圆孢子球虫感染一例

圆孢子球虫 (Ｃｙｃｌｏｓｐｏｒａｃａｙｅｔａｎｅｎｓｉｓ)是一种致病性肠道原虫 ,免疫功能正常的人群感染后 ,可引起持续几周或几个月的间歇性肠炎 ,常见于到过热带地区或国家的旅游者[1] 以及免疫缺陷的艾滋病 (ＡＩＤＳ)患者。感染圆孢子球虫后的主要临床症状为持续性水样便、厌食、乏力、恶心、呕吐及腹痛等。该原虫经粪口传播 ,患者大便中排出的卵囊在适宜的气候环境条件下经数天或几周发育为感染期卵囊后经口感染。一般夏秋季发病率较高。Ｓｏａｖｅ于 1986年首次报道从旅游海地、墨西哥的美国人中查出圆孢子球虫后 ,其它国家也有…     

云南省腹泻患者圆孢子虫和隐孢子虫感染情况调查分析

目的　调查腹泻患者中圆孢子虫和隐孢子虫的感染情况及分布特征。　方法　 1997～ 2 0 0 0年每年的 3～10月份 ,收集云南省 6个地 (州、市 )所属 7个县 (市、区 )寄生虫病防治试点 378例腹泻患者的粪便 ,进行碘液直接涂片和粪便涂片抗酸染色镜检。　结果　 7个县 (市、区 ) 378例腹泻患者的圆孢子虫和隐孢子虫的总感染率分别为 3.97%和5 .2 9% ,其中学龄前儿童的感染率最高 ,圆孢子虫和隐孢子虫的感染率分别为 10 .6 4%和 8.5 1%。圆孢子虫在罗平、元阳和普洱 3个县内查出 ,隐孢子则在泸水县、景洪市、普洱县、罗平县、元阳县和昆明西山区 6个县 (市 )内查出。　结论　圆孢子虫呈局部流行 ,隐孢子虫则流行分布广泛 ,学龄前儿童 2种孢子虫的感染率较高。     

Emerging pathogen Cyclospora cayetanensis infection in Nepal

Cylospora cayetanensis, an emerging parasitic pathogen of human is being increasingly recognized throughout the world, however the means of transmission and the possibility of a reservoir host remain an enigma. A longitudinal study on cyclosporiasis in different parts of Nepal was carried out from April, 1995 until November, 2000. Fecal specimens were collected from symptomatic and asymptomatic patients. The data shows a distinct seasonality with the highest infection rates occurring during the summer and rainy season of the year. Attempts have been made to determine the sources of infection and possible reservoir hosts. Stools were examined from nearly 700 animals such as chickens, pigs, buffalos, cows, dogs, cats, monkeys, rats, mice and pigeons. In addition, vegetable farms around the Kathmandu Valley were examined during the seasonal high and low periods of transmission. C. cayetanensis-like oocysts were found in sewage water and from vegetable washings on five occasions during June, July, August, October, and November. Similarly, C. cayetanensis-like oocysts were recovered from mice, rats, chickens, and dogs. These results suggest that these sources may be important in the transmission of this parasitosis. However, further studies will be required to obtain definitive answers on transmission.     

Prevalence and pathogenic role of Cyclospora cayetanensis in a Venezuelan community

The prevalence and pathogenic role of Cyclospora cayetanensis among 212 subjects (age range = two months to 70 years) in an impoverished community in Venezuela were assessed retrospectively. For identification of the coccidium, modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether concentrates was used. For other pathogenic parasites, iron-hematoxylin-stained smears and formalin-ether concentrates were examined. Cyclospora infections were identified in 13 (6.1%) subjects with a high percentage of asymptomatic carriers (11 of 13, 84.6%). Only two (15.4%) infants had diarrhea and the coccidium as the single detectable pathogenic parasite. The findings suggest that Cyclospora infections are relatively common and often asymptomatic in this region.     

