Diagnosis of human schistosomiasis by detection of circulating cathodic antigen with a monoclonal antibody.

Monoclonal antibody (MAb) 5H11 reacted with repeating epitopes on Schistosoma mansoni circulating cathodic antigen (CCA) and detected CCA in sera of Egyptian S. mansoni-infected patients. MAb 5H11 was both capture and biotinylated detection antibody in a sandwich ELISA of trichloroacetic acid-pretreated serum samples. Sera of patients with 7-500 eggs/g of stool were positive by MAb 5H11-CCA sandwich ELISA. Stool egg counts and CCA serum levels correlated (r = .52), and CCA levels decreased by 4 weeks after praziquantel treatment in patients with pretreatment egg counts of greater than or equal to 50/g of stool (P less than .05). Sera of Schistosoma haematobium-infected patients, uninfected individuals, and most patients with other helminths were negative in this assay. The MAb 5H11-CCA sandwich ELISA appears sensitive and specific for immunodetection of active schistosomiasis mansoni and useful for monitoring its chemotherapy.     

Quantitative determination of circulating antigens in human schistosomiasis mansoni using an indirect hemagglutination assay

In serum and urine specimens collected from a group of Schistosoma mansoni infected individuals from Makundju, Zaire, the schistosome circulating anodic antigen (CAA) and the circulating cathodic antigen (CCA) were quantitatively determined using an indirect hemagglutination reaction with sheep erythrocytes sensitized with mouse IgM monoclonal antibodies directed against these circulating antigens. Levels of CAA in serum (up to 5 ng/ml) and CCA in serum and urine (up to 50 ng/ml) were strongly correlated with egg excretion and with each other. No correlation was found between egg excretion and antibody levels against the circulating antigens. Antigen was detectable only in patients excreting greater than 500 eggs per gram of feces.     

Sensitive determination of circulating anodic antigen in Schistosoma mansoni infected individuals by an enzyme-linked immunosorbent assay using monoclonal antibodies

From a panel of mouse monoclonal antibodies reactive with a repeating epitope of the schistosome circulating anodic antigen, an IgG1 monoclonal antibody was selected. This monoclonal antibody was applied in a sandwich enzyme-linked immunosorbent assay as capture antibody and as alkaline phosphatase labeled conjugate. This assay allowed a sensitive quantitation of circulating anodic antigen in serum samples of infected individuals, detecting less than 1 ng antigen/ml serum. In Schistosoma mansoni infected individuals from Zaire, the level of antigen in serum correlated with fecal egg output. The lower detection level of the immunoassay corresponded to a level of about 10 eggs/gm feces.     

The effect of treatment of schistosomiasis on blood plasma HIV-1 RNA concentration in coinfected individuals

OBJECTIVE: To determine whether drug treatment of Schistosomiasis mansoni infection leads to a reduction in plasma HIV-1 RNA concentration in coinfected individuals. METHODS: Stool and plasma samples were obtained prospectively from a cohort of HIV-infected persons (n = 30) in Kisumu, Kenya, before and after treatment of schistosomiasis with praziquantel (mean follow-up, 5.6 months; range 1-15 months). Schistosomal circulating cathodic antigen (CCA) concentrations in plasma were determined by ELISA and fecal egg counts were determined by microscopy. HIV-1 RNA concentrations were measured in pre- and post-treatment plasma samples obtained from the patients whose stool samples remained free of schistosomal eggs for the great majority of the follow-up period. RESULTS: Comparison of pretreatment and follow-up samples revealed that mean +/- SD fecal egg burden was reduced by 96.7% (481.5+/-803.5 versus 16.1+/-24.4 eggs/g feces) and mean plasma CCA concentration decreased by 90.1% (3.22+/-3.26 versus 0.32+/-0.38 microg/ml). In contrast, mean plasma HIV-1 load increased from 3.60+/-0.90 to 3.93+/-0.95 log10 RNA copies/ml (P< 0.001). Although no correlation was found between changes in HIV-1 load and changes in schistosomal burden, there was a significant correlation between changes in plasma HIV load and the time interval between pretreatment and follow-up samples (r = 0.41; P = 0.027). CONCLUSIONS: Treatment of schistosomiasis was not associated with a reduction in plasma HIV-1 load. This study does not, however, exclude the possibility of an adverse effect of helminthic infections on HIV-1 pathogenesis.     

