The first detection of Ashworthius sidemi (Nematoda, Trichostrongylidae) in roe deer (Capreolus capreolus) in Russia

Non-native Nematode Ashworthius sidemi Currently Dominates the Abomasal Parasite Community of Cervid Hosts in the Czech Republic

Ashworthius sidemi is an abomasal nematode typical for Asiatic cervids such as sambar (Rusa unicolor) or sika deer (Cervus nippon). This non-native parasite was introduced into Europe via sika deer in the late 19th and early 20th centuries. The current dynamic spread of this parasite amongst autochthonous wild cervids occurs independently of human activities, and A. sidemi has a negative impact on the health of wild ruminants and may pose a threat to the conservation of endangered wild ungulates and to livestock. This invasive parasite has been previously detected in the Czech Republic, but more accurate information on A. sidemi is required. Only limited information is generally available on the factors influencing the spread of abomasal nematodes in wild ruminants, so more information is necessary for planning effective strategies of parasite control. We therefore conducted a survey on the abomasal nematodes in cervids in both game reserves and hunting grounds across the Czech Republic, taking into account the hosts (species, age, sex) and environmental factors (monthly average temperature). The abomasa of 104 animals belonging to five cervid species originating from various locations of the country were collected. Data on host (species, sex, and age group) and the monthly average temperature in the region were obtained for each animal. The parasitological analyses indicated that 92% of the abomasa were infected by nematodes. Ashworthius sidemi was the most prevalent (72%) and abundant (80% of the total recovered individuals) nematode species and was detected in all cervid species except white-tailed deer. The intensity of A. sidemi was highest in roe deer (Capreolus capreolus) and fallow deer (Dama dama), but A. sidemi abundance did not depend substantially on the host or environmental factors. In contrast, the abundance of nematodes from the subfamily Ostertagiinae was influenced by the host species and temperature. Parasitic load was significantly higher in roe deer and during the warmer periods of the survey. We also detected another non-native nematode species, Spiculopteragia houdemeri. The results of our study suggest that the non-native nematode A. sidemi is now widespread amongst cervid hosts in the Czech Republic, probably due to the high sensitivity of autochthonous cervids to A. sidemi infections as well as adaptation of this parasite to the current climatic conditions of this country.

The First Detection of Abomasal Nematode Ashworthius sidemi in Fallow Deer (Dama dama) in Russia

PURPOSE

The aim of the study was to supplement the data concerning the spreading of nematode Ashworthius sidemi among wild ruminants in Russia.

METHODS

The samples of A. sidemi were collected from two fallow deer, which were born and raised in the game farm in Smolensk region (55° 16' N-34° 29' E). The affiliation of the detected nematodes as A. sidemi was made using morphological features (shape of the spicules and the dorsal ray of bursa for males, as well as the presence and shape of the neodont in the buccal cavity for males and females).

RESULTS

The intensity of infection in 2 studied fallow deer was 7 and 19 individuals of A. sidemi. All of the specimens of A. sidemi had the features of juvenile forms. The registration of fallow deer as another one host of A. sidemi in Russia indicates a further spreading of this nematode and confirms the necessity of strengthening the control of this parasite.

CONCLUSION

The finding of this nematode in non-native captive animals shows the imperfection of control in this sphere. A. sidemi could have been introduced to the game farm both with imported or with native animals due to insufficient quarantine and isolation. More wide further research would be useful in the light of control this potentially dangerous parasite.

Ashworthius sidemi Schulz, 1933 (Trichostrongylidae: Haemonchinae) in mountain ecosystems - a potential risk for the Tatra chamois Rupicapra rupicapra tatrica (Blahout, 1971/1972)

The Asian native Ashworthius sidemi is now in Europe, and several dozen years after its introduction, it is a widespread parasite of all wild cervids. For bovids, the nematode is a significant threat to the European bison (Bison bonasus) population and has also been found in mouflon (Ovis ariesmusimon). Our study aimed to assess the risk of infection for the endemic subspecies of northern (Alpine) chamois (Rupicapra rupicapra) – the Tatra chamois (R. r. tatrica), which has a critically endangered status. We conducted the investigation in the mountainous areas of Slovakia and Poland occupied by Tatra chamois (R. r. tatrica), Alpine chamois (R. r. rupicapra), red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Animals (n = 93) shot during licensed hunting and killed in road accidents (roe deer, red deer), or which had died of natural causes (chamois) were post-mortem examined for the presence of Haemonchinae. The investigation confirmed the expansion of Ashworthius sidemi to high mountain regions via Cervidae. A. sidemi affected all of the examined roe deer and 90.0% of the red deer. As for the chamois, A. sidemi was found in one R. rupicapra originating from the Low Tatras, but not in any pure R. r. tatrica individuals living in the High and Western Tatras. Our work is the first confirmation of northern chamois infection with this alien and highly pathogenic blood-sucking nematode. Due to the important health hazard of A. sidemi infection for the Tatra chamois (R. r. tatrica), appropriate measures should be taken to reduce the possibility of parasite transmission between various cervid species living in the Tatra region, as well as the affected population of chamois and the pure Tatra chamois population inhabiting the higher parts of the mountains, constituting their natural habitat.

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A. sidemi distribution extends with cervid hosts into the high mountains.

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A. sidemi infection in northern chamois is confirmed for the first time.

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Critically endangered Tatra chamois becomes substantially exposed to A. sidemi.

Nematode-induced pathological lesions and alterations of mucin pattern identified in abomasa of wild ruminants

Pathological lesions as well as mucin alterations in abomasa infected by nematodes have been thoroughly studied in livestock, but such data from wild ruminants are limited or completely lacking. Pathological data for Ashworthius sidemi, an invasive nematode are particularly rare. We necropsied the abomasa of 21 wild ruminants belonging to five cervid species and detected mixed nematode infections, dominated by A. sidemi. Samples from both gross lesions and mucous membranes without macroscopically apparent pathological alterations were subjected to standard histological procedures and histochemical staining. Histological examination found chronic abomasitis, manifested by edema, and hyperemia. Various degrees of lymphoplasmacytic infiltration were observed in all samples. Initial fibrosis (8/20, 40%) was detected in samples from both gross lesions and areas without macroscopically visible changes. Tissue from hemorrhagic lesions was superficially eroded. Generalized loss of surface polysaccharides was apparent in all samples. Only residual periodic acid-Schiff and Alcian blue (pH2.5) positivity was detected in the upper abomasal pits and in mucosal neck. This study found that nematode infections, mostly by A. sidemi, caused chronic inflammation and negatively affected abomasal mucin formation in wild ruminants.

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Histological examination of tissue samples identified nematode-induced abomasitis.

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Loss of superficial polysaccharides was apparent in all tissue samples.

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Mainly acidic residual mucins were detected in abomasal pits and mucosal neck zone.