The roundworm Ascaris: Recent advances on the road to elimination

The giant roundworm Ascaris is an important nematode parasite of humans and pigs worldwide. Ascariasis, the disease associated with Ascaris infection, is classified as a neglected tropical disease and has been targeted for elimination as a public health problem by 2030. Despite increased efforts to control Ascaris in humans, it remains highly prevalent. A major challenge is the long-term viability of Ascaris eggs in the environment, resulting in a significant reservoir. Here, we review present understanding of Ascaris environmental contamination, and existing and emerging approaches for surveillance and control. Another potential challenge is represented by the emergence of resistance to the drugs (benzimidazoles) used for Ascaris control and treatment. We describe the current evidence for resistance in Ascaris and related ascarid parasites and recent work to understand mechanisms of resistance, which may be different to those described for other nematodes. There has been much recent progress in the availability and use of 'omic resources for Ascaris. We review how 'omic data is being employed to provide insights into Ascaris population structure, drug pressure and transmission dynamics at different scales. We also describe how 'omic data is being exploited through reverse vaccinology to identify new vaccine targets for Ascaris, offering a possible alternative avenue for control. We conclude by highlighting some emerging research areas which could be applied to Ascaris and reflecting on how recent advances can impact on progress towards achievement of the WHO 2030 target.