Detection of circulating antigen in serum of mice infected with Schistosoma japonicum by immunomagnetic bead ELISA based on IgY

We developed a novel immunomagnetic bead ELISA based on IgY (egg yolk immunoglobulin) for detection of circulating antigen (CA) in sera of mice infected with Schistosoma japonicum. The assay involved the use of chicken polyclonal antibodies IgY against soluble egg antigens (SEA) of S. japonicum as a capture antibody and anti-SEA mouse monoclonal antibody NP28-5B labeled horseradish peroxidase (HRP) as a detecting antibody. Two groups of BALB/c mice infected with S. japonicum cercariae were used: lightly infected mice (infected with 10 S. japonicum cercariae) and heavily infected mice (infected with 30 S. japonicum cercariae). The CA was detectable as early as 4 and 5 weeks after infection in the sera of heavily and lightly infected mice, respectively. The CA levels rose rapidly and reached a peak in 8 weeks after infection and then remained a plateau for at least another 6 weeks in both groups. Moreover, the effect of praziquantel on the CA levels was also investigated. The heavily infected mice were treated with praziquantel and the CA levels in sera increased dramatically in the first week post-treatment and then decreased to the control level by 6 weeks after treatment. The novel assay appears to be sensitive for detection of schistosomal antigenemia and valuable to judge the efficacy of chemotherapy in murine schistosomiasis.     

Schistosomiasis mansoni in Yemeni in California: duration of infection, presence of disease, therapeutic management

Investigations of schistosomiasis mansoni in 218 Yemeni agricultural workers in the San Joaquin Valley of California revealed a prevalence of 56%. In those infected, quantitative egg counts performed by the Kato thick smear method revealed that 57% had light infections (1-100 eggs/g), 27% moderate infections (101-400 eggs/g), and 16% heavy infections (greater than 400 eggs/g; mean--918 eggs/g). The Yemeni had been migrating to the USA for the past 20 years, a period in which the prevalence of schistosomiasis had remained constant in the Yemen. The prevalence of schistosomiasis in those who had been away from Yemen for less than 5 years was 59% with a mean egg output of 236 eggs/g, but in those away for more than 5 years (up to 20 years) it was 32% with a mean egg output of 75% eggs/g. This is in spite of the fact that 75% of the latter had returned to Yemen for short visits. Statistical analysis by the Fisher's exact probability test revealed a significantly lower egg output in those away from Yemen more than 5 years. On the basis of these findings the mean life span of the Yemen strain of Schistosoma mansoni in man was estimated to be between 5 and 10 years. The presence of disease was assessed in this population by traditional medical means without prior knowledge of the status of the infection in the individuals examined. Under these circumstances, there were no differences in symptoms such as weakness, diarrhea and abdominal pain among the uninfected proportion of the population, total infected group and a small subgroup of those most heavily infected. None of the patients had hepatomegaly and only two had splenomegaly--one lightly and the other heavily infected. Because of the toxicity of antischistosomal drugs and the lack of treatment facilities only the 22 most heavily infected (greater than 200 eggs/g) of the 122 individuals with schistosomiasis mansoni were treated with niridazole. In addition the two individuals with splenomegaly were treated with antimony dimercaptosuccinate. Side effects, though common, were not severe. Although follow-up in this migrant population was poor the nine patients examined 3 to 7 months after treatment showed a mean decrease in egg output of 97%.     

Immunochemical characterization and diagnostic potential of a 63-kilodalton Schistosoma antigen.

Schistosoma circulating antigens were used for the detection of active infection. Anti-S. mansoni IgG2a monoclonal antibody (MAb) designated C5C4 was generated. The target epitope of this MAb was detected in adult worms, eggs, and cercariae antigenic extracts of S. mansoni and S. haematobium, had a molecular size of 63 kD, and was not detected in Fasciola hepatica and Ascaris. In addition, a 50-kD degradation product was identified only in the urine of infected individuals. Analysis by high-performance liquid chromatography of the purified antigen demonstrated only one peak. The 63-kD antigen was characterized as a protein containing 40.4% hydrophobic, 7.5% acidic, and 8.8% basic amino acids. The C5C4 MAb was used in a Fast Dot-ELISA for rapid and simple diagnosis of human schistosomiasis. The 63-kD circulating antigen was detected in 92% of urine samples from 330 S. mansoni-infected individuals, with 16% false-positive results among 130 noninfected individuals.     

