Abdominal angiostrongyliasis can be diagnosed with a immunochromatographic rapid test with recombinant galactin from Angiostrongylus cantonensis

Angiostrongylus costaricensis is the causative agent of abdominal angiostrongyliasis, a zoonotic infection that may produce severe eosinophilic enterocolitis or hepatitis in humans. Parasites are usually not released in stools and serology has an important role in diagnosis. Since cross-reactivity is demonstrated between A. costaricensis and another metastrongylid worm, A. cantonensis, we tested heterologous recombinant galectin as a probe in an immunochromatographic rapid diagnostic test (ICT-RDT) for detection of anti-A. costaricensis antibodies. Almost all (11/12) positive control sera from A. costaricensis infected patients were positive at ICT RDT. These are preliminary indications that r-galectin ICT-RDT is useful for diagnosing A. costaricensis infection.

Molecular detection of Schistosoma japonicum in infected snails and mouse faeces using a real-time PCR assay with FRET hybridisation probes

A real-time polymerase chain reaction (PCR) assay with fluorescence resonance energy transfer (FRET) hybridisation probes combined with melting curve analysis was developed to detect Schistosoma japonicum in experimentally infected snails and in faecal samples of infected mice. This procedure is based on melting curve analysis of a hybrid between an amplicon from the S. japonicum internal transcribed spacer region 2 sequence, which is a 192-bp S. japonicum-specific sequence, and fluorophore-labelled specific probes. Real-time FRET PCR could detect as little as a single cercaria artificially introduced into a pool of 10 non-infected snails and a single egg inoculated in 100 mg of non-infected mouse faeces. All S. japonicum-infected snails and all faecal samples from infected mice were positive. Non-infected snails, non-infected mouse faeces and genomic DNA from other parasites were negative. This assay is rapid and has potential for epidemiological S. japonicum surveys in snails, intermediate hosts and faecal samples of final hosts.

Specificity of immunoblotting analyses in eosinophilic meningitis

Angiostrongylus cantonensis and Gnathostoma spinigerum are the two most common causative parasites of eosinophilic meningitis (EOM). Serological tests are helpful tools for confirming the identity of the pathogen. Recent reports determined the specificity of such tests by using normal healthy controls. There have been limited studies done to rule out the cross-reactivity between these two causative parasites of EOM. This study aims to assess the specificity of the serological test in EOM by using each condition as a control for the other. Thirty-three patients with a diagnosis of EOM were enrolled. Sera from 22 patients with a positive 29-kDa antigenic diagnostic band of A. cantonensis were tested for the 21 and 24-kDa antigenic bands of G. spinigerum. Similarly, sera of 11 gnathostomiasis patients were tested for the 29-kDa diagnostic band for A. cantonensis. Only one patient in the angiostrongyliasis group had a positive result for the 21 and 24-kDa antigenic bands of G. spinigerum, while no gnathostomiasis patients showed a positive result for the 29-kDa antigenic band of A. cantonensis. The specificity of the 21 and 24-kDa antigenic bands for gnathostomiasis and the 29-kDa antigenic band for A. cantonensis was 95.5 percent and 100 percent, respectively. The antigenic bands for the diagnosis of gnathostomiasis and angiostrongyliasis in EOM were highly specific.

Peripheral eosinophilia as an indicator of meningitic angiostrongyliasis in exposed individuals

The diagnosis of meningitic angiostrongyliasis (MA) is based on clinical criteria. A lumbar puncture is used as a diagnostic tool, but it is an invasive procedure. The blood eosinophil levels are also assessed and used in the diagnosis of this disease. We enrolled 47 patients with serologically proven MA and 131 controls with intestinal parasite infections. An absolute eosinophil count model was found to be the best marker for MA. An eosinophil count of more than 798 cells led to sensitivity, specificity, positive predictive and negative predictive values of 76.6 percent, 80.2 percent, 58.1 percent and 90.5 percent, respectively. These data support the use of testing for high blood eosinophil levels as a diagnostic tool for MA in individuals that are at risk for this disease.

Evaluation of IgG4 and total IgG antibodies against cysticerci and peptide antigens for the diagnosis of human neurocysticercosis by ELISA.

To support the clinical diagnosis of human neurocysticercosis (NCC), we evaluated two peptides, HP6-3 and Ts45W-1, as well as crude saline extract (SE) of Tenia solium cysticerci as antigens for the detection of specific IgG4 subclass and total IgG antibodies by an enzyme-linked immunosorbent assay (ELISA). The sera of definitive diagnosed NCC patients, patients infected with other parasitoses and healthy controls were examined. The diagnostic sensitivity for IgG4 and total IgG detection of the ELISA against SE antigen was 100% and 64.3% with a high amount of cross-reactions to taeniasis saginata at 88.9% (8/9) and 100% (9/9), respectively. The SE-based IgG4-ELISA showed the highest specificity (80.9%). Both peptide-based IgG4-ELISAs provided a superior sensitivity (78.6%) to the total IgG tests whereas their specificity was 66.7% for HP6-3 and 69.8% for Ts45W-1 only. The SE-based ELISA for the detection of specific IgG4 antibody can be used for the diagnosis of neurocysticercosis as well as for serological surveys of NCC endemic areas. The peptide-based IgG4 ELISAs potentially provide a reliable and cost effective alternative method independent from live parasite supply.

