The role of 'omics' in the quest to eliminate human filariasis

Lymphatic filariasis (LF) is a disease affecting approximately 120 million people in over 73 countries [1] and caused by infection with a group of filarial nematodes transmitted by mosquito vectors. Wuchereria bancrofti is responsible for approximately 90% of the disease worldwide, while the remaining cases are due to Brugia malayi and B. timori [2]. These filarial nematodes have important social and economic impact causing high morbidity and serious illnesses resulting in social stigmatization, marginalization, and loss of work for the afflicted [3]. In 2000, The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was launched with the objective to eliminate this disease as a public health problem by 2020 [4]. The eradication of lymphatic filariasis relies on mass drug administration (MDA) using the three drugs currently available for treatment: diethylcarbamazine (DEC), albendazole, and ivermectin. GPELF also has made significant progress in many countries, delivering, between the years 2000 and 2014, 5.6 billion treatments to more than 763 million people living in 61 countries. It was estimated that this directly prevented 36 million clinical cases and saved 175 million disability adjusted life years (DALYs) [5]. However, it is unlikely that LF will be eliminated by the target year of 2020 as 55 of the 73 countries considered to be endemic for LF in 2015 still require MDA [6]. Moreover, GPELF has lagged in Sub-Saharan Africa where only 2 of 35 LF-endemic countries have stopped MDA and started post-MDA surveillance. Notably, recent studies show that single-dose combination therapy with the three antifilarial drugs (ivermectin/albendazole/diethylcarbamazine, or IDA) appears to be superior to current regimens used in the elimination programs, which may help accelerate LF elimination in Africa. Although it has not yet been tested, IDA may also be useful for treating onchocerciasis [7,8]. However, reports of drug resistance to ivermectin and albendazole [9,10] as well as serious concerns about using DEC in Sub-Saharan Africa because of ocular adverse events after DEC treatment of onchocerciasis in the past, makes the discovery of novel drugs against onchocerciasis imperative [11]. The debilitating eye and skin disease known as onchocerciasis is caused by Onchocerca volvulus; it is the world’s second-leading infectious cause of blindness in humans with 99% of cases in Sub-Saharan Africa alone. Current estimates put 120 million people at risk and 17 million already infected, of which 1.2 million suffer from vision impairment or blindness [12,13]. While the focus of the control efforts has been to alleviate morbidity and lost productivity, onchocerciasis has more recently been targeted for elimination [14,15]. The three past and present onchocerciasis control programs; OCP, the Onchocerciasis Control Programme; APOC, African Programme for Onchocerciasis Control; and OEPA, the Onchocerciasis Elimination Program for the Americas, rely on annual or biannual MDA of ivermectin, a therapy effective at killing microfilariae but not adult worms, with the goal of interrupting disease