Serological studies on schistosomiasis mansoni in the northeast Brazil (I)

Sera from the patients (N = 10) with schistosomiasis mansoni of the hospital of Federal University of Pernambuco, the Schistosoma mansoni egg-positive (N = 51) and -negative (N = 452) inhabitants in Cabo City area, out-patients (N = 37) of the IMIP hospital and Japanese immigrants (N = 127) in Petrolina City area of northeast Brazil as well as Japanese healthy subjects (N = 30) were examined by serological tests including an enzyme-linked immunosorbent assay with antigens prepared from eggs (ELISA-egg) and adult worms (ELISA-adult). The ELISA with egg or adult antigen correctly identified 100% of the uninfected individuals lived in non-endemic area of schistosomiasis. Moreover, when examined cross-reactivity of our ELISA with sera isolated from 78 subjects infected with various intestinal parasitic infections, only one of these sera reacted with the egg and adult antigens. On the examination of 51 sera from the egg-positive subjects, the ELISA-egg revealed the highest sensitivity (98.0%), whereas a large number of false negative reactions of ELISA-adult, Ouchterlony method using adult antigen, circumoval precipitation and immediate intradermal skin test were observed. A low sensitivity of these serologic tests except for ELISA-egg appears to be primarily due to their inability to detect antibody in the sera from egg-positive infantiles. There was no positive correlation between the absorbance values of these two types of ELISA among the sera isolated from ELISA-positive subjects. Rather, by the reactivity of these sera to egg or adult antigen, they could be divided into two subgroups; one reacted more positively with egg antigen and the other with adult antigen. Moreover, it was confirmed that the sera from young subjects (under 20 years old) appear to be highly reactive to the egg antigen than did aged ones. These data suggest that the ELISA with egg antigen, but not with the adult antigen, appears to be useful for the serological survey of schistosomiasis mansoni in the endemic area of northeast Brazil.     

Seroprevalence of schistosomiasis in African patients infected with HIV

Background

Schistosomiasis is a highly prevalent parasitic infection causing significant morbidity and mortality in sub‐Saharan Africa. Infection is asymptomatic for many years. Long‐term complications such as portal hypertension and bladder cancer can be prevented by treatment with praziquantel.

Objectives

The aim of this study was to determine the prevalence of schistosomiasis in HIV‐infected African patients attending our department.

Methods

From March 2005, all patients of African origin attending our HIV clinics were tested for schistosomal antibodies using a peroxidase enzyme‐linked immunosorbent assay (ELISA). Stool and urine specimens from seropositive patients were examined for ova. All seropositive patients were offered treatment with praziquantel.

Results

Of 122 patients tested, 21 (17%) were ELISA positive for schistosomiasis. Ova were found in stools from four patients and on a cervical smear in one patient. There were no significant differences between infected and uninfected patients other than the presence of eosinophilia (48 vs. 6%; P<0.001), and 17 seropositive patients were treated with praziquantel.

Conclusions

The seroprevalence of schistosomiasis in HIV‐infected patients of African origin in the UK is high. We recommend that screening for schistosomiasis should be offered to these patients and those found to be positive treated with praziquantel.     

Susceptibility of Schistosoma japonicum to praziquantel in China

To look for possible evidence of the development of resistance in Schistosoma japonicum to praziquantel, we conducted a field study in China. During the non-transmission period of schistosomiasis a random sample of 2860 individuals from six villages in three provinces of China were examined using a parasitological stool examination. Of the 372 stool-positive subjects, 363 subjects were treated with a single oral dose of 40 mg/kg of praziquantel. Six to Seven weeks after treatment, of 334 subjects examined using the same stool examination, stool-negative results were found in 319 patients which represents a 95.5% parasitologic cure rate. Fifteen subjects still excreting eggs were treated a second time with the same dose of praziquantel. All stool samples, including those from participants re-treated with praziquantel, were re-examined 12 weeks after the first treatment and no stool-positive subjects were found. The results indicate that there was no evidence for reduced susceptibility of S. japonicum to praziquantel despite its extensive use in the main endemic areas of China for more than 10 years. The in vitro responses to praziquantel of cercariae, miracidia and eggs of S. japonicum compared with S. mansoni demonstrate that the cercariae, miracidia and eggs of S. japonicum are more sensitive to praziquantel than those of S. mansoni. More sensitive worms would be less likely to develop resistance and this could explain why no evidence for resistance was found in S. japonicum in China.     

