Serological and molecular detection of Toxoplasma gondii in terrestrial and marine wildlife harvested for food in Nunavik, Canada

Seroprevalence and risk factors for Toxoplasma gondii exposure in Australian feral and stray cats using an in-house modified agglutination test

Toxoplasma gondii is a globally distributed zoonotic protist, capable of infecting all warm-blooded animals. In Australia, cats (Felis catus) are the only definitive host capable of spreading T. gondii infection via oocysts. Free-roaming cats are widespread in Australia and can play a central role in the ecology of T. gondii. Therefore, understanding the epidemiology of this parasite in stray and feral cats is essential to understanding the potential risk of infection in animals and humans. Due to a lack of easily accessible commercial kits, an in-house modified agglutination test (MAT) was established to test for IgG antibodies against T. gondii, using cell culture-derived T. gondii tachyzoites, and compared with a commercial MAT. A total of 552 serum samples collected during 2018 - 2021 from stray (n = 456) and feral cats (n = 90) (samples with missing data n = 6) from four Australian states, representing different age groups of both sexes, were screened for antibodies against T. gondii. Risk factors for T. gondii infection were assessed using multivariable logistic regression analysis. The in-house MAT had excellent agreement with the commercial MAT and provided a reliable and economical serological tool for T. gondii screening in animals. The overall observed seroprevalence for T. gondii in cats was 40.4 % (223/552). Bodyweight (as a proxy for age), geographical location, season and whether cats were feral or stray, were factors associated with T. gondii seropositivity in cats. Sex was not found to be a risk factor for T. gondii infection in feral and stray cats. This study shows that Australian stray and feral cats have a high T. gondii seroprevalence, which may translate to significant health impacts for wildlife species, livestock and the public.

The geographic distribution, and the biotic and abiotic predictors of select zoonotic pathogen detections in Canadian polar bears

Increasing Arctic temperatures are facilitating the northward expansion of more southerly hosts, vectors, and pathogens, exposing naïve populations to pathogens not typical at northern latitudes. To understand such rapidly changing host-pathogen dynamics, we need sensitive and robust surveillance tools. Here, we use a novel multiplexed magnetic-capture and droplet digital PCR (ddPCR) tool to assess a sentinel Arctic species, the polar bear (Ursus maritimus; n = 68), for the presence of five zoonotic pathogens (Erysipelothrix rhusiopathiae, Francisella tularensis, Mycobacterium tuberculosis complex, Toxoplasma gondii and Trichinella spp.), and observe associations between pathogen presence and biotic and abiotic predictors. We made two novel detections: the first detection of a Mycobacterium tuberculosis complex member in Arctic wildlife and the first of E. rhusiopathiae in a polar bear. We found a prevalence of 37% for E. rhusiopathiae, 16% for F. tularensis, 29% for Mycobacterium tuberculosis complex, 18% for T. gondii, and 75% for Trichinella spp. We also identify associations with bear age (Trichinella spp.), harvest season (F. tularensis and MTBC), and human settlements (E. rhusiopathiae, F. tularensis, MTBC, and Trichinella spp.). We demonstrate that monitoring a sentinel species, the polar bear, could be a powerful tool in disease surveillance and highlight the need to better characterize pathogen distributions and diversity in the Arctic.

Use of stable isotopes to reveal trophic relationships and transmission of a food-borne pathogen

Predators in food webs are valuable sentinel species for zoonotic and multi-host pathogens such as Toxoplasma gondii. This protozoan parasite is ubiquitous in warm-blooded vertebrates, and can have serious adverse effects in immunocompromised hosts and foetuses. In northern ecosystems, T. gondii is disproportionately prevalent in Inuit people and wildlife, in part due to multiple routes of transmission. We combined data on T. gondii infection in foxes from Nunavik (northern Québec, Canada) with stable isotope data tracking trophic relationships between foxes and several of their main prey species. Red (Vulpes vulpes) and Arctic fox (Vulpes lagopus) carcasses were collected by local trappers from 2015 to 2019. We used magnetic capture PCR to detect DNA of T. gondii in heart and brain tissues, and enzyme-linked immunosorbent assay to detect antibodies in blood. By linking infection status with diet composition, we showed that infected foxes had a higher probability of consuming aquatic prey and migratory geese, suggesting that these may be important sources of T. gondii transmission in the Arctic. This use of stable isotopes to reveal parasite transmission pathways can be applied more broadly to other foodborne pathogens, and provides evidence to assess and mitigate potential human and animal health risks associated with T. gondii in northern ecosystems.

