我国肿瘤患者弓形虫感染情况研究进展

弓形虫是一种重要的机会性寄生原虫,可感染人、哺乳动物及鸟类,引起人兽共患弓形虫病。目前,弓形虫感染已经成为一种严重的、全球性的公共卫生安全问题,引起了医学界的广泛关注。肿瘤患者的机体存在免疫功能障碍,对其进行放疗或化疗的过程中,则会进一步的降低肿瘤患者的免疫功能,临床上因抗肿瘤治疗而引起的弓形虫为典型代表的难治愈性寄生虫病的重症化已经愈发明显。肿瘤患者合并弓形虫感染的相关研究逐渐成为弓形虫病研究热点。论文对我国肿瘤患者弓形虫的流行情况﹑基因分型﹑传播途径及防治措施做一概述,旨在为有效防控肿瘤患者弓形虫共感染提供参考。     

Detection of T. gondii in tissues of sheep and cattle following oral infection.

It has been reported in the literature that cattle are more resistant to toxoplasmosis than sheep. Congenital disease due to T. gondii infection is rarely reported in cattle whereas the parasite is a major cause of abortion and neonatal mortality in sheep. It is believed that sheep remain chronically infected for life. Undercooked meat from infected sheep is an important source of infection for man. In contrast cattle are thought to harbour fewer parasite tissue cysts which may not persist for the lifetime of the host. Therefore, cattle are believed to pose less of a risk for human infection. In this study we examined the presence of T. gondii within a range of tissues in sheep and cattle at 6 weeks and 6 months following oral infection with 10(3) or 10(5) sporulated oocysts of T. gondii. The presence of parasite was determined by bioassay in mice and using polymerase chain reaction (PCR). The results from this study show that T. gondii was more frequently and consistently detected in sheep, in particular within brain and heart tissues, whereas parasites were not detected in the samples of tissues taken from cattle. T. gondii was more frequently detected in sheep given the higher dose of T. gondii. Examination of tissues at either 6 weeks or 6 months after infection did not appear to affect the distribution of T. gondii. The polymerase chain reaction has more specificity and sensitivity when detecting the presence of T. gondii in large animals than histological detection.     

野生动物弓形虫病研究进展

弓形虫是一种重要的胞内寄生原虫,可以感染几乎所有的温血动物。食肉性动物中猫科动物对弓形虫病的传播起着重要的作用,它是惟一的可以排泄含有弓形虫的卵囊到环境中的动物,进而使全世界的人和动物都有机会感染弓形虫病,而草食性动物和杂食性动物则是重要的中间宿主。然而野生动物感染弓形虫病之后往往缺少明显的临床症状,很难在第一时间判断出是否感染弓形虫。野生动物关系到整个生态系统的稳定,对整个生物界起着至关重要的作用,应该引起我们极大的关注和重视。论文就弓形虫在野生动物中的感染情况及临床症状加以概括,为其在野生动物中的流行趋势、诊断和防控的深入研究提供资料。     

Seroprevalence of Toxoplasma gondii in cattle, sheep and goats slaughtered for food in Mazandaran province, Iran, during 2005

Serum samples from 290 cattle, 400 goats and 588 sheep slaughtered for food in various areas of the Mazandaran province, Iran were tested for antibodies to Toxoplasma gondii by the indirect immunofluorescence antibody test (IFAT), from December 2004 to April 2005. Antibodies to T. gondii were found in 30% (120/400) goats and 35% (206/588) sheep and 0% (0/290) cattle, at a dilution of 1:16 or more for goats and sheep and 1:128 or more for cattle. The highest titres observed in cattle, goats and sheep were 1:64 (0.7%), 1:128 (1%), 1:64 (2%), respectively. These results indicate that T. gondii antibodies are widespread in the animal populations and suggest that toxoplasmosis is a widely spread zoonotic infection in northern Iran.     

