Global programme to eliminate lymphatic filariasis: progress report, 2018

Overview

Overview

Lymphatic filariasis (LF) is a debilitating, disfiguring  disease  caused  by  infection with  the  filarial  parasites Wuchereria bancrofti, Brugia malayi and B. timori. The infection is transmitted by mosquito species  of  the genera Culex,  Anopheles,  Mansonia and Aedes.  Parasites  in  the lymphatic vessels impair lymphatic func-tion and cause lymphoedema and hydrocoele. Acute episodes of adenolymphangitis are  a  main  cause  of  physical  pain among  people  with LF. The  aims  of  the Global Programme to Eliminate Lymphatic Filariasis (GPELF),  established  by  WHO, are to  stop  transmission  of  infection  by mass drug administration (MDA) and to alleviate suffering among affected patients by morbidity management and disability prevention (MMDP). 

Before establishment of the GPELF, LF was responsible for an estimated 5.25 million disability-adjusted life-years (DALYs) and an  annual  economic loss of at least US$ 5.7 billion per year.1  WHO recommends feasible,  cost-effective  approaches to put an end to one of the world’s leading causes  of  avoidable  disability. After 16 years of the GPELF, LF was considered responsible for at least 1.3 million DALYs, representing a substantial effect of inter-ventions, although the remaining burden is considerable.

Achievements in 2018

Validation of elimination as a public health problem

For elimination of LF as a public health problem, the prevalence of infection in an area must be reduced to below the target threshold for at least 4 years after MDA and the recommended package of care is provided in all areas in which there are patients with lymphoedema or hydrocoele. In 2018, WHO recognized that Palau, Viet Nam and the Territory of the Wallis and Futuna Islands (France) had met the criteria for elimination of LF as a public health problem.

Scale-up of mass drug administration

MDA is the WHO-recommended strategy for stopping transmission of LF. MDA comprises treatment of all eligible people living in all endemic areas with recom-mended, setting-specific regimens of ivermectin, diethyl-carbamazine and albendazole in combinations that depend on co-endemicity with loiasis and onchocercia-sis and the status of the MDA programme.5 An imple-mentation unit (IU) is the smallest administrative unit used as the basis for deciding to implement MDA. The population living in an IU no longer requires MDA when the prevalence of infection has been reduced to such a level that transmission is considered to be no longer sustainable.6 WHO recommends monitoring and evaluation through sentinel and spot-check surveys, followed by a transmission assessment survey (TAS) to measure the impact of MDA and to determine whether the level of infection has decreased below the target threshold. Multiple rounds of MDA with effective coverage (>65% coverage of the total population receiving the medicines) are required to achieve the desired effect.