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.

Toxoplasma gondii and related Sarcocystidae parasites in harvested caribou from Nunavik, Canada

Caribou are keystone species important for human harvest and of conservation concern; even so, much is unknown about the impact of parasites on caribou health and ecology. The aim of this study was to determine the seroprevalence, tissue prevalence, and diversity of tissue-dwelling coccidian parasites (including Toxoplasma gondii, Neospora caninum and Sarcocystis spp.) in 88 migratory caribou (Rangifer tarandus) harvested for human consumption in two communities in Nunavik, Québec, Canada. Both T. gondii and N. caninum have potential to cause abortions and neurological disease in caribou. Seroprevalence for antibodies to T. gondii using ELISA on fluid from thawed hearts was 18% overall, and no DNA of T. gondii was detected in tissues, which has positive implications for food safety since this parasite is zoonotic. Seroprevalence for antibodies to N. caninum using competitive ELISA was 5%, and DNA of N. caninum was detected in only one heart sample. DNA of Sarcocystis, a non-zoonotic, related coccidian, was detected in tissue samples from 85% of caribou, with higher prevalence in heart (82%) than skeletal muscle (47%). This is the first time that Sarcocystis spp. from caribou in Canada have been identified to species level, many of which have been described in reindeer from Fennoscandia. The high prevalence and diversity of Sarcocystis spp. suggests intact trophic relationships between canids and caribou in Nunavik. Besnoitia spp. was serendipitously detected in three muscle samples, a parasite previously associated with skin lesions in caribou in Nunavik. Community-level differences in T. gondii exposure and prevalence of Sarcocystis spp. in skeletal muscle tissues may reflect differences in hunter selection of individual animals and muscles, or possibly regional differences in the ecology of carnivore definitive hosts for these parasites. Further work is needed to explore effects of tissue coccidians in caribou, their taxonomic classifications, and community level differences in parasite prevalence and diversity.

Migratory Wild Birds as Potential Long-Distance Transmitters of Toxoplasma gondii Infection

Toxoplasma gondii is a worldwide distributed zoonotic protozoan capable of infecting a wide range of mammals (including humans) and birds as intermediate hosts. Migratory wild birds, through interconnecting countries along their flyways, can play a role in the spatial spread of T. gondii and could contribute to its sylvatic cycle. Additionally, hunted wild birds used for meat consumption could represent a further source of human infection. To determine the presence of T. gondii in wild birds, a total of 50 individuals belonging to the Anseriformes and Charadriiformes orders were sampled during the 2021–2022 hunting season in Northern Italy. Cardiac muscle samples of three Northern shovelers (Anas clypeata), two wild mallards (A. platyrhynchos), one Eurasian teal (A. crecca), and one Northern lapwing (Vanellus vanellus) were positive for the molecular detection of T. gondii based on a targeted amplification of the B1 gene. A 14% (7/50) overall positivity was observed in the sampled population. Results from this study suggest a moderate exposure of wild aquatic birds to T. gondii, highlighting the importance of a further characterization of T. gondii in its wildlife hosts.

Toxoplasma gondii in African Wildlife: A Systematic Review

Toxoplasma gondii (T. gondii) is a protozoan parasite, which infects a wide variety of mammals and bird species globally. In large parts of the world, this parasite is relatively well documented in wildlife species, however, this topic is poorly documented in Africa. The current review systematically explores the presence and distribution of T. gondii in African wildlife species through a key word search in PubMed, Web of Science and CAB Direct. A total of 66 records were identified and included in the qualitative analysis, of which 19 records were retained for the quantitative synthesis. The presence of T. gondii was reported in a wide range of wildlife species, found in twelve countries, spread over the African continent. The retained records report a prevalence range of 6-100% in herbivores, 8-100% in omnivores and 14-100% in carnivores. In wild felines (cheetahs, leopards, and lions) a prevalence range of 33-100% was found. Reports from South Africa, and on the presence of T. gondii in lion were most common. Overall, the results indicate the scarcity of information on T. gondii in Africa and its circulation in wildlife. The lack of knowledge on the parasite in Africa, especially in areas at the human-livestock-wildlife interface, prevents us from understanding how prevalent it is on the continent, what strains are circulating in wildlife and what the most common routes of transmission are in the different habitats in Africa.