A Serological Study on The Prevalence of Toxoplasma Gondii in Meat-Producing Animals in Sweden

Sera from 200 sheep, swine and cattle, respectively, collected at slaughter at each of 3 abattoirs situated in the north, middle and south of Sweden were examined for the presence of antibodies to Toxoplasma gondii by the indirect fluorescent antibody test. Seropositive animals (titre ≥ 1:20) were found at the following rates from north to south: sheep 60%, 66% and 68.5%, swine 9%, 2.5% and 37%, and cattle 10%, 6 % and 35%. The significance of the serological findings is discussed, and it is concluded that T. gondii infection is common in Swedish farm animals. Thus the meat from particularly swine and sheep may provide a potential source of human toxoplasmosis.     

Effect of Feline Immunodeficiency Virus Infection on Toxoplasma gondii-specific Humoral and Cell-mediated Immune Responses of Cats with Serologic Evidence of Toxoplasmosis

Serum samples from 89 cats with serologic evidence of toxoplasmosis were identified by using an enzyme-linked immunosorbent assay (ELISA) that detected Toxoplasma gondii -specific immunoglobulin M (IgM) or T. gondii -specific immunoglobulin G (IgG). Concurrent feline immunodeficiency virus (FIV) infection was detected in 36 cats using an ELISA for detection of FIV-specific IgG. The majority of the cats in both the FIV-seropositive and FIV-seronegative groups were male and >5 years of age. FIV-seropositive cats were more likely to have T. gondii IgM titers without IgG ( P > 0.05) or any T. gondii IgM titer ( P > 0.05) than were FIV-seronegative cats. FIV-seronegative cats (1328) had a higher T. gondii IgG geometric mean titer than did FIV-seropositive cats (724) and were more likely to have T. gondii IgG titers 1:2048 than were FIV-seropositive cats ( P > 0.05). Cats with serologic evidence of both T. gondii and FIV infections had persistent T. gondii IgM titers for >12 weeks. Lymphoblast transformation in response to concanavalin A, T. gondii -specific intracellular antigens, and T. gondii -specific secretory antigens was compared in T. gondii seropositive and FIV-seronegative cats, cats with serologic evidence of T. gondii infection alone, and cats with serologic evidence of concurrent FIV and T. gondii infections. Lymphocytes from all but one cat in the FIV-seropositive group responded to concanavalin A. Whereas lymphocytes from FIV-seronegative cats with serologic evidence of toxoplasmosis responded to T. gondii -specific antigens, four of five of the FIV-seropositive cats with concurrent serologic evidence of toxoplasmosis did not.     

Toxoplasmosis in Tammar wallabies (Macropus eugenii) in the Budapest Zoo and Botanical Garden (2006-2010)

Smaller macropodid species (commonly referred to as wallabies) are extremely susceptible to toxoplasmosis: in most cases, infection with Toxoplasma gondii leads to death within a short time. Between June 2006 and July 2010, T. gondii was detected by immunohistochemical examination in six Tammar wallabies (Macropus eugenii) that died in the Budapest Zoo and Botanical Garden; in another four specimens histopathology revealed T. gondii-like organisms (which could not be differentiated from Neospora caninum solely by morphology), and in another 11 animals toxoplasmosis as the possible cause of death could not be excluded. The current zoo population of 12 Tammar wallabies was tested for T. gondii IgG antibodies by the modified agglutination test (MAT), with negative results. We suppose that most of the deaths were due to acute toxoplasmosis resulting from a recent infection.     

