Systematic review of gastrointestinal nematodes of horses from Australia

Abstract

Background Equine gastrointestinal nematodes (GINs) have been the subject of intermittent studies in Australia over the past few decades. However, comprehensive information on the epidemiology of equine GINs, the efficacy of available anthelmintic drugs and the prevalence of anthelmintic resistance (AR) in Australasia is lacking. Herein, we have systematically reviewed existing knowledge on the horse GINs recorded in Australia, and main aspects of their pathogeneses, epidemiology, diagnoses, treatment and control. Methods Six electronic databases were searched for publications on GINs of Australian horses that met our inclusion criteria for the systematic review. Subsets of publications were subjected to review epidemiology, diagnoses, pathogeneses, treatment and control of GINs of horses from Australia. Results A total of 51 articles published between 1950 to 2018 were included. The main GINs reported in Australian horses were cyathostomins (at least 28 species), Draschia megastoma , Habronema muscae , H. majus , Oxyuris equi , Parascaris equorum , Strongyloides westeri and Trichostrongylus axei across different climatic regions of Queensland, New South Wales, Victoria, and Western Australia. Nematodes are diagnosed based on the traditional McMaster egg counting technique, though molecular markers to characterise common GINs of equines were characterised in 1990s. The use of anthelmintic drugs remains the most widely-used strategy for controlling equine GIN parasites in Australia; however, the threshold of faecal egg count that should trigger treatment in horses, remains controversial. Furthermore, anthelmintic resistance within GIN population of horses is becoming a common problem in Australia. Conclusions Although GINs infecting Australian horses have been the subject of occasional studies over the past few decades, the effective control of GIN infections is hampered by a generalised lack of knowledge in various disciplines of equine parasitology. Therefore, coordinated and focused research is required to fill our knowledge gaps in these areas to maximise equine health and minimise economic losses associated with the parasitic infections in Australia. Electronic supplementary material The online version of this article (10.1186/s13071-019-3445-4) contains supplementary material, which is available to authorized users.

Dynamics of Gastro-Intestinal Strongyle Parasites in a Group of Translocated, Wild-Captured Asiatic Wild Asses in Kazakhstan

“…However, in a study in domestic horses, FECs under 500 EPG did correspond to significantly lower adult worm loads (43). Moreover, adult worms are for the most part not responsible for disease, in contrast to the larval stages (e.g., larval cyathostominosis caused by excystment of L4 small strongyle larvae, and verminous arteritis and tissue damage caused by migrating large strongyle larvae) (42). We therefore believe that monitoring FEC is a valid measure to assess parasite load relevant for equid health but acknowledge that the relationship between parasite load and egg shedding pattern should be investigated further.…”

“…FECs should be interpreted carefully because egg shedding is not the best estimate for parasite burden and there is often no correlation between egg counts and adult worm counts (42). However, in a study in domestic horses, FECs under 500 EPG did correspond to significantly lower adult worm loads (43).…”

Gastrointestinal helminths detected in wild horses in Konya Province, Turkey

“…Poteriostomum spp. (45.5%), S. vulgaris (34.9%), and S. equinus (27.3%) were determined as prevalent nematodes following Trichonema spp., with [28] reported helminth infections in horses affected by many environmental and host-related factors. Seasonal variation, rainfall, and temperature can be listed as some of the significant environmental factors.…”

Anthelmintic Activity of Extracts and Active Compounds From Diospyros anisandra on Ancylostoma caninum, Haemonchus placei and Cyathostomins

“…Also, they can negatively affect public health because of their zoonotic potential. Some examples of GINs include Ancylostoma caninum, Haemonchus placei and cyathostomins, which are the most prevalent and pathogenic in dogs, bovines and horses, respectively ( 1 – 4 ).…”

“…However, this has generated anthelmintic resistance, mainly to benzimidazoles and macrocyclic lactones. There are also reports of Ancylostoma caninum resistance to pyrantel, Haemonchus placei resistance to salicylanilides and imidazothiazoles and cyathostomin resistance to tetrahydropyrimidines ( 4 – 7 ). The situation is exacerbated by multi-resistance to numerous anthelmintics, which has been documented in the aforementioned three genera ( 8 – 11 ).…”