Hypereosinophilia and abdominopulmonary gnathostomiasis.

A 16-year-old Thai male presented with sudden onset severe epigastric and right upper quadrant pain, fever (39 degrees C), chills and malaise. He gave no history of underlying disease, migratory swelling or urticarial skin rash. He had a history of frequently eating raw pork. Physical examination revealed a soft abdomen with markedly tender hepatomegaly. His blood count showed extreme leukocytosis with hypereosinophilia. After admission he developed a non-productive cough with left sided chest pain, a chest x-ray showed a left pleural effusion. Serological findings were positive for Gnathostoma larval antigen but not Fasciola antigen. The patient recovered completely after albendazole treatment. His clinical presentation is compatible with abdominopulmonary hypereosinophilic syndrome or visceral larva gnathostomiasis. The presented case is interesting not only for physicians who work in endemic areas of gnathostomiasis but also for clinicians who work in travel medicine clinics in developed countries, to consider abdominopulmonary gnathostomiasis when patients present with the signs and symptoms of visceral larva migrans.

Eosinophilic meningitis associated with angiostrongyliasis: clinical features, laboratory investigations and specific diagnostic IgG and IgG subclass antibodies in cerebrospinal fluid.

Eosinophilic meningitis (EOM) associated angiostrongyliasis mostly induced by the nematode Angiostrongylus cantonensis, is a common disease with worldwide prevalence. Heavy infections can lead to chronic disabling disease and even death. This study was conducted to shed light on the overall specific IgG antibody response as well as the specific IgG antibody subclass responses in cerebrospinal fluid (CSF) of patients with EOM. Fifteen patients with EOM associated with angiostrongyliasis were included in the study. Sera were screened by immunoblotting for the presence of IgG antibody to the 29 kDaA. cantonensis antigenic polypeptide. CSF was examined by ELISA for the presence of specific IgG and IgG subclass antibodies. Patients presented with headache (100%), neck stiffness (20%), fever (40%), nausea (87%), vomiting (73%), paresthesia (7%), and muscle weakness (7%). Seven of 15 (47%) patients showed peripheral blood eosinophilia and all patients presented with eosinophils in CSF. A sensitivity of 80 % was obtained by combining the diagnostic values of immunoblotting in sera and IgG and IgG subclasses-based ELISA in CSF. The combination of a history of eating raw or semi-cooked infected foods, clinical features, complete blood count, differential cell counts, CSF profiles, and serum and CSF antibodies to A. cantonensis can be used to increase the sensitivity for the diagnosis of human angiostrongyliasis.

Enzyme-linked immunosorbent assay for serodiagnosis of Helicobacter pylori in dyspeptic patients and volunteer blood donors.

Helicobacter pylori, an important etiological agent in the development of gastritis, peptic ulcer and gastric carcinoma, can be detected by the enzyme-linked immunosorbent assay (ELISA). Our objectives were: (1) to evaluate the efficacy of a commercial ELISA kit (Pyloriset EIA-G III) in sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for diagnosis of H. pylori infection in Thai dyspeptic patients in Khon Kaen Thailand; and (2) to examine the seroprevalence of H. pylori among blood donors at Srinagarind Hospital's Blood Bank, Khon Kaen University, by the commercial ELISA. Gastric biopsies obtained from 137 dyspeptic patients were diagnosed by culture, rapid urease test (RUT) and histology. Serum samples from the same dyspeptic patients and 100 healthy blood donors were assayed using the commercial ELISA. H. pylori infection in dyspeptic patients was considered positive when the culture or both RUT and histology were positive. Using a cut-off value at a titer of 20 U/ml (as recommended by the manufacturer), we found the commercial ELISA kit had a sensitivity of 93.3%, specificity of 75.3%, PPV of 74.7%, NPV of 93.5% and accuracy of 83.2%. The overall H. pylori seroprevalence in the healthy blood donors was 57%. Of the 100 healthy blood donors, 39 (60.9%) of the males and 18 (50.0%) of the females were seropositive.

Communicating hydrocephalus as a complication of eosinophilic meningoencephalitis.

The authors reported an adult patient with communicating hydrocephalus in eosinophilic meningoencephalitis. He presented with localized peritonitis and then developed eosinophilic meningoencephalitis. Angiostrongylus cantonensis was the causative agent. This was confirmed by the positive serology test. His consciousness did not recover after supportive treatment. The MRI of the brain showed diffuse enlargement of the ventricular system two weeks after the diagnosis was made. The parameters for hydrocephalus were measured and were compatible with the Gyldensted's criteria.

