Comparison of the quantitative formalin ethyl acetate concentration technique and agar plate culture for diagnosis of human strongyloidiasis

The quantitative formalin ethyl acetate concentration technique (QFEC) was compared to agar plate culture (APC) for the detection of Strongyloides stercoralis larvae. QFEC could substitute for APC only when the parasite load was higher than 50 larvae per g of stool. This study serves as a good reminder to those conducting stool exams about the sensitivity and specificity limitations of both techniques.

First report and molecular identification of Opisthorchis viverrini infection in human communities from Lower Myanmar

Opisthorchis viverrini is endemic in the South East Asian region, especially in Cambodia, Lao People's Democratic Republic, Vietnam and Thailand, but there have been no previous records from Myanmar. During stool surveys of rural populations in three regions of Lower Myanmar, Opisthorchis-like eggs were found in 34 out of 364 (9.3%) participants by stool microscopy after using the modified formalin-ether concentration technique. DNA was extracted from these positive stool samples and a portion of the mitochondrial cytochrome c oxidase subunit I (cox1) gene was amplified using the polymerase chain reaction and then sequenced. DNA sequences, successfully obtained from 18 of 34 positive samples (Bago Region, n = 13; Mon State, n = 3; Yangon Region, n = 2), confirmed that the eggs were of O. viverrini. Sequences showed 99.7% identity with O. viverrini mitochondrial cox1 (GenBank accession no. JF739555) but 95%, 88.7%, 82.6% and 81.4% identities with those of Opisthorchis lobatus from Lao People's Democratic Republic (GenBank accession nos. HQ328539-HQ328541), Metorchis orientalis from China (KT239342), Clonorchis sinensis from China (JF729303) and Opisthorchis felineus from Russia (EU921260), respectively. When alignement with other Opisthorchiidae trematodes, 81% similarity with Metorchis bilis from Czech Republic (GenBank accession nos. KT740966, KT740969, KT740970) and Slovakia (GenBank accession nos. KT740971-KT740973), 84.6% similarity with Metorchis xanthosomus from Czech Republic (GenBank accession no. KT740974), 78.6% similarity with M. xanthosomus from Poland (GenBank accession no. KT740968) and 82.2% similarity with Euamphimerus pancreaticus from Czech Republic (GenBank accession no. KT740975) were revealed. This study demonstrated, for the first time, O. viverrini from rural people in Myanmar using molecular methods and is an urgent call for surveillance and control activities against opisthorchiasis in Myanmar.

Intraocular angiostrongyliasis: clinical findings, treatments and outcomes

Ocular angiostrongyliasis, diagnosed by identification of Angiostrongylus cantonensis in any part of the eye, is a very rare manifestation. We report seven cases of intraocular angiostrongyliasis in Srinagarind Hospital, Khon Kaen University, Thailand. From a total of 654 cases of angiostrongyliasis diagnosed between January 1995 and April 2005, 7 cases (1.1%) with ocular manifestations were found. Four men and three women were diagnosed, with a mean age of 32.1 years (range 21-46 years). All of the patients lived in the northeast of Thailand and acquired the infection by eating raw Pila spp. snails, the intermediate host of A. cantonensis. The incubation period lasted from 2 weeks to 2 months. The most common symptom, blurred vision without eosinophilic meningitis, occurred as a presenting symptom in five cases. The other two cases presented with eosinophilic meningitis prior to development of poor visual acuity. Both cases had papilloedema, neck stiffness and eosinophilia without fever. The visual acuity of the patient was mostly lower than 2/60 and, evidently, visual impairment in all patients was caused by retinal pigment epithelial defects. All cases had only one immature A. cantonensis worm in the eye, with the most common site being the intravitreous area. Several treatments, including oral prednisolone, topical prednisolone, argon laser, diode laser, Nd:YAG laser, surgical removal of the parasite and combination therapy, were used. There is no evidence that surgical and laser interventions improve the course of the disease, and both have associated risks. Visual outcome depends on the initial visual defects.

