Seroprevalence of anti-Toxoplasma gondii antibodies in wild boars (Sus scrofa), hunting dogs, and hunters of Brazil

Toxoplasma gondii infection in European brown hares (Lepus europaeus) in Brazil

Toxoplasmosis is a worldwide zoonosis that affects warm-blooded animals, including humans. Wild animals can act as intermediate hosts of this pathogen; thus, this study aims to detect Toxoplasma gondii infection in invasive European brown hares in Brazil. For this, 72 wild European brown hares were captured from July 2020 to June 2022 in three Brazilian states: São Paulo, Paraná, and Rio Grande do Sul. The diagnostic of Toxoplasma gondii infection was performed by bioassay in mouse, histopathology in Hematoxylin-Eosin-stained tissue sections (brain, liver, lungs, kidneys, and small intestine), serology by IFAT, and molecular techniques by conventional PCR and qPCR. The combined prevalence of the different diagnostic methods was 51.4% (37/72, CI= 40.1 - 62.6 %), and there was no statistical difference between sexes, age range, or geographical region of the hosts. Mouse bioassay was the technique that detected more positive hares. To our knowledge, this is the first confirmation of Toxoplasma gondii infection in invasive European brown hares in Brazil. These animals act as reservoirs and potential infection source for carnivores and other wild and domestic animals, including humans, thus contributing to perpetuate the disease cycle in São Paulo, Paraná, and Rio Grande do Sul States. Research such as the present study is necessary to raise awareness about the role of animals in the disease cycle.

One Health at gunpoint: Impact of wild boars as exotic species in Brazil - A review

Wild boars have been listed among the 100 most invasive species worldwide, spreading impacts to all continents, with the exception of Antarctica. In Brazil, a major source of introduction was a commercial livestock importation for exotic meat market, followed by successive escapes and releases to natural ecosystems. Currently found in all six Brazilian biomes, with reports in 11 Brazilian states, wild boars have invaded natural and agricultural areas. Wild boars have been reportedly indicated as hosts and reservoirs of several zoonotic diseases in Brazil, including toxoplasmosis, salmonelosis, leptospirosis, brucellosis, tuberculosis, trichinellosis, and hepatitis E. Wild boars have been also associated with Brazilian spotted fever and rabies, infected while providing plentiful exotic blood supply for native ticks and hematophagous bats. Due to their phylogenetic proximity, wild boars may present ecological niche overlapping and direct disease risk to native white-lipped and collared peccaries. Moreover, wild boars may post an economical threat to Brazilian livestock industry due to restrictive diseases such as Aujeszky, enzootic pneumonia, neosporosis, hemoplasmosis, and classic swine fever. Finally, wild boars have directly impacted in environmentally protected areas, silting up water springs, rooting and wallowing native plants, decreasing native vegetal coverage, disbalancing of soil components, altering soil structure and composition. Wild boar hunting has failed as a control measure to date, according to the Brazilian Ministry of Environment, due to private hunting groups mostly targeting males, intentionally leaving females and piglets alive, disseminating wild boar populations nationwide. Meanwhile, non-government animal welfare organizations have pointed to animal cruelty of hunting dogs and wild boars (and native species) during hunting. Despite unanimous necessity of wild boar control, eradication and prevention, methods have been controversial and should focus on effective governmental measures instead occasional game hunting, which has negatively impacted native wildlife species while wild boars have continuously spread throughout Brazil.

Molecular detection of Toxoplasma gondii, Neospora caninum and Sarcocystis spp in tissues of Sus scrofa slaughtered in southern Brazil

The aim of this study was to determine the presence of deoxyribonucleic acid (DNA) from Toxoplasma gondii, Sarcocystis spp. and Neospora caninum, in tissues of wild boars slaughtered in southern Brazil. A total of 156 samples were collected from different organs of 25 wild boars, and DNA from at least one of the protozoa investigated was detected in 79 samples. To differentiate between infectious agents, restriction fragment length polymorphism was performed using the restriction enzymes DdeI and HpaII. For N. caninum, conventional PCR was performed with specific primers. The DNA of at least one of the studied pathogens was detected in each animal: 26.58% for T. gondii, 68.36% for Sarcocystis spp. and 5.06% for N. caninum. Coinfection between T. gondii and Sarcocystis spp. occurred in 14 animals, between T. gondii and N. caninum in only one male animal, between Sarcocystis spp. and N. caninum in a female, while co-infection with the three agents was equally observed in only one male animal. Considering the high frequency of detection and its zoonotic risk, especially T. gondii, it appears that wild boars can be potential sources of transmission of infectious agents and the adoption of monitoring measures in these populations should be prioritized.

