Sex-biased polyparasitism in moose (Alces alces) based on molecular analysis of faecal samples

Abstract

Simultaneous infection with multiple parasite species in an individual host is often observed in wild populations. The understanding of parasite species distribution across populations of wild animals is of basic and applied importance, because parasites can have pronounced effects on the dynamics of host population. Here, we quantified prevalence and endoparasite species richness in moose and explored sex-biased polyparasitism using diagnostic PCR method coupled with DNA sequencing of moose faecal samples from the Biebrza River valley, North-Eastern Poland. This is the largest moose population in Central Europe that has not been harvested for almost 20 years. We also evaluated the appropriate quantity of faeces for detecting DNA of parasite species. Faecal samples were screened for molecular markers of 10 different species of endoparasites. Endoparasite prevalence was high in the studied population. Almost all of the samples (98%) tested positive for at least one parasite species, and we found polyparasitism in the majority of the tested individuals. The number of different parasite species found in a single individual ranged from 0 to 9. The parasite species richness was significantly higher in male than in female individuals. The most prevalent were liver fluke Parafasciolopsis fasciolaemorpha and gastrointestinal nematodes Ostertargia sp. Of the ten endoparasite species detected, only the prevalence of the tapeworm Moniezia benedeni was significantly higher in males than in females. Additionally, we identified co-occurrence associations of parasite species, which tended to be random, but we noted some evidence of both positive and negative associations. Our findings promote applications of molecular methods for parasite species identification from non-invasively collected faecal samples in management and scientific study of moose population, which should include investigation of parasite status, and in health monitoring programs for other wild cervids.

Gastrointestinal Helminths of a European Moose Population in Poland

“…On the other hand, these values are significantly lower than those observed in a previous study based on molecular examination of moose feces [ 14 ]. As molecular evaluation is more sensitive, the results obtained by fecal egg counts based on traditional coproscopic examination should be treated with caution [ 3 , 14 ].…”

“…Parafasciolopsis fasciolaemorpha was isolated from 65% of the examined moose livers and over 66% of small intestines in the present study, which is slightly less than in previous studies based on fecal analysis [ 13 , 14 ]. Its presence appears to be limited to central and eastern Europe and its occurrence varies depending on the presence of wetlands inhabited by water snails, these being the typical intermediate hosts of the trematode [ 13 ].…”

“…Access to water sources enables the survival of intermediate hosts or some larval forms of parasites and thus favors the transmission of parasitoses, e.g., parafasciolopsosis [ 13 ]. Individual factors, like immunological status or age of the host, might also favor or decrease the risk of parasitic infections [ 2 , 14 ], e.g., tapeworms from the genus Moniezia are more prevalent in young animals, whereas gastrointestinal nematodes dominate in adult moose. During the present study, no differences in parasitic loads were observed between moose sexes, despite such relationships being observed previously [ 3 , 13 , 14 ].…”

“…Individual factors, like immunological status or age of the host, might also favor or decrease the risk of parasitic infections [ 2 , 14 ], e.g., tapeworms from the genus Moniezia are more prevalent in young animals, whereas gastrointestinal nematodes dominate in adult moose. During the present study, no differences in parasitic loads were observed between moose sexes, despite such relationships being observed previously [ 3 , 13 , 14 ]. Therefore, when analyzing parasitic infections in the moose population, a number of factors should be taken into consideration, especially in the face of global warming and, with it, increasing parasite pressure.…”

“…Most previous studies concerning moose parasites have been conducted in Scandinavia [ 3 , 12 ]. The only available data from central Europe involve the results of fecal examinations [ 13 , 14 ]. Although such fecal studies may serve as an effective screening method for assessing the parasite fauna of moose, their findings cannot provide a comprehensive view of the intensity of parasitic infections or histopathological changes associated with moose parasitoses.…”