Eighteen-month follow-up on the treatment of urinary schistosomiasis with a single dose of metrifonate

Egg excretion of school children with urinary schistosomiasis treated with a single 10 mg/kg dose of metrifonate was monitored over a period of 18 months. At 18 months 68.8% of infected children showed a greater than 90% reduction in egg excretion and 23.7% had ceased excreting eggs. During the study period 25% of children with no evidence of infection at the start of the trial had become infected, while 45.5% of children apparently cured by the metrifonate treatment had recommenced egg excretion. The evidence suggested that reinfection rather than recovery of adult worms was responsible. Children with scanty or light infections, in general, showed increasing egg excretion rates during the following period, while those with heavy or severe infections showed a sustained reduction. In view of this, single dose metrifonate may be a useful approach to mass treatment in a schistosomiasis control program, resulting in significant reduction in egg excretion in those most likely to be important sources of transmission.     

Praziquantel for treatment of schistosomiasis in patients with advanced hepatosplenomegaly

We evaluated praziquantel for therapy of active Schistosoma mansoni infection in 15 rural Egyptian males with hepatosplenic schistosomiasis. Criteria for inclusion in this study were two pre-treatment S. mansoni egg counts with a mean of greater than 100 eggs g-1 faeces and an enlarged spleen. Fourteen of 15 patients had hepatomegaly, five had ascites, and six had serum albumin below 3 g dl-1. Schistosoma haematobium infection (less than 10 eggs ml-1 urine) was present in three patients. Praziquantel was administered in a single oral dose of 30 mg kg-1 body weight. Eight of the 15 patients (53%) had mild and transient reactions in the form of fever (usually one day), gastrointestinal symptoms, headache and skin rash. Criteria for parasitological cure were the absence of live eggs in two stool samples and a negative rectal snip biopsy three months after therapy. Ten patients ceased to pass live eggs (cure rate 67%). For the five who were still passing live eggs there was a mean egg reduction of 95%. The three patients with S. haematobium demonstrated parasitological cures. We conclude that praziquantel is an effective and well tolerated drug for treatment of S. mansoni infection in patients with advanced hepatosplenic schistosomiasis, and it is the drug of choice for patients with coexisting S. haematobium infection.     

过碘酸钠氧化可溶性虫卵抗原ELISA诊断血吸虫病的研究

目的改进可溶性虫卵抗原-酶联免疫吸附试验(SEA-ELISA),进一步提高其诊断血吸虫病的敏感性、特异性及疗效考核价值。方法应用过碘酸钠(sodiumPerodate,SP)处理SEA,氧化其糖基化表位,建立SP-SEA-ELISA,检测血吸虫病患者血清中的特异性抗体,并与常规SEA-ELISA进行比较。结果分别用两种方法检测患者血清,其中慢性血吸虫病64例、华支睾吸虫病34例、卫氏并殖吸虫病33例、囊尾蚴病36例,检测健康人血清119例。SP-SEA-ELISA特异性为99.2％,高于SEA-ELISA,敏感性为98.4％,与SEA-ELISA比较无明显降低。用SP-SEA-ELISA及SEA-ELISA检测治疗后12个月的慢性血吸虫病患者血清,阴性率为89.0％,明显优于SEA-ELISA(42.1％)。结论过碘酸钠处理SEA,可提高免疫诊断特异性,降低交叉反应,有一定的疗效考核价值。     

吡喹酮直肠给药治疗小鼠血吸虫病实验研究

目的 观察吡喹酮直肠给药对小鼠日本血吸虫病的治疗效果.方法 各实验组每只小鼠分别腹部贴片感染日本血吸虫尾蚴40±2条.感染后第42天以吡喹酮直肠给药,按给药不同剂量设为3组,每组每只小鼠按100、200、400 mg/kg一次给药,同时设不给药对照组.给药1周后进行剖杀,计算减虫率、减肝卵率以及减配对率.结果 200 ...     