Angiostrongylus cantonensis and A. malaysiensis Broadly Overlap in Thailand, Lao PDR, Cambodia and Myanmar: A Molecular Survey of Larvae in Land Snails

Angiostrongylus cantonensis is a zoonotic nematode parasite causing human eosinophilic meningitis (or meningoencephalitis) worldwide. A closely related species, Angiostrongylus malaysiensis, might also be a human pathogen. Larvae were obtained from land snails in Lao PDR, Cambodia, Myanmar and Thailand. We sequenced two nuclear gene regions (nuclear ribosomal ITS2 and SSU rRNA) and a portion of one mitochondrial gene (COI) from these larvae. Angiostrongylus cantonensis and A. malaysiensis were identified. This is the first report of the molecular identification of the two Angiostrongylus species in Lao PDR, Cambodia and Myanmar. The regional distributions of the two species broadly overlap. Phylogenetic relationships were inferred including data from Angiostrongylus species deposited in public databases. All the gene regions we sequenced have potential value in distinguishing between species of Angiostrongylus. The COI gene exhibited the greatest intraspecific variation in the study region (five haplotypes in A. cantonensis and four in A. malaysiensis) and might be suitable for more detailed phylogeographic studies.

Clinical factors predictive of encephalitis caused by Angiostrongylus cantonensis

Angiostrongylus cantonensis is mainly caused eosinophilic meningitis in humans, whereas a minority of patients develop encephalitic angiostrongyliasis (EA). EA is an extremely fatal condition, and the clinical factors predictive of EA have never been reported. A comparison study was conducted in a hospital situated in an endemic area of Thailand. We enrolled 14 and 80 angiostrongyliasis patients who developed encephalitis and meningitis, respectively. Logistic regression analysis was used to assess the clinical variables predictive of encephalitis. Age (adjusted odds ratio [OR], 1.22; 95% confidence interval [CI], 1.05-1.42), duration of headache (adjusted OR, 1.26; 95% CI, 1.03-1.55), and fever > 38.0 degrees C (adjusted OR, 37.05; 95% CI, 1.59-862.35) were identified as statistically significant factors for EA prediction. Elderly patients with angiostrongyliasis experiencing fever and prolonged headaches were at the highest risk of developing EA.

Rapid detection and differentiation of Clonorchis sinensis and Opisthorchis viverrini eggs in human fecal samples using a duplex real-time fluorescence resonance energy transfer PCR and melting curve analysis

We developed a single step duplex real-time fluorescence resonance energy transfer (FRET) PCR merged with melting curve analysis for the fast detection and differentiation of Clonorchis sinensis and Opisthorchis viverrini eggs in human fecal samples. Two species of mitochondrial NADH dehydrogenase subunit 2 (nad2) DNA elements, the 165-bp nad2 product of C. sinensis and the 209-bp nad2 product of O. viverrini, were amplified by species-specific primers, and the fluorescence melting curve analyses were generated from hybrid of amplicons and two pairs of species-specific fluorophore-labeled probes. By their different fluorescence channels and melting temperatures, both C. sinensis and O. viverrini eggs in infected human fecal samples were detected and differentiated with high (100%) sensitivity and specificity. Detection limit was as little as a single C. sinensis egg and two O. viverrini eggs in 100 mg of fecal sample. The assay could distinguish the DNA of both parasites from the DNA of negative fecal samples and fecal samples with other parasitosis, as well as from the well-defined genomic DNA of human leukocytes and other parasites. It can reduce labor time of microscopic examination and is not prone to carry over contamination of agarose electrophoresis. Our duplex real-time FRET PCR method would be useful to determine the accurate range of endemic areas and/or to discover the co-endemic areas of two liver flukes, C. sinensis and O. viverrini, in Asia. This method also would be helpful for the differential diagnosis of the suspected cases of liver fluke infections among travelers who had visited the endemic countries of those parasites.

First molecular identification and genetic diversity of Strongyloides stercoralis and Strongyloides fuelleborni in human communities having contact with long-tailed macaques in Thailand

The parasitic nematodes, Strongyloides stercoralis and Strongyloides fuelleborni, can infect humans and non-human primates. We amplified and sequenced a portion of the 18S ribosomal RNA gene (rRNA) and of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of Strongyloides from humans in the study area in Thailand, where people have frequent contact with long-tailed macaques. Fresh stool samples were obtained from 213 people and were examined using the agar plate culture method. The overall prevalence of Strongyloides infection was 8.92% (19/213). From a total of 19 worms (one per infected person), 18 adult males had 18S rRNA sequences identical with that of S. stercoralis and one adult female had a sequence almost identical with that of S. fuelleborni. A median-joining network of cox1 sequences revealed nine new haplotypes from S. stercoralis, and an overall haplotype diversity (Hd) of 0.9309. The single haplotype of S. fuelleborni was also new and contributed to an overall haplotype diversity for that species of 0.9842. This is the first molecular identification of S. stercoralis and S. fuelleborni in a human community having contact with long-tailed macaques in Thailand. It is also the first report of S. fuelleborni infecting a human in Thailand.

