首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 406 毫秒
1.
Cats are considered essential for the maintenance of Toxoplasma gondii in nature. However, T. gondii infection has been reported in arctic fox (Vulpes lagopus) from the Svalbard high arctic archipelago where felids are virtually absent. To identify the potential source of T. gondii, we attempted to isolate and genetically characterize the parasite from arctic foxes in Svalbard. Eleven foxes were trapped live in Grumant (78 degrees 11'N, 15 degrees 09'E), Svalbard, in September 2005 and 2006. One of the foxes was found to be seropositive to T. gondii by the modified agglutination test (MAT). The fox was euthanized and its heart and brain were bioassayed in mice for the isolation of T. gondii. All 10 mice inoculated with brain tissue and one of the five inoculated with heart developed MAT antibodies, and tissue cysts were found in the brains of seropositive mice. Two cats fed tissues from infected mice shed T. gondii oocysts. Genotyping using 10 PCR-RFLP markers and DNA sequencing of gene loci BSR4, GRA6, UPRT1 and UPRT2 determined the isolate to be Type II strain, the predominant T. gondii lineage in the world.  相似文献   

2.
Characterization of Toxoplasma gondii genotypes in hosts living in remote, isolated regions is important for elucidating the population structure and transmission mode of this parasite. Herein, we report the results of direct genotyping of T. gondii in brain tissue of arctic foxes (Vulpes lagopus) from the remote, virtually cat-free, high arctic islands of Svalbard. DNA extracts from brains of 167 seropositive arctic foxes (including four cases of fatal toxoplasmosis) and 11 seronegative arctic foxes were genotyped at 10 loci (SAG1, SAG2, SAG3, BTUB, GRA6, L358, c22-8, c29-2, PK1, and Apico) using the polymerase chain reaction-restriction fragment length polymorphism method. Of the 167 samples from seropositive foxes (including toxoplasmosis cases), 31 were genotyped at all 10 loci and 24 were genotyped at four to nine loci. To ensure confidence in T. gondii strain genotyping, samples for which less than four loci were genotyped were not considered positive. None of the 11 samples from seronegative foxes was positive for the 10 markers. Of the 55 samples that genotyped positively, 46 were of the Type II strain, 7 were of the Type III strain, and 2 were of atypical T. gondii strains. Five representative samples of the three genotypes were sequenced at loci SAG2, SAG3, GRA6, PK1, and UPRT-1. The DNA sequences confirmed the genotyping results. This study shows that the archetype Type II T. gondii strain, which is most widely distributed in North America and Europe, also predominates in arctic foxes on the Svalbard archipelago. This suggests that the T. gondii at this location originate from continental Europe and that transmission may be mediated by migrating birds. This study highlights the significance of long-distance transport of T. gondii and demonstrates that high-resolution genotyping protocols are useful for direct genetic studies of T. gondii when isolation of live parasites is infeasible.  相似文献   

3.
Acute disseminated toxoplasmosis was diagnosed in three wild arctic foxes (Alopex lagopus) that were found dead in the same locality on Svalbard (Norway). The animals included one adult female and two 4-months-old pups. The adult fox was severely jaundiced. Necropsy revealed multifocal, acute, necrotizing hepatitis, acute interstitial pneumonia, and scattered foci of brain gliosis, often associated with Toxoplasma tachyzoites. One pup also had Toxoplasma-associated meningitis. In addition, the latter animal was infected with Yersinia pseudotuberculosis serotype 2b and Salmonella Enteritidis phage type 1 (PT1), which may have contributed to the severity of the Toxoplasma infection in this animal. The diagnosis of toxoplasmosis was confirmed by positive immunohistochemistry and detection of anti-Toxoplasma gondii antibodies in serum of all foxes. The animals were negative for Neospora caninum, canine distemper virus, canine adenovirus, and rabies virus on immunolabelling of tissue sections and smears.  相似文献   

