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COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can stimulate a systemic inflammatory response with severe lung involvement, multisystem dysfunction, and death in some cases. Immunosuppressive treatments have been proposed for management of COVID-19 patients, but these bring the risk of flare-up of pre-existing infections. Strongyloidiasis can become severe or fatal in immunocompromised individuals. This cross-sectional study determined the prevalence of anti-Strongyloides IgG antibody in sera collected from SARS-CoV-2 infected persons in a tertiary-care Thai hospital from January 2021 to January 2022. The survey was conducted using a rapid immunochromatographic test (ICT) kit based on a recombinant antigen of Strongyloides stercoralis known to be IgG-immunoreactive. High prevalence of anti-Strongyloides IgG antibody was found. Out of 297 SARS-CoV-2-infected patients 117 (39.4 %, 95 % CI 33.8–45.2 %) were positive for S. stercoralis according to the ICT kit. In areas where strongyloidiasis is endemic, we suggest using this point-of-care ICT kit for routine rapid screening in seriously ill COVID-19 patients who will be subjected to immunosuppressive treatment. Prompt anthelminthic treatment should be administered to prevent serious systemic strongyloidiasis in at-risk patients.

Human cysticercosis is a life-threatening zoonotic disease caused by infection with larvae (cysticerci) of the pork tapeworm, Taenia solium. This can affect the nervous system causing chronic headache and intracranial hypertension, potentially leading to epileptic seizures and paralysis. The disease is found in developing countries, especially in Southeast and South Asia, Sub-Saharan Africa, and Central and South America where porcine cysticercosis is endemic and people have a habit of eating undercooked pork. An immunochromatography-based test (ICT) kit, using T. solium cyst fluid as antigen, was manufactured to detect anti-T. solium IgG antibodies in human serum. To evaluate the kit, we used 187 serum samples including 24 from proven/confirmed cysticercosis cases, 133 from cases with other parasitosis and 30 healthy controls. Diagnostic efficiencies were calculated. The sensitivity, specificity, and accuracy were 83.3%, 92.0%, and 90.9%, respectively. Moreover, the ICT was positive before treatment but became negative after treatment, implying that this kit is also useful for follow-up monitoring post-treatment. In conclusion, we have successfully developed and present preliminary evaluation of an easy-to-handle rapid diagnostic tool for human cysticercosis in the form of an ICT platform using as antigen fluid from T. solium cysticerci.

Objective: Trichinellosis is a globally distributed food-borne parasitic disease. Initially, diagnosis is usually made based on clinical signs, symptoms, and history of eating raw or undercooked meat. In the present study, an immunochromatographic test (ICT) kit was developed to diagnose trichinellosis by detecting IgG antibodies in sera of infected humans.Methods: Somatic extract from Trichinella spiralis larvae was used as the antigen for the ICT kit development. Diagnostic efficacy was evaluated using human serum samples from proven trichinellosis patients, healthy persons, and those with other parasitic infections.Results: The diagnostic sensitivity, specificity, positive and negative predictive values and accuracy of the ICT kit were 100.0% (95%; CI 88.8 to 100.0%), 92.5% (95% CI; 86.9 to 96.2%), 73.8% (95% CI; 58.0 to 86.1%), 100.0% (95% CI; 97.3 to 100.0%) and 93.8% (95% CI; 89.2 to 96.9%), respectively.Conclusions: This ICT diagnostic kit can be used as a testing tool for human trichinellosis. This test should permit rapid detection of infection to enable prompt anthelminthic treatment. It can also be used for retrospective diagnoses and field surveys based at laboratories where sophisticated equipment is lacking.