Rapid detection of Opisthorchis viverrini and Strongyloides stercoralis in human fecal samples using a duplex real-time PCR and melting curve analysis

Human opisthorchiasis caused by the liver fluke Opisthorchis viverrini is an endemic disease in Southeast Asian countries including the Lao People's Democratic Republic, Cambodia, Vietnam, and Thailand. Infection with the soil-transmitted roundworm Strongyloides stercoralis is an important problem worldwide. In some areas, both parasitic infections are reported as co-infections. A duplex real-time fluorescence resonance energy transfer (FRET) PCR merged with melting curve analysis was developed for the rapid detection of O. viverrini and S. stercoralis in human fecal samples. Duplex real-time FRET PCR is based on fluorescence melting curve analysis of a hybrid of amplicons generated from two genera of DNA elements: the 162 bp pOV-A6 DNA sequence specific to O. viverrini and the 244 bp 18S rRNA sequence specific to S. stercoralis, and two pairs of specific fluorophore-labeled probes. Both O. viverrini and S. stercoralis can be differentially detected in infected human fecal samples by this process through their different fluorescence channels and melting temperatures. Detection limit of the method was as little as two O. viverrini eggs and four S. stercoralis larvae in 100 mg of fecal sample. The assay could distinguish the DNA of both parasites from the DNA of negative fecal samples and fecal samples with other parasite materials, as well as from the DNA of human leukocytes and other control parasites. The technique showed 100% sensitivity and specificity. The introduced duplex real-time FRET PCR can reduce labor time and reagent costs and is not prone to carry over contamination. The method is important for simultaneous detection especially in areas where both parasites overlap incidence and is useful as the screening tool in the returning travelers and immigrants to industrialized countries where number of samples in the diagnostic units will become increasing.

Detection of Opisthorchis viverrini in experimentally infected bithynid snails and cyprinoid fishes by a PCR-based method

A PCR procedure for the detection of Opisthorchis viverrini in experimentally infected bithynid snails and cyprinoid fishes was developed. This procedure was based on primers designed from a pOV-A6 specific probe sequence giving a 330 base-pair product. The detection was accomplished in host tissue homogenates to which a single cercaria or metacercaria was introduced. PCR can detect as little as a single cercaria artificially inoculated in a snail or a single metacercaria artificially inoculated in a fish sample. The method gave a 100% positivity rate for all infected snails or fishes. The method did not yield a 330 base-pair amplified product with other digenean fluke DNAs such as Haplorchis taichui, Centrocestus spp., Echinostoma malayanum, Fasciola gigantica, animal schistosomes, Paragonimus heterotremus or Haplorchoides spp. The assay has great potential for application in epidemiological surveys of both snail and fish intermediate hosts as well as for investigation of foodborne parasites in freshwater fishes.

Evaluation of human IgG class and subclass antibodies to a 24 kDa antigenic component of Gnathostoma spinigerum for the serodiagnosis of gnathostomiasis

The immunoglobulin G class (total IgG) and subclass (IgG1, IgG2, IgG3, and IgG4) antibody responses to the spirurid worm Gnathostoma spinigerum were analyzed by immunoblotting technique for the antibodies' potential use in the serodiagnosis of human gnathostomiasis. Serum samples from patients with proven gnathostomiasis and from clinically suspected cases of gnathostomiasis with migratory swelling were tested. Sera from patients with other parasitic illnesses and from healthy volunteers were also analyzed. The total IgG antibody to an antigenic band of approximately 24 kDa from a somatic extract of G. spinigerum advanced third-stage larvae (GS24) gave the highest sensitivity (91.6%) and 87.8% specificity. Individual IgG subclass detection had a lower sensitivity than the detection of specific total IgG antibody, but IgG4 had a slightly higher specificity (93.9%). However, for cost effectiveness, we suggest that anti GS24 total IgG is sufficient for the routine serodiagnosis of human gnathostomiasis as well as for seroepidemiological studies in developing countries.

