Fatal toxoplasmosis in brown hares (Lepus europaeus): possible reasons of their high susceptibility to the infection

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.

European Brown hare (Lepus europaeus) as a source of emerging and re-emerging pathogens of Public Health importance: A review

European brown hare (Lepus europaeus, EBH) is probably the most important game animal in Europe throughout its historical distribution. The decline in its populations across its geographic range in Europe have been attributed to factors such as reproductive rate and the ability for adaptation, climate, feed availability, predators, anthropogenic factors and diseases. Apart from common diseases of hares with a high impact on their mortality such as European Brown hare Syndrome, EBH has been involved in the epidemiology of pathogens with zoonotic potential. In this work, the role of EBH as a source of Crimean–Congo haemorrhagic fever virus (CCHFV), Hepatitis E virus (HEV), Yersinia spp., Brucella spp., Francisella tularensis, Toxoplasma gondii and Leishmania infantum is discussed. Hares may significantly contribute to the epidemiology of important emerging zoonotic pathogens through maintenance of high endemicity levels as in the case of CCHFV, as a reservoir of important pathogens such as Yersinia spp., B. suis, F. tularensis and L. infantum and as a potential source of T. gondii for other animals, especially for carnivores but also for humans. However, EBH may also be a host of minor importance as in the case of HEV. The continuous surveillance of hare populations will enable the collection of information on the population health status and the pathogens currently circulating in the area posing risk for wildlife, domestic animals and humans. The possible live animal translocations of infected hares, the fact that this species acts as a host of vectors (fleas, ticks, mosquitoes and sandflies) and the prey of carnivores and omnivores that travel in great distances getting into contact with domestic animals and humans, further highlights the need to be included in surveillance studies. Besides, the hunter‐harvested EBH population is an excellent indicator for recent pathogen transmission due to its short lifespan.

The present review provides an overview of the role of European Brown Hare as a source of Crimean–Congo haemorrhagic fever virus (CCHFV), Hepatitis E virus (HEV), Yersinia spp., Brucella spp., Francisella tularensis, Toxoplasma gondii and Leishmania infantum aiming to highlight the contribution of this species to the epidemiology of important emerging zoonotic pathogens.

Variation in Toxoplasma gondii seroprevalence: effects of site, sex, species and behaviour between insular and mainland macropods

Context Feral cats threaten wildlife conservation through a range of direct and indirect effects. However, most studies that have evaluated the impacts of feral cats on species of conservation significance have focussed on direct impacts such as predation; few studies have considered the indirect impacts of cat-borne disease. Toxoplasma gondii, a cat-borne parasite, causes both acute and latent disease in a range of wildlife species, and macropods are particularly susceptible. Kangaroo Island is Australia’s third largest island and supports a high density of feral cats and high seroprevalence of T. gondii in multiple species, relative to the mainland. This suggests that Kangaroo Island has a high environmental contamination with the parasite and a high risk of infection for other species. Aims We aimed to describe T. gondii seroprevalence in culled and road-killed macropods, so as to assess the effects of island versus mainland location, sex, species and behaviour. Methods Macropod sera were tested for T. gondii IgG antibodies using a commercially available modified agglutination test. Key results The seroprevalence of T. gondii in culled western grey kangaroos (Macropus fuliginosus) was significantly higher on the island (20%, 11/54 positive) than on the mainland (0%, 0/61 positive). There was no difference in T. gondii seroprevalence between culled and road-killed (21%, 21/102 positive) kangaroos from the island. The seroprevalence of T. gondii was significantly higher in female (32%, 12/38 positive) than in male (13%, 8/60 positive) kangaroos, but we observed no sex effect in tammar wallabies (Macropus eugenii), and no effect of species. Conclusions The higher T. gondii seroprevalence in insular macropods supports previous reports of higher T. gondii exposure in other Kangaroo Island fauna. The lack of difference in T. gondii seroprevalence between culled and road-killed kangaroos suggests that T. gondii-positive animals are not more vulnerable to road mortality, in contrast to that suggested previously. Implications Our findings suggest greater potential adverse conservation impacts owing to toxoplasmosis on the island than on the mainland. In light of a recent study demonstrating higher cat abundance on the island than on the mainland, the higher observed T. gondii seroprevalence in insular macropods is likely to be a consequence of higher cat density.

