Alistair Antonopoulos and Johannes Charlier (Kreavet) together with John Gilleard (University of Calgary) published a new review on the current state of Next Generation Sequencing in helminths of veterinary importance. Here they come back on the outline of the article and some of the conclusions made.
Parasitic worm, or helminth, infections are a major problem worldwide for livestock farming. Helminths affecting grazing ruminants can broadly be divided into the gastrointestinal nematodes (or roundworms), the flukes (or flatworms), and lungworms. Each type of helminth leads to different clinical signs and severity of disease, with some species leading to subclinical infections that cause widespread undetected production losses. Furthermore, different species of the same type of helminth can cause quite different disease, with some species even causing deaths, particularly in lambs.
Unfortunately, helminth infections are unavoidable in outdoor grazing systems. It is of paramount importance, therefore, that they are detected and managed appropriately. For many years, the mainstay for management of helminth infections has been preventative treatment with various anthelmintic drugs, however, the sustainability and efficacy of these drugs is seriously threatened by widespread resistance. It is imperative that more sustainable worm control strategies are employed, with the diagnosis and detection of helminth infections and anthelmintic resistance of paramount importance to achieve this.
Until recently, the main option for detecting helminths or anthelmintic resistance was the microscopy based faecal egg count tests. However, these tests are often inaccurate, require specifically trained staff, and in the case of resistance testing need drug treatment to be carried out, followed by a waiting period of several days to up to two weeks to see if the drug reduced egg output. In recent years, genomic technology has advanced significantly in the field of veterinary medicine, also in parasitology. This has lead to a wide range of new next-generation sequencing based technologies being developed, leading to faster and more accurate detection of veterinary helminths. With sequencing technology now multiple individual species of helminths can be detected simultaneously. With more and more epidemiological data being generated with these technologies, we are getting closer to deliver improved treatment plans based on knowing exactly which parasites are present and in which “numbers” they are present. In addition, for the first time, multi-drug resistance detection is now possible. Next-generation sequencing panels have been developed which can simultaneously detect benzimidazole and levamisole resistance and this simultaneously with species specific identification, thus catching 2 birds with one stone. In the coming years we also expect to see the integration of macrocyclic lactone and monepantel resistance into these diagnostic tests. Finally, with the recent development of portable nanopore sequencing, the possibility of carrying this testing out at the farm side is becoming a real possibility.
We would like to acknowledge the inputs of Roz Laing (University of Glasgow) in this publication. She critically reviewed the draft manuscript and served as a sound reflection board, allowing us to write this work.
Alistair Antonopoulos, Johannes Charlier, John Gilleard
23 May 2014
Full article:
Antonopoulos A, Gilleard JS, Charlier J., 2024. Next-generation sequencing technologies for helminth diagnostics and surveillance in ruminants: shifting diagnostic barriers. Trends Parasitol. doi: 10.1016/j.pt.2024.04.013.