Toxoplasmosis in Human and Animals Around the World. Diagnosis and Perspectives in the One Health Approach

Toxoplasmosis is a unique health disease that significantly affects the health of humans, domestic animals, wildlife and is present in ecosystems, including water, soil and food. Toxoplasma gondii is one of the best-adapted parasites in the word. This parasite is able to persist for long periods in its hosts, in different geographic regions of the word. This review summarizes the current literature of these themes, focusing on: (1) toxoplasmosis, a zoonotic infection; (2) One health approach and toxoplasmosis; (3) human toxoplasmosis; (4) animal toxoplasmosis; (5) toxoplasmosis diagnosis, as immunological, parasitological and molecular diagnosis; (6) T. gondii outbreaks caused by infected meat, milk and dairy products, as well as, vegetables and water consume; (7) studies in experimental models; (8) genetic characterization of T. gondii strains; (9) extracellular vesicles and miRNA; and (10) future perspectives on T. gondii and toxoplasmosis. The vast prevalence of toxoplasmosis in both humans and animals and the dispersion and resistence of T. gondii parasites in environment highlight the importance of the one health approach in diagnostic and control of the disease. Here the different aspects of the one health approach are presented and discussed.

Are foxes (Vulpes spp.) good sentinel species for Toxoplasma gondii in northern Canada?

BACKGROUND

In changing northern ecosystems, understanding the mechanisms of transmission of zoonotic pathogens, including the coccidian parasite Toxoplasma gondii, is essential to protect the health of vulnerable animals and humans. As high-level predators and scavengers, foxes represent a potentially sensitive indicator of the circulation of T. gondii in environments where humans co-exist. The objectives of our research were to compare serological and molecular assays to detect T. gondii, generate baseline data on T. gondii antibody and tissue prevalence in foxes in northern Canada, and compare regional seroprevalence in foxes with that in people from recently published surveys across northern Canada.

METHODS

Fox carcasses (Vulpes vulpes/Vulpes lagopus, n = 749) were collected by local trappers from the eastern (Labrador and Québec) and western Canadian Arctic (northern Manitoba, Nunavut, and the Northwest Territories) during the winters of 2015-2019. Antibodies in heart fluid were detected using a commercial enzyme-linked immunosorbent assay. Toxoplasma gondii DNA was detected in hearts and brains using a magnetic capture DNA extraction and real-time PCR assay.

RESULTS

Antibodies against T. gondii and DNA were detected in 36% and 27% of foxes, respectively. Detection of antibodies was higher in older (64%) compared to younger foxes (22%). More males (36%) than females (31%) were positive for antibodies to T. gondii. Tissue prevalence in foxes from western Nunavik (51%) was higher than in eastern Nunavik (19%). At the Canadian scale, T. gondii exposure was lower in western Inuit regions (13%) compared to eastern Inuit regions (39%), possibly because of regional differences in fox diet and/or environment. Exposure to T. gondii decreased at higher latitude and in foxes having moderate to little fat. Higher mean infection intensity was observed in Arctic foxes compared to red foxes. Fox and human seroprevalence showed similar trends across Inuit regions of Canada, but were less correlated in the eastern sub-Arctic, which may reflect regional differences in human dietary preferences.

CONCLUSIONS

Our study sheds new light on the current status of T. gondii in foxes in northern Canada and shows that foxes serve as a good sentinel species for environmental circulation and, in some regions, human exposure to this parasite in the Arctic.