4.
Toxoplasma gondii is an intracellular coccidian parasite found worldwide and is known to infect virtually all warm-blooded animals. It requires a cat (family Felidae) to complete its full life cycle. Despite the absence of wild felids on the Arctic archipelago of Svalbard, T. gondii has been found in resident predators such as the arctic fox and polar bear. It has therefore been suggested that T. gondii may enter this ecosystem via migratory birds. The objective of this study was to identify locations where goose populations may become infected with T. gondii, and to investigate the dynamics of T. gondii specific antibodies. Single blood samples of both adults and juveniles were collected from selected goose species (Anser anser, A. brachyrhynchus, Branta canadensis, B. leucopsis) at Arctic brood-rearing areas in Russia and on Svalbard, and temperate wintering grounds in the Netherlands and Denmark (migratory populations) as well as temperate brood-rearing grounds (the Netherlands, non-migratory populations). A modified agglutination test was used on serum, for detection of antibodies against T. gondii. Occasional repeated annual sampling of individual adults was performed to determine the antibody dynamics. Adults were found seropositive at all locations (Arctic and temperate, brood-rearing and wintering grounds) with low seroprevalence in brood-rearing birds on temperate grounds. As no juvenile geese were found seropositive at any brood-rearing location, but nine month old geese were found seropositive during spring migration we conclude that geese, irrespective of species and migration, encounter T. gondii infection in wintering areas. In re-sampled birds on Svalbard significant seroreversion was observed, with 42% of seropositive adults showing no detectable antibodies after 12 months, while the proportion of seroconversion was only 3%. Modelled variation of seroprevalence with field data on antibody longevity and parasite transmission suggests seroprevalence of a population within a range of 5.2–19.9%, in line with measured values. The high occurrence of seroreversion compared to the low occurrence of seroconversion hampers analysis of species- or site-specific patterns, but explains the absence of an increase in seroprevalence with age and the observed variation in antibody titre. These findings imply that even though infection rate is low, adults introduce T. gondii to the high Arctic ecosystem following infection in temperate regions.  相似文献   

5.
Thoracic fluid (pleural fluid and clotted blood) from 206 foxes were examined for antibodies to Toxoplasma gondii and 220 thoracic fluid samples were tested for Neospora caninum antibodies using indirect immunofluorescent antibody tests (IFAT). A total of 115 (56%) and six (3%) foxes had antibodies to T. gondii and N. caninum, respectively. The brains from 148 foxes were examined for histological lesions and pathological changes suggestive of parasitic encephalitis were observed in 33 (22%). Two thirds of these foxes had antibodies to T. gondii and one fox had antibodies to both T. gondii and N. caninum. PCR assays carried out on DNA extracted from the 33 brains with histological lesions were negative for N. caninum but one of the brains was positive for T. gondii. Microsporidian DNA was also amplified from the brains of two of these foxes. Sequencing these amplicons revealed 100% homology with Encephalitozoon (Septata) intestinalis in one fox and Encephalitozoon cuniculi in the second fox. This is the first report of Encephalitozoon infections in wildlife in Ireland.  相似文献   

6.
Data on the genotypes of Toxoplasma gondii circulating in wildlife are scarce. In the present study, foxes and rodents from two Federal States in Central or Eastern Germany were examined for T. gondii infections. Body fluids were collected at necropsy or fluids were obtained from frozen tissues of naturally exposed red foxes (Vulpes vulpes), voles (Microtus arvalis), shrews (Neomys anomalus) and a striped field mouse (Apodemus agrarius) and tested for T. gondii by serology. DNA isolated from tissues of seropositive foxes and all the rodents was examined by PCR. In the German Federal States of Brandenburg and Saxony-Anhalt 152/204 (74.5%) and 149/176 (84.7%) of foxes, respectively, but none of the rodents (0/72) had antibodies to T. gondii. Only 28/152 (18.4%) and 20/149 (13.4%) of seropositive foxes from Brandenburg and Saxony-Anhalt, respectively, but none of the rodents tested PCR-positive for T. gondii. The complete T. gondii genotype could be determined for twelve samples using nine PCR-restriction fragment length polymorphism (PCR-RFLP) markers (newSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, PK1, L358 and Apico). In addition to T. gondii clonal type II (Apico II) and type II (Apico I), type III and T. gondii genotypes showing non-canonical allele patterns were observed in foxes. This suggests that, while T. gondii type II prevails in foxes, other genotypes circulate in wildlife. The population structure of T. gondii in Germany may be more diverse than previously thought.  相似文献   

7.
Intestinal washes, faecal flotations and serological examinations for antibodies to Toxoplasma gondii and Neospora caninum were used to assess the prevalence of parasites in carcases of foxes killed on roads or shot in the Dublin area and surrounding counties. The ascarids Uncinaria stenocephala and Toxocara canis were prevalent, as was the trematode Alaria alata. Taenia species, eggs of Capillaria species and sporocysts of Sarcocystis species were also found. Only one fox out of 70 examined was seropositive for N. caninum, whereas 24 of 51 were seropositive for T. gondii.  相似文献   

