弓形虫病临床特征及诊治研究新进展

刚地弓形虫是一种专性细胞内寄生的机会致病原虫,可感染人及200多种动物,引起人兽共患弓形虫病。人类对弓形虫有较强的自然免疫力,感染后绝大多数无明显症状表现,或只出现亚急性弓形虫病,当机体免疫功能受损时,可出现多种临床表现。孕妇感染弓形虫可引起胎儿先天感染或引发流产、畸胎、死胎等。本文概述了弓形虫病的临床特征、诊断、预防及治疗等相关研究新进展。     

鸟类弓形虫基因型研究进展

弓形虫(Toxoplasma gondii)是一种世界性分布、广泛寄生于人和温血动物有核胞内的顶复门原虫(Apicom-plexan),由于宿主、地域分布等因素,其种群结构具有丰富的遗传多样性。目前,关于鸟类弓形虫株基因型的研究报道和综述论文相对较少。本文综述了世界已经报道的关于家养禽类、观赏鸟类、野生珍稀鸟类的弓形虫基因型,为研究鸟类弓形虫病流行病学及虫株种群结构等生物学信息提供借鉴。     

Ocular toxoplasmosis in an immunocompetent 8-year-old child: a new active lesion or a late manifestation of a congenital toxoplasmosis?

Infection with the protozoan Toxoplasma gondii is one of the most frequent parasitic infections worldwide and the common infection of the retina in the general population. We describe a case report of a chorioretinitis in an immunocompetent 8-year-old patient as a consequence of a underdiagnosed neonatal toxoplasmosis. The boy was successfully managed with pyrimethamine and sulfadiazine. The present case we would like to empathize the importance of considering toxoplasma gondii as a possible cause of chorioretinitis in children living in developed countries and we provide a detailed reviewed of the literature about treatment of Toxoplasma gondii infection.     

分子诊断技术在弓形虫检测和基因分析中的研究进展

弓形虫是一种专性细胞内寄生的寄生虫,人感染后多呈隐性感染,临床表现缺乏特异性,检测及诊断较为困难.分子诊断是应用分子生物学方法,检测患者体内遗传物质结构或表达水平的变化,继而做出诊断的技术,它为疾病的预防、诊断、治疗和转归提供更为准确的信息.目前,分子诊断技术主要有核酸探针技术、PCR及其衍生技术、环介导等温扩增技术、基因芯片技术等.该文对分子诊断技术在弓形虫中的应用进行综述.     

阿奇霉素抗弓形虫感染的体外实验研究

目的　为探索孕期弓形虫感染治疗效果好的药物。方法　本实验采用体外细胞培养技术 ,MTT(四甲基偶氮唑盐 )比色法 ,观察阿齐霉素抗弓形虫侵袭的猴肾细胞的活力及功能状态及通过透射电镜、扫描电镜观察猴肾细胞内弓形虫的形态、体积并超微结构的改变。结果　猴肾细胞的增殖在不同浓度的阿齐霉素加药组比未加药组差异均有显著性 ,P <0 0 1。经透射电镜观察发现 :虫体在药物作用下有的发生破裂、崩解 ,细胞内留下空泡 ,有的呈团块 ,没有明显的细胞器可见。扫描电镜观察显示猴肾细胞内的虫体与未加药组相比明显皱缩。结论　阿齐霉素具有很好的抗弓形虫效应 ,而对猴肾细胞无显著影响。这为阻断孕期弓形虫宫内垂直感染胎儿治疗时提供科学的实验依据     

非人灵长类弓形虫病研究进展

弓形虫(Toxoplasma gondii)是一种专性细胞内寄生的机会性致病原虫, 呈世界性分布, 引起严重的人兽共患弓形虫病, 目前防控该病尚无理想的药物和疫苗。非人灵长类动物由于其遗传物质、形态结构与人类具有更高的相似性而成为人类疾病研究中理想的动物模型。新大陆灵长类对弓形虫具有较强的易感性, 而旧大陆灵长类感染弓形虫与人类感染弓形虫一样多呈亚临床感染。非人灵长类弓形虫病的研究主要集中在流行病学研究、临床症状、先天性弓形虫病的防治、治疗药物的筛选和疫苗开发等方面, 本文就近年来国内外非人灵长类动物弓形虫病研究进展作一综述。     

