Toxoplasma gondii infection in raptors from Italy: Seroepidemiology and risk factors analysis

Serological Prevalence of Toxoplasma gondii, Neospora caninum, and Sarcoptes scabiei var. suis in Wild Boars (Sus scrofa) Hunted in a Highly Anthropized Area in Italy

Due to the increasing expansion into urban and rural areas, wild boars represent a potential source of infection with zoonotic and animal-specific parasites for both humans and animals. Therefore, the aim of this study was to investigate the serological prevalence to Toxoplasma gondii, Neospora caninum, and Sarcoptes scabiei var. suis in blood samples from wild boars (Sus scrofa) hunted in an anthropized area in Italy. Enzyme-linked immunosorbent assay (ELISA) tests were used to detect antibodies anti-T. gondii and anti-S. scabiei and an immunofluorescence antibody test (IFAT) for antibodies anti-N. caninum. 81 out of 128 wild boars (P = 63.3%) resulted positive for at least one of the three parasites. 68 of them were seropositive to T. gondii (P = 53.1%) and 14 to N. caninum (P = 10.9%). 9 wild boars resulted seropositive to S. scabiei var. suis (P = 7.0%). Sampling season was the only significant risk factor related to S. scabiei var. suis seroprevalence (OR = 7.8). The high occurrence of T. gondii supports the role of this species as a source of infection for other animals and humans. Furthermore, the serological prevalence of N. caninum and S. scabiei var. suis in wild boars from the study area characterized by the presence of numerous dairy cattle and pig farms is relevant to demonstrate its suitability for the circulation of these parasites both in domestic and wild species.

The Dangerous Side of Being a Predator: Toxoplasma gondii and Neospora caninum in Birds of Prey

Toxoplasma gondii and Neospora caninum are apicomplexan protozoa of major concern in livestock and T. gondii is also considered one of the major threats and a public health concern. These protozoa have a wide range of intermediate hosts, including birds. The present work aimed to assess the prevalence of these cyst-forming parasites in migratory and sedentary birds of prey. The skeletal muscle and myocardium of 159 birds of prey from Central Italy, belonging to 19 species and recovered across 6 Wildlife Recovery Centers/Care structures along the Italian migratory route, were collected specifically for molecular (PCR) and for histopathological analysis to detect T. gondii and N. caninum. For the molecular analysis, genomic DNA was extracted. The DNA was tested by sequence typing, targeting GRA6, 529 bp repeated element, B1, PK1, BTUB, SAG2, alt.SAG2, and APICO genes for T. gondii and to end-point PCR targeting NC5 gene for N. caninum. Thirty-seven out of the one hundred and fifty-nine analyzed samples tested positive for T. gondii with a prevalence of 23.27% and nine for N. caninum, with a prevalence of 5.66%. Thirty-two sequences were obtained from the thirty-seven isolates of T. gondii. Among these, 26 presented alleles compatible with type I strain in 1 or more loci, 4 with type II strain and 2 consisted of atypical strains. Toxoplasma gondii genetic variability in birds of prey confirms previous findings of wildlife as reservoirs of atypical strains. Results from the histology showed few protozoal tissue cysts in skeletal muscle (n. 4) and hearts (n. 2).

Toxoplasmosis in Captive Ring-Tailed Lemurs (Lemur catta)

Toxoplasma gondii is one of the most common protozoan parasites and is widely present in all warm-blooded animals. Although clinical disease is uncommon, some species, including ring-tailed lemurs (Lemur catta), have been found to develop acute and lethal toxoplasmosis. The aim of this study was to describe the pathologic, immunohistochemical, serological, and molecular findings of an outbreak of fatal toxoplasmosis in three captive ring-tailed lemurs in Central Italy in 2009. The animals died acutely within few days. The necropsy was immediately performed; necrotic lesions in the spleen, liver, and kidney, as well as interstitial pneumonia, were found histologically. All animals had high titers of anti-T. gondii-specific antibodies (1:1280 IgM and 1:640 IgG) according to a modified agglutination test (MAT) and immunohistochemistry showed scattered tachyzoites in the target organs. Diagnosis was confirmed by PCR and clonal type II was identified. In addition, the seven co-habiting lemurs were seronegative. This paper reports the first outbreak of acute disseminated toxoplasmosis in captive ring-tailed lemurs in Italy. These findings confirm the high susceptibility of this endangered species to toxoplasma infection, which may be considered a further threat to captive population viability.

