visits by PHFOs and entomology staff
- Screening outdoor workers, military camps, and farming communities
2. Early Referral and Laboratory Confirmation
Suspected cases undergo:
- Slit-skin smear (SSS)
- Biopsy and histopathology
- PCR where available
This ensures prompt confirmation and treatment.
3. Monitoring Transmission Hotspots
Villages reporting clusters or increased cases undergo:
- Entomological surveillance
- Reservoir host assessments
- Environmental evaluations
4. Seasonal Surveillance
Case peaks occur after monsoon rains (Feb–Mar and Jul–Oct). Enhanced surveillance is carried out during these months.
5. Surveillance for Visceral Leishmaniasis (VL)
Although rare, VL remains a serious threat.
High-risk individuals with:
- Prolonged fever
- Weight loss
- Enlarged liver and spleen
are screened using rK-39 rapid diagnostic tests and bone marrow biopsy.
How Communities Benefit
Early Detection Saves Time & Prevents Spread
Risk-group surveillance helps diagnose cases early, preventing complications and reducing the transmission cycle.
Improved Access to Care
Mobile clinics and community screening bring dermatology services closer to remote populations.
Better Social and Environmental Response
When hotspots are identified early, vector control and community awareness programmes can begin immediately.
AMC's Commitment
The AMC is strengthening risk-group surveillance by:
- Establishing a national surveillance plan for CL, MCL, and VL
- Conducting active case detection in endemic and emerging districts
- Training health staff in surveillance and integrated vector management
- Improving access to diagnostic tools and strengthening PHFO-led community surveillance
- Engaging communities, schools, and local institutions in early detection and prevention
Through focused surveillance of high-risk groups, Sri Lanka aims to reduce the burden of cutaneous leishmaniasis and prevent the emergence of more severe forms of the disease.