# Global Lymphatic Filariasis Post-Validation Surveillance Activities in 2025: A Scoping Review

## TL;DR

This paper reviews post-validation surveillance strategies for lymphatic filariasis in countries that have eliminated the disease, highlighting common approaches and challenges.

## Contribution

The study provides a global synthesis of post-validation surveillance activities for lymphatic filariasis from 2007 to 2025.

## Key findings

- Targeted surveillance and integration with other health programs were the most common PVS approaches.
- Molecular xenomonitoring and health facility-based screening were used in fewer countries.
- Sustained PVS was achieved in Sri Lanka, Thailand, China, and South Korea through national policies and funding.

## Abstract

Following World Health Organization (WHO) validation of lymphatic filariasis (LF) elimination as a public health problem, countries are required to implement post-validation surveillance (PVS) to detect potential resurgence and ensure sustained elimination. WHO’s guidelines released in 2025 recommend implementation of at least two of four PVS strategies—targeted surveys, integration into standardised surveys, health facility-based screening, and molecular xenomonitoring (MX) of mosquitoes. This review synthesised global evidence on PVS activities from 2007 to 2025 in the 23 countries and territories validated as having eliminated LF. Studies were identified through PubMed, Scopus, Embase, Web of Science, and the WHO Institutional Repository for Information Sharing (IRIS). Data on publication information, surveillance strategies, priority populations, and operational challenges and enablers were extracted. Narrative synthesis using deductive content analysis was applied. Thirty documents from 17 countries were included. Targeted surveillance and integration of PVS with other health programmes were the most common approaches noted (reported in ten and nine countries, respectively), followed by MX (seven countries) and health facility-based screening (four countries). Surveillance often focused on migrants and previous hotspots, with operational challenges linked to limited funding, workforce, and supply chains. Documents indicated that Sri Lanka, Thailand, China, and South Korea developed sustained PVS through national policies and domestic funding. Findings highlight the need for clear, contextualised guidance to operationalise sustainable PVS in different settings.