Serodiagnosis of human gnathostomiasis

An enzyme-linked immunosorbent assay (ELISA) was evaluated for serodiagnosis of human ocular and visceral gnathostomiasis in comparison to an indirect haemagglutination (IHA) and precipitin (PPT) tests. The ELISA antibody titers were found to range from 1:400 to 1:51,200 against somatic and 1:200 to 1:25,600 against excretory-secretory (ES) antigens. When sera were tested at single dilutions, the ELISA was positive in 7 of 8 gnathostomiasis cases while only 5 and 3 were positive by IHA and PPT respectively. The overall specificity of the ELISA was 96.7% and 97.4% with somatic and ES antigens respectively. Since somatic and ES antigens produced similar ELISA results, either can be used for diagnostic purpose. It was suggested that the ELISA was a reliable serodiagnostic test for human gnathostomiasis.     

Immunopathogenesis of human schistosomiasis

Schistosomiasis continues to be a significant cause of parasitic morbidity and mortality worldwide. This review considers the basic features of the pathology and clinical outcomes of hepatointestinal and genitourinary schistosomiasis, presents an overview of the numerous studies on animal models that have clarified many of the immunopathological features, and provides insight into our current understanding of the immunopathogenesis and genetic control of human schistosomiasis. In murine schistosomiasis, pathology is induced by a CD4⁺ Th2 driven granulomatous response directed against schistosome eggs lodged in the host liver. The Th2 cytokines IL-4 and IL-13 drive this response, whereas IL-10, IL13Rα2, IFN-γ and a subset of regulatory T-cells act to limit schistosome induced pathology. A variety of cell types including hepatic stellate cells, alternatively activated macrophages and regulatory T-cells have also been implicated in the pathogenesis of schistosomiasis. Current knowledge suggests the immunopathogenic mechanisms underlying human schistosomiasis are likely to be similar. The review also considers the future development of anti-pathology schistosome vaccines. As fibrosis is an important feature of many other diseases such as Crohn's disease and sarcoidosis, a comprehensive understanding of the cellular and molecular mechanisms involved in schistosomiasis may also ultimately contribute to the development an effective disease intervention strategy for other granulofibrotic diseases.     

血吸虫肠病的内镜诊断及病理特征

目的 探讨血吸虫肠病的内镜表现及病理特征,以引起对血吸虫肠病的重视,减少漏诊和误诊.方法 回顾性分析72例血吸虫肠病的大肠镜观察结果并结合病史、组织病理学检查分析血吸虫肠病的内镜诊断和组织学特征.结果 内镜下表现为急性肠炎型16例;慢性肠炎型27例;肠黏膜兼有急性和慢性炎症改变,称之为混合型肠炎,共29例.急性肠炎型的病理特征为大量嗜酸性粒细胞浸润,伴有未钙化的虫卵沉积;慢性型者则有大量淋巴细胞和浆细胞浸润,黏膜下纤维化,伴有已钙化的虫卵沉积;混合型肠炎则兼有上述2型的组织病理学表现.并发结直肠癌5例.在外院误诊为溃疡性结肠炎7例,回盲部肿瘤5例,肠结核2例.结论 血吸虫肠病可分为急性、慢性与混合型结直肠炎3型,混合型血吸虫肠病是区别于急性和慢性血吸虫肠病的又一重要类型.内镜检查加多部位多组织活检发现虫卵沉积是诊断血吸虫肠病的重要方法.     

Serodiagnosis of human paragonimiasis caused by Paragonimus heterotremus

Enzyme-linked immunosorbent assay (ELISA) and indirect hemagglutination tests (IHA) were evaluated for serodiagnosis of human paragonimiasis caused by Paragonimus heterotremus using homologous adult worm extract as antigen. IgG-ELISA was the most sensitive, being positive in all paragonimiasis sera tested while IHA and IgA-ELISA gave 88% and 59% positive rates respectively. Cross reactivity in IgG-ELISA was detected with fascioliasis sera, producing overall assay specificity of 97%. It is suggested that IgG-ELISA is a reliable serodiagnostic test for human paragonimiasis caused by Paragonimus heterotremus.     

Serodiagnosis of human hydatid disease in Riyadh, Saudi Arabia

The Indirect Haemagglutination (IHA) test was used routinely for the diagnosis of hydatid disease in patients at the King Abdul Aziz and King Khalid University Hospitals, Riyadh, Saudi Arabia. Among 52 patients with suspected human hydatid disease, 30 positive cases were detected by means of serodiagnosis. As a control group, the level of hydatid IHA antibodies were determined in blood donors and in patients with no history of human hydatid disease. The serological results obtained in this control group showed that 70% had no hydatid IHA antibodies whereas 25% had antibody titres of 1:4 to 1:8, which are of no clinical significance.     