Prevalence of Antibodies to Toxoplasma gondii in Different Wild Bird Species Admitted to Rehabilitation Centres in Portugal

Toxoplasma gondii is a worldwide zoonotic parasite. According to the “One Health” approach, studies on toxoplasmosis are essential since it affects humans and domestic and wild animals. In the present study, antibodies to T. gondii were determined in serum samples from 263 wild birds located in five wildlife rehabilitation centres in mainland Portugal by using the modified agglutination test (MAT) with a cut-off titre of 20. An overall seroprevalence of 36.5% (95% confidence interval [CI]: 30.7–42.6) was observed. For the first time, antibodies to T. gondii were detected in some avian species, including pallid swift (Apus pallidus) (33.3%), black-backed gull (Larus fuscus) (39.3%), European turtle-dove (Streptopelia turtur) (100%), bee-eater (Merops apiaster) (50.0%), carrion crow (Corvus corone) (33.3%), and Egyptian vulture (Neophron percnopterus) (100%), which expands the list of intermediate hosts of T. gondii. A lower seroprevalence was found in juvenile birds (31.9%) compared to adults (48.7%) (p = 0.016). The central region of Portugal was considered a risk factor for T. gondii infection in wild birds (odds ratio: 3.61; 95% CI: 1.09–11.91). This pioneer study calls attention to the need for further studies, to provide a clearer understanding of T. gondii epidemiology in Portugal, because it reflects wide dispersion of T. gondii oocysts in the environment.

Toxoplasma gondii prevalence in carnivorous wild birds in the eastern United States

Toxoplasma gondii is an important zoonotic protozoan parasite that can infect all warm-blooded animals including mammals and birds. Raptors can be intermediate hosts for T. gondii and the infection may be dependent on their feeding habits. In this study, we investigated the seroprevalence of T. gondii in ten raptor species from Florida, Pennsylvania, and Tennessee followed by a parasite bioassay on select seropositive samples. From a total of 155 raptors, we detected T. gondii antibodies using a modified agglutination test (cutoff 1:25) in 32 (20.6%) birds. The T. gondii seroprevalence was 44.8% in Falconiformes (13/29), 75% in Strigiformes (15/20), and 3.8% in Ciconiiformes (4/106). All Ciconiiformes samples (hearts and sera) were collected from Pennsylvania during nuisance wildlife removal projects and all birds were apparently healthy. Falconiform and Strigiform samples were collected from an exotics clinic in Tennessee and a rehabilitation center in Florida. All sampled birds were dead or euthanatized due to failure of rehabilitation or treatment. There was no statistically significant difference in T. gondii seroprevalence between Tennessee and Florida in the tested raptors. There was also no statistically significant difference in T. gondii exposure between males and females or adults and subadults. Mice bioassay attempts using fresh brain and/or heart tissue were performed on four seropositive birds. We isolated viable T. gondii tachyzoites from one red-shouldered hawk (Buteo lineatus) and genotyped the isolate using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of ten genetic markers. The isolated strain was designated as TgHawkFL1, which is ToxoDB PCR-RFLP genotype #28. Further research is needed to investigate the prevalence of T. gondii in raptors in the United States to obtain a better understanding of the life cycle, wildlife population impacts, and transmission dynamics of the parasite.

Molecular Survey on Toxoplasma gondii and Neospora caninum Infection in Wild Birds of Prey Admitted to Recovery Centers in Northern Italy

Toxoplasma gondii and Neospora caninum (Apicomplexa, Sarcocystidae) are protozoan parasites infecting a wide range of intermediate hosts worldwide, including birds. Raptors acquire the infections through the ingestion of both infected preys and oocysts in the environment suggesting they might be used as indicators of the spread of these pathogens. Here, we report an epidemiological survey with the aim of determining the prevalence of T. gondii and N. caninum infections in wild birds of prey, hospitalized in two Wildlife Recovery Centres (WRCs) in Northern Italy. Genomic DNA extracted from brain tissue samples was submitted to Real Time PCR targeting T. gondii B1 and N. caninum Nc5 genes. T. gondii genotyping was then performed by multilocus sequence typing (MLST) analysis, targeting three polymorphic genes (GRA6, BTUB, and altSAG2). T. gondii DNA was found in 35 (62.5%) out of 56 examined samples; concerning genotyping, it was possible to amplify at least one gene for 26 animals, and obtained sequences belonged to Type II. N. caninum DNA was only detected in two (3.6%) common kestrels (Falco tinnunculus), adding a new species to the list of suitable intermediate hosts for this pathogen. Data obtained in the present study thus confirmed the spread of both T. gondiiand N. caninum in wild bird of prey, endorsing the role of WRCs in the epidemiological surveillance of wildlife.