Molecular evidence of Trichostrongylus colubriformis and Trichostrongylus axei infections in humans from Thailand and Lao PDR

Human trichostrongylosis has been reported in Thailand. Recent reports in Lao People's Democratic Republic concerning species identification urged us to investigate species distribution in Thailand. We report eight human cases in Thailand and Lao People's Democratic Republic that were found to be infected by Trichostrongylus colubriformis and T. axei identified and confirmed by molecular techniques. This evidence is the first molecular evidence of human T. colubriformis and T. axei infection in Thailand. Infection by these two species was apparently epidemic in these areas. It is necessary to proceed with more comprehensive veterinary and epidemiologic studies to enable the practical prevention and control of this parasitic zoonosis.

Molecular identification of Ascaris lumbricoides and Ascaris suum recovered from humans and pigs in Thailand, Lao PDR, and Myanmar

Ascaris lumbricoides is the largest roundworm known from the human intestine while Ascaris suum is an internal parasite of pigs. Ascariasis, caused by Ascaris lumbricoides, has a worldwide distribution. Here, we have provided the first molecular identification of Ascaris eggs and adults recovered from humans and pigs in Thailand, Lao PDR, and Myanmar. We amplified and sequenced nuclear ribosomal DNA (ITS1 and ITS2 regions) and mitochondrial DNA (cox1 gene). Sequence chromatograms of PCR-amplified ITS1 region revealed a probable hybrid genotype from two human ascariasis cases from Chiang Mai Province, northern Thailand. All complete ITS2 sequences were identical and did not differ between the species. Phylogenetic trees and haplotype analysis of cox1 sequences showed three clusters with 99 haplotypes. Forty-seven samples from the present study represented 14 haplotypes, including 7 new haplotypes. To our knowledge, this is the first molecular confirmation of Ascaris species in Thailand, Lao PDR, and Myanmar. Zoonotic cross-transmission of Ascaris roundworm between pigs and humans probably occurs in these countries.

Current high prevalences of Strongyloides stercoralis and Opisthorchis viverrini infections in rural communities in northeast Thailand and associated risk factors

Background

Two important helminths, Strongyloides stercoralis (an intestinal roundworm) and Opisthorchis viverrini (a liver fluke), are endemic in northeast Thailand. There have been national campaigns in place aimed at the control and eradication of soil-transmitted helminthiasis and opisthorchiasis in Thailand for several decades. However, these helminths still exist and raise concerns regarding public health. This study aimed to evaluate the current prevalence of S. stercoralis and O. viverrini infections in rural communities in northeast Thailand. The data from this study will be useful to improve strategies for future helminth prevention and control.

Methods

A cross-sectional study was conducted from December 2016 to June 2017 in Mueang Khon Kaen district in Khon Kaen, Thailand. The participants were selected using a simple random sampling method. Demographic data were collected using a questionnaire. Stool samples were collected and processed using agar plate culture to determine the presence of S. stercoralis infection and an in-house formalin-ethyl acetate concentration technique to determine the presence of O. viverrini and other intestinal parasite infections (IPIs).

Results

In total, 602 persons were enrolled. However, only 526 were analyzed for S. stercoralis and 387 for O. viverrini risk factors. The overall prevalence of S. stercoralis infection was 23.0% (95% confidence interval [95%CI]: 19.4 to 26.6). The prevalence of O. viverrini infection and IPIs other than S. stercoralis was 20.4% (95%CI: 16.5 to 24.8). The prevalence of O. viverrini infection was 19.4% (95%CI: 15.6 to 23.7). Male sex was significantly associated with S. stercoralis infection [Adjusted Odds Ratio (aOR) 4.0; 95%CI: 2.5 to 6.2; P-value < 0.001]. Males were significantly more likely to be infected with O. viverrini and other IPIs (aOR 4.1; 95%CI: 2.3 to 7.2, P-value < 0.001).

Conclusions

This study demonstrated that the updated prevalence of intestinal parasite infections is still high in rural communities in northeast Thailand, especially that of strongyloidiasis and opisthorchiasis.

Evaluation of human IgG subclass antibodies in the serodiagnosis of angiostrongyliasis

Immunoglobulin G subclass antibody (IgG1, IgG2, IgG3, and IgG4) responses to the rat lungworm, Angiostrongylus cantonensis, were analyzed using the immunoblotting technique in an attempt to further improve the sensitivity and specificity for the serodiagnosis of human angiostrongyliasis. Serum samples from patients with proven angiostrongyliasis and from clinically suspected cases of angiostrongyliasis with eosinophilic meningitis were tested. Sera from patients with other parasitic illnesses and from healthy volunteers were also analyzed. The results indicate that the immunoblotting used to detect IgG4 antibodies to the antigenic band of an approximate molecular mass of 29 kDa from young adult somatic extract of A. cantonensis is the most reliable test. It gives accuracy, sensitivity, specificity, and positive and negative predictive values of 89.2%, 75%, 95%, 85.7% and 90.4%, respectively. More importantly, the test can discriminate between human angiostrongyliasis, gnathostomiasis and cysticercosis, three diseases that produce eosinophilic meningitis.

