Sero-prevalence and risk factors of Toxoplasma gondii infection in wild cervids in Denmark

Seroprevalence of Toxoplasma gondii Infection in Wild Boar (Sus scrofa) and Korean Water Deer (Hydropotes inermis argyropus) in the Republic of Korea

Toxoplasma gondii is a ubiquitous zoonotic parasite with a wide range of warm-blooded animals as intermediate hosts, where the transmission primarily occurs through ingesting T. gondii oocysts in the environment. Hence, animals inhabiting a wide geographical range can be sentinels for the environmental contamination of T. gondii oocysts. The aim of this study was to determine the seroprevalence of T. gondii in two generalist ungulates in the Republic of Korea (ROK), wild boar (Sus scrofa) and Korean water deer (Hydropotes inermis argyropus), and identify the risk factors associated with this infection. Commercial ELISA kits confirmed a seroprevalence of 34.9% in wild boar (170/487, 95% CI: 30.7-39.3%) and 29.9% in Korean water deer (135/452, 95% CI: 25.7-34.3%). In both species, the seroprevalence was highest in winter, and showed no sex-related differences. In wild boars, the seroprevalence showed steep reduction in 2020 and increased with body mass. Meanwhile, in Korean water deer, seroprevalence did not show significant association with any of the tested variables, although an increase in seroprevalence was observed in 2020 compared to previous years. This study documents the widespread yet heterogeneous nature of T. gondii prevalence in its intermediate host population. Hence, the constant monitoring of T. gondii prevalence in its host species, both definitive and intermediate, while simultaneously considering risk factors would be necessary to identify the drivers behind the fluctuating pattern of T. gondii prevalence.

Seroprevalence of infectious pathogens of zoonotic and veterinary importance in wild ruminants from Slovenia

Introduction

Wildlife represents an increasingly important source of pathogens of medical and veterinary importance. Surveillance in wildlife offers an insight on current epidemiological status of selected pathogens and help to prevent spillovers to humans and livestock.

Material and methods

Our study included 312 wild ruminants belonging to five species: Roe deer (n = 134), red deer (n = 113), Alpine chamois (n = 53), European mouflon (n = 10) and Alpine ibex (n = 2). Seven pathogens that may have profound effect on human/livestock health and economic viability of the farms were tested using serological methods.

Results

Antibodies against Toxoplasma gondii, Neospora caninum, Coxiella burnetii, Brucella spp., Chlamydophila abortus, Mycobacterium avium subsp. paratuberculosis (MAP) and Mycobacterium bovis were detected in 34.62% (108/312), 0.96% (3/312), 2.24% (7/312), 0, 0.96% (3/312), 0, 0.64% (2/312) of animals tested, respectively. Because of low prevalences, risk factors were assessed only for T. gondii. Sex (female>male) and species (roe deer>red deer, roe deer>Alpine chamois) were significantly associated with the T. gondii positive outcome, while age was not.

Discussion

Adult males had the lowest T. gondii prevalence which offers future research opportunities. The lower seroprevalence of most investigated pathogens suggests game meat, if properly cooked, as being relatively safe for human consumption. This is the first study investigating the seroprevalence and associated risk factors of selected pathogens in wild ruminants in Slovenia.

Drivers of infection with Toxoplasma gondii genotype type II in Eurasian red squirrels (Sciurus vulgaris)

BACKGROUND

In September 2014, there was sudden upsurge in the number of Eurasian red squirrels (Sciurus vulgaris) found dead in the Netherlands. High infection levels with the parasite Toxoplasma gondii were demonstrated, but it was unclear what had caused this increase in cases of fatal toxoplasmosis. In the present study, we aimed to gain more knowledge on the pathology and prevalence of T. gondii infections in Eurasian red squirrels in the Netherlands, on the T. gondii genotypes present, and on the determinants of the spatiotemporal variability in these T. gondii infections. The presence of the closely related parasite Hammondia hammondi was also determined.

METHODS

Eurasian red squirrels that were found dead in the wild or that had died in wildlife rescue centres in the Netherlands over a period of seven years (2014-2020) were examined. Quantitative real-time polymerase chain reaction was conducted to analyse tissue samples for the presence of T. gondii and H. hammondi DNA. Toxoplasma gondii-positive samples were subjected to microsatellite typing and cluster analysis. A mixed logistic regression was used to identify climatic and other environmental predictors of T. gondii infection in the squirrels.

RESULTS

A total of 178 squirrels were examined (49/178 T. gondii positive, 5/178 H. hammondi positive). Inflammation of multiple organs was the cause of death in 29 squirrels, of which 24 were also T. gondii polymerase chain reaction positive. Toxoplasma gondii infection was positively associated with pneumonia and hepatitis. Microsatellite typing revealed only T. gondii type II alleles. Toxoplasma gondii infection rates showed a positive correlation with the number of days of heavy rainfall in the previous 12 months. Conversely, they showed a negative association with the number of hot days within the 2-week period preceding the sampling date, as well as with the percentage of deciduous forest cover at the sampling site.

CONCLUSIONS

Toxoplasma gondii infection in the squirrels appeared to pose a significant risk of acute mortality. The T. gondii genotype detected in this study is commonly found across Europe. The reasons for the unusually high infection rates and severe symptoms of these squirrels from the Netherlands remain unclear. The prevalence of T. gondii in the deceased squirrels was linked to specific environmental factors. However, whether the increase in the number of dead squirrels indicated a higher environmental contamination with T. gondii oocysts has yet to be established.