Recovery of Cyclospora cayetanensis among asymptomatic rural Thai schoolchildren

Objective:To obtain the prevalence with clinical symptoms of Cyclospora cayetanensis(C.cayetanensis),a coceidian protozoan parasite,in Thailand which is the cause of an intestinal infection characterized by sporadic-to-frequent explosive diarrhea.Methods:In a field surveyconducted by the Faculty of Tropical Medicine.Mahidol Lniversity.as part of the existing parasite-control program,a total of 2 540 faecal samples from villagers in Nan Province,Thailand,were collected and examined to determine the prevalence and clinical characteristics of parasitic infections.Results:Twelve cases of C.cayetanensis infection were found duritig faecal examination of schoolchildren aged 5-12 years.None exhibited obvious clinical symptoms,especially evidence of diarrhea:5 of 12 had loose faeces,one reported frequent symptoms of abdominal discomfort,and another had pale conjunctiva with low hematocrit.The children were generally asymptomatic.Conclusions:This finding confirms a public-health issue with potentially serious consequences whereby children can be exposed to an environment contaminated with food-und water-borne transmitted oocysts,anil can hence become infected with C.cayetunensis.     

Cyclospora cayetanensis infections among diarrheal patients from Venezuela.

The prevalence and importance of Cyclospora cayetanensis as an enteropathogen among 71 patients (22-45 years old) with acquired immunodeficiency syndrome (AIDS) and 132 children with diarrhea (0-12 years old) from Venezuela was assessed retrospectively. Two to three stool samples from each patient attending our parasitology laboratory for parasitologic and medical assistance were examined. For identification of the coccidium, modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether stool concentrates was used, and for other intestinal parasites, iron-hematoxylin-stained smears and formalin-ether concentrates were examined. Cyclospora oocysts were found in seven (9.8%) of 71 AIDS patients and seven (5.3%) of 132 children with diarrhea. Other pathogenic parasites were present in most of the patients (9 of 14, 64.3%) shedding oocysts. Cyclosporiasis predominated in children 2-5 years of age with respect to those < or = one year of age (P < 0.05). The findings suggest that C. cayetanensis is common in diarrheal patients from Venezuela. However, the role of the parasite as the causal agent of diarrhea in these patients is uncertain.     

人类环孢子虫病的研究进展

近年来 ,人环孢子虫病已经被确认为是引起人类腹泻的一种新的肠道致病原虫 ,它的严重感染可以引起十二指肠和空肠上皮的炎症损伤。本文从生物学 (形态学、生活史、动物病理 )、流行病学、临床表现、实验室检查及治疗等几个不同的方面对近年来国外对其研究的进展作一简要地概述。环孢子虫 (Cyclospora)首先由 Elimer在 1870年从鼹鼠的肠道中分离得到 [1 ] 。 1881年 Schneider建立环孢子虫属 (Cy-clospora) ,Schaudin等于 190 2年对寄生于鼹鼠的 C.carydytica的生活史作了详细观察 ,发现该虫是在宿主小肠上皮细胞中发育 ,并可引起严重的肠…     

Cyclospora cayetanensis in patients with AIDS and chronic diarrhea

Cyclospora spp. is a protozoan parasite responsible for significant gastrointestinal disease in patients infected with the human immunodeficiency virus. We report the clinical features of two patients with chronic diarrhea and intestinal cyclosporosis caused by Cyclospora cayetanensis. The average value for CD4 count in these patients was lower than or equal to 100 cells/mm3. The oocysts were detected in smears from stool samples stained with modified acid-fast or safranin technique. Light microscopy revealed parasites in the enterocytes and these parasites were associated with villous atrophy. Cyclospora cayetanensis infection might be an important cause of diarrhea in patients with AIDS in Argentina.     

Cyclospora cayetanensis in sputum and stool samples

We report the observation of acid-fast Cyclospora cayetanensis oocysts in a sputum sample. The patient, a 60 year-old, HIV negative man, was successfully treated for pulmonary tuberculosis during 1997. On February 1998, he was admitted to our center due to loss of weight, cough with purulent expectoration, dysphonia and a radiological picture of pulmonary fibrosis. Bacilloscopic study of sputum (negative for acid-fast bacilli) stained with Ziehl-Neelsen technique showed large (8-10 microm) spherical, acid-fast Cyclospora cayetanensis oocysts. No other pathogens were isolated on cultures from this sample or from laryngeal biopsy. Serial parasitologic studies showed C. cayetanensis and also eggs of Trichuris trichiura, Ascaris lumbricoides and Hymenolepis nana and of Entamoeba coli cysts. The patient lives in the outskirts of Buenos Aires in a brick-made house with potable water and works as builder of sewers. He travelled in several occasions to the rural area of province of Tucumán which has poor sanitary conditions. C. cayetanensis is an emergent agent of diarrhea and as far as we know this is the first time the parasite is observed in respiratory samples.     