Background Amebic liver abscess (ALA) caused by Entamoeba histolytica is usually diagnosed based on its clinical symptoms, medical imaging abnormalities of the liver, and serological tests, the most common being the enzyme-linked immunosorbent assay (ELISA). For more than three decades, no investigation has evaluated the diagnostic performance of immunoglobulin G (IgG) subclasses in the serodiagnosis of ALA. Herein, we assessed the efficiencies of anti-amebic IgG and IgG subclasses for diagnosing ALA. Methods A serological ELISA-based test was performed to assess its diagnostic performance using a total of 330 serum samples from ALA patients (n = 14), healthy individuals (n = 40), and patients with other diseases (n = 276). Results ELISA targeting the total IgG antibody to E. histolytica antigen exhibited 100% sensitivity 95% CI [76.8–100.0] and 97.8% specificity 95% CI [95.5–99.1], whereas the assay targeting IgG1 showed the same sensitivity (100% 95% CI [76.8–100.0]) and a slightly higher specificity (99.1% 95% CI [97.3–99.8]). The other IgG subclasses (IgG2, IgG3, and IgG4) displayed a lower sensitivity and specificity. The sensitivity and specificity did not significantly differ between tests measuring total IgG and IgG1 (Exact McNemar’s test; p > 0.05), with a concordance of 98.2%, represented by a Cohen’s kappa of 0.83 (p < 0.001), indicating almost perfect agreement. Conclusion ELISA targeting IgG1 can provide valuable information to clinicians in differentiating ALA from other parasitic diseases, cancers, cirrhosis, and viral hepatitis. However, enzyme-conjugated anti-human total IgG is cheaper than anti-human IgG subclasses. Therefore, we suggest that total IgG-based ELISA is sufficient for the routine serodiagnosis of human ALA and possibly other clinical manifestations of invasive amebiasis.

Objective: Schistosomiasis japonica is an important helminthic disease in Asia. Sensitive and accurate diagnostic tools are indispensable for clinical diagnosis, screening infection and monitoring its control. In this study, we developed an immunochromatographic test (Sj-ICT) to detect anti-Schistosoma japonicum immunoglobulin G antibodies in human sera. Methods: Somatic extract from adult S. japonicum was used as an antigen. The Sj-ICT was developed and optimized as a point-of-care test. All 214 human serum samples were evaluated for diagnostic usefulness and comparison with an enzyme-linked immunosorbent assay (ELISA). Results: The diagnostic sensitivity, specificity, positive and negative predictive values, and accuracy of the Sj-ICT were 90.8%, 87.9%, 86.4%, 91.9% and 89.3%, respectively. For ELISA the values were respectively 91.8%, 87.9%, 86.5%, 92.7% and 89.7%. The concordance between both methods was 86.4 % (Cohen’s kappa value = 0.729). Conclusions: The immunochromatographic test kit developed can support clinical diagnosis and large-scale surveys in endemic areas without requiring additional facilities or ancillary supplies.

Bacterial content in mosquito larvae and adults is altered by dynamic interactions during life and varies substantially in variety and composition depending on mosquito biology and ecology. This study aimed to identify the microbiota in Aedes aegypti and Aedes albopictus and in water from their breeding sites in northeastern Thailand, a dengue-endemic area. Bacterial diversity in field-collected aquatic larvae and subsequently emerged adults of both species from several locations were examined. The microbiota was characterized based on analysis of DNA sequences from the V3-V4 region of the 16S rRNA gene and exhibited changes during development, from the mosquito larval stage to the adult stage. Aedes aegypti contained a significantly higher number of bacterial genera than did Ae. albopictus, except for the genus Wolbachia, which was present at significantly higher frequencies in male Ae. albopictus (p < 0.05). Our findings also indicate likely transstadial transmission from larva to adult and give better understanding of the microbial diversity in these mosquitoes, informing future control programs against mosquito-borne diseases.

Intestinal parasitic infections (IPIs) remain a public-health problem worldwide, including in countries of the Lower Mekong subregion. Increases in human migration from neighboring countries might cause reemerging parasitic infections, leading to spread of parasites in the landscape. Here, we conducted a cross-sectional study to identify the prevalence of IPIs in migrant workers from Myanmar, Lao PDR, and Cambodia who were dwelling in Nakhon Ratchasima Province, northeastern Thailand. The identification of Strongyloides species and genetic differentiation of worms from migrant workers with different countries of origin was also assessed. Fresh stool samples were collected from 338 migrant workers and examined for evidence of IPIs using agar plate culture (APC) and the formalin-ethyl acetate concentration technique (FECT). Among those nine samples positive for nematodes by APC, the Strongyloides or hookworm species present was confirmed using the polymerase chain reaction (PCR) followed by DNA sequencing. This revealed eight cases of Strongyloides stercoralis infection and one of Necator americanus. Fifty-one out of 338 individuals (15.09%) were positive for IPIs using FECT and APC. Eggs of Opisthorchis-like flukes were the most common parasite (11.83% of samples), followed by S. stercoralis (2.37%), Entamoeba coli (1.50%), hookworm (0.89%), Taenia sp. (0.60%) and Hymenolepis nana (0.30%). The genetic differentiation of S. stercoralis recovered from migrant workers with different countries of origin was analyzed. Specimens of S. stercoralis isolated from workers from Lao PDR, Cambodia and Myanmar were genetically similar to those sequenced from Thailand. However, there were population-genetic differences between S. stercoralis from these Southeast Asian countries and other regions of the world. This study demonstrated that IPIs were prevalent in migrant workers in the northeastern region of Thailand. Our findings provided molecular confirmation of the presence of S. stercoralis and explored the genetic differentiation of S. stercoralis from those infected migrant workers. An effective anti-parasitic drug should be provided for migrant workers and its administration enforced.

