Comparison of Direct and Indirect Toxoplasma gondii Detection and Genotyping in Game: Relationship and Challenges

The Presence of Bacterial and Protozoan Pathogens in Wild Fallow Deer (Dama dama) from a Protected Area in Central Italy

Wild ruminants often harbor pathogens transmissible to other animals and humans, but their epidemiological role is not always defined for all microorganisms. In this survey, spleens, kidneys, and hearts sampled from 162 fallow deer (Dama dama) were subjected to molecular analyses to detect bacterial (Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Brucella spp., Chlamydia abortus, Coxiella burnetii, Francisella tularensis, Leptospira spp.) and protozoan (piroplasms, Neospora caninum, Toxoplasma gondii) pathogens. Five (3.08%) spleens were positive for A. phagocytophilum, and twelve (7.40%) spleens were positive for Theileria cervi. The remaining pathogens investigated were not detected, and no coinfections were found. The analyzed animals do not seem to have a relevant role in the spreading of these pathogens; however, monitoring is pivotal to understand the epidemiological scenarios and take appropriate preventive measures in areas frequently visited by people.

Toxoplasma gondii in Wild Boars (Sus scrofa) in Germany: Serological Screening from Thuringia

Game meat is an important source of meat borne parasitic infections. Due to its omnivorous diet, the wild boar is an important host of zoonotic parasites such as Toxoplasma gondii. T. gondii can cause severe to fatal disease in immunosuppressed patients, as well as congenital disorders in foetus and neonates. Consumption of undercooked infected meat is a main source of T. gondii infection. Information about the risk of toxoplasmosis through game meat is scarce. We collected serum samples from 42 wild boars from the federal state of Thuringia (Germany) between December 2017 and February 2018. Identification of anti-T. gondii IgG antibodies was conducted using a commercial indirect ELISA kit. Seropositivity was confirmed in 18 of the 42 samples (37.50%). From these, the highest seroprevalence was found in adult animals. This study joins another single database from wild boars in Brandenburg. The necessity of a country-wide database regarding T. gondii prevalence in wild boar and other game meat is pivotal for a profound risk analysis with its consequential impact in future mean hygiene policies.

A ring trial to harmonize Toxoplasma gondii microsatellite typing: comparative analysis of results and recommendations for optimization

A ring trial among five European laboratories was organized to reach consistency in microsatellite (MS) typing of the zoonotic parasite Toxoplasma gondii. Three sample sets were circulated and analyzed by each laboratory following a previously published method that is based on fragment length polymorphism of 15 MS markers. The first sample set compared typing results in general and focused on effects of DNA concentration; the second sample set focused on the polymorphic fingerprinting markers that can differentiate T. gondii strains within the same archetypal lineage; and the third set focused on non-archetypal genotypes. Methodological variations between laboratories, including the software programs used to determine MS fragment length, were collated using a questionnaire. Overall, lineage-level typing results reached a high level of agreement, especially in samples with the highest DNA concentrations. However, laboratory-specific differences were observed for particular markers. Major median differences in fragment length, of up to 6 base pairs, were related to the fluorophore used to label fragment-specific primers. In addition, primer pairs with identical sequences obtained from different suppliers resulted in fragments of differing length. Furthermore, differences in the way the sequencing profiles were assessed and interpreted may have led to deviating results in fragment length determination. Harmonization of MS typing, for example, by using the same fluorophores or by numerical adjustments applied to the fragment-lengths determined, could improve the uniformity of the results across laboratories. This is the first interlaboratory comparison, providing guidelines (added as a supplement) for the optimization of this technique.

Direct detection and quantification of Toxoplasma gondii in meat samples from feral raccoons (Procyon lotor) in Germany by magnetic-capture real-time PCR

Because the number of wild raccoons in Germany is increasing constantly, it appears to be economic reasonable to use their meat as food. For this purpose, it is essential to generate data regarding the pathogen load of the meat to be consumed and handled. It is known that raccoons, particularly in Germany, show a high seroprevalence of Toxoplasma gondii. Because serological data only indicates contact of a host to a parasite additional direct detection is needed to prove presence of parasitic stages in particular tissues. Therefore, a total of 150 samples from raccoons with known serostatus were tested and quantified using magnetic-capture real-time PCR for Toxoplasma gondii. As it represents potentially consumption-relevant parts of raccoons, meat from forelimb and hindlimb was examined. Samples were stratified into three groups based on the animals' serostatus (each 50 negative, low positive, and high positive). All samples from seronegative animals were found negative by MC-PCR as well. In a total of 56 meat samples from 100 seropositive animals, T. gondii DNA was detected. Statistically significant more samples were positive by MC-PCR in the high positive than in the low positive serostatus group (38/50 vs. 18/50, p < 0.0001). Furthermore, samples from the former group were also found to have statistically significant higher DNA equivalent values compared to samples from the low positive serostatus group (p < 0.0001). These results suggest that meat from seropositive raccoons may contain considerable numbers of T. gondii presenting a potential public health risk for humans whilst handling and consumption.