杭州市高危人群弓形虫感染血清流行病学调查

目的了解杭州市高危人群弓形虫感染和弓形虫病防治知识知晓情况。方法采用ELISA方法检测杭州市100例HIV/AIDS患者、100例恶性肿瘤患者、100例孕妇和100例健康对照者血清抗弓形虫抗体,对全部调查对象进行弓形虫病防治知识问卷调查。结果 HIV/AIDS、恶性肿瘤患者和孕妇血清抗弓形虫抗体阳性率分别为31%、30%和21%,均显著高于健康对照者的5%(χ~2=14.68,13.96和7.56,P均0.01)。孕妇对弓形虫病防治知识的知晓率整体较高,健康对照者对弓形虫病防治知识的知晓率整体较低;调查对象对"你知道弓形虫感染的危害吗?"、"你知道生食或食用未煮熟的肉类会感染弓形虫吗?"和"你知道接触被污染的土壤会感染弓形虫吗?"等问题的知晓率较低。结论杭州市HIV/AIDS、恶性肿瘤患者和孕妇等高危人群弓形虫感染率较高,且对部分弓形虫病防治知识知晓率较低。有必要加强对高危重点人群的弓形虫病防治知识健康教育,有效预防和控制弓形虫感染。     

乙酰螺旋霉素联合阿奇霉素治疗孕期弓形虫感染的临床效果

目的 目的 探讨螺旋霉素联合阿奇霉素治疗孕期弓形虫感染的综合治疗方法。方法 方法 应用ELISA方法检测孕妇血清 特异性弓形虫IgG和IgM抗体, 并采用PCR方法检测羊水中弓形虫感染情况; 选取其中3例弓形虫IgM抗体阳性孕妇作为 治疗对象, 应用螺旋霉素联合阿奇霉素进行综合治疗, 通过血清学特异性抗体检测和PCR检测结果初步判断其疗效。结 结 果 果 经ELISA检测, 孕期妇女血清特异性弓形虫IgG和IgM抗体的阳性率分别为5.97% （17/285） 和1.05% （3/285）, 对3例血 清IgM抗体阳性孕妇的羊水进行PCR检测特异性弓形虫基因, 有2例呈阳性。经过2种药物的联合治疗, 这2例孕妇血清 特异性弓形虫IgM抗体滴度阴转, PCR检测产妇脐带血中弓形虫基因为阴性。结论 结论 螺旋霉素联合阿奇霉素治疗孕期弓 形虫感染安全、 有效。     

Acute toxoplasmosis: evaluation of a thin-layer immunoassay technic for detection of IgM antibodies, anti-Toxoplasma gondii

A solid phase method, thin-layer immunoassay (IgM-TIA) was standardized and evaluated for the immunodiagnosis of acute toxoplasmosis, through the detection of IgM antibodies to Toxoplasma gondii. A total of 300 serum samples from serologically defined acute toxoplasmosis and, from non-related infections, was investigated by IgM-TIA. Statistical analysis were carried out in comparison with conventional tests, the immunofluorescence test for the detection of IgM antibodies (IgM-IFI) and hemagglutination test which uses 2-mercaptoethanol serum treatment (2ME-HA). Also the correlation coefficients were calculated for various Toxoplasma gondii antigen concentrations, as well as, the influence of the antigenic concentration on the relative indices of sensitivity and specificity were verified. The intra and inter test reproducibilities were demonstrated statistically, as well as, the reutilization of T. gondii antigen was proven to be possible for at least 10 times. The data indicated that antigenic concentrations, from 70 to 100 Cmg/ml, were able to provide maximum sensitivity and specificity. IgM-TIA displayed similar diagnostic efficiency to those two conventional tests here utilized, and may be employed to make diagnosis of acute toxoplasmosis, mainly if laboratory animals are available.     

The biological aspects of the therapy of parasitic diseases

Specific drugs, most of them heterocyclic compounds, are leading in the therapy of parasitic infections despite their relative toxicity and potent mutagenicity. In some parasitic diseases chemotherapy is of low efficacy (hydatid and multilocular echinococcosis, African trypanosomiasis) or practically absent (American trypanosomiasis) mostly due to suppression or distortion of an immune response. Methods of immunocorrection using recombinant cytokines (interleukins, interferons) or their inducers are to be borrowed from the practice of treatment of oncological, lymphoproliferative diseases and other immune deficiencies. For instance, alpha-interferon and gamma-interferon inducers should be used in echinococcosis, where, as our studies have shown, the production of these cytokines is markedly suppressed. The enforcement of chemotherapeutic effect by "parachemotherapy" (Sh. D. Moshkovski?, 1944), the effect of nonspecific pharmacological drugs upon the cells and tissues damaged by parasites (like Ca2+ transport blockers in drug-resistant falciparum malaria), should be used, for instance, recombinant gamma-interferon plus specific drugs in toxoplasmosis. Modern methods of immunotherapy based on the molecular mechanisms of a host-parasite relationship should be created, for instance, monoclonal antibodies to C3 receptors of membranes of cells invaded with Toxoplasma gondii. Immunotoxins such as monoclonal antibodies to myoblast receptors conjugated to 5-nitroimidazolyl-thiadiazole in Chagas' disease should be tested. The above mentioned biological approaches should increase the efficacy of chemotherapy in parasitic diseases with smaller amounts of specific drugs and less courses of treatment.     