Fasciola gigantica-specific antigens: purification by a continuous-elution method and its evaluation for the diagnosis of human fascioliasis

Immunodominant antigens of an approximate molecular mass of 27 kD were obtained from an excretory-secretory product of adult Fasciola gigantica by a continuous-elution method. An indirect ELISA using the antigens obtained by this relatively simple procedure was developed for detecting specific antibodies from patients infected with F. gigantica. Sera from patients with other parasitic infections, healthy volunteers, and cholangiocarcinoma were also analyzed. The sensitivity, specificity, and positive and negative predictive values for this ELISA using the fractionated antigens were 100%. The data indicated a possible correlation of antibodies to F. gigantica with cholangiocarcinoma.

Immunoblot diagnostic test for neurognathostomiasis

Neurognathostomiasis is a rare but severe form of human gnathostomiasis. Diagnosis of neurognathostomiasis is made presumably by using clinical manifestations. Serologic tests for neurognathostomiasis are not widely available and limited. We studied 12 patients with diagnoses of neurognathostomiasis at Srinagarind Hospital, Khon Kaen University, Thailand. There were three types of neurognathostomiasis (five patients with intracerebral hemorrhage, one patient with subarachnoid hemorrhage, and six patients with myelitis). All patients were tested for antibodies against Gnathostoma spinigerum by an immunoblotting technique. The sensitivity and specificity of the 21-kD and 24-kD diagnostic bands were 83.3% and 100%, and 91.7% and 100%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value for the 21-kD and 24-kD diagnostic bands were all 100%. Both diagnostic bands are a helpful diagnostic tool for neuro gnathostomiasis and show good diagnostic properties.

First molecular identification and report of genetic diversity of Strongyloides stercoralis, a current major soil-transmitted helminth in humans from Lao People's Democratic Republic

Strongyloidiasis is a major soil-transmitted helminth (STH) disease that affects people worldwide. We present updated data on prevalence in the Lao People's Democratic Republic (Lao PDR) in 2015, arising from a community cross-sectional helminthiasis survey. Fecal samples were collected from 327 individuals across three provinces in Lao PDR (Luang Prabang in the north, Khammouane in the center, and Champasack in the south). Agar plate culture and Kato-Katz methods were used to examine duplicate stool samples from each participant to detect Strongyloides stercoralis and co-infecting helminths. Overall prevalences of S. strercoralis human hookworm, Taenia spp., Trichuris trichiura, Ascaris lumbricoides, and Enterobius vermicularis were 41.0, 28.1, 4.9, 4.0, 1.5, and 0.9 %, respectively. The prevalence of miscellaneous trematodiases (including opisthorchiasis) was 37.9 % and of Schistosoma mekongi infection was 0.3 %. Strongyloidiasis is a current major STH disease in Lao PDR. We also report the molecular-phylogenetic identification of S. stercoralis adult males collected from 40 representative human strongyliodiasis fecal samples. DNA was extracted, amplified, and sequenced from a portion of the mitochondrial cox1 gene and the nuclear 18S ribosomal DNA. Phylogenetic analyses indicated that all specimens sequenced belonged to S. stercoralis (Bavay, 1876) Stiles and Hassall, 1902. The cox1 sequences exhibited great diversity (24 haplotypes) in Lao PDR. This is the first molecular identification and report of genetic diversity of S. stercoralis in humans from Lao PDR. An effective parasite control program is needed to reduce the serious health impacts.

A comparative study of neuroimaging features between human neuro-gnathostomiasis and angiostrongyliasis

Gnathostoma spinigerum and Angiostrongylus cantonensis are human parasites that can cause neurological symptoms. The human diseases produced by these parasites can usually be differentiated by clinical symptoms. The aim of this study was to report neuroimaging abnormalities detected with computed tomography (CT) and MR in patients with gnathostomiasis and angiostrongyliasis. We enrolled 15 and 12 patients with serologically proven gnathostomiasis and angiostrongyliasis, respectively, who had brain or spinal imaging done. The neuro-gnathostomiasis group had significantly more patients with intracerebral hemorrhage and myelitis patterns. The angiostrongyliasis group had no specific findings and most patients had normal CT brain images. The variety of neuroimaging findings is shown here. This study emphasizes that neuroimaging studies may be useful to differentiate gnathostomiasis and angiostrongyliasis particularly in patients with indistinct clinical presentations.