Toxoplasma gondii infection in Amami spiny rat on Amami-Oshima Island, Japan

The Amami spiny rat (Tokudaia osimensis) is an endangered rodent species that is endemic to the forests of Amami-Oshima Island, Kagoshima, Japan. In July 2018, a deceased adult male Amami spiny rat was found on the Yuwandake Mountain Trail on the south-central coast of Amami-Oshima Island. Histopathological observations revealed protozoan infections in the liver, lungs, and heart. Nested or semi-nested PCRs targeting the B1, SAG3, GRA6, and ROP18 genes successfully detected the genomic DNA of Toxoplasma gondii in the formalin-fixed and paraffin-embedded specimen. Sequence analyses of the SAG3, GRA6, and ROP18 genes suggested that the strain detected in the study specimen was related to the type II strain of T. gondii. This is the first confirmed case of T. gondii infection in an Amami spiny rat.

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A deceased Amami spiny rat was diagnosed with disseminated toxoplasmosis.

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We present the first case report of T. gondii infection in the Amami spiny rat.

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Feral cat populations require control to avoid the spread of T. gondii infection.

Epizootological study on Toxoplasma gondii in zoo animals in the Czech Republic

Toxoplasma gondii is protozoan parasite with ability of causing disease in wide-spectrum of animals; many species of animals in captivity died of clinical toxoplasmosis. The monitoring of T. gondii antibodies in zoo animals can be an important indicator of T. gondii circulation in zoo. The aim of this study was to examine sera of animals from eight Czech zoos by latex agglutination test with statistical evaluation and detect T. gondii DNA in stray cats and rodents captured in the zoos. T. gondii antibodies were detected in 33% of 1043 zoo animals without statistical difference between birds (27%, n = 74) and mammals (33%, n = 969). In birds, the chance to be infected with T. gondii was higher in Accipitriformes (71%) compared to Pelecaniformes (6%) (p < 0.0001). In mammals, the chance to be infected with T. gondii was higher in Carnivora (63%) compared to Cetarodactyla (30%), Perissodactyla (26%), Primates (28%) and Rodentia (13%) (p < 0.0001) and higher in Felidae (70%) compared to Bovidae (28%) and Equidae (28%) (p < 0.0001). Mammals with carnivore/scavenger way of feeding were in a higher risk of T. gondii infection compared to herbivores and omnivores (p < 0.0001). T. gondii DNA was detected in tissue of one stray cat while in none of 77 rodents caught in zoo. This study is the first report on toxoplasmosis in zoos from the Czech Republic including seroepidemiology and molecular detection.

Serological survey on some pathogens in wild brown hares (Lepus europaeus) in Central Italy

OBJECTIVE

To determine the exposure of wild brown hares [Lepus europaeus (L. europaeus), pallas] to Anaplasma phagocytophilum (A. phagocytophilum), Borrelia burgdorferi (B. burgdorferi) sensu lato, Encephalitozoon cuniculi (E. cuniculi), Leishmania sp., Neospora caninum (N. caninum) and Toxoplasma gondii (T. gondii).

METHODS

Two hundred twenty-two blood serum samples of wild brown hares captured in protected areas of the province of Pisa (Central Italy) were tested to detect antibodies against the reported pathogens.

RESULTS

Thirty one (14.0%) animals resulted positive for at least one tested agent, with antibody titres ranging from 1:20 to 1:320. In particular, 13 (5.8%) samples were positive to B. burgdorferi s.l., 11 (4.9%) to N. caninum, 3 (1.3%) to T. gondii, 2 (0.9%) to A. phagocytophilum and 2 (0.9%) to Leishmania sp. No samples scored positive to E. cuniculi. Four animals (14.8%) resulted coinfected with 2 different pathogens.

CONCLUSION

The obtained results showed that B. burgdorferi s.l. N. caninum, T. gondii, A. phagocytophilum and Leishmania sp. circulate in wild brown hares in Central Italy, suggesting a possible role of L. europaeus as reservoir of these pathogens. The obtained results showed that autochthonous wild brown hares living in Central Italy have been exposed to several pathogens circulating in this area, suggesting a possible role of L. europaeus as reservoir.

