Silvia Miguélez

Mixed Production of Filamentous Fungal Spores for Preventing Soil-Transmitted Helminth Zoonoses: A Preliminary Analysis

Helminth zoonoses are parasitic infections shared by humans and animals, being the soil-transmitted helminths (STHs) mainly caused by roundworms (ascarids) and hookworms. This study was aimed to assess the individual and/or mixed production of two helminth-antagonistic fungi, one ovicide (Mucor circinelloides) and other predator (Duddingtonia flagrans). Fungi were grown both in Petri plates and in a submerged culture (composed by water, NaCl, Na2HPO4 · 12 H2O, and wheat (Triticum aestivum)). A Fasciola hepatica recombinant protein (FhrAPS) was incorporated to the cultures to improve fungal production. All the cultured plates showed fungal growth, without difference in the development of the fungi when grown alone or mixed. High counts of Mucor spores were produced in liquid media cultures, and no significant differences were achieved regarding single or mixed cultures, or the incorporation of the FhrAPS. A significantly higher production of Duddingtonia spores after the incorporation of the FhrAPS was observed. When analyzing the parasiticide efficacy of the fungal mixture, viability of T. canis eggs reduced to 51%, and the numbers of third stage cyathostomin larvae reduced to 4%. It is concluded, the capability of a fungal mixture containing an ovicide (Mucor) and a predator species (Duddingtonia) for growing together in a submerged medium containing the FhrAPS offers a very interesting tool for preventing STHs.

Potential use of Mucor circinelloides for the biological control of certain helminths affecting livestock reared in a care farm

A preliminary study to evaluate the possibilities of biological control procedures against parasites affecting livestock reared in a care farm has been conducted. Adults with mental disabilities were involved in spreading the spores of the filamentous fungus Mucor circinelloides directly onto the faeces, or as a food additive. In the first assay, the spores were sprayed directly onto the faeces of piglets and calves parasitised by roundworms (Ascaris suum) and liver flukes (Fasciola hepatica), respectively. In the second assay, the spores were mixed with on-farm mash feed. Participation of the adults in the experiments was fully satisfactory. In the manure sprayed Mucor spores, the viability of eggs of roundworms and flukes reduced by 53% and 74%, respectively. Significant reductions of viability of eggs of Ascaris (60%) and Fasciola (67%) in the faeces of piglets and calves given mash feed-added Mucor spores were achieved, which demonstrates their ability to survive in the digestive tract of the animals. It is concluded that biological control of parasites could be helpful to decrease the risk of infection in animals reared by intellectually disabled adults in a care farm, and it could motivate them to accomplish new tasks.

Isolation of Ovicidal Fungi from Fecal Samples of Captive Animals Maintained in a Zoological Park

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.

A combined trial of chemotherapy and biological control measures against parasites in grazing horses

Horses under grazing regime are at a high risk for infection by several parasites affecting the digestive tube, especially the strongyles. Infection occurs by the ingestion of free-living third stage larvae (also called L3) when grazing in pastures. While deworming reduces the presence of adult parasites in the horses, some action against the L3 in the pasture is needed for reducing the risk of infection. Eight adult horses exceeding a cut-off value of 300 eggs per gram of feces (EPG) were utilized in the current study. Control of parasitic strongyles consisted of the combination of two measures. Firstly, the horses were given moxidectin (Equest® oral gel, Pfizer, Madrid, Spain; 0.4 mg/kg bw dosage), and in addition, a dose of 2×106 Duddingtonia flagrans chlamydospores kg/bw was bi-weekly given to each horse. The effect of this combined procedure was assessed by estimating the reduction in the faecal egg counts. After the horses received the chemotherapy and the D. flagrans chlamydospores a significant reduction in the EPG was observed (Z=-11.391, P= 0.001). No strongyle egg-output was observed for 2 months, whereas the need for applying a new dosage of chemotherapy was established at the 6th month after the initial deworming of the equines. Our results point the efficacy of a combined strategy by giving chemotherapy and chlamydospores for reducing the frequency of antiparasitic drug administration to grazing horses. Besides the presence of free-infective larval stages can be significantly lowered and thus the risk of infection in the horses, this procedure seems a very valuable and helpful contribution to the sustainability of the environment by minimizing the effect of chemical residues dangerous for some organisms as dung beetles, essential for the natural fertilization of the soil.