BackgroundAn approach to preventing strongyle infection in horses was tested, comprising rotational pasturing and the administration of spores of two parasiticidal fungi, Mucor circinelloides and Duddingtonia flagrans.MethodsTwenty-two adult Spanish Sport Horses were dewormed with ivermectin (1 mg pour-on/kg body weight) and then randomly divided into three groups. G-1 was maintained with continuous grazing, and G-2 and G-3 were kept on a four-paddock rotation system. Commercial pelleted feed (2.5 kg/horse) was supplied to G-1 and G-2 twice a week; horses in G-3 received pellets containing 2 × 106 spores/kg of each fungus. Fecal samples were analyzed by the flotation method to estimate the reduction in the fecal egg counts (FECR), the percentage of horses shedding eggs (PHR), and the egg reappearance period (ERP).ResultsThird-stage larvae were identified in fecal pats as Cyathostomum (sensu lato) types A, C and D, Gyalocephalus capitatus, Triodontophorus serratus, Poteriosthomum spp., Strongylus vulgaris and S. edentatus. Two weeks after treatment, the FECR values were 100% in G-1, 96% in G-2 and 99% in G-3; the PHR values were 100% in G-1, 75% in G-2 and 88% in G-3. A strongyle ERP of 6 weeks was observed in G-1, ERP of 10 weeks was observed in G-2, and ERP of 16 weeks was observed in G-3. The counts of eggs per gram of feces (EPG) were > 300 EPG in G-1 and G-2 but remained below 250 EPG in G-3 throughout the observation period of 12 months.ConclusionsThese results suggest that horse strongyle infection could be decreased by combining rotational pasturing with feeding pellets containing the spores of parasiticidal fungi.

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Baylisascaris procyonis is a soil-transmitted helminth mainly found in raccoons (Procyon lotor) which can also affect other domestic and sylvatic animals, as well as humans, when the eggs released in the feces of parasitized raccoons are accidentally ingested. Three assays have been conducted to assess the effect of three saprophytic fungi, Mucor circinelloides, Paecilomyces lilacinus, and Verticillium sp., on the eggs of B. procyonis. Firstly, their ovicidal effect was in vitro ascertained by placing 1 mL with 2 × 10(6) spores of each fungus in Petri plates with water-agar (2 %) and simultaneously adding 200 eggs of Baylisascaris/plate. Two in vivo probes were carried out, by spraying the fungal spores (3 mL containing about 2 × 10(6) spores/mL) on the feces of raccoons and coatis (Nasua narica) passing eggs of B. procyonis in a zoological park; the other assay consisted of evaluating the activity of the fungi after adding sand to fecal samples from raccoons. An ovicidal type 3 activity characterized by morphological damage of the eggshell with hyphal penetration, internal egg colonization, and embryo alteration was observed for all the tested fungi. In the plate assays, viability of Baylisascaris eggs reduced significantly by 53-69 % with Mucor, 45-62 % with Paecilomyces, and 52-67 % with Verticillium. A similar ovicidal effect was detected in the feces with sand. These results demonstrate the usefulness of spraying spores of M. circinelloides, Pa. lilacinus, or Verticillium sp. on the feces of animals infected by Baylisascaris to decrease the numbers of viable eggs and, thus, the risk of infection.

There are certain saprophytic fungi in the soil able to develop an antagonistic effect against eggs of parasites. Some of these fungal species are ingested by animals during grazing, and survive in their feces after passing through the digestive tract. To identify and isolate ovicidal fungi in the feces of wild captive animals, a total of 60 fecal samples were taken from different wild animals kept captive in the Marcelle Natureza Zoological Park (Lugo, Spain). After the serial culture of the feces onto Petri dishes with different media, their parasicitide activity was assayed against eggs of trematodes (Calicophoron daubneyi) and ascarids (Parascaris equorum). Seven fungal genera were identified in the feces. Isolates from Fusarium, Lecanicillium, Mucor, Trichoderma, and Verticillium showed an ovicidal effect classified as type 3, because of their ability to adhere to the eggshell, penetrate, and damage permanently the inner embryo. Penicillium and Gliocladium developed a type 1 effect (hyphae attach to the eggshell but morphological damage was not provoked). These results provide very interesting and useful information about fungi susceptible for being used in biological control procedures against parasites.

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