One Health Approach in Serosurvey of Toxoplasma gondii in Former Black Slave (Quilombola) Communities in Southern Brazil and Among Their Dogs

Brazilian quilombos are rural semi-isolated remnant communities of former black slaves and their descendants who traditionally maintained themselves through archaic subsistence livestock and agriculture practices and historically lacked specific public health policies. Although such individuals and their dogs may be exposed to zoonotic pathogens such as Toxoplasma gondii, no study to date has assessed these human-animal populations together. Populations in four different Brazilian quilombos in southern Brazil were evaluated. Overall, 93/208 people (44.7%) and 63/100 dogs (63.0%) were seropositive for IgG anti-T. gondii antibodies by indirect immunofluorescent antibody test (IFAT), 4/208 (1.9%) human samples seropositive for IgM anti-T. gondii antibodies, with a human-dog seropositivity ratio for IgG of 0.71. Quilombola individuals ingesting game meat were 2.43-fold more likely (95% CI: 1.05-5.9) to be seropositive. No risk factors were associated with seropositivity among dogs, thus suggesting that their exposure to T. gondii was random. Surprisingly, our research group had previously found an inverted human-dog ratio for T. gondii seropositivity of 2.54 in the urban area of a nearby major city. Because consumption of raw/undercooked game meat by quilombola individuals may have contributed to higher exposure, higher overall seroprevalence among dogs may have also indicated interaction with wildlife. Although these dogs may hunt wildlife without their owners' awareness, the higher dog seropositivity may also be related to feeding from discarded food in the community or backyard livestock animals and drinking surface water contaminated with oocysts. Thus, wildlife cannot be singled out as the reason, and future studies should consider sampling water, soil, wildlife, and livestock tissues, to fully establish the source of infection in dogs herein.

Toxoplasma gondii exposure in Brazilian indigenous populations, their dogs, environment, and healthcare professionals

Although Toxoplasma gondii exposure has been reported in indigenous populations worldwide, a One Health approach has not been applied to date. This study concurrently assessed T. gondii exposure in indigenous populations, and their dogs, environment, and indigenous or non-indigenous healthcare professionals (HPs). Human and dog serum samples from 9 indigenous communities in Brazil were assessed by indirect immunofluorescence antibody test for anti-T. gondii antibodies. Soil samples (30 per community) were processed with PCR to amplify T. gondii DNA. Associated risk factors and seroprevalence were analyzed using logistic regression models. Human seropositivity and type of water source were assessed by generalized linear mixed model (GLMM) with binomial error distribution, and game meat consumption with chi-squared test. Overall, 225/463 (49%) indigenous persons were seropositive for anti-T. gondii antibodies. Of all the HPs, 67/168 (40%) were positive, and included 54/147 (37%) positive non-indigenous HPs. Indigenous persons more likely to be seropositive compared with non-indigenous HPs (OR: 1.63; 95% CI: 1.11-2.39). A total of 97/253 (38%) dogs were seropositive and highly associated with seropositive owners (p < 0.001). Based on univariate analysis for indigenous individuals, state location of community (p < 0.001), ethnicity (p < 0.001), consumption of game meat (p < 0.001), type of water source (p < 0.001), and educational level (p = 0.026) were associated with seropositivity. Logistic regression showed that indigenous seropositivity was associated with eating game meat (p = 0.002), drinking water from rivers (p < 0.001), and inversely proportional to the educational level. According to univariate analysis for non-indigenous HP, age (p = 0.005), frequency of visits to the indigenous populations (p < 0.001), consumption of water at the indigenous communities (p < 0.001), and ingestion of raw meat (p = 0.023) were associated with T. gondii seropositivity. Logistic regression revealed living outdoors (p = 0.042), habit of hunting (p = 0.008), and drinking river water (p = 0.007) as risk factors associated to seropositivity in dogs. In addition, indigenous communities lacking water treatment had higher seroprevalence for all groups including indigenous persons (GLMM; z = -7.153; p < 0.001), their dogs (GLMM; z = -2.405; p = 0.0162), and all HPs (GLMM; z = -2.420; p = 0.0155). Human seropositivity was associated with that of their dogs (p < 0.001). A single soil sample, out of 270 (0.37%), was positive for T. gondii by PCR. Our results indicate water source is a risk for human and dog toxoplasmosis in indigenous communities; both share similar exposure. Moreover, quality water access was shown to be crucial to prevent toxoplasmosis in both total and non-indigenous HPs who work in these indigenous communities.