The clinico-immunological characteristics of intestinal schistosomiasis in the Republic of Guinea

The results of clinic and immunological examination of patients with intestinal schistosomiasis at the stage of developed infection in the natives of Guinea are presented. Polymorphism of clinical manifestations was accompanied by diagnostically significant changes in hematological (eosinophilia, increased erythrocyte sedimentation rates) and immunological (higher absolute count of B lymphocytes, IgM levels, amount of T suppressors, lower Tx/Tc ratio) parameters, which, together with the results of parasitological studies, are to be taken into account during the choice of treatment and control over its efficacy.     

Serodiagnosis of histoplasmosis

The standard serologic tests for diagnosis of histoplasmosis include the complement fixation test (CF), which is quite sensitive, and the immunodiffusion test (ID), which is fairly specific. Radioimmunoassay (RIA) is an experimental serological test even more sensitive than CF, but also less specific. Problems with the specificity of serodiagnosis are addressed followed by a discussion of the sensitivity of the three tests in the different forms of histoplasmosis-chronic cavitary histoplasmosis, progressive disseminated histoplasmosis, and acute pulmonary histoplasmosis. Next, serologic results from a large point-source outbreak of acute pulmonary histoplasmosis in Orono, Minn, are presented. These results are used to define the sensitivity of the three tests in acute symptomatic pulmonary histoplasmosis and also to detail the time course of the appearance of antibodies measurable by each test. Finally, a case of sporadic severe acute pulmonary histoplasmosis is presented in which the approach to serodiagnosis was based on lessons learned from the Orono outbreak.     

Protein losing enteropathy: an unusual presentation of intestinal schistosomiasis.

A patient presenting with features suggestive of malabsorption syndrome is described who had florid intestinal schistosomiasis on peroral biopsy of the jejunum. Liver biopsy and rectal biopsy also revealed schistosomal ova. Biochemical studies revealed severe hypoproteinaemia and hypoalbuminaemia, caused by a protein losing enteropathy. This is the first reported case of protein losing enteropathy caused by intestinal schistosomiasis.     

Antibody isotypes in human schistosomiasis mansoni

Summary Summary Schistosoma mansoni-infected subjects from the Gezira Irrigated Area of Sudan were studied for serum immunoglobulin levels, and specific antibody titres to larval, adult and egg stage antigens, by class and IgG subclass. The 276 subjects were adult chronic cases (frequently exposed male canal cleaners), primary school children, and hospital-referred cases with acute symptoms including hepatosplenomegaly. Chronic untreated cases were compared with a similar group of canal cleaners 3 months after successful chemotherapy with Praziquantel administered at the start of the non-transmission season. All cases, except those previously treated, were egg positive at the time of blood sampling. Data from infected and treated cases were compared with measurements of serum immunoglobulin in a panel of European blood donors. The major findings are as follows: There is a consistently elevated total serum IgG concentration in infected groups which is accounted for mainly by an increased IgG1 subclass (greatest in chronic cases) and by a remarkable 10-to 11-fold increase in IgG4 in the untreated chronically infected group and in the schoolchildren. All infected groups showed high IgG antibody responses to all life cycle stage antigens, and IgM titres were high to adult and egg antigens in untreated canal cleaners. Major differences were evident in the distribution of IgG subclass antibodies between the infected groups: the response to larval and adult antigens is poor or absent in IgG1, IgG2 and IgG3 in untreated chronic infections but is high in IgG4, whereas in acute cases with hepatosplenomegaly and in schoolchildren IgG1, IgG2 and IgG3 antibodies to larval antigens are in high titre but IgG4 and IgM responses to larvae are low or absent, the response in these isotypes being restricted in these cases to adult and egg antigens. Comparing the treated and untreated canal cleaners, although these are separate groups, the data suggest that Praziquantel reduces total serum IgA and IgM levels but has little effect on the raised IgG component except for the IgG4 subclass. The treated chronic cases show a reversal in the ratio of IgG1, IgG2 and IgG3 to IgG4 antibodies to larval and adult antigens compared with the untreated chronic group—the IgG4 response being low by 3 months after treatment and the IgG1, IgG2 and IgG3 being high. These data are discussed in relation to the possible importance of antibody isotype selection in determining host susceptibility to infection, with reference to age, exposure and treatment of the host.     