Comparison of an enzyme-linked immunosorbent assay using crude S. haematobium soluble egg antigen with a radioimmunoassay using purified S. mansoni egg antigen for the serodiagnosis of schistosomiasis haematobium

An enzyme-linked immunosorbent assay (ELISA) using crude Schistosoma haematobium soluble egg antigen (ShSEA) was compared with a radioimmunoassay (RIA) employing purified heterologous species S. mansoni egg antigen (MSA1) for the serodiagnosis of schistosomiasis haematobium in a group of 45 Nigerian school children living in an area endemic for S. haematobium. Both assay systems appeared applicable. The ELISA proved to be more sensitive detecting 100% of the 27 parasitologically positive individuals while the RIA defined 89% of this group. Neither test had false-positive results for the 10 non-endemic area parasitologically negative controls, although the ELISA demonstrated that 56% of the 18 endemic area parasitologically negative controls had anti-ShSEA antibodies. The RIA indicated that 44% of this group had anti-MSA1 antibodies. These latter findings were interpreted as related to the hyperendemicity of schistosomiasis haematobium for the study area.     

血吸虫对吡喹酮抗药性的研究ⅩⅦ 日本血吸虫吡喹酮抗性株在小鼠体内的生物学特性

目的实验观察日本血吸虫吡喹酮抗性株在终宿主小鼠体内的生物学特性,探索日本血吸虫吡喹酮抗性株对终宿主的致病力及传播强度。方法分别采用日本血吸虫江苏吡喹酮敏感株和抗性株、湖南吡喹酮敏感株和抗性株尾蚴定量感染小鼠,建立小鼠-钉螺-小鼠生活史循环,观察比较各虫株的虫卵开放前期、产卵量及虫卵分布、对终宿主的易感性、虫体生长发育等生物学特性。结果日本血吸虫江苏吡喹酮敏感株和抗性株虫卵开放前期分别为36.1 d和36.8d(t=0.907,P=0.372),粪便中虫卵数分别为14.6只/100 mg和21.2只/100 mg(t=2.946,P=0.007),回收成虫数分别为20.5条/鼠和25.1条/鼠(t=2.128,P=0.042),组织中虫卵数分别为31 303只/对成虫和38 594只/对成虫(t=2.185,P=0.040)、肝脏虫卵数分别为14 810只/对成虫和19 715只/对成虫(t=2.934,P=0.007),肠组织中虫卵数分别为16 493只/对成虫和18 879只/对成虫(t=1.044,P=0.309);江苏敏感株和抗性株雌雄合抱虫体长度(t=0.328,P=0.744)、雌虫体长(t=0.386,P=0.701)及雄虫体长(t=0.332,P=0.741)差异均无统计学意义。日本血吸虫湖南吡喹酮敏感株和抗性株虫卵开放前期分别为35.5 d和35.6 d(t=0.169,P=0.867),粪便中虫卵数分别为13.3只/100 mg和18.9只/100 mg(t=3.622,P=0.001),回收成虫数分别为17.6条/鼠和25.1条/鼠(t=3.153,P=0.004),组织中虫卵数分别为30 932只/对成虫和53 903只/对成虫(t=3.865,P=0.001),肝脏虫卵数分别为12 307只/对成虫和26 363只/对成虫(t=4.388,P0.01),肠组织中虫卵数分别为18 625个/对成虫和27 541个/对成虫(t=2.679,P=0.012);湖南敏感株和抗性株雌雄合抱虫体长度(t=0.853,P=0.397)、雌虫体长(t=0.573,P=0.569)及雄虫体长(t=0.742,P=0.461)差异均无统计学意义。结论日本血吸虫吡喹酮抗性株产卵量和肝组织虫卵沉积量均明显高于敏感株,提示其对终宿主的致病性更强;抗性株感染鼠粪便中排出虫卵数明显多于敏感株,提示抗性株的传播能量高于敏感株。     

