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Received Nov 24, 2017; Revised Apr 11, 2018; Accepted May 15, 2018
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1. Introduction
Wild animals captive in zoological parks are frequently confined to the same area, which enhances that elevated concentrations of parasites are attained in the ground [1]. This problem worsens due to stress, living conditions, and/or limitations of space increasing susceptibility of animals to some parasitic infections [2, 3].
Prior investigations suggested that parasites involving an intermediate host, as trematodes or cestodes, are more difficult to develop in zoos [4]; then those having a direct life-cycle are highly prevalent in captivity, especially parasites capable of surviving for long periods in the environment as strongyles or ascarids [5–7]. Clinical signs attributable to parasites are seldom observed in captive animals, which might point that subclinical infections develop in most of cases [8]. However, helminths can cause fatal infections if control fails [9, 10].
Control of parasites in zoo animals remains a pendant question, comprising the administration of parasiticide drugs [11, 12]. Nevertheless, analyses for establishing the presence of parasitic infection are rarely asked before the deworming, and the evaluation of the successful is seldom considered. Another inconvenience relies on that confinement of wild animals in the same parcel enhances the risk of exposure to infective stages of several parasites; thus frequent deworming can be needed, in a similar way to that reported in domestic animal species [13].
Recent investigations pointed out that certain saprophytic fungi are capable of performing antagonistic activity against parasitic stages (eggs, larvae) in the ground. Hyphae of Pochonia chlamydosporia, Verticillium chlamydosporium, or Paecilomyces lilacinus attach to the eggshells of trematodes, ascarids, and trichurids and penetrate and destroy the embryo inside [14, 15]. Duddingtonia flagrans and Monacrosporium thaumasium elaborate traps in their mycelia where larvae of strongyles are immobilized and finally disrupted [16, 17]. A beneficial effect has been reported on avoiding infection by strongyles among wild captive equids, consisting of mixing chlamydospores of D. flagrans with feedstuff [13]. Herein, the integrated control of strongyles among equids from a zoological park was carried out; accordingly, zebras, African asses,...