Acute toxoplasmosis in squirrel monkeys (Saimiri sciureus) in Mexico

Toxoplasma gondii causes fatal multisystemic disease in New World primates, with respiratory failure and multifocal necrotic lesions. Although cases and outbreaks of toxoplasmosis have been described, there are few genotyping studies and none has included parasite load quantification. In this article, we describe two cases of lethal acute toxoplasmosis in squirrel monkeys (Saimiri sciureus) of Mexico city. The main pathological findings included pulmonary edema, interstitial pneumonia, hepatitis and necrotizing lymphadenitis, and structures similar to T. gondii tachyzoites observed by histopathology in these organs. Diagnosis was confirmed by immunohistochemistry, transmission electron microscopy and both end point and real time PCR. The load was between <14 and 23 parasites/mg tissue. Digestion of the SAG3 gene amplicon showed similar bands to type I reference strains. These are the first cases of toxoplasmosis in primates studied in Mexico, with clinical features similar to others reported in Israel and French Guiana, although apparently caused by a different T. gondii variant.     

Toxoplasmosis in Indo-Pacific humpbacked dolphins (Sousa chinensis), from Queensland

OBJECTIVE: To describe the clinical signs, gross pathology, serology, bacteriology, histopathology, electron microscopy and immunohistochemistry findings associated with toxoplasmosis in four Indo-Pacific humpbacked dolphins (Sousa chinensis) that stranded in Queensland in 2000 and 2001. DESIGN: Clinical assessment, gross necropsy, and laboratory examinations. PROCEDURE: Necropsies were performed on four S. chinensis to determine cause of death. Laboratory tests including serology, bacteriology, histopathology and transmission electron microscopy were done on the four dolphins. Immunohistochemistry was done on the brain, heart, liver, lung, spleen and adrenal gland from various dolphins to detect Toxoplasma gondii antigens. RESULTS: Necropsies showed all of four S. chinensis that stranded in Queensland in 2000 and 2001 had evidence of predatory shark attack and three were extremely emaciated. Histopathological examinations showed all four dolphins had toxoplasmosis with tissue cysts resembling T. gondii in the brain. Tachyzoite stages of T. gondii were detected in the lungs, heart, liver, spleen and adrenal gland, variously of all four dolphins. Electron microscopy studies and immunohistochemistry confirmed the tissues cysts were those of T. gondii. All four dolphins also had intercurrent disease including pneumonia, three had peritonitis and one had pancreatitis. CONCLUSION: Four S. chinensis necropsied in Queensland in 2000 and 2001 were found to be infected with toxoplasmosis. It is uncertain how these dolphins became infected and further studies are needed to determine how S. chinensis acquire toxoplasmosis. All four dolphins stranded after periods of heavy rainfall, and coastal freshwater runoff may be a risk factor for T. gondii infection in S. chinensis. This disease should be of concern to wildlife managers since S. chinensis is a rare species and its numbers appear to be declining.     

A review of toxoplasmosis of animals in the U.S.S.R

Information on the serologic and parasitologic prevalence of Toxoplasma gondii infection in domestic and wild animals of the U.S.S.R. is reviewed. Although complement-fixing antibodies to T. gondii were widely prevalent in animals, little information is available on the presence of viable T. gondii in tissues of animals. Reports of epizootics in which T. gondii was suspected to be the causative agent of toxoplasmosis are summarized. Also, the strict economic impact of toxoplasmosis on agriculture in the U.S.S.R. needs evaluation.     

Prevalence and relevance of avian Toxoplasma gondii infections in Europe

Toxoplasma (T.) gondii is a parasitic protozoon whose life cycle includes a definite and an intermediate host. Besides a wide range of mammals also birds are suitable intermediate hosts. There are a high number of case reports, prevalence data and experimental studies regarding avian toxoplasmosis. In many domestic, wild and zoo bird species which are relevant in Europe the susceptibility for T. gondii infection could be demonstrated though susceptibility for clinical disease often seems to be low, especially in gallinaceous birds. Comprehensive Europe-wide studies concerning the occurrence of avian toxoplasmosis have not been conducted so far. The general infestation ratio of birds on European free-range poultry farms seems to be relatively high. The European wild bird population represents a significant reservoir for the pathogen. When evaluating the seroprevalence it has to be considered that sensitivity and specificity of the detection methods for T. gondii specific antigens which are used frequently in mammals often are not satisfying in birds.     