A Field-Deployable Insulated Isothermal PCR (iiPCR) for the Global Surveillance of Toxoplasma gondii Infection in Cetaceans

Simple Summary

Since high trophic levels marine mammal species share the coastal environments and diets with humans, cetaceans provide an indication of contaminant bioaccumulation in humans and may serve as sentinels for public health problems. Parasite monitoring in marine sentinels can assist in evaluating the quality of the aquatic ecosystem’s health. T. gondii infection in cetaceans is an indicator of land-to-sea coastal pollution. Although T. gondii infection cases in cetaceans have been reported in several countries, an information gap still exists in some areas. The present study employs a portable insulated isothermal PCR (iiPCR) with an automatic extraction device as a rapid, affordable, user-friendly, and field-deployable platform to rapidly detect nucleic acid of T. gondii in stranded cetaceans. The platform utilizes duplex iiPCR designed to simultaneously detect T. gondii and a housekeeping gene of cetacean on the samples, which can prevent the false-negative results of pathogen detection and improve the accuracy of surveillance. This study would contribute to improving the environment through the warning of the sentinel animals and building new strategies by detecting the occurrence of land-based biological pollution.

Abstract

Toxoplasmosis is a zoonotic disease with veterinary and public health importance worldwide. Toxoplasma gondii infection in cetaceans is an indicator of land-to-sea oocyst pollution. However, there is a critical knowledge gap within the distribution of the T. gondii infection in cetaceans. To facilitate the global surveillance of this important zoonotic pathogen, we developed a field-deployable duplex insulated isothermal PCR (iiPCR) with automated magnetic bead-based DNA extraction for the on-site detection of T. gondii in stranded cetaceans. It targets the B1 gene of T. gondii combined with β2-microglobulin (B2M) gene of cetaceans as an internal control. Compared with the conventional qPCR assay, B1/B2M duplex iiPCR assay showed comparable sensitivity (21~86 bradyzoites in 25 mg of tissue) to detect spike-in standard of T. gondii DNA in cerebrum, cerebellum, skeletal muscle and myocardium tissues. Moreover, the overall agreement between the duplex iiPCR and qPCR was in almost perfect agreement (92%; 95% CI: 0.78–0.90; κ = 0.84) in detecting a synthetic spike-in standards. The B1/B2M iiPCR assay coupled with a field-deployable system provides a prompt (~1.5 h), feasible, highly sensitive and specific on-site diagnostic tool for T. gondii in stranded cetaceans. This platform provides one approach to evaluating aquatic ecosystem health and developing early warnings about negative impacts on humans and marine animals.

Long-term increases in pathogen seroprevalence in polar bears (Ursus maritimus) influenced by climate change

The influence of climate change on wildlife disease dynamics is a burgeoning conservation and human health issue, but few long-term studies empirically link climate to pathogen prevalence. Polar bears (Ursus maritimus) are vulnerable to the negative impacts of sea ice loss as a result of accelerated Arctic warming. While studies have associated changes in polar bear body condition, reproductive output, survival, and abundance to reductions in sea ice, no long-term studies have documented the impact of climate change on pathogen exposure. We examined 425 serum samples from 381 adult polar bears, collected in western Hudson Bay (WH), Canada, for antibodies to selected pathogens across three time periods: 1986-1989 (n = 157), 1995-1998 (n = 159) and 2015-2017 (n = 109). We ran serological assays for antibodies to seven pathogens: Toxoplasma gondii, Neospora caninum, Trichinella spp., Francisella tularensis, Bordetella bronchiseptica, canine morbillivirus (CDV) and canine parvovirus (CPV). Seroprevalence of zoonotic parasites (T. gondii, Trichinella spp.) and bacterial pathogens (F. tularensis, B. bronchiseptica) increased significantly between 1986-1989 and 1995-1998, ranging from +6.2% to +20.8%, with T. gondii continuing to increase into 2015-2017 (+25.8% overall). Seroprevalence of viral pathogens (CDV, CPV) and N. caninum did not change with time. Toxoplasma gondii seroprevalence was higher following wetter summers, while seroprevalences of Trichinella spp. and B. bronchiseptica were positively correlated with hotter summers. Seroprevalence of antibodies to F. tularensis increased following years polar bears spent more days on land, and polar bears previously captured in human settlements were more likely to be seropositive for Trichinella spp. As the Arctic has warmed due to climate change, zoonotic pathogen exposure in WH polar bears has increased, driven by numerous altered ecosystem pathways.

