The prevalence, relative abundance and site distribution of nematodes of the subfamily Cyathostominae in horses killed in Britain

Abstract

A total of 21 species of Cyathostominae was found in the lumen of the large intestine of 86 mature horses of various ages and breeds killed in south-west England during 1972–1974. Cylicostephanus longibursatus, C. goldi, C. calicatus, Cyathostomum catinatum, C. coronatum and Cylicocylus nassatus were found in over 80% of the horses, while 12 of the remaining species were detected in less than 30%. Quantitative studies on 55 horses showed the adult cyathostome burdens to rise to a sharp peak (average over 400,000/horse) in April-June and a lower one in November-December. Parallel fluctuations occurred in the lumen populations of 4thstage larvae. The most numerous cyathostomes were generally those species with the highest prevalence. The five most plentiful (C. nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, C. minutus and C. goldi) comprised over 90% of the total number of adult cyathostomes recovered. The three regions of the large intestine had adult cyathostome faunas of different composition. That of the dorsal colon was dominated by C. longibursatus and C. goldi, the ventral colon by Cylicocyxlus nassatus and Cyathostomum catinatum, while the sparsely inhabited caecum accommodated several equally numerous species. Each species showed a characteristic site distribution, 11 occurring predominantly in the ventral colon, eight in the dorsal colon and two in the caecum. Seasonal changes in the site distributions of C. catinatum and Cylicocyclus nassatus and in the size of the cyathostome burdens are discussed in relation to the epidemiology of cyathostome infections.

Anthelmintic resistance in nematodes of horses

“…Additionally, the relative prevalence and intensity of these common species has not demonstrated any noticeable changes over the past few decades despite the frequent use of anthelmintics and the increasing prevalence of resistant worms. Studies performed in Great Britain [74], the United States [80], Australia [8], and Brazil [87] spanning the period 1976 to 1999 all report the same three most abundant species; Cys. longibursatus, Cya.…”

“…calicatus, and Cys. minutus) are highly prevalent, comprising about 99% of total cyathostome burdens [8,68,74,80,87]. Other uncommon species not on this list will sometimes be present at greater levels than the least common of these 12, but always at relatively low prevalence and/or intensity.…”

Recent developments in research into the Cyathostominae and Anoplocephala perfoliata

“…Traditionally, identification relied on the examination of the morphology of the head and tail of adult parasites [26]. Prevalence studies based on parasite identification at post mortem examination, indicated that many (up to 27) species can be identified in one study [4,17,39,41]. However, most reports indicate that 90% of the parasites present belong to one of several common species, for example Cylicostephanus longibursatus, Cylicocyclus nassatus, Cyathostomum catinatum, Cylicostephanus minutus and Cylicostephanus goldi [41].…”

Cyathostominae distribution in experimentally infected ponies

“…Mfi tilodze and Hutchinson (1985), Ogbourne (1976), Collobert-Laugier et al (2002) and Lyons et al (2011) reported that the highest number of species prefer the ventral colon to the dorsal colon and caecum. Ogbourne (1976) and Collobert-Laugier et al (2002) reported the following preferred parts in descending order: dorsal colon (50 %; 64 %), ventral colon (45 %, 27 %) and caecum (5 %, 9 %). Only Stancampiano et al (2010) published results which differed from previous studies: the ventral colon (67.34 %), the caecum (27.52 %) and the dorsal colon (5.…”

“…Cyathostominae consist of 52 different species, of which more than 40 have been described in horses (Lichtenfels et al, 2002). In individual animals, 8 -12 common species usually account for the majority of the parasite burden (i.e.> 90 %) (Ogbourne, 1976). Cyathostominae, like other gastrointestinal nematodes of the order Strongylida, are gonochorists with marked sexual dimorphism.…”