Tom van Gool

High Seroprevalence of Encephalitozoon Species in Immunocompetent Subjects

Encephalitozoon species are important pathogens in human immunodeficiency virus-infected patients. However, in immunocompetent persons, little is known about Encephalitozoon infections, mainly because of the lack of reliable diagnostic tests. To improve diagnosis, three serologic techniques that use Encephalitozoon intestinalis as antigen were developed: an ELISA, an immunofluorescence technique (IFAT), and a counterimmunoelectrophoresis (CIE) method. The serologic response against E. intestinalis was studied in sera from 300 Dutch blood donors and 276 pregnant French women. For confirmation of specificity, sera from 150 subjects with various infectious and noninfectious diseases were examined. ELISA, IFAT, and CIE were specific for microsporidia infections, and IFAT and CIE were specific for Encephalitozoon infections. High antibody titers against Encephalitozoon organisms were found in 24 (8%) of 300 Dutch blood donors and in 13 (5%) of 276 pregnant French women. The high seroprevalence against Encephalitozoon species in Dutch blood donors and French women suggests that Encephalitozoon infection is common in immunocompetent subjects.

Use of Enzyme-Linked Immunosorbent Assay and Dipstick Assay for Detection of Strongyloides stercoralis Infection in Humans

ABSTRACT A homemade enzyme-linked immunosorbent assay (ELISA) (Academic Medical Center ELISA [AMC-ELISA]) and a dipstick assay for the detection of anti-Strongyloides stercoralis antibodies in serum were developed and evaluated together with two commercially available ELISAs (IVD-ELISA [IVD Research, Inc.] and Bordier-ELISA [Bordier Affinity Products SA]) for their use in the serodiagnosis of imported strongyloidiasis. Both commercially available ELISAs have not been evaluated previously. The sensitivities of the assays were evaluated using sera from 90 patients with parasitologically proven intestinal strongyloidiasis and from 9 patients with clinical larva currens. The sensitivities of the AMC-ELISA, dipstick assay, IVD-ELISA, and Bordier-ELISA were 93, 91, 89, and 83%, respectively, for intestinal strongyloidiasis. In all tests, eight of nine sera from patients with larva currens were positive. The specificity was assessed using a large serum bank of 220 sera from patients with various parasitic, bacterial, viral, and fungal infectious diseases; sera containing autoimmune antibodies; and sera from healthy blood donors. The specificities of AMC-ELISA, dipstick assay, IVD-ELISA, and Bordier-ELISA were 95.0, 97.7, 97.2, and 97.2%, respectively. Our data suggest that all four assays are sensitive and specific tests for the diagnosis of both intestinal and cutaneous strongyloidiasis.

Serodiagnosis of Imported Schistosomiasis by a Combination of a Commercial Indirect Hemagglutination Test with Schistosoma mansoni Adult Worm Antigens and an Enzyme-Linked Immunosorbent Assay with S. mansoni Egg Antigens

ABSTRACT A commercial indirect hemagglutination (IHA) test using erythrocytes coated with Schistosoma mansoni adult worm antigens (WA) and an enzyme-linked immunosorbent assay (ELISA) with S. mansoni egg antigens (SEA) were assessed for their use in serodiagnosis of imported schistosomiasis (hereafter these tests are designated WA/IHA and SEA/ELISA, respectively). The sensitivity of the tests was evaluated with sera from 75 patients with proven S. mansoni infection, 25 with proven S. haematobium infection, and 10 with clinical Katayama fever. The specificity was assessed with sera from 283 patients with various parasitic, bacterial, viral, and fungal infections and sera containing autoimmune antibodies. Sensitivities of the WA/IHA with a cutoff titer of 1:160 (WA/IHA160) in detecting S. mansoni, S. haematobium, S. mansoni and S. haematobium combined, and clinical Katayama fever were 88.0, 80.0, 86.0, and 70.0%, respectively, with a specificity of 98.9%. The WA/IHA with a cutoff of 1:80 (WA/IHA80) showed sensitivities of 94.7, 92.0, 94.0, and 90.0%, respectively, with a specificity of 94.7%. The comparable values of SEA/ELISA were 93.3, 92.0, 93.0, and 50.0%, respectively, with a specificity of 98.2%. Combined use of ELISA and WA/IHA80 gave sensitivities of 100% for S. mansoni, S. haematobium, and S. mansoni and S. haematobium combined and 90% for Katayama fever. The specificity of this combination in detecting schistosomiasis was 92.9%. Combination of SEA/ELISA with WA/IHA160 gave sensitivities of 98.7, 96.0, 98.0, and 80% with a specificity of 97.2%. Our findings suggest that WA/IHA and SEA/ELISA are each sensitive and specific serological tests that are easy to use for the diagnosis of imported schistosomiasis. The combined use of these two tests enabled the serological diagnosis of schistosomiasis to be achieved with very high degrees of both sensitivity and specificity.