Analysis of seroprevalence data on Hepatitis E virus and Toxoplasma gondii in wild ungulates for the assessment of human exposure to zoonotic meat-borne pathogens

Seroprevalence data for Toxoplasma gondii and Hepatitis E virus (HEV) in wild boar (Sus scrofa), roe deer (Capreolus capreolus), red deer (Cervus elaphus), mouflon (Ovis aries/musimon) and chamois (Rupicapra rupicapra) hunted/culled in northern Italy were used to fit seroprevalence distributions describing the exposure and co-exposure of the species to the two pathogens. The higher proportion of T. gondii and HEV seropositive animals was observed in wild boars with point estimate seroprevalence of 49% (N = 331) and 15% (N = 326) respectively. Data allowed comparisons by area (pre-Alpine Vs Alpine environment) for roe deer, red deer and mouflons. Contrasts between the distributions describing the uncertainty in seroprevalence suggest roe deer, red deer and mouflons have higher probability of being seropositive to T. gondii in pre-Alps. When considering HEV, few seropositive animals were detected and contrasts were symmetrically centred to zero for roe deer and red deer; mouflons shown higher probability of being seropositive in Alpine environment. HEV seropositive animals also included chamois (P = 5.1%, N = 97) in the Alpine districts, confirming circulation of HEV in remote areas. Evidence of HEV and T. gondii co-exposure was limited except for wild boars where it was observed in 30 samples representing 60% of the overall HEV-positive samples. Seroprevalence data of single infection and co-infection are extremely useful to investigate circulation of zoonotic pathogens in wild animals and estimate the foodborne risk of human exposure, however, these type of data do not directly translate into the presence/absence of the pathogen in seropositive and seronegative animals. At benefit of future development of quantitative risk assessments aiming at estimating the risk of human infection/co-infection via consumption of game meat, we developed and made available an online application that allows estimating the probability of the pathogen(s) being present as a function of seroprevalence data.

Epidemiology associated with the exposure to Toxoplasma gondii in Nunavik's Inuit population using the 2017 Qanuilirpitaa cross-sectional health survey

Foci of high seroprevalence against Toxoplasma gondii are observed in Nunavik, the Inuit land of Northern Quebec (Canada). Considering the rare occurrence of felids in the region, exposure is suspected to be driven by water- and food-borne transmission routes. Hypotheses were that drinking untreated water from natural sources and eating country food mostly raw increased the risk of exposure to the parasite. Data from 1,300 Inuit participants of the 2017 Nunavik Health Survey were included in three weighted robust Poisson regression models. The effect of three types of exposure variables: (1) water treatment (yes/no) and if country food was mostly eaten raw (yes/no); (2) main source of drinking water (bottled/municipal/natural) and frequency of country food consumption (continuous) and (3) drinking water risk (low/intermediate/high) and frequency of a raw country food consumption (continuous), on the presence of Toxoplasma antibodies were estimated. Models were adjusted for age, sex and ecological region, with multiple sensitivity analyses being performed. Toxoplasma gondii seroprevalences were consistently correlated with age quadratically, sex (prevalence ratio = PR_woman/man ranged from 1.18 to 1.22), ecological region (PR_{HudsonBay/HudsonStrait} ranged from 2.18 to 2.41; PR_{HudsonBay/UngavaBay} ranged from 1.52 to 1.59) and consuming bivalve mollusc/urchin (PR varied from 1.02 to 1.21) across all three models. Each increase of two consumptions per month of beluga (PR ranged from 1.01 to 1.03), seal liver (PR ranged from 1.01 to 1.02) and goose (PR ranged from 1.01 to 1.02) were also associated with seropositivity, albeit more clearly in models 2 and 3, while drinking water mainly from natural (PR of 1.47) or municipal (PR = 1.42) sources compared to bottled water, was correlated with seroprevalence, although results were compatible with the null. Our results suggest that both the oocyst- (mollusc/urchin, drinking water) and cyst-borne (walrus, seal liver and goose) transmission pathways could be present in Nunavik.