Toxoplasmosis in pregnancy

Pregnant women who acquire infection from Toxoplasma gondii usually remain asymptomatic, although they can still transmit the infection to their fetuses with severe consequences. Given the asymptomatic nature of most Toxoplasma infections, primary prevention in pregnant women may lower the risk of congenital toxoplasmosis. Both consumption of undercooked meat and unprotected contact with soil are independent risk factors for T. gondii seroconversion during pregnancy, while contact with cat litter may pose a risk in certain situations. However, many pregnant women lack knowledge of these risk factors. This article reviews toxoplasmosis infection in pregnancy, with an emphasis on risk factors and appropriate counseling of pregnant women.     

Toxoplasma gondii pneumonitis in patients infected with the human immunodeficiency virus.

Pulmonary toxoplasmosis is a rarely recognized opportunistic infection in immunocompromised patients. A few case reports have described pulmonary toxoplasmosis in human immunodeficiency virus-infected patients in association with Toxoplasma gondii central nervous system disease. We encountered six cases of pulmonary toxoplasmosis in human immunodeficiency virus-infected patients who presented with a protracted febrile illness, respiratory symptoms, and an abnormal chest roentgenogram in the absence of neurologic findings. No clinical or roentgenographic features distinguished T gondii pneumonitis from more common opportunistic pulmonary infections. As the acquired immunodeficiency syndrome epidemic progresses, the presenting illnesses have evolved. Toxoplasma gondii must be considered a potential cause of pulmonary disease during the evaluation of human immunodeficiency virus-infected patients with respiratory symptoms.     

Congenital parasitic infections: a review

This review defines the concepts of maternal-fetal (congenital) and vertical transmissions (mother-to-child) of pathogens and specifies the human parasites susceptible to be congenitally transferred. It highlights the epidemiological features of this transmission mode for the three main congenital parasitic infections due to Toxoplasma gondii, Trypanosoma cruzi and Plasmodium sp. Information on the possible maternal-fetal routes of transmission, the placental responses to infection and timing of parasite transmission are synthesized and compared. The factors susceptible to be involved in parasite transmission and development of congenital parasitic diseases, such as the parasite genotypes, the maternal co-infections and parasitic load, the immunological features of pregnant women and the capacity of some fetuses/neonates to overcome their immunological immaturity to mount an immune response against the transmitted parasites are also discussed and compared. Analysis of clinical data indicates that parasitic congenital infections are often asymptomatic, whereas symptomatic newborns generally display non-specific symptoms. The long-term consequences of congenital infections are also mentioned, such as the imprinting of neonatal immune system and the possible trans-generational transmission. The detection of infection in pregnant women is mainly based on standard serological or parasitological investigations. Amniocentesis and cordocentesis can be used for the detection of some fetal infections. The neonatal infection can be assessed using parasitological, molecular or immunological methods; the place of PCR in such neonatal diagnosis is discussed. When such laboratory diagnosis is not possible at birth or in the first weeks of life, standard serological investigations can also be performed 8-10 months after birth, to avoid detection of maternal transmitted antibodies. The specific aspects of treatment of T. gondii, T. cruzi and Plasmodium congenital infections are mentioned. The possibilities of primary and secondary prophylaxes, as well as the available WHO corresponding recommendations are also presented.     

Immune response and diagnostic aspects during Toxoplasma gondii infection

Toxoplasmosis is a common and generally benign disease in immunocompetent persons caused by Toxoplasma gondii, which is an intestinal coccidian parasite of felines. Diagnosis of toxoplasmosis is mainly based on the results of serological tests detecting anti-T. gondii specific antibodies, but T lymphocytes and cytokines they produce play a crucial role in determining the outcome of parasitic infection in terms of both protective immunity and immunopathology.     