8.
The direct and interactive effects of climate change on host species and infectious disease dynamics are likely to initially manifest\ at latitudinal extremes. As such, Alaska represents a region in the United States for introspection on climate change and disease. Rabies is enzootic among arctic foxes (Vulpes lagopus) throughout the northern polar region. In Alaska, arctic and red foxes (Vulpes vulpes) are reservoirs for rabies, with most domestic animal and wildlife cases reported from northern and western coastal Alaska. Based on passive surveillance, a pronounced seasonal trend in rabid foxes occurs in Alaska, with a peak in winter and spring. This study describes climatic factors that may be associated with reported cyclic rabies occurrence. Based upon probabilistic modelling, a stronger seasonal effect in reported fox rabies cases appears at higher latitudes in Alaska, and rabies in arctic foxes appear disproportionately affected by climatic factors in comparison with red foxes. As temperatures continue a warming trend, a decrease in reported rabid arctic foxes may be expected. The overall epidemiology of rabies in Alaska is likely to shift to increased viral transmission among red foxes as the primary reservoir in the region. Information on fox and lemming demographics, in addition to enhanced rabies surveillance among foxes at finer geographic scales, will be critical to develop more comprehensive models for rabies virus transmission in the region.  相似文献   

9.
The occurrence and ecology of Trichinella in marine mammals   总被引：1，自引：0，他引：1  
Trichinella in marine mammals has a circumpolar arctic distribution and a narrow range of host species. It is commonly found in polar bears (Ursus maritimus), and increasingly in walruses (Odobenus rosmarus) where it presents a significant zoonotic hazard. This has resulted in the implementation of food safety programs in some arctic communities to test harvested walrus meat for Trichinella larvae prior to consumption. Trichinella has been reported infrequently in bearded seals (Erignathus barbatus) and ringed seals (Phoca hispida), and was once observed in a Beluga whale (Delphinapterus leucas). Cannibalism is probably the most important factor in maintaining a Trichinella cycle in polar bears. Arctic carnivores such as polar bears, arctic foxes (Alopex lagopus) and domestic dogs (Canis familiaris) have a high prevalence of Trichinella infection and the carcasses of at least some of these animals are deposited in the ocean. Scavenging of these carcasses by walruses probably occurs, but may not account for the high prevalence the parasite seen in this host species. Predation, carrion feeding and cannibalism have been documented for walruses and a sylvatic cycle similar to that of bears may exist in walrus populations. Seals and whales are likely infected through infrequent exposure to infected carcasses, either directly by scavenging or indirectly by consuming amphipods or fish that have fed on infected carcasses. The inefficiency of this mechanism may account for the low prevalence of Trichinella in seals and whales. It is known that isolates from marine mammals are cold tolerant, and infectious for man, and have been identified as Trichinella nativa (T2). Molecular and other phylogenetic studies would be useful to facilitate studies on the inter-relationship of Trichinella cycles involving marine and terrestrial mammals in the arctic and subarctic, and in the investigation of human outbreaks of trichinellosis in these areas.  相似文献   

10.
Little is known about the epidemiology of Neospora caninum in wild mammal populations. It has been suggested that a sylvatic cycle exists for N. caninum. Dogs and potentially other canids are a definitive host for N. caninum. The present study was done to determine the prevalence of antibodies to N. caninum in a population of gray foxes (Urocyon cinereoargenteus) from a nonagricultural setting in South Carolina. We also determined the prevalence of antibodies to Toxoplasma gondii in these animals. Antibody levels were measured in direct agglutination tests using either N. caninum or T. gondii formalin-fixed tachyzoites as antigen. Four (15.4%) of the 26 gray foxes had titers to N. caninum. Titers to N. caninum were low being 1:25 in three gray foxes and 1:50 in the fourth gray fox. Antibodies to T. gondii were observed in 16 (61.5%) gray foxes. Titers to T. gondii were usually >1:50 and two gray foxes had titers of 1:1600. Results of this study indicate that gray foxes have more exposure to T. gondii than to N. caninum in this environment.  相似文献   

11.
Coat colour variation is determined by many genes, one of which is the melanocortin receptor type 1 (MC1R) gene. In this study, we examined the whole coding sequence of this gene in four species belonging to the Canidae family (dog, red fox, arctic fox and Chinese raccoon dog). Although the comparative analysis of the obtained nucleotide sequences revealed a high conservation, which varied between 97.9 and 99.1%, we altogether identified 22 SNPs (10 in dogs, six in farmed red foxes, two in wild red foxes, three in arctic foxes and one in Chinese raccoon dog). Among them, seven appeared to be novel: one silent in the dog, three missense and one silent in the red fox, one in the 3′‐flanking region in the arctic fox and one silent in the Chinese raccoon dog. In dogs and red foxes, the SNPs segregated as 10 and four haplotypes, respectively. Taking into consideration the published reports and results of this study, the highest number of missense polymorphisms was until now found in the dog (9) and red fox (7).  相似文献   