Epidemiologic and Public Health Significance of Toxoplasma gondii Infections in Venison: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The ingestion of food or water contaminated with oocysts excreted by infected cats or ingestion of uncooked or undercooked meat containing tissue cysts of T. gondii are the 2 major modes of transmission of T. gondii. Deer are a popular game. Recently, outbreaks of clinical toxoplasmosis were reported in humans in North America linked to ingestion of undercooked venison. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and public health risks of T. gondii infections in deer and other cervids for the past decade. Estimates of worldwide serological prevalence are summarized individually for each species of deer, elk, moose, and caribou. Genetic diversity of 112 viable isolates of T. gondii from cervids is discussed, including its public health significance. Prevalence of T. gondii in deer is very high. Any part of a deer, including liver, spleen, and muscles, should be cooked thoroughly before human consumption.

Clams and potential foodborne Toxoplasma gondii in Nunavut, Canada

The prevalence of Toxoplasma gondii exposure in Inuit living in Nunavut (20%) is twice that of the US (11%); however, routes of exposure for Inuit communities in North America are unclear. Exposure to T. gondii in humans has been linked with consumption of raw or undercooked shellfish that can accumulate environmentally resistant oocysts. Bivalve shellfish, such as clams, are an important, nutritious, affordable and accessible source of food in many Northern Communities. To date, presence of T. gondii in clams in Northern Canada has not been reported. In this study, we tested for T. gondii presence in clams (Mya truncata) that were harvested in Iqaluit, Nunavut over a 1-week period in September 2016. Of 390 clams, eight (2.1%) were confirmed to contain T. gondii DNA (≥99.7% identity), as determined using polymerase chain reaction (PCR) and sequence confirmation. Additionally, three clams (0.8%) were confirmed to contain Neospora caninum-like DNA (≥99.2% identity). While N. caninum is not known to be a zoonotic pathogen, its presence in shellfish indicates contamination of the nearshore with canid faeces, and the potential for marine mammal exposure through marine food webs. Notably, the PCR assay employed in this study does not discriminate between viable and non-viable parasites. These findings suggest a possible route for parasite exposure through shellfish in Iqaluit, Nunavut. Future research employing viability testing will further inform public health messaging on the infectious potential of T. gondii in shellfish.

Seroprevalence and risk factors of Toxoplasma gondii infection in wild ungulates that cohabit in a natural park with human-animal interaction in the Mediterranean ecosystem

The possibility of Toxoplasma gondii transmitted from game meat to humans is of public health concern. Here we determined seroprevalence and risk factors associated with T. gondii in large game ungulates that cohabit in Sierras de Cazorla, Segura and Las Villas Natural Park (SCSV-NP) (Southern Spain), a natural park with high human-animal interaction. Antibodies against T. gondii in 328 wild ungulates were assayed by the modified agglutination test (MAT ≥ 1:25). Antibodies were found in 39 (11.9%, 95% CI: 8.4-15.4) wild ungulates, with seroprevalence levels of 20.8% in wild boars (Sus scrofa) (5/24), 19.0% in fallow deer (Dama dama) (12/63), 13.9% in Iberian ibex (Capra pyrenaica hispanica) (14/101), 7.9% in red deer (Cervus elaphus) (6/76), and 3.1% in mouflons (Ovis aries musimon) (2/64). Significantly higher seroprevalence was observed in fallow deer and wild boars compared to mouflons. Animals living close to urban areas (<2 km) had 4.6-times higher risk compared to those living at >5 km of urban areas. The results indicate high circulation of T. gondii in wild ungulates in SCSV-NP, which is of animal and public health concern. The increased seroprevalence of T. gondii detected in wildlife ungulates living close to urban areas may increase human infection in those areas if meat from infected animals is consumed raw or undercooked.

Molecular prevalence, risk factors and genotypes of Toxoplasma gondii DNA in wild marine snails collected from offshore waters in eastern China