Cerebrospinal fluid cytokine responses in human eosinophilic meningitis associated with angiostrongyliasis

The levels of interleukin 5 (IL5), IL10, and IL13 in the cerebrospinal fluid (CSF) were markedly higher in 30 patients with eosinophilic meningitis associated with angiostrongyliasis (EOMA) than in the controls (P<0.001). IL2, IL4, interferon gamma (IFNgamma), and tumor necrosis factor alpha (TNFalpha) levels were not significantly different (P>0.05). IL5, IL10, and TNFalpha levels correlated with eosinophil levels (P=0.023, P=0.018, and P=0.005, respectively) while IL2, IL4, IL13, and IFNgamma did not (P>0.05). Our data suggest that local T-helper-2 (TH2) cytokine responses are predominant in the CSF of patients with EOMA. Data on T lymphocyte-parasite interactions are important for the design of effective vaccines and immunotherapies. The measurement of T-helper-1 (TH1)/TH2 cytokines in the CSF may also have some potential for the diagnosis of parasite associated meningitis.

Potential use of Trichinella spiralis antigen for serodiagnosis of human capillariasis philippinensis by immunoblot analysis

Intestinal capillariasis is an emerging helminthic zoonosis caused by Capillaria philippinensis and is frequently fatal if not diagnosed correctly. The present study demonstrates cross-reactivity between Trichinella spiralis larval antigens and C. philippinensis-infected human sera by immunoblotting. Sera from 16 proven intestinal capillariasis patients and 16 proven trichinosis patients were tested. The antigenic patterns recognized by intestinal capillariasis sera varied with the molecular masses, ranging from less than 20.1 to more than 94 kDa. The immunoblotting profiles of the trichinosis sera were similar to those of the intestinal capillariasis sera. The antigenic bands with 100% reactivity were located at 36.5, 40.5, and 54 kDa, respectively. Sera from patients with trichuriasis, strongyloidiasis, opisthorchiasis, and healthy controls differed clearly from the previous two and produced very faint patterns of reactivity and attenuated bands. This assay is potentially useful for large-scale screenings of persons at risk for C. philippinensis infection. Parasitological stool examinations of the positive cases are necessary as second-tier laboratory tests for confirming the diagnosis.

Clinical manifestations of Eosinophilic meningitis due to infection with Angiostrongylus cantonensis in children

Eosinophilic meningitis, caused by the nematode Angiostrongylus cantonensis, is prevalent in northeastern Thailand, most commonly in adults. Data regarding clinical manifestations of this condition in children is limited and may be different those in adults. A chart review was done on 19 eosinophilic meningitis patients aged less than 15 years in Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Thailand. Clinical manifestations and outcomes were reported using descriptive statistics. All patients had presented with severe headache. Most patients were males, had fever, nausea or vomiting, stiffness of the neck, and a history of snail ingestion. Six patients had papilledema or cranial nerve palsies. It was shown that the clinical manifestations of eosinophilic meningitis due to A. cantonensis in children are different from those in adult patients. Fever, nausea, vomiting, hepatomegaly, neck stiffness, and cranial nerve palsies were all more common in children than in adults.

Evaluation of immunoglobulin G subclass antibodies against recombinant Fasciola gigantica cathepsin L1 in an enzyme-linked immunosorbent assay for serodiagnosis of human fasciolosis

A cystatin capture enzyme-linked immunosorbent assay (ELISA) using recombinant Fasciola gigantica cathepsin L1 antigen was developed to detect specific immunoglobulin G (IgG) subclass antibodies (IgG1, IgG2, IgG3, and IgG4) and was evaluated for its diagnostic potential for human fasciolosis. In an analysis of the sera of 13 patients infected with F. gigantica, 209 patients with other parasitic infections, 32 cholangiocarcinoma patients, and 42 healthy controls, the IgG4-ELISA gave the highest diagnostic values. The sensitivity, specificity, accuracy, and positive and negative predictive values of this method based on the detection of IgG4 antibody were 100%, 99.3%, 99.3%, 86.7%, and 100%, respectively. The results revealed that restricting the ELISA to the detection of specific IgG4 antibody enhanced the specificity and accuracy for the serodiagnosis of human fasciolosis.