Entomology data from Lymphatic filariases and soil-transmitted helminthiases in Sri Lanka: the challenge of eliminating residual pockets of transmission

Sri Lanka has successfully met the challenge of controlling both lymphatic filariasis (LF) and soil-transmitted helminthiases (STH) as public health problems. The primary public health strategy for combatting both conditions has been preventive chemotherapy. The national programme for the elimination of LF implemented five annual rounds of mass chemotherapy in the endemic districts from 2002 to 2006 using a combination of diethylcarbamazine and albendazole. The overall microfilaria rate declined from 0.21% in 2001 before the mass chemotherapy, to 0.06% in 2016, at declaration of elimination of LF as a public health problem by the World Health Organization. Currently Sri Lanka is in the phase of post-validation surveillance. Achieving control of STH has been more difficult. Mass deworming programmes have been implemented for nearly a century, and national-level surveys reported prevalence rates declining from 6.9% in 2003 to 1% in 2017. However, neither of these infections has been completely eliminated. A situation analysis indicates continued transmission of both among high-risk communities. This paper explores the reasons for persistence of transmission of both LF and STH in residual pockets and the measures that are required to achieve long-term control, or perhaps even interrupt transmission in Sri Lanka.This article is part of the theme issue ‘Challenges in the Fight Against Neglected Tropical Diseases’.

斯里兰卡已成功应对将淋巴丝虫病（lymphatic filariasis, LF）与土源性蠕虫病（soil-transmitted helminthiases, STH）作为公共卫生问题开展防控的挑战。针对这两类疾病的核心公共卫生防控策略均为预防性化疗（preventive chemotherapy）。该国针对淋巴丝虫病消除的国家规划于2002年至2006年间，在流行地区实施了五轮年度集体化疗（mass chemotherapy），用药方案为乙胺嗪（diethylcarbamazine）联合阿苯达唑（albendazole）。在世界卫生组织（World Health Organization）宣布将淋巴丝虫病作为公共卫生问题消除的2016年，整体微丝蚴率（microfilaria rate）已从集体化疗启动前2001年的0.21%降至0.06%。目前斯里兰卡已进入验证后监测（post-validation surveillance）阶段。相较而言，实现土源性蠕虫病的防控难度更高。该国集体驱虫项目（mass deworming programmes）已开展近百年，全国性调查显示其感染率（prevalence rates）从2003年的6.9%降至2017年的1%。但目前两类感染均未被完全消除，现状分析表明二者仍在高风险社区持续传播。本文探讨了斯里兰卡淋巴丝虫病与土源性蠕虫病在残留传播区域持续存在的原因，以及实现长期防控乃至彻底阻断传播所需采取的措施。本文属于“抗击被忽视的热带病（Neglected Tropical Diseases）的挑战”专题特刊。