Efficacy of azithromycin in a murine toxoplasmosis model,employing a Toxoplasma gondii strain from Turkey

A murine toxoplasmosis model with Balb/C mice was used to investigate the therapeutic and prophylactic efficacy of azithromycin in a native strain of Toxoplasma gondii. Initially, seven groups--four studies and three controls--were established and 10(3) tachyzoites of this native strain of T. gondii were injected intraperitoneally to the mice in groups 1, 2, 3, 4 and 7. Azithromycin was given to groups 1-4 at different times of infection orally between 100 and 300 mg/kg/day for 10 days. Azithromycin was found to be effective at 200 mg/kg/day and above in the prophylaxis, at 250 mg/kg/day and above in the treatment of toxoplasmosis. These results suggest that azithromycin is effective in the prophylaxis and early infection of a highly virulent strain of T. gondii, and it doubled the survival time in the late infection. Azithromycin could be an alternative treatment regimen for human toxoplasmosis, if supported by further clinical investigations.     

弓形虫基因分型研究进展

弓形虫感染可引起严重的弓形虫病, 而不同宿主感染的弓形虫株基因型差异较大, 不同基因型弓形虫株的致病力及药物敏感性亦存在较大差异。目前, 对弓形虫基因型的分析多选用限制性片段长度多态性PCR（PCR?RFLP）、 高度重复序列PCR、 多重PCR和巢氏PCR等技术, 扩增位点多选择B1、 SAG2、 HSP70、 GRA6等遗传标记。传统的弓形虫基因型主要有3个, 随着研究的不断深入, 越来越多的基因型被发现。本文就弓形虫基因分型研究进展进行综述。     

Toxoplasma gondii spreading in an urban area evaluated by seroprevalence in free-living cats and dogs

Infection by the protozoan parasite, Toxoplasma gondii is widely prevalent in humans and animals throughout the world. Transmission takes place mainly by ingestion of raw or undercooked meat that contains parasite cysts or by ingestion of oocysts excreted in cat faeces, which can contaminate water and raw vegetables. The incidence of toxoplasmosis in urban areas can thus be also related to environmental contamination with oocysts. A direct measure of this environmental contamination by oocyst counting is unfeasible for technical reasons. An interesting alternative for measuring T. gondii urban spreading is the seroprevalence in free-living urban animals, used as sentinels, once they are exposed to similar risks of Toxoplasma infection-like humans. With this aim, we tested serum samples from stray cats and dogs for antibodies to T. gondii by indirect haemagglutination assay (IHA) and enzyme-linked immunosorbent assay (ELISA). Antibodies to T. gondii were found in 40% (40 of 100) of the cats, less than the 50.5% (101 of 200) found in dogs by ELISA (P < 0.05). Haemagglutination showed low resolution and concordance, precluding their use for diagnosis of T. gondii infection compared with ELISA. The prevalence of T. gondii was lower among stray cats probably due to their selective alimentary habits and lower water and food intake. Toxoplasma gondii seroprevalence in stray dogs and cats could be an indirect indicator of the parasite spreading in urban areas.     

弓形虫病疫苗研究进展概述

弓形虫是一种专性细胞内寄生原虫,能引起人畜共患弓形虫病,严重威胁着人类健康且对畜牧业的发展造成巨大的经济损失。研制安全有效的疫苗是防制弓形虫病的策略之一。目前,弓形虫病疫苗包括灭活疫苗、减毒活疫苗、核酸疫苗、亚单位疫苗和卡介苗。本文对弓形虫病疫苗的研究现状进行了综述。     

Sensitive and specific detection of toxoplasma DNA in an experimental murine model: use of Toxoplasma gondii-specific cDNA and the polymerase chain reaction

Toxoplasma gondii, an apicomplexan parasite of mammals and birds, is well recognized as a cause of encephalitis in AIDS patients and as a cause of congenital infections. The polymerase chain reaction (PCR) and toxoplasma cDNA clones were used to diagnose T. gondii infection in an acute murine model of toxoplasmosis. Diagnosis of tissue infection by Southern blot hybridization with cDNA clones of T. gondii was possible within 5 days of infection. This technique could detect as few as 10,000 organisms. Specific T. gondii gene amplification by PCR using the primers 5'CACACGGTTGTATGTCGGTTTCGCT3' and 5'TCAAGGAGCTCAATGTTACAGCCT3' followed by oligonucleotide hybridization using 5'GCGGTCATTCTCACACCGACGGAGAACCACTTCACTCTCA3' allowed detection of T. gondii in the tissue of mice by day 2 after infection and in the blood of mice by day 5 after infection with RH strain T. gondii. This technique could detect as few as 10 organisms. Thus, these techniques may be useful in the diagnosis of toxoplasmosis.     

Cell structure and metabolism of the parasite Toxoplasma gondii--new aspects

The article is based on newly published data concerning cell structure (cytoskeleton and cytoplasmic organelle) and biochemistry of the protozoon Toxoplasma gondii, many of which can be applied in therapy of toxoplasmosis.