Increasing evidence exisits for the role that shellfish play in the epidemiology of Toxoplasma gondii in marine environment. However, limited information is available on the level of T. gondii infection in wild marine snails, which can play a role in the transmission of T. gondii to other marine organisms and humans. In this study, the prevalence of T. gondii DNA in wild marine snails collected from three coastal cities in China was determined. Between January 2018 and November 2019, 1,206 wild marine snails were randomly collected and examined for the presence of T. gondii DNA using a nested polymerase chain reaction (PCR) targeting T. gondii B1 gene. The amplified products were genotyped using multilocus PCR-restriction fragment length polymorphism analysis. We also examined whether species of snail, sampling region, sampling season, surface runoff near samplic site, residential water discharge near samplic site, and proximity to livestock farms are associated with the occurrence of T. gondii DNA in marine snails. Our results showed that 23 (1.91%) snails were positive for T. gondii B1 gene. The genotype of two of the 23 T. gondii amplicons was consistent with ToxoDB Genotype #9. Multiple logistic regression revealed that surface runoff near the sampling site (P = 0.039, odds ratio [OR] = 3.413, 95% confidence interval [CI]: 1.07-10.94) and residential water discharge near the sampling site (P = 0.021, OR = 3.990, 95%CI: 1.24-12.87) are more likely to be associated with the presence of T. gondii DNA in marine snails. The detection of T. gondii DNA in marine snails in China highlights the potential impact of the anthropogenic activities on marine organisms and the potential foodborne risk posed to humans with such an important terrestrial pathogen.

Epidemiologic significance of Toxoplasma gondii infections in turkeys, ducks, ratites and other wild birds: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Wild and domestic avian species are important in the epidemiology of T. gondii infections because felids prey on them and excrete millions of oocysts in the environment, disseminating the infection. Herbivorous birds are also excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Toxoplasma gondii infections in birds of prey reflect infections in intermediate hosts. Humans can become infected by consuming undercooked avian tissues. Here, the authors reviewed prevalence, persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from turkeys, geese, ducks, ratites and avian species (excluding chickens) worldwide 2009-2020. Genetic diversity of 102 T. gondii DNA samples isolated worldwide is discussed. The role of migratory birds in dissemination of T. gondii infection is discussed.

Exposure of the Gulf of St. Lawrence grey seal Halichoerus grypus population to potentially zoonotic infectious agents

The population of grey seals Halichoerus grypus in Canadian waters is currently used as a commercial source of meat for human consumption. As with domestic livestock, it is important to understand the occurrence in these seals of infectious agents that may be of public health significance and thus ensure appropriate measures are in place to avoid zoonotic transmission. This study examined the prevalence of antibodies against Brucella spp., Erysipelothrix rhusiopathiae, 6 serovars of Leptospira interrogans, and Toxoplasma gondii in 59 grey seals and determined by polymerase chain reaction (PCR) the presence of these potentially zoonotic agents in specific organs and tissues of seropositive animals. The presence of encysted Trichinella spp. larvae was also investigated by digestion of tongue, diaphragm and other muscle samples, but none were detected. Seroprevalence against Brucella spp. and E. rhusiopathiae was low (5 and 3%, respectively). All 59 seals tested had antibodies against L. interrogans, but no carrier of this bacterium was detected by PCR. Seroprevalence against T. gondii was 53%, and DNA of this protozoan was detected by PCR in 11/30 (37%) seropositive animals. Standard sanitary measures mandatory for commercialization of meat products for human consumption should greatly reduce the potential for exposure to these infectious agents. However, special consideration should be given to freezing seal meat for at least 3 d to ensure destruction of tissue cysts of T. gondii.

Fatal toxoplasmosis in wild European brown hares (Lepus europaeus) in tularaemia endemic areas of the Czech Republic: Poses risk of infection for humans?

Toxoplasma gondii may cause fatal infection in European brown hares (Lepus europaeus). However, the role of this parasite in terms of mortality rate in tularaemia endemic areas, amount of parasites in affected organs and circulating genotypes, is still unknown. In total, 36 hares (killed or found dead) were submitted for pathomorphological examination as a part of the national tularaemia and brucellosis monitoring. Tissue samples (lung, heart, liver, spleen and kidney) were tested by quantitative real-time PCR targeting 529 bp region of T. gondii. Genotyping was performed by a 15 microsatellite markers method in a single multiplex PCR assay. The same tissues of hares were simultaneously used for the bacteriological cultivation. Toxoplasma gondii was detected by qPCR in the tissues of two hares. Spleen and lungs of one infected hare have been found harbouring up to ~7 millions of T. gondii parasites per gram of tissue. Both positive samples were characterized as T. gondii type II, one archetypal clonal type II and the other one a type II variant (W35 = 244). Bacteria Francisella tularensis was proved in pooled samples of three hares but without coinfection with T. gondii; all hares were negative for Brucella suis. Toxoplasma gondii has significant impact on mortality of European brown hares in tularaemia endemic areas and parasite load within the animal tissues may present high risk of human infection.