Human gastrointestinal helminthic infections have a direct and/or indirect effect on the composition of the host gut microbial flora. Here, we investigated the effect of infection with a soil-transmitted intestinal nematode, Strongyloides stercoralis, on the gut microbiota of the human host. We also investigated whether composition of the microbiota in infected persons might vary across endemic regions. Fecal samples were obtained from volunteers from two areas endemic for strongyloidiasis, Khon Kaen Province in northeastern Thailand and Nakhon Si Thammarat Province in southern Thailand. Samples from Khon Kaen were from infected (SsNE) and uninfected (NegNE) individuals. Similarly, samples from the latter province were from infected (SsST) and uninfected (NegST) individuals. DNA sequences of the V3-V4 regions of the bacterial 16S rRNA gene were obtained from the fecal samples. No statistical difference in alpha diversity between groups in terms of richness or diversity were found. Statistical difference in beta diversity was observed only between NegNE and NegST. Some significant differences in species abundance were noted between geographical isolates. The SsNE group had a higher abundance of Tetragenococcus holophilus than did the SsST group, whereas Bradyrhizobium sp. was less abundant in the SsNE than the SsST group. For the uninfected groups, the NegNE had a higher abundance of T. holophilus than the NegST group. Our data showed that S. stercoralis infection leads to only minor alterations in the relative abundance of individual bacterial species in the human gut: no detectable effect was observed on community structure and diversity.

Chronic human liver fluke infections caused by Opisthorchis viverrini and Clonorchis sinensis can last for decades and cause liver and biliary diseases, including life-threatening pathology prior to cholangiocarcinoma (CCA). CCA generally has a poor prognosis. Serological diagnosis can support parasitological examination in diagnosing disease and screening for the risk of CCA. Here, we present an improved and innovative lateral flow immunochromatographic test (ICT) kit that uses whole-blood samples (WBS) rather than serum to diagnose human opisthorchiasis, which also successfully diagnosed human clonorchiasis. This ICT includes a soluble worm extract of O. viverrini adults and colloidal-gold-labeled conjugates of the IgG antibody to evaluate the diagnostic values with simulated WBS (n = 347). Simulated WBS were obtained by the spiking infection sera with red blood cells. The diagnostic sensitivity, specificity, positive and negative predictive values, and accuracy for detecting opisthorchiasis were 95.5%, 87.0%, 80.5%, 97.2%, and 90.1%, respectively. For clonorchiasis, these findings were 85.7%, 87.0%, 53.6%, 97.2%, and 86.8%, respectively. Combined for both diseases, they were 93.2%, 87.0%, 84.0%, 94.6%, and 89.6%, respectively. The ICT kit can possibly replace the ICT platforms for antibody detection in serum samples in field surveys in remote areas where sophisticated equipment is not available.