12.
北极狐化脓性子宫内膜炎病原分离鉴定   总被引：6，自引：1，他引：5  
某养狐场饲养的北极狐于人工授精３～５日后，２０％出现拒食和高热。部分病狐从阴门流出少量脓样物。对病死狐剖检，可见典型的化脓性子宫内膜炎变化。采集子宫腔脓汁分离病原，经培养和生理生化鉴定证实为假单胞绿脓杆菌。毒力测定结果表明，该菌对实验动物小鼠于接种后１８小时内致死，确定其为引起北极狐原发性子宫内膜炎的致病菌。  相似文献   

13.
A seroepidemiological survey was conducted to investigate the prevalence of antibodies reactive with Ehrlichia canis and Hepatozoon canis antigens in free-ranging red foxes (Vulpes vulpes) in Israel. Of 84 fox sera assayed, 36% were seropositive for E. canis by the indirect fluorescent antibody (IFA) test and 24% were positive for H. canis using an enzyme-linked immunosrbent assay (ELISA). Canine ehrlichiosis and hepatozoonosis appear to be endemic in the wild red fox populations in Israel, and foxes may serve as a reservoir for infection of domestic dogs and other wild canine species.  相似文献   

14.
Hematologic, serum biochemistry, and serum cortisol reference ranges were established and tonsil/rectal bacterial and fecal parasite examinations were performed on 21 wild arctic fox (Alopex lagopus) cubs during July 1996. Several of the hematologic and serum biochemistry values fell within normal ranges for other wild canids or domestic dogs of the same age class. Serum alanine transaminase and creatine phosphokinase values were significantly higher in the youngest cubs. Proteus vulgaris and Escherichia coli were isolated from both tonsilar and rectal swabs of several cubs in all dens. The most common gastrointestinal parasite ova were Toxascaris leonina (59%), Isospora spp. (52%), Uncinaria stenocephala (33%), and Capillaria spp. (26%). Prevalence of T. leonina differed significantly between dens and between age groups. Hematologic and serum biochemistry values and degree of parasitism may be indicators of health, stress, and nutritional status of arctic foxes.  相似文献   

15.
Sera from 1770 dogs and 94 red foxes from Austria were examined for antibodies against Neospora caninum using the indirect immunofluorescent antibody test (IFAT). 3.6% of the dogs were seropositive with titres ranging from 1:50 to 1:6400. Dogs from rural areas were significantly more often seropositive for N. caninum than those from the urban area of Vienna (5.3% versus 2.1%). There were no significant differences in sex or breed, but a slight increase in seropositivity with age was apparent, indicating postnatal infection. None of the foxes had antibodies against N. caninum. Additionally, sera from 242 dogs and 94 foxes were examined for antibodies against Toxoplasma gondii using the IFAT. Thirty-five percent foxes and 26% of the dogs were positive; 1.7% of the dogs were positive for both parasites. This is the first report of the prevalence of N. caninum infections in dogs and foxes in Austria.  相似文献   

16.
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.  相似文献   

17.

Canine adenovirus type 1 (CAdV-1) is the aetiological agent of infectious canine hepatitis (ICH) in domestic dogs (Canis familiaris). In spite of the widespread use of vaccination, CAdV-1 continues to circulate in the dog population. Although a high number of serological screenings have indicated that CAdV-1 is widespread in fox species, little is known about the potential role of foxes as reservoirs of CAdV-1. Furthermore, very little data exist on the molecular features of this virus in foxes. To add to existing knowledge on CAdV-1 circulating in wild carnivores, tissue samples from CAdV-seropositive red foxes (Vulpes vulpes, n?=?10) from the northern mainland of Norway and arctic foxes (Vulpes lagopus, n?=?10) from the Svalbard archipelago, Norway, were investigated using a molecular approach to detect CAdV-1 DNA and important structural and non-structural genes of the detected viruses were sequenced and analysed. Amplicons characteristic for CAdV-1 were amplified from 14 out of 20 foxes (7 red foxes and 7 arctic foxes) and spleen and lymph node tissues resulted optimal targets for the viral DNA detection. The nucleotide sequences showed unique features that distinguished the viruses detected in this study from the CAdV-1 to date identified in wild carnivores and dogs. Greater attention should be given to genetically different CAdV-1 circulating in wild carnivores that may be transferred to dogs, potentially causing disease and reducing the effectiveness of available vaccines.