A review of toxoplasmosis in wild birds

Toxoplasma gondii affects most species of warm-blooded animals, including birds. There is considerable confusion regarding the identity of T. gondii-like parasites and the diagnosis of toxoplasmosis in wild birds. In this review, T. gondii-like infections in different species of wild birds are reviewed with particular reference to prevalences, clinical signs, pathology, diagnosis, and treatment. Although subclinical T. gondii infections are prevalent in many avian species, toxoplasmosis can be clinically severe in pigeons and canaries. Blindness associated with T. gondii in canaries is reviewed in detail.     

Application of assays for the diagnosis of toxoplasmosis in a colony of woolly monkeys (Lagothrix lagotricha).

Toxoplasma gondii infection is a common cause of morbidity and mortality in New World primate species. Clinical abnormalities associated with toxoplasmosis can be nonspecific, making it difficult to make a definitive antemortem diagnosis and initiate appropriate treatment. Toxoplasmosis in New World primates can have a rapid clinical course, which may lessen the diagnostic utility of antemortem tests. However, while there are a variety of T. gondii serum antibody tests and T. gondii polymerase chain reaction (PCR) assays available that are not species specific, these assays have not been comparatively applied to New World primate cases. Woolly monkeys (Lagothrix lagotricha), a species of New World primate, are highly susceptible to fatal toxoplasmosis. Archived serum samples from 15 living and deceased woolly monkeys housed at the Louisville Zoological Garden (Louisville, Kentucky) were tested for T. gondii antibodies by a commercially available latex agglutination kit, a commercially available indirect hemagglutination kit, and the modified agglutination test. In addition, aliquots of the sera were assayed for T. gondii DNA using a PCR assay. Both woolly monkeys that died of disseminated toxoplasmosis were positive in all four assays, indicating that each could be used to aid in the diagnosis of toxoplasmosis in this species. We suspect that these assays have applications to other species of New World primates.     

Toxoplasma gondii antibodies in the white stork Ciconia ciconia

The prevalence of Toxoplasma gondii in chicks of wild birds and captive individuals was studied in the Poznań environs and in the Poznań Zoological Garden in the years 2002-2003. Bird blood was tested for T. gondii antibodies by an indirect fluorescent antibody test. T. gondii antibodies were detected from 5.8% of 205 analysed white stork chicks and 13.6% of 44 analysed adult storks in the zoo. Because toxoplasmosis is one of the more common parasitic zoonoses worldwide, we briefly discuss the potential epidemiological importance of stork toxoplasmosis to humans.     

Use of a multiplex polymerase chain reaction assay in the antemortem diagnosis of toxoplasmosis and neosporosis in the central nervous system of cats and dogs

OBJECTIVE: To develop a multiplex polymerase chain reaction (PCR) assay for the detection of Toxoplasma gondii and Neospora caninum DNA in canine and feline biological samples. SAMPLE POPULATION; Biological samples from 7 cats with systemic (n = 4) or CNS (3) toxoplasmosis, 6 dogs with neospora- or toxoplasma-associated encephalitis, and 11 animals with nonprotozoal disease. PROCEDURE: Primers for T gondii, N caninum, and the canine ferritin gene (dogs) or feline histone 3.3 gene (cats) were combined in a single PCR assay. The DNA was extracted from paraffin-embedded brain tissue, CSF, or skeletal muscle. The PCR products with positive results were cloned, and sequence identity was confirmed. RESULTS: Of 7 cats and 4 dogs with immunohistochemical or serologic evidence of toxoplasmosis, PCR results were positive for all cats and 3 dogs for T gondii, and positive for T gondii and N caninum for 1 dog. Another dog had negative PCR results for both parasites. Of 2 dogs with immunohistochemical or serologic evidence of neosporosis, PCR results were positive for 1 for N caninum and positive for the other for T gondii. All negative-control samples yielded negative results for T gondii and N caninum on the PCR assay. CONCLUSIONS AND CLINICAL RELEVANCE: Standard tests for toxoplasmosis or neosporosis associated with the CNS rely on serologic, histologic, or immunohistochemical analysis and can be difficult to interpret. The multiplex PCR assay with built-in control reactions could be a complementary clinical tool for the antemortem diagnosis of toxoplasmosis or neosporosis associated with the CNS.     