DNA-sequencing was performed on the V3-V4 regions of 16S rRNA genes to investigate the microbial diversity of five samples of fermented freshwater fish (pla-ra) from three provinces in northeastern Thailand. The samples had salt concentrations ranging from 7 to 10%, pH values from 4.83 to 7.15, and D-/L-lactic acid concentrations of 90 to 450 mg/l. A total of 598 operational taxonomic units were annotated at various taxonomic ranks based on the SILVA Database. The lactic-acid and halophilic genera Tetragenococcus, Halanaerobium and Lactobacillus were among the dominant taxa of bacteria. The top 20 non-redundant taxa were considered in more detail. In two pla-ra samples, Tetragenococcus muriaticus was commonly identified. Halanaerobium fermentans was the most abundant species in a third sample and co-dominant in another sample. Lactobacillus rennini was dominant in the pla-ra sample from Roi Et Province. Additionally, other beneficial bacteria were detected including Staphylococcus nepalensis, Lactobacillus sakei, Lactobacillus pentosus, Weissella confusa, and Bifidobacterium bifidum. Differences between samples may be due to use of different raw materials, salt concentrations, recipes, processes and fermentation periods. The microbial communities in pla-ra provide a better understanding of the production outcomes of traditional products. Further optimization of the fermentation process, for example by using dominant bacterial taxa in starter cultures, may improve processes of food fermentation, food quality and flavor control, providing useful guidelines for industrial applications.

Hyperinfection and disseminated infection by the parasitic nematode Strongyloides stercoralis can be induced by iatrogenic administration of steroids and immunosuppression and lead to an elevated risk of mortality. Responses of free-living stages of S. stercoralis to the therapeutic corticosteroid dexamethasone (DXM) were investigated using RNA-seq transcriptomes of DXM-treated female and male worms. A total of 17,950 genes representing the transcriptome of these free-living adult stages were obtained, among which 199 and 263 were differentially expressed between DXM-treated females and DXM-treated males, respectively, compared with controls. According to Gene Ontology analysis, differentially expressed genes from DXM-treated females participate in developmental process, multicellular organismal process, cell differentiation, carbohydrate metabolic process and embryonic morphogenesis. Others are involved in signaling and signal transduction, including cAMP, cGMP-dependent protein kinase pathway, endocrine system, and thyroid hormone pathway, as based on Kyoto Encyclopedia of Genes and Genomes analysis. The novel findings warrant deeper investigation of the influence of DXM on growth and other pathways in this neglected tropical disease pathogen, particularly in a setting of autoimmune and/or allergic disease, which may require the clinical use of steroid-like hormones during latent or covert strongyloidiasis.

Human gnathostomiasis is a harmful food-borne zoonosis caused by roundworms of the genus Gnathostoma. The parasite can occasionally migrate to the central nervous system, causing life-threatening disease and death. Here, we report a new point-of-care (POC) test kit, the gnathostomiasis blood immunochromatographic test (GB-ICT) kit. The kit is based on recombinant Gnathostoma spinigerum antigen and detects specific IgG4 antibody in whole-blood samples (WBSs). The GB-ICT kit showed potentially high diagnostic values with simulated WBSs (n = 248), which were obtained by spiking patients’ sera with red blood cells. The accuracy, sensitivity, specificity, and positive and negative predictive values were 95.2%, 100%, 93.8%, 81.5%, and 100%, respectively. Ten WBSs from clinically suspected gnathostomiasis patients were all positive according to the GB-ICT kit, while 10 WBSs from healthy volunteers were negative. The GB-ICT kit is a simple and convenient POC testing tool using finger-prick blood samples: venous blood sampling and serum separation processes are not required. The GB-ICT kit can support clinical diagnosis in remote areas and field settings without sophisticated equipment facilities.

Human strongyloidiasis is an important soil-transmitted helminthiasis that affects millions worldwide and can develop into fatal systemic strongyloidiasis in immunosuppressed patients. We have developed two new rapid and simple-to-use immunochromatographic test (ICT) kits for rapid serodiagnosis that support stool examination for clinical diagnosis. Strongyloides stercoralis recombinant IgG immunoreactive antigen (GenBank: AAB97359.1; rSsIR-based ICT kit) was used for detection of IgG and IgG4 antibodies. The diagnostic efficacy of both kits was evaluated using human serum samples from strongyloidiasis patients, healthy individuals, and those with other parasitosis. At a prevalence of infection of 36.4%, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the rSsIR-based IgG ICT kit were 91.7%, 83.8%, 76.4%, 94.6%, and 86.7%, respectively, and those of the rSsIR-based IgG4 ICT kit were 78.3%, 84.8%, 74.6%, 87.3%, and 82.4% respectively. The concordance between the two kits was 89.7%. The recombinant antigen can be produced to an unlimited extent and the kits can be used as point-of-care diagnostic tools and in large-scale surveys in endemic areas throughout tropical regions without necessitating additional facilities or ancillary supplies.