Increased seroprevalence of anti-Toxoplasma gondii antibodies in dogs in southern Brazil after an outbreak of human toxoplasmosis

Toxoplasmosis is a worldwide disease caused by Toxoplasma gondii, which can infect diverse hosts, including dogs. Although T. gondii infection in dogs is usually subclinical, they are susceptible to infection and develop a specific immune response to the parasite. In 2018, the largest outbreak of human toxoplasmosis in the world occurred in Santa Maria, in southern Brazil; however, the impact of this outbreak on other hosts was not investigated at the time. Considering that dogs often share the same environmental sources of infection as humans, mainly water sources, and that in Brazil, the detection rates of anti-T. gondii immunoglobulin G (IgG) in dogs is very high, this study investigated the frequency of anti-T. gondii IgG in dogs in Santa Maria before and after the outbreak. A total of 2.245 serum samples were analyzed, 1159 collected before the outbreak and 1086 collected after the outbreak. Serum samples were tested for anti-T. gondii antibodies using an indirect immunofluorescence antibody test (IFAT). The infection detection of T. gondii was 16% (185/1159) before the outbreak and 43% (466/1086) after the outbreak. These results showed the infection of dogs with T. gondii and the high frequency of anti-T. gondii antibodies in dogs after the outbreak in humans in 2018, reinforcing water as a possible source of infection and the importance of including toxoplasmosis in the differential diagnosis of dogs.

Seropositivity of Anti-Toxoplasma gondii Antibodies in Owners and Their Dogs Living on Island and Mainland Seashore Areas of Southern Brazil

Although toxoplasmosis has been considered among the most neglected zoonoses worldwide, no study has focused on the frequency and associated risk factors of owners and their dogs living on an island and mainland seashore areas. Accordingly, anti-Toxoplasma gondii IgG antibodies were screened by indirect fluorescent antibody test (IFAT) in owners and dogs from three oceanic islands and two nearby mainland harbor areas, with associated risk factors for toxoplasmosis assessed by univariable and multivariable logistic regression models. Overall, anti-T. gondii seropositivity was observed in 59/328 (18.0%) owners and 66/283 (23.3%) dogs, with no statistical difference between owners (p = 0.360) and dogs (p = 0.655) from islands and mainland areas. Consumption of local water springs (p = 0.016; OR = 2.11) was an associated risk factor for T. gondii seropositivity, and owners with the habit of spring water intake were twice more likely seropositive (p = 0.014; OR = 2.14). Presence of anti-T. gondii antibodies in dogs was associated with seropositive owners (p = 0.008; OR = 2.81), household consumption of beef meat (p = 0.042; OR = 1.7) and chicken (p = 0.026; OR = 2.9). Despite being lower than the worldwide prevalence, toxoplasmosis seropositivity in owners and their dogs in southern Brazil was influenced by the positive owner, water source, and meat consumption, and not by inhabiting islands or seashore mainland areas, presence of dogs, cats, or both. In addition, drinking water quality should always be considered a critical risk factor for toxoplasmosis on islands.

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.

Toxoplasma gondii in Australian macropods (Macropodidae) and its implication to meat consumption

Toxoplasma gondii is a worldwide occurring apicomplexan parasite. Due to its high seroprevalence in livestock as well as in game animals, T. gondii is an important food-borne pathogen and can have significant health implications for humans as well as for pets. This article describes the prevalence of T. gondii in free-ranging macropods hunted for consumption. All hunted macropod species (commercial as well as non-commercial hunt) show a positive seroprevalence for T. gondii. This seroprevalence is influenced by various factors, such as sex or habitat. Furthermore, the parasite shows a high level of genetic variability in macropods. Genetically variable strains have already caused outbreaks of toxoplasmosis in the past (Canada and the US). These were attributed to undercooked game meat like venison. Despite this risk, neither Australia nor New Zealand currently have food safety checks against foodborne pathogens. These conditions scan pose a significant health risk to the population. Especially, since cases of toxoplasmosis have already been successfully traced back to insufficiently cooked kangaroo meat in the past.