Presentation and diagnosis of imported schistosomiasis: relevance of eosinophilia, microscopy for ova, and serology.

BACKGROUND In nonendemic countries a steady rise in cases of imported schistosomiasis has been observed. The objective of this study was to describe the presentation of patients diagnosed with schistosomiasis in the Outpatient Department (OPD) for Tropical Diseases in the Academic Medical Center, Amsterdam, the Netherlands. METHODS In a retrospective study, patients with schistosomiasis from our OPD (1997-1999), including a subgroup of persons asking for screening for schistosomiasis and found positive, were analyzed. Diagnosis was based on freshwater exposure in an endemic area and positive serology for schistosomal antibodies. The following data were recorded: age, gender, country of birth, travel destination, symptoms, eosinophil count, and results of serology and stool and urine microscopy. RESULTS Seventy-eight patients (42 travelers, 16 expatriates, and 20 immigrants) were diagnosed with schistosomiasis; 47% were infected in southern Africa. Twenty-four percent had specific symptoms, 57% had eosinophilia, and in 17 patients (22%) Schistosoma ova were found. Eleven travelers suffered from Katayama syndrome. Of the subgroup of 42 persons screened for schistosomiasis, 15 (36%) had schistosomal antibodies; the majority of these persons (10/15 [67%]) were infected in southern Africa. CONCLUSION In our OPD schistosomiasis was diagnosed in about 26 patients per year, 3% of all new presentations. Infections were almost exclusively acquired in Africa. In travelers high eosinophilia was due to acute schistosomiasis; in immigrants it was due to concomitant helminthic infections. One of three people asking to be screened for schistosomiasis had schistosomal antibodies. Eosinophilia was indicative but an insufficient screening tool, and stool and urine microscopy for ova were not sensitive. Screening by serology is easy and reliable and the method of choice in asymptomatic persons with a history of freshwater exposure in a high-risk area.

Direct Amplification and Genotyping of Dientamoeba fragilis from Human Stool Specimens

ABSTRACT Dientamoeba fragilis is a globally occurring parasite that has been recognized as a causative agent of gastrointestinal symptoms. A single-round PCR was developed to detect D. fragilis DNA directly from human stool samples. The genetic diversity of D. fragilis from 93 patients and 6 asymptomatic carriers was examined by PCR followed by restriction fragment length polymorphism and sequencing of part of the small-subunit rRNA gene. The data show that D. fragilis sequences can be studied directly from fecal specimens despite the absence of a cyst stage and without the need for prior culturing. In addition, the results suggest strongly that D. fragilis shows remarkably little variation in its small-subunit rRNA gene.

Evaluation of the Eiken latex agglutination test for anti-Toxoplasma antibodies and seroprevalence of Toxoplasma infection among factory workers in Addis Ababa, Ethiopia.

Sera from 170 factory workers aged 18-45 years enrolled in a pilot study of human immunodeficiency virus 1 (HIV-1) infection in Addis Ababa, Ethiopia, were screened for anti-Toxoplasma immunoglobulin G antibodies by the Sabin-Feldman test (reference standard) and the Eiken latex agglutination test (under evaluation for use in developing countries). Based on the Sabin-Feldman test, the prevalence of anti-Toxoplasma antibodies was 80.0% (95% confidence interval 73.9-86.1%). The sensitivity and specificity of the Eiken latex agglutination test were 96.3% and 97.1%, respectively, showing its validity for the detection of anti-Toxoplasma antibodies. The prevalence of antibodies did not differ between individuals infected and uninfected with HIV-1 (74.2% versus 83.3%, P > 0.05). However, antibody titres were higher in HIV-infected persons than in those who were uninfected (P < 0.001). Based on these findings, we expect that toxoplasmic encephalitis will be a common opportunistic infection among HIV-infected Ethiopians, and chemoprophylaxis with co-trimoxazole may be beneficial to those with low CD4+ T cell counts. The prognostic significance of high titres of anti-Toxoplasma antibodies remains to be established among Ethiopian HIV-infected individuals.