Serosurvey of Toxoplasma gondii, Neospora caninum and Sarcocystis neurona in raptors and risk factor analysis

Raptors are carnivorous birds with great hunting ability. Toxoplasma gondii, Neospora caninum and Sarcocystis spp. are intracellular Apicomplexan protozoans which infect a wide range of intermediate hosts, including birds. The aims of this study were to evaluate the serological reactivity of captive raptors serum to T. gondii, N. caninum and S. neurona antigens and identify possible risk factors associated with the infection. From August 2014 to September 2015, blood samples from 72 raptors were collected and serum samples were tested by immunofluorescence antibody test (IFAT). Antigen slides were prepared using tachyzoites of T. gondii and N. caninum and using merozoites of S. neurona. Serum samples were tested at the following cut-off dilutions: 1:16 for T. gondii and 1:50 for N. caninum and S. neurona. An anti-chicken IgY antibody conjugated with FITC was used as a secondary antibody at 1:50 dilution. Out of the 72 raptors serum tested by IFAT, 2.7% reacted to N. caninum, 8.3% to T. gondii and 11.1% to S. neurona antigens. The region in which the sample was collected, the reason the raptors were kept in captivity and diet were statistically associated with seropositivity to T. gondii and the use of the birds and diet were statistically associated with seropositivity to N. caninum and S. neurona (p ≤ 0.05). We highlight the occurrence of these protozoans in birds of prey and the importance of good hygiene and feeding management of these birds in captivity to reduce the risk of protozoal infections.

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.

Toxoplasma gondii seroprevalence in beef cattle raised in Italy: a multicenter study

Toxoplasmosis represents an important public health issue, with the consumption of raw or undercooked meat being a major way of human infection. The role of beef in the transmission of the parasite to humans is questioned due to lower quantity of tissue cysts compared with other meat-producing species. However, the habit of consuming raw beef is regionally diffused, and the risk posed by Toxoplasma gondii infection in cattle should not be overlooked. Therefore, to update information on T. gondii in cattle reared in Italy, a multicentric seroepidemiological survey was designed and implemented in four Northern regions (Liguria, Lombardy, Piedmont, and Trentino Alto Adige) and Sardinia. Overall, a convenience sampling was performed, collecting 1444 serum samples from 57 beef cattle herds. Thirteen beef breeds were sampled, besides cross-breed; bovines age varied from 3 months to over 12 years. Sera were tested with a commercial ELISA for the detection of anti-T. gondii antibodies. Individual and herd data were analyzed by binary logistic regression analysis. A T. gondii seroprevalence of 10.2% was recorded, with differences among regions and values ranging from 5.3% in Liguria to 18.6% in the Piedmont region (p value = 0.0001). Both young and adult animals and males and females tested positive, without any significant difference (age and gender: p value > 0.05). Lower seroprevalence values were recorded in cattle born in Italy (8.7%) if compared with animals imported from abroad (13.4%) (p value = 0.046). The spread of T. gondii in beef cattle destined to Italian consumers is confirmed, suggesting the need of continuous monitoring of the infection.

Toxoplasma gondii in the Eurasian kestrel (Falco tinnunculus) in northern Italy

Background

Identifying factors that sustain parasite transmission is important for understanding their spread and emergence, including how changes in biodiversity may affect parasite prevalence and spread. Toxoplasma gondii is a protozoan parasite infecting humans and animals. Birds can acquire T. gondii infection through ingestion either of oocysts from the ground or of tissue cysts present in infected prey and are therefore suitable indicators of the presence of T. gondii in the natural environment.

Methods

The aim of the study included the evaluation of T. gondii seroprevalence in clinically healthy Eurasian kestrels (Falco tinnunculus) using a modified agglutination test. Birds were captured in a small area of Parma (northern Italy) for two consecutive years (2016–2017), sex and age determined and serological study carried out. Food sources for the birds were also evaluated, in particular rodent and grasshopper population estimates in the study area. The biomass of rodents and grasshoppers per hectare was estimated in order to directly compare food availability. Statistical analyses were performed in order to evaluate factors influencing the probability of kestrels being T. gondii-seropositive using R 3.4.4 fitting linear mixed-effect models with the ‘glmer’ function of the package lme4, ‘lsmean’ in package lsmean for pair-wise post-hoc comparisons using differences of least square means (DLSM) and the ‘betareg’ function of the package betareg for beta regression.