Exploratory assessment of CD4+ T lymphocytes in brown hares (Lepus europeus) using a cross-reactive anti-rabbit CD4 antibody

In lagomorphs, lymphocyte subset distributions and the importance of CD4(+) T cell levels has so far only been considered in the frame of rabbit disease models. In this study, the first assessment of CD4(+) T lymphocytes in peripheral blood cells in brown hares (Lepus europaeus L., 1758), a further leporid species using a cross-reactive rabbit anti-CD4 antibody in flow cytometry, is presented. In addition, the entire coding region of the hare CD4 gene (1380 bp) coding for a polypeptide of 459 amino acids has been sequenced. Using generalized least squares fitting by maximum likelihood (GLS) test, significantly (p=0.0095) higher CD4(+) T cell frequencies in males than in females and significantly (p=0.0001) higher frequencies for leverets (younger than 2 months of age) than for subadult and adult (older than 7 months of age) individuals were detected. No significant age influence, however, was found for subadult and adult hares. The study is particularly meant to provide a first step in establishing a toolbox for the assessment of the immune response in this leporid species.

Seroprevalence of Toxoplasma gondii and Encephalitozoon cuniculi in rabbits from different farming systems

The breeding of domestic rabbit (Oryctolagus cuniculus) for human consumption has a long tradition mainly in European and Asian countries. Infections that can affect the production of meat or even be transmitted from animals to humans are important to monitor, especially for public health reasons as well as for their impact on animals health. This study aimed to collect sera from rabbits bred in different conditions and test the presence of Toxoplasma gondii and Encephalitozoon cuniculi antibodies. Whether infections were active or latent was assessed by determining the occurrence of IgM or IgM together with IgG antibodies which indicated active infection whereas latent infection was characterized by finding IgG antibodies only. An ELISA test was performed with 1883 sera samples collected throughout the Czech and Slovak Republics. The seroprevalence of T. gondii in 902 samples from 6 commercial farms (CF) was very low with only 4 rabbits (0.4%) being positive. In total 99 (10.1%) individuals out of 981 samples from 29 household farms (HF) were positive for T. gondii antibodies. Only 2 (50%) of the T. gondii positive CF rabbits had active infections while the rest were latently infected. The serological results showed that 35 (35.4%) rabbits from the T. gondii positive HF group suffered from active infection. Out of CF samples 185 (20.5%) were positive for E. cuniculi. Antibodies of E. cuniculi were detected in 497 (50.7%) HF rabbits. Active E. cuniculi infections were determined in 85.9% of CF and 56.3% of HF rabbits; respectively. Interestingly, the E. cuniculi positive rabbits were significantly more often positive for anti-T. gondii antibodies in comparison to E. cuniculi negative individuals. Prevalence of T. gondii in CF rabbits was negligible. According to our results meat of HF rabbits still poses a risk of T. gondii infection. Nevertheless, the risk is on its lowest level in 20 years which is apparently caused due to changes in feeding practices. The occurrence of E. cuniculi antibodies was significantly lower in rabbits from commercial farms, apparently because of better hygiene conditions.

Epidemiology and prevalence of Toxoplasma gondii infection in the Iberian hare (Lepus granatensis)

Hares are important game species in Europe and their meat is consumed by humans. Toxoplasmosis is an important cause of mortality in hares in Nordic countries but little is known of Toxoplasma gondii infection in the Iberian hare (Lepus granatensis). Sera from 298 Iberian hares from Navarra (North Spain) were assayed for antibodies against T. gondii by the modified agglutination test. The samples were collected at necropsy during three consecutive years (2009-2011). Titers of 1:25 and higher were found in 34 hares (11.4%; CI95%: 7.8-14.9). Significant differences in seroprevalence were observed among geographical areas, years of sampling and age groups. The highest seroprevalence and the highest titers were observed in 2009, indicating fluctuating rates of transmission. Significantly higher seroprevalence was observed in the juvenile age group compared to the adult hare group. More than 40% of juvenile hares were seropositive the first year of study, seroprevalence drastically decreased in the juvenile animals sampled in the second year and was negligible in those sampled in the third year in this group. No clinical cases were detected in the study area and T. gondii was not detected by PCR in the liver of the 34 seropositive hares tested. These data may indicate that most juvenile seropositive hares did not survive as adults in the consecutive year or that there is a short-term humoral immune response against T. gondii in Iberian hares.