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The kangaroo hunt is an important industry in Australia.

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7 species of kangaroos and wallabies are hunted for commercial purpose (for human and pet consumption).

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Food security checks against foodborne pathogens (including T. gondii) are not a requirement of the Australia New Zealand Food Standard Code.

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The databases Medline, Web of Science, SCOPUS and Informit were used.

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6 scientific publications were reviewed in this publication.

Diet of invasive wild pigs in a landscape dominated by sugar cane plantations

Understanding the mechanisms by which alien species become invasive can assure successful control programs and mitigate alien species’ impacts. The distribution of invasive wild pigs (Sus scrofa) has been sharply expanding throughout all regions of Brazil in the last few years. Here we demonstrate that large monocultural plantations provide the primary resource subsidies to invasive wild pigs in Brazil. We analyzed 106 stomach contents and carbon stable isotopes (δ13C) of 50 hair samples of wild pigs from a population immersed in a landscape dominated by sugar cane agriculture. Stomach contents were dominated by corn (41%), sugarcane (28.5%), vegetal matter (all other vegetation besides crops, 27%), and animal matter (vertebrates and invertebrates, 4%). Bayesian mixing model analysis of δ13C showed that food sources from C4 photosynthetic pathway (represented by corn and sugarcane) accounted for 94% of the long-term diet, while C3 food sources for only 6.2%. Our results indicate that corn and sugar cane are subsidizing the diet of wild pigs and can facilitate the population growth of this invasive species. Given that Brazil is a major agricultural producer and a hotspot of biodiversity, it is extremely concerning that extensive agriculture may accelerate the expansion of this invasive species, resulting in economic losses and cascading effects on natural habitats.

Toxoplasma gondii Infection in Swine: Implications for Public Health

Toxoplasmosis, due to Toxoplasma gondii, is a parasitic disease with global importance. Among livestock, chronic T. gondii infection has been reported in higher rates in pigs and small ruminants, but with subclinical infections in case commonly encountered in pigs. Seroprevalence in the global pig population ranges according to the age or species of pigs, geographical distribution, production programs, and systems. Generally, T. gondii infections are noticed in low prevalence rates in conventional pig farms with high hygiene standards. In contrast, higher prevalence is common on free-ranging farms, outdoor or backyard small pig fams, as well as in farmed or hunted wild boars. The T. gondii average worldwide seroprevalence in pigs is reported to be 13% in Europe, 21% in Africa, 25% in North America, 21% in Asia, and 23% in South America. Human toxoplasmosis outbreaks have been correlated with the consumption of raw or undercooked meat, especially from infected pigs or wild boars, as well as of contaminated drinking water. The risk of infection in processed pork products is lower compared with fresh pork, as meat processing can reduce or inactivate T. gondii tissue cysts. Hence, the prevalence of T. gondii in the pig population may be a useful indicator of the risk of human toxoplasmosis associated with the consumption of pork products. The lack of obligatory screening methods at farm level for the detection of antibodies in farmed animals or the viable T. gondii in carcasses at slaughterhouse level increases the risk of contaminated pork or meat products. For this reason, the application of biosecurity and surveillance programs at farm level is very important to prevent a T. gondii infection.

Hunting Dogs

Herding and hunting dogs are intense, high-drive dogs that work, and often live, outdoors and in constant or repeated close contact with domestic and wild animals. These dogs are at increased risk for injury and exposure to infectious diseases, toxic substances, and environmental threats. The common practice of feeding or allowing access to raw meat from farm or game animals enhances disease transmission risk. These dogs can be affected by infectious diseases and injurious agents that are rarely encountered in other groups of dogs. In addition, their extreme work ethic may lead to delays in diagnosis.

Toxoplasma gondii infection in wild boars (Sus scrofa) from the State of São Paulo, Brazil: Serology, molecular characterization, and hunter's perception on toxoplasmosis