Results

Seroprevalence for T. gondii was 33.3% (49/147) in 2016, while in 2017 seroprevalence decreased to 14.3% (13/91). An increase in the probability of kestrels being T. gondii-seropositive was associated with a higher rodent biomass in the environment, suggesting a positive feedback of the biotic factors driving infection risk.

Conclusions

These results underline the need for multidisciplinary studies aimed at better understanding pathogen-host relationships and for predictions in disease ecology.

Epidemiologic Survey on Toxoplasma gondii and Trichinella pseudospiralis Infection in Corvids from Central Italy

Free-ranging corvids—678 magpies (Pica pica) and 120 hooded crows (Corvus cornix) from nine protected areas of the Pisa province (central Italy)—were examined for Toxoplasma gondii and Trichinella pseudospiralis. The intracardiac blood clots from 651 magpies and 120 hooded crows were serologically examined for T. gondii. The DNA extracted from the hearts of seropositive birds was then used to perform a nested PCR for the amplification of the T. gondii B1 gene and for genotyping for SAG genetic markers. Breast muscle samples from 678 magpies and 91 hooded crows were tested by an artificial digestion method for Trichinella. Data were statistically analyzed. Forty-five (5.8%—41 magpies and four hooded crows) out of the 771 examined animals scored seropositive for T. gondii, with titers ranging from 1:25 to 1:100. T. gondii DNA was detected in 15 of the 45 positive birds and T. gondii genotypes II and III were identified. No positivity for T. pseudospiralis was found. No significant differences between the two species of corvids and among the different areas of origin were observed for seropositivity to T. gondii. This is the first extensive study on both T. gondii and T. pseudospiralis in magpies and hooded crows, as well as the first detection of T. gondii SAG genotypes in magpies.

Serological diagnosis of Toxoplasma gondii: analysis of false-positive IgG results and implications

BACKGROUND

Primary infection by Toxoplasma gondii in pregnant women can result in serious outcomes for the foetus. A false-positive IgG result during pregnancy can lead to a misdiagnosis of past infection and to stopping preventive measures. We collected 189 sera with positive Architect® Toxo IgG assay (Abbott Laboratories) and negative IgG results with at least two other serological tests, in order to find an explanation for the suspected false-positive IgG results. We used the recomLine Toxoplasma IgG® immunoblot (Mikrogen Diagnostik) to search for specific antigenic reactivities of the sera, and the LDBio Toxo II IgG® immunoblot (LDBio Diagnostics) as a confirmatory test.

RESULTS

The bands GRA8 and/or GRA7 were positive for 148 samples (78.3%). GRA8 was the most frequent band, appearing in 133 patterns (70.4%), whereas GRA7 was present for 49 samples (25.9%). Of the 81 samples tested with LDBio®, 23 (28.4%) turned out to be positive. Of the 58 negative LDBio® tests (71.6%) (real false-positive Architect® IgG), 23 samples (39.6%) did not show either a GRA8 or p30 band by recomLine®. Their false positivity with Architect® remains unexplained since Abbott uses these two recombinant antigens for their assay.

CONCLUSIONS

The Architect® IgG false positivity for T. gondii seems to be due to reactivity against GRA8 for the majority of the sera and GRA7 to a lesser extent. The hypothesis of past contact with parasites genetically close to T. gondii such as Hammondia hammondi or Neospora caninum seems promising and should be assessed further.

Toxoplasma gondii infection in meat-producing small ruminants: Meat juice serology and genotyping

The consumption of ovine and caprine meat is considered one of the major transmission routes for Toxoplasma gondii infection in humans. The present study aimed at obtaining epidemiological and molecular data on T. gondii infection in small ruminants slaughtered or commercialized in Italy. Meat juices from 227 sheep and 51 goats were analyzed with a commercial ELISA and antibodies were detected in 28.6% sheep and 27.5% goats. A significant difference was highlighted between adult sheep and the other considered categories (young sheep, young and adult goats) concerning the detection of antibodies (94.1%; p-value = .008). Muscles of positives samples were submitted to molecular analysis, and T. gondii DNA was detected in 15 sheep and three goats; sequencing of B1 gene showed that all belonged to Type II. The present study confirmed small ruminants' meat as a possible source of T. gondii infection for consumers eating raw or undercooked meat, particularly in those countries where the consumption of sheep and goats' meat products is a traditional gastronomic habit.

