HERBIVORES AS ACCIDENTAL HOSTS FOR TRICHINELLA: SEARCH FOR EVIDENCE OF TRICHINELLA INFECTION AND EXPOSURE IN FREE-RANGING MOOSE (ALCES ALCES) IN A HIGHLY ENDEMIC SETTING.

Herbivores can be accidental hosts for the zoonotic nematode parasites Trichinella spp., which are endemic at high prevalence in wildlife in northeastern Europe. Using direct and indirect detection methods for Trichinella spp., we investigated samples from 463 wild moose (Alces alces) harvested by hunters in Estonia in 2015. A total of 460 moose were tested directly by artificial digestion of diaphragm muscle, 463 moose were tested indirectly by enzyme-linked immunosorbent assay (ELISA), and 34 moose also by western blot. Positive-control reference sera were from other host species. Nematode larvae were found in six muscle samples; five of which were pooled samples. None of the larvae were identified as Trichinella spp., based on their morphology and molecular analyses. Twelve moose (2.6%) were positive by ELISA, but none were positive by the western blot test. Trichinella spp. infection was not detected, but ELISA results may suggest Trichinella spp. exposure in a small proportion of moose in Estonia.

Toxoplasma gondii seroprevalence in free-ranging moose (Alces alces) hunted for human consumption in Estonia: Indicator host species for environmental Toxoplasma gondii oocyst contamination.

In Estonia, northeastern Europe, antibodies against Toxoplasma gondii are common in many host species, including wildlife, domestic animals, and humans. Our nationwide study aimed to estimate T. gondii seroprevalence and its geographical distribution, and to evaluate plausible risk factors for seropositivity in free-ranging moose (Alces alces) hunted for human consumption in 2015. We screened sera or plasma from 463 moose for presence of anti-T. gondii immunoglobulin G antibodies with a commercial direct agglutination test, using a cut-off titer 40 for seropositivity. Altogether 111 moose tested seropositive, yielding a seroprevalence estimate of 23.97%. Seropositive moose were detected in all the 13 counties where the samples originated from. Based on a multivariable logistic regression model, 'being female', 'being adult', and 'being from the northern part of the country' were significant risk factors, with odds ratios of 2.91, 3.07, and 3.11, respectively, and there was interaction between the variables 'being female' and 'being from the northern part of the country'. A substantial proportion of the moose investigated had been exposed to T. gondii. Presence of the parasite in edible tissues of the moose was not shown in the present study, but moose hunted in Estonia should be considered a potential T. gondii infection source to other hosts, including humans. Seropositivity indicates previous exposure, and because the seroprevalence was higher in adults than in calves and because moose are herbivores, the exposure was likely exposure to and ingestion of T. gondii oocysts. The results can thus be interpreted to indicate that the environment in Estonia was widely contaminated with T. gondii oocysts, in particular in the northern part of the country. Investigation of samples from a free-ranging herbivorous host that is hunted in large numbers appears useful in revealing environmental distribution patterns of T. gondii.