The consumption of wild boar meat, common in many countries, became popular in Brazil after the hunting of these animals was authorized in 2013. The meat of these animals is often consumed by hunters and their social groups, and their offal is occasionally used as supplemental food in the diet of hunting dogs. Given the high frequency of foodborne diseases related to wild boar meat consumption in other countries, including toxoplasmosis, knowledge on these diseases is essential for risk assessment and elaboration of education campaigns for the exposed public. Thus, this study aimed diagnosing, isolating, and genotyping Toxoplasma gondii in hunted wild boars. For that, we obtained samples of serum and tissues (brain, tongue, diaphragm, and heart) from 26 wild boar hunted in three areas in São Paulo State, Brazil, based on convenience sampling strategy. The serum samples were submitted to the indirect immunofluorescence reaction test (IFAT) test while the tissue samples (n = 22) were used to perform a bioassay in mice to isolate the parasite. The isolated samples were genetically characterized by PCR-RFLP with SAG1, 5' and 3' SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico markers. Questionnaires were also formulated and applied to wildlife hunters to assess knowledge about toxoplasmosis. The seroprevalence of T. gondii was 76.9% (20/26), with titers ranging from 16 to 1024. Viable parasites accounted for 4.5% (1/22) of the samples. The ToxoDB #6 genotype of TgJava1 alone was detected. Most interviewed hunters, 84.2% (16/19) consume game meat and a few of them (15.7%; 3/19) prefer undercooked meat. Also, 15.7% (3/19) of the hunters reported supplementing their hunting dogs' diet with wild boar meat and/or offal. As antibodies to T. gondii were detected in 76.9% (20/26) of the studied wild boars, we concluded that infection by T. gondii is frequent in wild boars used for human and animal consumption in the studied areas. Although genotype #6 is commonly found in Brazil in domestic animals, wild animals, and humans, causing everything from mild clinical symptoms to death, this study found, for the first time, the detection of this genotype in wild boars. These results also reaffirm the importance of these animals as a possible source of T. gondii infection for humans and domestic animals.

Serosurvey of anti-Neospora caninum antibodies in wild boars (Sus scrofa), hunting dogs and hunters of Brazil

The protozoan Neospora caninum is an important cause of abortion in cattle worldwide, with domestic dogs serving as the definitive hosts. Although hunting activities have been indicated as a potential risk factor for N. caninum infection in dogs, no serological evidence has so far been reported in hunting dogs, wild boars (Sus scrofa), and hunters. A total of 98 wild boars, 168 hunting dogs, and 15 hunters from three Brazilian regions were sampled and tested for anti-N. caninum antibodies by indirect immunofluorescence antibody test, resulting in 15/168 (9%) seropositive hunting dogs, and 0/98 wild boars, and 0/15 hunters seropositive. The absence of N. caninum antibodies in wild boars may suggest low exposure to oocysts shed by hunting dogs and wild canids in three different Brazilian regions. Finally, the absence of hunter seropositivity supports the current lack of evidence that N. caninum is a zoonotic parasite.

Toxoplasma gondii infections in dogs: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, diagnosis, and genetic diversity of T. gondii in dogs (Canis familiaris) from 2009-2020. Seroprevalence estimates of T. gondii worldwide were tabulated. Reports of high seroprevalence in canine population and high congenital transmission of T. gondii in dogs in Brazil are reviewed. Most reports from China were published in Chinese, and these reports are now summarized here. Dogs have an additional importance in some countries such as China, Vietnam, and Nigeria; whereas in many cities dog meat is sold commercially for human consumption and given to felids, and transmission of T. gondii could occur if meat is not cooked properly. Dogs can ingest T. gondii-infected cat feces and these oocysts remain viable after passage through the digestive tract of the dog; T. gondii DNA was found in feces of dogs from New York City parks in USA. Most clinical canine cases of toxoplasmosis were in immunosuppressed dogs, and ulcerative dermatitis was one of the main presentations. Genetic diversity based on PCR-RFLP markers using DNA derived from 133 viable T. gondii isolates from dogs from several countries is discussed. T. gondii strains from Asia and Americas were more genetically diverse than those from Africa. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

All about Toxoplasma gondii infections in pigs: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasma gondii infection in pigs continues to be of public health concern. Pigs are important for the economy of many countries, particularly, USA, China, and European countries. Among the many food animals, pigs are considered the most important for T. gondii transmission in USA and China because viable parasites have rarely been isolated from beef or indoor raised chickens. Besides public health issues, T. gondii causes outbreaks of clinical toxoplasmosis in pigs in China, associated with a unique genotype of T. gondii (ToxoDB genotype #9 or Chinese 1), rarely found in other countries. The safety of ready to eat pork products with respect to T. gondii infection is a matter of recent debate. Here, we review in detail seroprevalence, prevalence of viable and nonviable T. gondii, epidemiology, risk assessment, diagnosis, and curing of pork products containing T. gondii for the past decade. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.