Small intestinal inflammation following oral infection with Toxoplasma gondii does not occur exclusively in C57BL/6 mice: review of 70 reports from the literature

Small intestinal immunopathology following oral infection with tissue cysts of Toxoplasma gondii has been described in C57BL/6 mice. Seven days after infection, mice develop severe small intestinal necrosis and succumb to infection. The immunopathology is mediated by local overproduction of Th1-type cytokines, a so-called 'cytokine storm'. The immunopathogenesis of this pathology resembles that of inflammatory bowel disease in humans, i.e., Crohn's disease. In this review, we show that the development of intestinal pathology following oral ingestion of T. gondii is not limited to C57BL/6 mice, but frequently occurs in nature. Using a Pubmed search, we identified 70 publications that report the development of gastrointestinal inflammation following infection with T. gondii in 63 animal species. Of these publications, 53 reports are on accidental ingestion of T. gondii in 49 different animal species and 17 reports are on experimental infections in 19 different animal species. Thus, oral infection with T. gondii appears to cause immunopathology in a large number of animal species in addition to mice. This manuscript reviews the common features of small intestinal immunopathology in the animal kingdom and speculates on consequences of this immunopathology for humankind.

Prevalence of antibodies against Toxoplasma gondii and Neospora caninum in Hungarian red foxes (Vulpes vulpes)

In the present study we have investigated the seroprevalence to the protozoan parasites Toxoplasma gondii and Neospora caninum in 337 red foxes (Vulpes vulpes) from 16 out of 19 counties in Hungary. The foxes were originally collected within a National vaccination program against rabies. Antibodies to T. gondii were detected in as many as 228 (68%) of the foxes using a commercial direct agglutination test (DAT). In an indirect iscom ELISA, five foxes (1.5%) were positive for antibodies against N. caninum. The high prevalence of foxes positive for T. gondii might be explained by the widespread occurrence of the parasite in the diet of foxes. As a contrast, latent infections of N. caninum among red foxes in Hungary are much less common.

Factors affecting the seroprevalence of Toxoplasma gondii infection in wild rabbits (Oryctolagus cuniculus) from Spain

Sera from 456 wild rabbits (Oryctolagus cuniculus) collected between 1992 and 2003 from five geographical regions of Spain were examined for antibodies to Toxoplasma gondii by the modified agglutination test. Antibodies to T. gondii were found in 65 (14.2%) wild rabbits. Prevalence of infection was significantly higher in samples collected from wild rabbits from Catalonia, northeast Spain (53.8%), where rabbits lived in forest, compared to other areas (Huelva and Cádiz, Andalucía, south Spain; Toledo, Castilla-La Mancha, central Spain; and Zaragoza, Aragón, northeast Spain) with more dry conditions, where prevalence ranged from 6.1 to 14.6%. No differences were observed on prevalence and age (young animals <7 months of age compared to older animals), sex, date of samples collection or season of samples collection. The results indicate that prevalence of T. gondii in some areas of Spain is high, and this finding could have environmental and/or public health implications if wild rabbits are to be used as a source of food.

Experimental infection of budgerigars (Melopsittacus undulatus) with a low virulent K21 strain of Toxoplasma gondii

In total 53 budgerigars (Melopsittacus undulatus) were divided into six groups and orally infected with a suspension of oocysts of low virulent Toxoplasma gondii K21 strain in the doses of 10(2), 10(3), 10(4), 10(5) and 10(6), respectively. Blood was collected from the birds prior to the inoculation and then on days 10, 20 and 30 post infection. Latex-agglutination test (LAT) was used for the detection of antibodies in the inoculated birds. The infected birds showed no apparent signs of disease. The antibodies were found in all but two birds inoculated a dose of 10(2) oocysts. Haematological values remained unchanged after infection. T. gondii was isolated by bioassay in mice from all 37 birds fed 10(3) or more oocysts and 6 of 9 fed 10(2) oocysts. The results demonstrate that budgerigars are resistant to T. gondii infection.