Cyclospora cayetanensis: oocyst characteristics and excystation

In Thailand in 1999-2000, Cyclospora oocysts from two HIV-infected patients and one patient with prolonged diarrhea were detected by formalin-ether concentration technique. Sporulation was performed by mixing stool samples in 2.5% potassium dichromate solution, sporulated oocysts were then treated with various solutions before mechanical rupturing in order to establish excystation, fewer than 10% of the sporulated oocysts could be excysted. Our techniques provided more details of the characteristic appearance of sporocysts and sporozoites within the oocysts (DMSO-modified acid-fast technique with our modification).     

Prevalence of Cryptosporidium parvum infection in children along the Texas-Mexico border and associated risk factors

We examined the epidemiology of Cryptosporidium parvum in children aged 6 months to 13 years living in 1) colonias along the border (n = 105), 2) a clinic in an urban border community (n = 65), and 3) clinics in a large urban nonborder area (n = 109). Serum IgG and IgA anticryptosporidial antibodies were measured by enzyme-linked immunosorbent assay (ELISA). Overall, 70.2% (196/279) of subjects had detectable C. parvum antibodies. Prevalence rates were higher (93/105 [89%]) in the colonias and urban border community (53/65 [82%]) compared to the urban nonborder community (50/109 [46%]). Within colonias, independent risk factors for C. parvum infection included consumption of municipal water instead of bottled water, older age, and lower household income. Children living along the Texas-Mexico border have a higher rate of infection with C. parvum compared to children living in a large nonborder urban area. Within colonias, C. parvum infection was associated with source of water supply, age, and socioeconomic status.     

Innate immune responses against Cryptosporidium parvum infection

Cryptosporidium parvum infects intestinal epithelial cells and is commonly the parasite species involved in mammalian cryptosporidiosis, a major health problem for humans and neonatal livestock. In mice, immunologically mediated elimination of C. parvum requires CD4⁺ T cells and IFN‐γ. However, innate immune responses also have a significant protective role in both adult and neonatal mice. NK cells and IFN‐γ have been shown to be important components in immunity in T and B cell‐deficient mice, but IFN‐γ‐dependent resistance has also been demonstrated in alymphocytic mice. Epithelial cells may play a vital role in immunity as once infected these cells have increased expression of inflammatory chemokines and cytokines and demonstrate antimicrobial killing mechanisms, including production of NO and antimicrobial peptides. Toll‐like receptors facilitate the establishment of immunity in mice and are involved in the development of inflammatory responses of infected epithelial cells and also dendritic cells.     

卡耶塔环孢子虫的生物学和流行病学研究进展

环孢子虫病是一种新现的寄生虫病。卡耶塔环孢子虫是环孢子虫属内惟一感染人类的虫种。本文重点综述了卡耶塔环孢子虫的生物学特点及人感染的流行病学现状,可为国内研究者开展环孢子虫病的相关研究工作提供参考。     

The contrasting epidemiology of Cyclospora and Cryptosporidium among outpatients in Guatemala.

We compared epidemiologic characteristics of Cryptosporidium and Cyclospora in surveillance data from outpatient departments in Guatemala. Routinely-submitted stool specimens were screened by microscopy. Age, sex, and symptom data were collected. Cyclospora was detected in 117 (2.1%) and Cryptosporidium in 67 (1.2%) of 5,520 specimens. The prevalence of Cyclospora peaked in the warmer months, while Cryptosporidium was most common in the rainy season. Both affected children more than adults, but Cryptosporidium affected children at a younger age than Cyclospora (median age 2 years versus 5 years; P < 0.001). Cyclospora showed a stronger association with diarrhea than Cryptosporidium, even when data were stratified by age. These contrasts may reflect differences in the relative importance of transmission modes, the frequency of exposure, and the development of immunity.     

