Formulating fungal spores to prevent infection by trichostrongylids in a zoological park: Practical approaches to a persisting problem

Abstract

Two different formulations containing a blend of spores of the filamentous fungi Mucor circinelloides and Duddingtonia flagrans have been assayed against trichostrongylids in wapitis captive in a grassy parcel from a zoological park and dewormed with fenbendazole. One approach (sprayed-on pellets) consisted of providing them, during 10 months, nutritional pellets sprayed the spores just before to be ingested, and the other (formulated pellets) involved the administration of pellets industrially manufactured with the spores for an identical period. Data collected on wapitis treated with fenbendazole without receiving spores during a 10-months interval were considered as controls. The effect of these strategies was evaluated through the analysis of feces collected directly from the soil, by estimating the reduction of the counts of eggs of trichostrongylids per gram of feces (EPG). The possibility of side effects in the digestive tract, respiratory apparatus or on the skin was assessed. The coprological analyses showed that, despite the successfulness of fenbendazole, the values of trichostrongylids egg-output increased four months later above 300 EPG. Through the administration of pellets sprayed spores, a significant EPG reduction of 69% (30–100) was recorded, and 71% (36–100) by giving the wapitis pellets industrially enriched with the spores. No unfavorable effects were observed among the wapitis taking the spores. It is concluded that ingestion of a blend of spores of M. circinelloides and D. flagrans every two days affords a beneficial long-term effect on controlling the infection by trichostrongylids in wild captive animals.