Disseminated Infection with a New Genovar of Encephalitozoon cuniculi in a Renal Transplant Recipient

ABSTRACT Disseminated microsporidiosis is a life-threatening opportunistic infection. Here, we report about a previously undescribed genovar of Encephalitozoon cuniculi causing disseminated infection in a non-HIV-infected renal transplant recipient. Disseminated microsporidiosis must be considered in the differential diagnosis of chronic fever in renal allograft recipients, even those without urinary symptoms.

Serodiagnostic Studies in an Immunocompetent Individual Infected with Encephalitozoon cuniculi

Little is known about the prevalence and clinical significance of infection with Encephalitozoon species in immunocompetent individuals. In the present study, by using indirect immunofluorescence technique (IFAT), Western blot, and recombinant antigens of the spore wall (SWP1) and polar tube (PTP1, PTP2, and PTP3 ), we analyzed the IgG antibody response of a laboratory worker who was infected with Encephalitozoon cuniculi. Serum samples were analyzed 1, 20, 32, and 38 months after infection. After 1 month, by use of IFAT, only spore-wall antigens were recognized, an antibody reaction that changed toward both the spore wall and polar tube in the following months. By use of Western blot analysis, a characteristic pattern that recognized multiple bands was noticed. Reaction against SWP1 was present in all 4 serum samples. The IgG response against PTP1, PTP2, and PTP3 was not detectable 1 month after infection, but became evident in the follow-up serum samples. Serum samples showed cross-reactivity with the spore wall of Encephalitozoon hellem and Encephalitozoon intestinalis, but only little cross-reactivity with the polar tube of these parasites. This is the first study to our knowledge that provides full details about the antibody response against a specified Encephalitozoon species in an immunocompetent person. The results strongly encourage the development and use of reliable serodiagnostic methods, which will provide information about the prevalence and clinical significance of Encephalitozoon species infection in humans.

Frequent Occurrence of Human-Associated Microsporidia in Fecal Droppings of Urban Pigeons in Amsterdam, The Netherlands

ABSTRACT Human-associated microsporidia were frequently observed in fecal samples of 331 feral pigeons in Amsterdam, The Netherlands, obtained during high- and low-breeding periods. Thirty-six of 331 samples (11%) contained the human pathogens Enterocytozoon bieneusi (n = 18), Encephalitozoon hellem (n = 11), Encephalitozoon cuniculi (n = 6), and Encephalitozoon intestinalis (n = 1); 5 samples contained other microsporidia. Pigeon feces can be an important source of human microsporidian infection.

Detection of Imported Malaria with the Cell-Dyn 4000 Hematology Analyzer

ABSTRACT The sensitivity and specificity of the Cell-Dyn 4000 hematology analyzer in the diagnosis of imported malaria were studied with samples from patients in an academic hospital setting. The performance of the Cell-Dyn 4000 hematology analyzer was compared with that of conventional diagnostic methods for malaria. The Cell-Dyn 4000 hematology analyzer detected hemozoin-containing depolarizing monocytes in 29 of 58 patients with malaria and 2 of 55 patients without malaria. The presence or absence of depolarizing monocytes in patients with malaria was related to duration of symptoms before presentation for malaria analysis. A second parameter, pseudoreticulocytosis due to nuclear material of intraerythrocytic malaria parasites, was detected by the Cell-Dyn 4000 hematology analyzer almost exclusively in Plasmodium falciparum malaria patients with parasitemia levels of ≥0.5%. Attention to these abnormalities in medical centers without tropical disease expertise may decrease a delay in the diagnosis of malaria.