  相似文献   

18.
To investigate the possible role of common brushtail possums (Trichosurus vulpecula) in the transmission of Toxoplasma gondii within a zoo environment, a serological survey of a free-ranging population resident within Taronga Zoo, Sydney, Australia was undertaken using the modified agglutination test (MAT). For comparison, the seroprevalence of T. gondii antibodies was also assessed in a possum population inhabiting a felid-free, non-urban woodland habitat. Six of 126 possums (4.8%) from the zoo population had antibodies to T. gondii with a MAT titre of 25 or higher, while in contrast, all of the 17 possums from woodland were seronegative. These observations suggest that possums were at a higher risk of exposure to the parasite as a consequence of co-existing with domestic, stray and captive felids associated with urbanisation. Screening of captive felids at the zoo indicated 16 of 23 individuals (67%) and all 6 species were seropositive for T. gondii, implicating them as a possible source of the parasite within the zoo setting. In addition captive, non-felid carnivores including the chimpanzee (Pan troglodytes), saltwater crocodile (Crocodylus porosus), dingo (Canis lupis) and leopard seal (Hydrurga leptonyx) were tested for the presence of T. gondii antibodies as these species predate and are a leading cause of death amongst zoo possums. In total, 5 of 23 individuals (22%) were seropositive, representing 2 of the 4 carnivorous species; the dingo and chimpanzee. These data suggest that carnivory was not a highly efficient pathway for the transmission of T. gondii and the free-ranging possum population posed minimal threat to the health of zoo animals.  相似文献   

19.
The red fox (Vulpes vulpes) population, in Norway, was na?ve to Sarcoptes scabiei prior to the late 1970s when this parasite was first recorded and a still ongoing epidemic started. During the course of this protracted epidemic some degree of host/parasite adaptation, with the occurrence of healthy antibody positive foxes, might be expected. In the present study the prevalence of sarcoptic mange and serologically identified S. scabiei exposure was investigated in 363 Norwegian red foxes, shot by hunters during two different study periods (1994-1995 and 2002-2005). The sarcoptic mange diagnosis was based upon the presence of clearly visible lesions in the skin of the cadaver with confirmatory demonstration of S. scabiei. The serodiagnosis was based on an indirect-ELISA. There was a significant decrease in prevalence of both mange cases and seropositive animals from the first to the second study period. Whilst the mange prevalence fell more than threefold, from 30.0% to 6.6%, the seroprevalence dropped less dramatically from 53.3% to 19.1%. The smaller decrease in seroprevalence compared to mange cases reflected a significantly higher ratio of seropositive-mange negative versus seropositive-mange positive foxes, during the second study period, 40:18, compared to the first, 14:18. These findings indicate that the red fox population is adapting to live with the parasite and that low-grade or sub-clinical infections, and even recoveries, occur amongst exposed foxes. Mange positive foxes had significantly poorer body condition than those without sarcoptic mange. No significant difference in body condition was seen between seropositive-mange negative versus seronegative-mange negative foxes. The ELISA sensitivity was found to be 95% and proved a useful tool for investigating the exposure to S. scabiei in wild foxes. This study is believed to be the first pointing to a long-term Sarcoptes/fox adaptation, combining long-term prevalence studies of clinical sarcoptic mange and serological evidence of exposure to the parasite in the general fox population.  相似文献   

20.
Blood samples were obtained from native mammals and birds on a sheep range (Hopland Field Station) in northern California. Serums were tested for antibodies to Toxoplasma gondii by the indirect hemagglutination test. Of 382 deer that were tested from 1964 to 1973, 77 (20%) were seropositive for T gondii. Among 36 serums representing 6 species of wild carnivores (badgers, bobcats, coyotes, foxes, raccoons, and skunks), 18 (50%) were seropositive. All of the 5 bobcats tested were seropositive, with antibody titers ranging from 1:65,536. The testing of 175 serums from small wild mammals indicated antibody prevalence of 8% among jackrabbits, 6% among brush rabbits, and 2% among squirrels. None of the native mice tested was seropositive for T gondii. Of 120 native birds tested, 6 (5%) were seropositive. Of the resident domestic species of animals tested, antibodies were found in 1 of 7 domestic cats, 1 of 5 feral cats, 1 of 2 dogs, and 54 (13%) of 405 sheep.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号