Spatial Analysis of Infections by Toxoplasma gondii and Neospora caninum (Protozoa: Apicomplexa) in Small Ruminants in Northern Italy

The objectives of this study were: (i) To investigate possible geographical or environmental factors influencing the infections by Toxoplasma gondii and Neospora caninum in sheep and goats in northern Italy; (ii) to identify areas at risk of infection to set up preventive measures. Forty-three sheep and goat farms were included. Their locations were plotted and associated with T. gondii and N. caninum seroprevalence, then the distribution of farms' prevalence was evaluated by spatial analysis. Significant clusters for both low and high prevalence were obtained, and a generalized linear model with ordinal logistic regression was implemented to verify if spatial clustering could be due to climate factors (temperature, rainfall, and their interaction). Clusters of high (80.0%) and low prevalence (28.12%) resulted for T. gondii seroprevalence in sheep farms. No significant clusters resulted for goat farms. Clusters of high (38.68%) and low prevalence (21.23%) resulted for N. caninum seroprevalence in sheep farms. One high-prevalence cluster (15.62%) resulted for goat farms. For goats, spatial analysis and analysis on climatic data showed the absence of environmental significant risk factors associated with T. gondii or N. caninum infection. On the contrary, for sheep, annual temperature, rainfall, and their association affected the risk of T. gondii and N. caninum infection. Particularly, high temperatures and abundant rainfalls were related to T. gondii seroprevalence, while low temperatures and scarce rainfalls were related to N. caninum seroprevalence.

Toxoplasma gondii in naturally infected goats: Monitoring of specific IgG levels in serum and milk during lactation and parasitic DNA detection in milk

The zoonotic protozoa Toxoplasma gondii is one of the major abortive pathogens in small ruminants. Nevertheless, data on T. gondii infection in goats during lactation and on the presence of T. gondii in goat milk are lacking. A longitudinal study was planned in a T. gondii naturally infected dairy goat farm with the aim of (i) evaluating the variation of anti-T. gondii antibodies in blood and milk during the lactation; (ii) identifying the optimal phase during lactation for T. gondii monitoring; (iii) detecting the presence of T. gondii DNA in the milk. From March to July 2017, 30 goats in a farm were fortnightly visited seven times and sampled for blood and, when in lactation, for milk. Individual data regarding age, reproductive disorders, and the day of lactation were recorded. For the detection of anti-T. gondii antibodies in blood and milk a commercial ELISA kit was used. Milk samples (n = 63) of selected nine seropositive animals were also molecularly analysed to amplify a sequence within the ITS1 region of T. gondii. The seroprevalence of T. gondii infection was 63.3% (19/30); a high agreement was obtained between serum and milk results (Spearman's coefficient = 0.793 and Kendall's tau = 0.624), particularly between the 15^th and the 60^th day of lactation. In the statistical analysis, performed with generalized linear mixed models (GLMMs), the variable "phase of lactation" was strongly associated to ELISA values obtained in both serum and milk (p-value = 0.0001, F = 5.197, and p-value = 0.016, F = 2.755, respectively). Finally, molecular analyses revealed the presence of parasitic DNA in 20.6% (13/63) of milk samples, with a discontinuous parasite excretion; statistical analyses did not reveal any association among the parasite excretion and the considered variables. Milk could be considered as a valid alternative to blood for monitoring T. gondii infection in goat herds. Moreover, the detection of T. gondii DNA in milk enhanced the possibility for raw goat's milk consumption to be considered as a risk to public health.

Serological and Molecular Investigation on Toxoplasma gondii Infection in Wild Birds

Toxoplasma gondii is an obligate apicomplexan zoonotic parasite that infects humans and other animals and is responsible for toxoplasmosis. This parasite causes one of the most common parasitic infections in humans worldwide. Toxoplasmosis meets the requirements for a One Health Disease due to its ability to affect the health of human beings as well as domestic and free ranging animals. Integrating human, domestic animal, and wildlife data could better assess the risk and devise methods of control. A first step of such an approach would be the knowledge of the prevalence of parasitosis in humans and animals in selected areas. Therefore, the aim of the present study was to evaluate the occurrence of Toxoplasma infection in 216 free ranging birds belonging to different genera/species by serology and molecular techniques. Twenty-five out of 216 animals (11.6%) were positive to the immunofluorescence antibody test (IFAT) with antibody titers ranging from 1/20 to 1/320, and 19 of them (8.8%) also showed a positive PCR for Toxoplasma DNA. The results confirmed the widespread occurrence of Toxoplasma infection in wild birds and serological data were corroborated by molecular results in birds that also had low antibody titers. The knowledge of the wide occurrence of the parasite in game and wild birds should enhance the accurate estimation of the risks in handling, managing, and eating these species with regard to domestic carnivores as well as the impact of viscera and offal in the environment.