Cyclospora cayetanensis associated with diarrhea in a patient with idiopathic compensated hepatic cirrhosis

A 52 year-old male patient with idiopathic hepatic cirrhosis complaining of diarrhea and weakness was accepted to the gastroenterology clinic. In order to find out the causative etiologic agent of diarrhea, stool samples were examined by different methods and stained using modified Kinyoun's acid-fast stain. Following examination, approximately 9 microns diameter, acid-fast variable wrinkled spheres were seen and diagnosed as Cyclospora cayetanensis. Confirmation of the diagnosis was established by fluorescent microscope (380 to 420 nm excitation filter), which showed bright green to intense blue autofluorescent oocysts. It has been shown that, Cyclospora cayetanensis is a coccidian parasite mainly found in immunocompromised patients and that it may be the agent of prolonged diarrhea. Only three cyclosporiosis cases have been previously reported in our country; all three cases were AIDS patients. We report here a further case of Cyclospora cayetanensis infection in a patient with hepatic cirrhosis and we consider that this is the first case, which was reported in hepatic cirrhosis.     

Prevalence and epidemiology of human Cryptosporidium parvum IIc infections in England and Wales

Background Cryptosporidium parvum causes acute diarrhoeal disease, long-standing illness in immunosuppressed individuals, and longer-term problems, including stunting in malnourished children. C parvum IIc is a genotype that is genetically distinct, is anthroponotic in contrast to other C parvum genotypes, and is a major genotype causing disease in the developing world. This study aimed to characterise the prevalence and epidemiology of C parvum IIc infections in England and Wales over a 2 year period.

The ecology of Cryptosporidium parvum infection in small rodent populations

The prevalence and abundance of Cryptosporidium parvum were studied over a three year period (1997-1999) in three species of rodents sampled from forest and abandoned fields in the Mazury Lake District, Poland. The overall prevalence was consistently higher in voles compared with Apodemus flavicollis (70.6% in Clethrionomys glareolus, 73.0% in Microtus arvalis and 27.8% in A. flavicollis). The prevalence and abundance of infection also varied across the 3 years of the study with 1998 being the year of higher prevalence and abundance of the parasite. Fewer older animals carried the infection, and their infections were relatively mild. We found no consistent pattern of seasonal changes despite the significance of seasonal differences. Host sex did not influence either the prevalence or abundance of infection with C. parvum. A great proportion of recaptured voles developed chronic infections between consecutive trapping sessions and only a small number of animals recovered. However, yellow-necked mice seem to be much more resistant to infection that became self-limiting. Our results firmly establish that the common woodland and grassland wild rodents in the Mazury Lake District constitute a significant and hazardous reservoir of C. parvum for animals and humans.     

Variability among Cryptosporidium parvum genotype 1 and 2 immunodominant surface glycoproteins

Published genomic differences between Cryptosporidium parvum genotype 1 (human-derived) and genotype 2 (animal and human-derived) isolates suggest that these may belong to two distinct species. This is of significant interest since genotype 1 isolates are associated with sporadic cases of human cryptosporidiosis in 30-40 % of cases in contrast to 60-70 % of cases caused by genotype 2. The lower genetic sequence similarity between genotype 1 and 2 surface glycoproteins (gp40/15) suggests that antigenic differences should also occur, a feature that was investigated in this study. Using immune and convalescent serum samples from gnotobiotic piglets previously inoculated with genotype 1 and 2 isolates, we demonstrated that C. parvum gp15 was immunodominant for both genotype 1 and 2 isolates. Lower genetic sequence similarity between genotype 1 and 2 Cpgp40/15 did correspond to gp15 protein differences as detected by Western blot. Moreover, we confirmed that gp15 contains epitopes that are also immunodominant. Deglycosylation of C. parvum proteins resulted in decreased ability of gp15, gp23 and gp900 to react with homologous polyclonal antibodies, suggesting that these proteins also express carbohydrate epitopes. Taken together, our data suggest that there is a high phenotypic variability between C. parvum genotype 1 and 2 isolates at the level of gp15. We contemplate that gp15 surface glycoprotein plays an important role in the biology of C. parvum as a potent inducer of immune response and a possible virulence factor.