Toxoplasma gondii seroprevalence in reindeer (Rangifer tarandus tarandus L.) in northern Sweden: a cross-sectional study from 2014

BACKGROUND

Toxoplasma gondii is a parasitic protozoan that can infect a wide range of warm-blooded animals, including humans. The infection with T. gondii, is of particular concern due to its potential impact on human and animal health. In Sweden, semi-domesticated reindeer (Rangifer tarandus tarandus L.) is an important species both economically and culturally, but susceptibility to Toxoplasma infection and seroprevalence in reindeer herds remain relatively understudied.

RESULTS

A total of 528 reindeer, sampled at two slaughterhouses in Sweden in 2014, were investigated for antibodies to T. gondii. Specific antibodies to T. gondii were found in 5 of 209 (2.3%) tested adult reindeer and in 6 of 308 (1.9%) tested calves, giving an apparent total prevalence of 2.1% (95% confidence interval 1.1-3.8%). None of four putative risk factors studied (sex, age, type of grazing area, county) were statistically associated with T. gondii seroprevalence.

CONCLUSIONS

Swedish semi-domesticated reindeer are exposed to T. gondii and may harbour infectious tissue cysts. To mitigate the risk of T. gondii infection in consumers, reindeer meat should be frozen or cooked thoroughly before consumption. The global climate change may influence the seroprevalence and possible associated risk factors for T. gondii in reindeer. To be able to manage the risk and get better advice to the consumers there is a need for further investigations covering the whole spectra of herding conditions for reindeer.

Estimating parasite-condition relationships and potential health effects for fallow deer (Dama dama) and red deer (Cervus elaphus) in Denmark

Parasites can exert a substantial influence on the ecology of wildlife populations by altering host condition. Our objectives were to estimate single and multiparasite-condition relationships for fallow deer (Dama dama) and red deer (Cervus elaphus) in Denmark and to assess potential health effects along the parasite burden gradient. Fallow deer hosted on average two endoparasite taxa per individual (min = 0, max = 5) while red deer carried on average five parasite taxa per individual (min = 2, max = 9). Body condition of both deer species was negatively related to presence of Trichuris ssp. eggs while body condition of red deer was positively related to antibodies of the protozoan Toxoplasma gondii. For the remaining parasite taxa (n = 12), we either found weak or no apparent association between infection and deer body condition or low prevalence levels restricted formal testing. Importantly, we detected a strong negative relationship between body condition and the sum of endoparasite taxa carried by individual hosts, a pattern that was evident in both deer species. We did not detect systemic inflammatory reactions, yet serology revealed reduced total protein and iron concentrations with increased parasite load in both deer species, likely due to maldigestion of forage or malabsorption of nutrients. Despite moderate sample sizes, our study highlights the importance of considering multiparasitism when assessing body condition impacts in deer populations. Moreover, we show how serum chemistry assays are a valuable diagnostic tool to detect subtle and sub-clinical health impacts of parasitism, even at low-level infestation.

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.

Comparison of a commercial ELISA and indirect hemagglutination assay with the modified agglutination test for detection of Toxoplasma gondii antibodies in giant panda (Ailuropoda melanoleuca)

Toxoplasma gondii is a worldwide-distributed zoonotic protozoan parasite which causes toxoplasmosis and has a significant effect on public health. In the giant panda (Ailuropoda melanoleuca), toxoplasmosis can cause asymptomatic infections, reproductive disorder and even death, which poses a serious threat to the conservation of this rare protected species. Therefore, serological investigation of T. gondii is essential to understanding its risk to giant pandas, however, there are no specific testing kits for giant pandas. Previous research has used MAT as the reference method for screening T. gondii, to investigate this further, this study focused on the agreement comparing of MAT with ELISA and IHA tests for detecting T. gondii antibodies in 100 blood samples from 55 captive giant pandas in Chengdu, China. The results showed 87.0%, 87.0%, 84.0%, samples were sero-positive for T. gondii using ELISA (kits a, b, c), respectively, while MAT and IHA tests were 84.0% and 9.0% sero-positive, respectively. There was no significant difference between MAT and the three ELISA kits and these two methods had substantial agreement (0.61 < қ ≤ 0.80). Meanwhile, there was a significant difference (P < 0.001) between MAT and IHA, and these two methods had only a slight agreement (қ ≤ 0.20). The relative sensitivity of the ELISA (kits a, b, c) were 89.0%, 91.5% and 95.1%, and the specificity were 86.7%, 80.0% and 80.0%, respectively, which showed these three ELISA kits all had great accuracy. It is suggested that MAT is the recommended test method for primary screening T. gondii in giant pandas and then verified by ELISA.

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It's the first report to compare the agreement of the three test kits for detecting T. gondii antibodies in giant panda.

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No significant difference and substantial agreement between MAT and ELISA, slight agreement, meanwhile, the contrary result between MAT and IHA.

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The relative sensitivity of ELISA kits was 89%, 91.5% and 95.1%, and the specificity was 86.7%, 80% and 80%, respectively.

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The two commonly used commercial MAT and ELISA kits tested were valuable tools for T. gondii diagnosis for giant panda.