Sensitive and specific polymerase chain reaction detection of Toxoplasma gondii for veterinary and medical diagnosis.

A polymerase chain reaction (PCR) method was developed for the detection of Toxoplasma gondii. A universal- and a T. gondii-specific primer was used to amplify a region of the small subunit ribosomal RNA gene. This approach allows for a theoretical detection limit of 0.01 zoite of T. gondii per sample assayed. Experiments showed that this PCR method could detect 0.1 pg of T. gondii DNA, which represents about one organism. Polymerase chain reaction tests using DNAs of cat, dog, swine, cattle, human, Sarcocystis cruzi, Eimeria ahsata, E. vermiformis, and Escherichia coli indicated no cross-reaction with nucleic acids of hosts, related coccidia, or bacteria. Data on the sensitivity and specificity suggest that this PCR assay could be extremely useful for the diagnosis of toxoplasmosis in human and veterinary medicine, as well as for food safety surveys.     

Direct high-resolution genotyping of Toxoplasma gondii in arctic foxes (Vulpes lagopus) in the remote arctic Svalbard archipelago reveals widespread clonal Type II lineage

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.     

Feline ocular toxoplasmosis

Ocular infection with Toxoplasma gondii is a well-recognized and important clinical entity in many animal species. In the cat, ocular toxoplasmosis is commonly associated with systemic infection, yet its role in causing anterior uveitis in an otherwise healthy cat is unclear. The purpose of this article is to review the salient epidemiological, clinical, and histopathologic features of systemic and ocular toxoplasmosis in the cat. Additionally, pathogenesis and possible immunopathogenic mechanisms of ocular toxoplasmosis, which may account for the higher prevalence of anterior uveitis in cats seropositive for T. gondii , are discussed. Finally, diagnosis, treatment and prevention of feline toxoplasmosis are reviewed.     

Serological evidence of Toxoplasma gondii infection in captive marine mammals in Mexico

Toxoplasma gondii infection in marine mammals is important because they are considered as a sentinel for contamination of seas with T. gondii oocysts, and toxoplasmosis causes mortality in these animals, particularly sea otters. Serological evidence of T. gondii infection was determined in 75 captive marine mammals from four facilities in southern and central geographical regions in Mexico using the modified agglutination test (MAT). Antibodies (MAT, 1:25 or higher) to T. gondii were found in 55 (87.3%) of 63 Atlantic bottlenose dolphins (Tursiops truncatus truncatus), 3 of 3 Pacific bottlenose dolphins (Tursiops truncatus gillii), 2 of 4 California sea lions (Zalophus californianus), but not in 3 West Indian manatees (Trichechus manatus), and 2 Patagonian sea lions (Otaria flavescens). Seropositive marine mammals were found in all 4 (100%) facilities sampled. All marine mammals were healthy and there has not been any case of clinical toxoplasmosis in the facilities sampled for at least the last 15 years. The seroprevalence of T. gondii infection in marine mammals of the same species did not vary significantly with respect to sex and age. This is the first report on the detection of antibodies to T. gondii in marine mammals in Mexico.     

宠物犬弓形虫病诊疗措施

弓形虫病属于一种分布范围非常广泛的人畜共患原虫病,幼犬、猫的发病率比较高。弓形虫宿主非常广泛,目前国内对弓形虫病的研究以家禽为主要研究对象,针对宠物犬弓形虫病诊疗及流行病学进行探讨对人类健康也有积极意义。