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E.T. Lyons and S.C. Tolliver

Summary

Review of several aspects of the biology of Strongyloides westeri, especially on the life cycle, are presented. The main reason is because of the potential renewed importance of these parasites since the recently recognized increase in their prevalence in horse foals. Indications are that the first and main source of enteric infections in foals maturing to adults in their small intestines is from parasitic third stage larvae (L3) passing to them in milk of their dams. It appears that a lesser source of infection is from free-living L3 which, when they are ingested with food or penetrate the skin, can mature in foals. In conclusion, the source of enteric infections of adult S. westeri in foals is mainly from parasitic L3 that they ingest in milk of their dams.

Open access

S. C. Tolliver, E. T. Lyons, M. K. Nielsen and J. L. Bellaw

Abstract

The present research is a continuation of studies conducted periodically over 40 years on transmission of natural infections of internal parasites in the same horse herd on pasture (Field 10) on a farm in Central Kentucky. It included 12 mixed light horse foals born in 2013 and euthanatized between July, 2013 and April, 2014 for collection of internal parasites. Parasites found: Gasterophilus intestinalis, Strongyloides westeri, Parascaris equorum, Anoplocephala perfoliata, small strongyles (cyathostomes), Strongylus vulgaris, Strongylus edentatus and Thelazia lacrymalis. Prevalence generally was related to age of the foals. Overall prevalence and number of specimens were lower than in earlier studies except for P. equorum. There were 15 species (much fewer than previously) of small strongyles found and recorded by location in the large intestines. All stages of small strongyles encysted in the mucosa of the large intestine were recovered by artificial digestion and in significantly lower numbers in older foals

Open access

E.T. Lyons, T.A. Kuzmina, J.L. Carie, S.C. Tolliver and T.R. Spraker

Abstract

Prevalence of Hookworms, Uncinaria lucasi (Ancylostomatidae), in Northern Fur Seals (Callorhinus ursinus) on St. Paul Island, Alaska. Lyons, E. T., Kuzmina, T. A., Carie, J. L., Tolliver, S. C., Spraker, T. R. — Review of main studies on biology and ecology of the hookworm Uncinaria lucasi Stiles, 1901 performed on St. Paul Island, Alaska, is presented. Current data on prevalence of adult hookworms parasitizing northern fur seals (NFS), Callorhinus ursinus Linnaeus, 1758, were obtained based on the examination of the intestines of dead NFS pups and subadult 3-4 year-old males in July and August of 2011-2013. In addition, blubber samples collected from subadult NFS males were examined for parasitic third stage hookworm larvae (L3). All current data were compared with previously published studies performed in 1950s-1960s. Current prevalence of U. lucasi in dead pups collected from Reef Rookery was 4.9 % in 2011, 0 % in 2012 and 10.5 % in 2013. This rookery has a rocky substrate. On sandy rookeries prevalence was up to 75 % on Morjovi Rookery and 50 % on Vostochni Rookery. Parasitic L3 were recovered in 2.5 % of subadult males examined in 2013. Decreasing prevalence of hookworm infection of dead pups and subadult males during the last several years follows the tremendous decline in the number of fur seals in the herd on St. Paul Island during last several decades.