Control of helminth parasites is a key challenge for human and veterinary medicine. In the absence of effective vaccines and adequate sanitation, prophylaxis and treatment commonly rely upon anthelmintics. There are concerns about the development of drug resistance, side-effects, lack of efficacy and cost-effectiveness that drive the need for new classes of anthelmintics. Despite this need, only three new drug classes have reached the animal market since 2000 and no new classes of anthelmintic have been approved for human use. So where are all the anthelmintics? What are the barriers to anthelmintic discovery, and what emerging opportunities can be used to address this? This was a discussion group focus at the 2019 8th Consortium for Anthelmintic Resistance and Susceptibility (CARS) in Wisconsin, USA. Here we report the findings of the group in the broader context of the human and veterinary anthelmintic discovery pipeline, highlighting challenges unique to antiparasitic drug discovery. We comment on why the development of novel anthelmintics has been so rare. Further, we discuss potential opportunities for drug development moving into the 21st Century.

控制蠕虫寄生虫是人类医学和兽医学面临的主要挑战。在缺乏有效疫苗和适当卫生条件的情况下，预防和治疗通常依赖于驱虫药。人们对耐药性、副作用、缺乏疗效和成本效益的发展感到担忧，这推动了对新型驱虫药的需求。尽管有这种需求，但自 2000 年以来只有三种新的药物类别进入了动物市场，并且没有新类别的驱虫药被批准用于人类。那么，所有的驱虫药在哪里呢？发现驱虫药的障碍是什么，有哪些新兴机会可以用来解决这个问题？这是在美国威斯康星州举行的 2019 年第 8 届抗蠕虫药耐药性和易感性联盟 (CARS) 的讨论组重点。在这里，我们在人类和兽医驱虫药发现管道的更广泛背景下报告了该小组的发现，突出了抗寄生虫药物发现所特有的挑战。我们评论了为什么新型驱虫药的开发如此罕见。此外，我们还讨论了进入 21 世纪的药物开发的潜在机会。