Retrospective Molecular Survey on Bacterial and Protozoan Abortive Agents in Roe Deer (Capreolus capreolus) from Central Italy

Bacterial and protozoan agents can determine abortion and other reproductive disorders in domestic ruminants, but data regarding their occurrence in wild ruminants are scanty worldwide, including in Italy. The aim of this retrospective study was to verify the occurrence of the main bacterial and protozoan abortive agents in 72 spleen samples previously collected from roe deer (Capreolus capreolus) living in mountain areas of Central Italy. All samples were collected and submitted to DNA extraction for other investigations. Molecular analyses were carried out on the DNA samples to detect Brucella spp., Chlamydia abortus, Coxiella burnetii, Salmonella enterica, Listeria monocytogenes, Neospora caninum, and Toxoplasma gondii. Three (4.16%) roe deer resulted PCR positive for C. burnetii and one (1.38%) for T. gondii. These findings suggest that roe deer living in the investigated areas do not act as important reservoirs of the searched agents. However, the tested animals lived in a closed area without contact with domestic animals that are usually involved in the epidemiology of the investigated pathogens. Monitoring of wild ruminants is pivotal to verify changes in the epidemiological scenario from a One Health perspective, too.

Toxoplasma gondii in Foods: Prevalence, Control, and Safety

Toxoplasma gondii is an obligate intracellular parasite that causes toxoplasmosis, with approximately one third of the population around the world seropositive. The consumption of contaminated food is the main source of infection. These include meat products with T. gondii tissue cysts, and dairy products with tachyzoites. Recently, contamination has been detected in fresh products with oocysts and marine products. Despite the great health problems that are caused by T. gondii, currently there are no standardized methods for its detection in the food industry. In this review, we analyze the current detection methods, the prevalence of T. gondii in different food products, and the control measures. The main detection methods are bioassays, cell culture, molecular and microscopic techniques, and serological methods, but some of these do not have applicability in the food industry. As a result, emerging techniques are being developed that are aimed at the detection of multiple parasites simultaneously that would make their application more efficient in the industry. Since the prevalence of this parasite is high in many products (meat and milk, marine products, and vegetables), it is necessary to standardize detection methods, as well as implement control measures.

Standardised Sampling Approach for Investigating Pathogens or Environmental Chemicals in Wild Game at Community Hunts

Simple Summary

Wild game can host pathogens capable of infecting humans, livestock, and companion animals or accumulate environmental chemicals that may be transferred via food of animal origin. For food safety research, as well as for various other scientific purposes, the provision of a sufficient number of samples without unnecessary disturbance or killing of animals is a major limitation. With the presented approach, it was possible to obtain samples from game animals killed as part of standard ungulate management practice. Examples of organs, tissues, and other matrices that have been used in wild ungulate studies in Europe and that may be obtained through this approach are summarised as well. The basis of this approach was a framework agreement with the BImA, whereby federal forest officials carried out sampling with the help of hunters at drive hunts from 2017/18 to 2020/21 in Brandenburg, Germany. Numerous samples from four ungulate species were obtained. The number of sampled animals per hunt differed between hunting districts and hunting seasons. Districts with higher hunting bags also promise higher sampling success. This approach can serve as the basis for long-term monitoring of animal and public health threats associated with wildlife and is adaptable to other regions.

Abstract

Wildlife may host pathogens and chemicals of veterinary and public health relevance, as well as pathogens with significant economic relevance for domestic livestock. In conducting research on the occurrence and distribution of these agents in wildlife, a major challenge is the acquisition of a sufficient number of samples coupled with efficient use of manpower and time. The aim of this article is to present the methodology and output of a sampling approach for game animals, which was implemented from 2017/18 to 2020/21 at drive hunts in Brandenburg, Germany. The central element was a framework agreement with the BImA, whereby federal forest officials and other hunters collected most of the samples during field dressing. Further samples of game carcasses were obtained by scientists during subsequent gathering at a collection point. Altogether, 3185 samples from 938 wild ungulates of four species were obtained for various studies analysing—in this case—food-borne agents in game animals. Sampling was representative and reflected the proportional distribution of ungulate species hunted in Brandenburg. Hunting district and hunting season strongly influenced hunting bag and hence sampling success. This sampling approach was demonstrated to be a suitable basis for monitoring programs, that can be adapted to other regions.

Editorial for the Special Issue "Parasitic Diseases from Wild Animals with Emphasis on Zoonotic Infections"

The present Editorial intends to briefly describe the findings published in the Special Issue, "Parasitic diseases from wild animals with an emphasis on zoonotic infections". Prevalence data or diagnostic techniques were the focus of several zoonotic parasites transmitted from wildlife, including the protozoa Toxoplasma, Cryptosporidium, Giardia, Blastocystis and Leishmania, and the helminths Echinococcus and Anisakis.