Serodiagnosis of intestinal tuberculosis by the soluble antigen fluorescent antibody test (SAFA test)

The diagnosis of intestinal tuberculosis can only be established by the tissue obtained during surgery or endoscopy. We investigated the role of the soluble antigen fluorescent antibody (SAFA) test with the possibility that it may prove to be a valuable technique for the serodiagnosis of intestinal tuberculosis. The sera of 38 patients and 60 control subjects were studied. Mycobacterial saline extract was used as an antigen in the test. Thirty-two (84%) of 38 patients with intestinal tuberculosis yielded positive values (fluorescence coefficient greater than 3). Among the control subjects a false positive result was observed in only one patient who had eosinophilic enteritis. Patients with intestinal tuberculosis had a significantly higher level of antibodies than patients with non-tuberculous intestinal disease and healthy subjects. These results suggest that this technique may be used for the diagnosis of intestinal tuberculosis and in differentiating it from other non-tuberculous intestinal diseases.     

Genetic epidemiology of human schistosomiasis in Brazil

Human schistosomiasis presents the classic, complex disease phenotype, with marked variation in the intensity of infection, the immune response to infection, and the development of schistosome-related pathology. Determining the role of host genetics in schistosomiasis is complicated by the numerous parasite and environmental factors involved in transmission. However, as a result of the increased availability of sequence data, novel statistical methods, and new methods of study design, the last decade has seen significant advances in identifying the role of host genetics in schistosome infection around the world. Many of these advances have taken place in Brazil. Epidemiological studies in Brazil have shown that the intensity of infection (worm burden) is a heritable phenotype (41%). Human genome scans have identified a locus responsible for controlling Schistosoma mansoni infection intensity on chromosome 5q31-q33. There is also evidence for genetic control of pathology due to S. mansoni, with linkage reported to a region containing the gene for the interferon-gamma receptor 1 subunit. Numerous association studies have also provided evidence for major histocompatibility complex control of pathology in schistosomiasis. Recent candidate gene studies suggest a role of other immune response genes in controlling helminth infection and pathology. We chronicle the many advances made in understanding the role of host genetics in S. mansoni infection that have taken place in Brazil by phenotype studied: infection intensity, immune response, and disease development. Results from Brazilian studies are compared with studies of S. mansoni and other schistosome species elsewhere in the world.     

Concurrent urinary and intestinal schistosomiasis and intestinal helminthic infections in schoolchildren in Ilobu, South-western Nigeria

A cross-sectional study was conducted in a schistosome-endemic rural community in Southwestern Nigeria. We assessed prevalence and intensity of soil-transmitted nematodes and the co-occurrence with Schistosoma haematobium and Schistosoma mansoni. Urine and stool samples from 419 schoolchildren were examined, and a questionnaire was administered to obtain socio-demographic characteristics. In total, 78.3% (328/419) were infected with at least one helminth species, with a prevalence (mean egg-count) of 55.1% (3069.2) of Ascaris lumbricoides, 41.1% (127.5) of S. haematobium, 22.7% (98.6) of hookworms, 17.9% (161.3) of Trichuris trichiura, and 10.3% (12.9) of S. mansoni. Multiple infections were significantly more common among children from households with more playmates, absence of toilet facilities and low income level (all p<0.001). Children with heavy hookworm burden were at a significantly higher chance of acquiring S. mansoni (OR=36.35; 95% Cl: 13.22-100.97; p<0.0001). The risk of S. mansoni and A. lumbricoides infections was increased in co-infections with S. haematobium. Logistic regression analysis revealed infections by hookworms and S. mansoni (adjusted odds ratio [aOR]=3.90, 95% Cl: 2.03-7.46; p<0.0001), and by hookworms and T. trichiura (aOR=2.46, 95% Cl: 1.44-4.22; p=0.001) as significant risk factors for multiple infections. Our study shows that polyparasitism is common in the study area. Focused interventions such as mass treatment with anthelminthics and health education are needed to improve the well-being of the affected population.     

Symptoms of intestinal schistosomiasis presenting during treatment of large B cell lymphoma

We report a case of chronic intestinal schistosomiasis presenting in a previously asymptomatic 34-year-old woman from Saudi Arabia with large B cell lymphoma. The patient presented with abdominal pain, constipation, recurrent rectal bleeding, and persistent mild eosinophilia during chemotherapy. Stools were repeatedly negative for parasite ova, but duodenal and colonic biopsies demonstrated Schistosoma eggs and eosinophilic granulomatous inflammation. Immunosuppressed patients with schistosomiasis may have diminished egg excretion. Diagnosis requires a high index of suspicion since stool test results may be negative and intestinal biopsies may be needed to make the diagnosis.