Randomized comparative trial of two high-dose albendazole regimens for uncomplicated human strongyloidiasis.

A randomized trial study was conducted comparing the efficacy of two high-dose regimens of albendazole for the treatment of uncomplicated human strongyloidiasis. Agar plate culture (APC) was used as an evaluation technique for coprological diagnosis. All 115 subjects infected with Strongyloides stercoralis from 7 provinces in northeastern Thailand were divided randomly into two groups. Regimen-1 group received albendazole 800 mg/day twice daily for 3 consecutive days, and regimen-2 group received the same dose for 5 consecutive days. For each regimen, the same treatment was repeated once 7 days later. Stools were parasitologically examined at 14 days, and 10 days after the second course of treatment, respectively. A coprological cure rate of 87.9% (51/58) was obtained in the regimen-1 group, with 89.5% (51/57) in the regimen-2 group, which was not statistically significantly different (P = 0.794). The mild adverse effects were not statistically different between the two groups, at 8.6% and 8.8%, respectively (P = 0.977). We therefore suggest albendazole treatment using regimen 1 should be recommended. However, the use of new effective drugs should be considered, especially in hyperinfective strongyloidiasis.

Evaluation of human IgG subclass antibodies in the serodiagnosis of Paragonimiasis heterotremus.

Immunoglobulin G subclass antibodies (IgG1, IgG2, IgG3, and IgG4) responses to the excretory-secretory antigens of the lung fluke, Paragonimus heterotremus, were analyzed using the immunoblotting technique in an attempt to further improve the sensitivity and specificity for serodiagnosis of human paragonimiasis. Serum samples from patients with proven paragonimiasis, from patients with other parasitic infections, pulmonary tuberculosis and from healthy counterparts were analyzed. The results indicate that immunoblotting for the detection of IgG4 antibodies to an excretory-secretory product of P. heterotremus of an approximate molecular mass of 31.5 kDa, is the most reliable test. It gives accuracy, sensitivity, specificity, and positive and negative predictive values of 97.6%, 100%, 96.9%, 90% and 100%, respectively.

Immunodiagnosis of human fascioliasis using an antigen of Fasciola gigantica adult worm with the molecular mass of 27 kDa by a dot-ELISA.

Immunodominant antigens of an approximate molecular mass of 27 kDa (FG 27) were obtained from an excretory-secretory product of adult Fasciola gigantica by a simple continuous-elution method. A dot-ELISA using the FG 27 antigen was developed for the detection of specific antibodies from patients infected with F. gigantica. Control sera were obtained from patients with other parasitic infections and healthy volunteers. The accuracy, sensitivity, specificity, and positive and negative predictive values were 98.2%, 100%, 97.4%, 76.9% and 100%, respectively. This dot-ELISA is a specific, sensitive and easy to perform method for the rapid diagnosis of fascioliasis, particularly when more complex laboratory tests are unavailable.

Prevalence of Strongyloides stercoralis infection in northeastern Thailand (agar plate culture detection).

The prevalence of Strongyloides stercoralis infection was studied in the rural and urban populations of 19 provinces of Northeastern Thailand. A total of 1233 fecal samples was collected from July to September 2002 and examined using agar plate culture method. The overall prevalence of S. stercoralis was 23.5 per cent with the highest infection rate in Kalasin Province (61.0%), predominantly among 60 year olds and older (28.0%), and in males (32.8%). The factors associated with Strongyloides infection were sex (males) and age (the over 19 year-old age group). CONCLUSION: S. stercoralis infection remains highly prevalent among the population of northeastern Thailand as confirmed by the agar plate culture method. The authors recommend that a program for effective strongyloidiasis control should have a justifiable priority.

Specific IgG antibody subclasses to Angiostrongylus cantonensis in patients with angiostrongyliasis.

Total IgG, IgG1, IgG2, IgG3, IgG4, IgA and IgM specific antibodies against Angiostrongylus cantonensis somatic antigen were determined by enzyme-linked immunosorbent assay (ELISA) in sera from proven human angiostrongyliasis (PA) cases, clinically suspected angiostrongyliasis cases with eosinophilic meningitis (EM) and healthy control (HC). The specific IgA antibody in each of the patient groups was significantly higher than those of the HC group (p < 0.05). The mean ELISA value of the specific IgM in the PA group was not significantly different from that of the HC group (p > 0.05). However, the mean specific IgM ELISA value in the EM group was significantly higher than that of the HC group (p < 0.05). The levels of the specific IgG and IgG subclasses in both patient groups were significantly higher than in the healthy control (HC) group (p < 0.001). Major differences were evident in the distribution of the IgG subclass antibodies between the patient groups. The IgG1 antibody demonstrated the highest sensitivity and specificity while the IgM and IgA responses were generally poor in both patient groups. The levels of the specific IgG antibody subclasses possibly explain immune responses to the parasite.