Recent epidemiologic and clinical importance of Toxoplasma gondii infections in marine mammals: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. T. gondii causes mortality in several species of marine mammals, including threatened Southern sea otters (Enhydra lutris) and endangered Hawaiian monk seals (Monachus schauinslandi). Marine mammals are now considered sentinels for environmental exposure to protozoan agents contaminating marine waters, including T. gondii oocysts. Marine mammals also serve as food for humans and can result in foodborne T. gondii infections in humans. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, and genetic diversity of T. gondii infecting marine mammals in the past decade. The role of genetic types of T. gondii and clinical disease is discussed.

Multi-pathogen serological survey of migratory caribou herds: A snapshot in time

Pathogens can impact host survival, fecundity, and population dynamics even when no obvious disease is observed. Few baseline data on pathogen prevalence and diversity of caribou are available, which hampers our ability to track changes over time and evaluate impacts on caribou health. Archived blood samples collected from ten migratory caribou herds in Canada and two in Greenland were used to test for exposure to pathogens that have the potential to effect population productivity, are zoonotic or are emerging. Relationships between seroprevalence and individual, population, and other health parameters were also examined. For adult caribou, the highest overall seroprevalence was for alphaherpesvirus (49%, n = 722), pestivirus (49%, n = 572) and Neospora caninum (27%, n = 452). Lower seroprevalence was found for parainfluenza virus type 3 (9%, n = 708), Brucella suis (2%, n = 758), and Toxoplasma gondii (2%, n = 706). No animal tested positive for antibodies against West Nile virus (n = 418) or bovine respiratory syncytial virus (n = 417). This extensive multi-pathogen survey of migratory caribou herds provides evidence that caribou are exposed to pathogens that may have impacts on herd health and revealed potential interactions between pathogens as well as geographical differences in pathogen exposure that could be linked to the bio-geographical history of caribou. Caribou are a keystone species and the socio-economic cornerstone of many indigenous cultures across the North. The results from this study highlight the urgent need for a better understanding of pathogen diversity and the impact of pathogens on caribou health.

Comparison of tissues (heart vs. brain) and serological tests (MAT, ELISA and IFAT) for detection of Toxoplasma gondii in naturally infected wolverines (Gulo gulo) from the Yukon, Canada

Toxoplasmosis is an important parasitic zoonosis worldwide. Many human and animal surveys use serological assays based on Toxoplasma gondii antibody detection in serum, a matrix that is not routinely available from wildlife. Commonly used serological assays have rarely been validated for use with fluids other than serum, nor validated for their performance in wildlife species. New molecular assays, such as magnetic capture DNA extraction and real-time PCR (MC-qPCR), offer high sensitivity for detection of T. gondii DNA in tissues. The aims of this study were to (1) assess prevalence of T. gondii DNA based on MC-qPCR detection in brain and heart of naturally infected wolverines (Gulo gulo) from the Yukon, Canada (2) compare two matrices [heart fluid (collected from thawed heart) and filter eluate (eluted from blood soaked filter paper)] for antibody detection in the same species, and (3) evaluate the performance of three serological tests [modified agglutination test (MAT), enzyme linked immunosorbent assay (ELISA) and indirect fluorescent antibody test (IFAT)] to detect naturally infected wolverines as determined by MC-qPCR. DNA of T. gondii was detected in heart and/or brain in 16 of 68 wolverines (24%, 95% CI: 15.0-34.8). Tissue prevalence and infection intensity was higher in heart [16 positives, mediantachyzoites equivalents per gram (TEG) =1221] compared to brain (10 positives, median TEG = 347). Heart fluid (HF) and filter eluates (FE) performed equally well in ELISA and IFAT in terms of relative sensitivity, but HF performed better with MAT. ELISA and IFAT had higher relative sensitivity (94%) and relative specificity (100%) compared to MAT (relative sensitivity 75% and relative specificity 92%). Overall, our findings indicate that the parasite burden in naturally infected wolverines was higher in heart compared to brain, heart fluid performed better than filter paper eluate for serological testing using MAT, and both IFAT and ELISA had higher relative sensitivity, relative specificity, and accuracy compared to MAT.