日本血吸虫病流行区人群吡喹酮治疗前后细胞因子水平的研究

观察日本血吸虫病流行区人群的细胞免疫应答状态及吡喹酮治疗对其影响。 [方法 ]采集日本血吸虫病流行区 12 9人 (粪检阳性者 6 4例 ,粪检阴性者 6 5例 ) ,吡喹酮治疗前及治疗后 45d的静脉血 ,以血吸虫成虫和虫卵抗原分别刺激诱生细胞因子 ,检测培养上清中的细胞因子IL 5、IL 10和IFN γ水平。 [结果 ]12 9例中 ,对血吸虫抗原刺激诱生的细胞因子水平粪检阴性组明显高于粪检阳性组 ;治疗后 ,细胞因子诱生水平较治疗前显著升高 ,特别是IL 5和IFN γ。 [结论 ]流行区人群的细胞免疫应答显示总体下调趋势 ;吡喹酮治疗后出现细胞因子水平的明显升高。     

日本血吸虫模拟虫卵抗原表位的筛选和鉴定

目的　通过噬菌体肽文库技术探索可用于诊断日本血吸虫病的模拟虫卵抗原。　方法　用日本血吸虫虫卵单克隆抗体 6 B12作“诱饵”,采用生物淘金法从噬菌体 15 -肽文库中经过 3轮筛选 ,有效地富集与 6 B12有亲和力的噬菌体肽克隆。随后采用 EL ISA、竞争 EL ISA、Western blotting等检测方法 ,从 4 0 0个单克隆化的噬菌体株中得到 13株与 6 B12有特异性、高亲和力反应的噬菌体克隆。　结果　对噬菌体所携带的外源 DNA片段序列测序结果表明 ,13株噬菌体所携带的外源多肽序列完全相同。该噬菌体多肽抗原包被酶标板经 EL ISA方法对血吸虫病患者及健康人血清Ig G抗体检测结果表明 ,两者有显著性差异。　结论　噬菌体多肽模拟抗原有可能替代天然抗原用于血吸虫病诊断     

Detection of a circulating antigen in human schistosomiasis japonica using a monoclonal antibody

A double antibody enzyme-linked immunosorbent assay (sandwich ELISA) was used for the detection of a circulating antigen from human schistosomiasis japonica infections. This assay involves the use of polyclonal rabbit Schistosoma japonicum soluble egg antigen (SEA) antiserum to bind circulating antigen and a monoclonal antibody (MabH4) to identify and quantify this antigen. Sera from 108 S. japonicum-infected patients (acute and chronic) were tested. Sera from 93 of 95 patients with chronic infection were positive for this antigen; sera from 12 of 13 patients with acute infections were also positive. Antigen was not detectable in control human sera. Sera from 35 chronic schistosomiasis patients were collected 6-12 months after praziquantel treatment. Circulating antigen was not detectable in the sera of 33 of these patients and was dramatically reduced in 2. This ELISA system may prove valuable in differentiating past and current infections.     

洞庭湖渔民血吸虫感染情况及化疗效果分析

目的　调查洞庭湖渔民感染血吸虫的严重程度,评估其化疗防治效果。　方法　 2 0 0 1年11月选择湖南省岳阳县麓角镇洞庭湖水上作业渔民,询问血吸虫感染与化疗史。用改良加藤法检查虫卵和毛蚴孵化法检查毛蚴,酶联免疫吸附测定(ELISA)和间接血凝试验(IHA)检测抗可溶性虫卵抗原(SjSEA)的抗体,B超检查肝/脾病变程度。人群顿服吡喹酮40mg/kg,一个感染季节过后复查。用SPSS软件进行分析。 　结果　①询问调查渔民268人,“经常”或“间常”接触疫水的人数占907%;近5年每年平均化疗人数占240%,从未化疗者占394%;②粪检阳性率为681%(111/163),克粪虫卵数(EPG)为4877,男性均显著高于女性。 11～20岁阳性率最高(83 3 %),“经常”或“间常”接触疫水与从未化疗的两种人群阳性率分别为 763 %(106/139)和797%(51/64);③IHA检测阳性率为880%,ELISA检测阳性率为787%,均明显高于粪检阳性率;④肝/脾受损率为774%(82/10 6),其中,肝实质呈Ⅱ～Ⅲ级纤维化病变者占377%,肝肿率为585%,脾肿率为198%;⑤多次化疗人群感染率和EPG显著低于从未化疗人群;⑥复查结果表明,化疗人群粪检阳性率(354%)和EPG(3613)较未化疗人群(565%和684