Exposure to dexamethasone modifies transcriptomic responses of free-living stages of Strongyloides stercoralis.

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.

Prevalence of Enterobius vermicularis infections and associated risk factors among schoolchildren in Nakhon Si Thammarat, Thailand.

BACKGROUND: Enterobius vermicularis infection is an important public health problem worldwide, especially among schoolchildren in tropical and subtropical countries. The prevalence of E. vermicularis infections varies in each region of Thailand; however, its status remains unknown among children who live in rural areas of the southern region. This study aimed to evaluate the current prevalence of E. vermicularis infections and to identify the risk factors for infection among schoolchildren who live in rural communities in Nakhon Si Thammarat, Southern Thailand. RESULTS: The overall prevalence of E. vermicularis infections was 5.79% (23 of 397). According to a multivariate analysis, the following were found to be risk factors associated with E. vermicularis infections (P < 0.05): those of the male sex (AOR = 4.03, 95% CI 1.22-13.29), those in the 3-6 year age group (AOR = 4.85, 95% CI 1.51-15.59), those who have a mother with a primary school education level (AOR = 11.22, 95% CI 1.75-71.77), those who have older sibling(s) (AOR = 6.25, 95% CI 1.83-21.26), those who have younger sibling(s) (AOR = 6.24, 95% CI 2.00-19.44), those who sometimes wash their hands after using the toilet (AOR = 5.25, 95% CI 1.24-22.21), those who keep their fingernails long (AOR = 29.97, 95% CI 6.16-145.85), and those who suck their fingers (AOR = 3.59, 95% CI 1.21-10.66). CONCLUSIONS: This was the first report that revealed the prevalence of E. vermicularis infections among children who live in rural areas of Southern Thailand through detection using the Scotch tape technique. This study demonstrated that the high prevalence of E. vermicularis infections in schoolchildren with siblings was a significant independent predictor and that the transmission of this infection may occur in the family through their school-age siblings. In addition, children who have poor personal hygiene have a high prevalence of E. vermicularis infections. Therefore, maintaining good handwashing habits, keeping one's fingernails short, and avoiding sucking one's fingers should be important preventive measures against infection. Moreover, health literacy or health education, especially for parents or the principal caretakers of children, should be implemented to reduce E. vermicularis infections.

Prevalence of Soil-Transmitted Helminth Infections and Associated Risk Factors among Schoolchildren in Nakhon Si Thammarat, Thailand.

BACKGROUND: Soil-transmitted helminth infections constitute a public health problem in the rural areas of tropical and subtropical regions, including Thailand. We aimed to determine the prevalence of soil-transmitted helminth infections and underlying risk factors among the schoolchildren living in the rural areas of southern Thailand. METHODS: A cross-sectional survey was conducted between Sep and Nov 2018 in the district of Thasala, Nakhon Si Thammarat, Thailand. A total of 192 children, aged 6-12 yr were enrolled. Each child provided a single stool sample that was subjected to a suite of microscopic diagnoses for soil-transmitted helminth. A questionnaire was administered to determine risk factors of the infections. Logistic regression models were applied to investigate associations. RESULTS: The overall prevalence of soil-transmitted helminth infections was 3.13%; Strongyloides stercoralis 2.08%; hookworm 1.04% and Trichuris trichiura 0.52%. Children who cutting fingernails short can prevent soil-transmitted helminth infections highly up to 90% (crude OR = 0.1; 95% confidence interval = 0 - 0.8; P = 0.020). CONCLUSION: The finding of the study shows a sharp decrease in the prevalence of soil-transmitted helminth among schoolchildren in the southern Thailand in the past two decades with prevalence dropping below 5% for soil-transmitted helminth. However, the prevalence of S. stercoralis remained stable over time. These results suggest that the culture method should be used to access strongyloidiasis situation in the older age group who greater contact with soil for agriculturists.

Impact of the health education and preventive equipment package (HEPEP) on prevention of Strongyloides stercoralis infection among rural communities in Northeast Thailand: a cluster randomized controlled trial.

BACKGROUND: Strongyloidiasis is prevalent in northeast Thailand. This study aimed to evaluate the impact of the Health Education and Preventive Equipment Package (HEPEP), a package we developed to improve awareness and aid in the prevention of Strongyloides stercoralis infection among rural communities in northeast Thailand. METHODS: This was an intervention trial conducted in 12 villages (six interventions and six controls) in rural areas of northeast Thailand from March 2016 to September 2017. Single stool sample was collected from each participant and examined using agar plate culture (APC) technique. Each participant was interviewed using a pre-tested questionnaire, treated with single dose of ivermectin (200 µg/Kg), and allocated to either the intervention or control group. Members of the intervention group were given "Practices to Prevent Strongyloidiasis" poster and vinyl boards containing information aimed at raising awareness of S. stercoralis and strongyloidiasis. In addition, they were given a poster lecture regarding the lifecycle of S. stercoralis before being treated with ivermectin. Aside from that, they were also given a protective equipment package. Monthly refresher courses were provided by village health volunteers (VHVs) regarding the health information they had received and proper equipment usage. The control group, on the other hand, was only provided with a five-minute lecture regarding strongyloidiasis. Assessment of new infection was conducted 3 months later in 327 and 318 participants in the intervention group and control group, respectively. RESULTS: The HEPEP had 41% greater efficacy in preventing S. stercoralis infection in the intervention group than the measures taken in the control group (adjusted Odds Ratio (aOR) = 0.59; 95%CI: 0.41 to 0.85, P-value = 0.005). The intervention group also scored significantly higher on all aspects of a test of S. stercoralis knowledge compared with the control group (mean difference (mean dif.) = 2.89, P-value = < 0.05). CONCLUSIONS: The HEPEP was the first model that has been found to be effective in controlling of S. stercoralis in rural communities in the northeast Thailand. The results should encourage policy makers and public health personnel to improve control programs, as well as health promotion, with regard to parasites. TRIAL REGISTRATION: Thai Clinical Trials Registry (TCTR), Medical Research Foundation of Thailand, Medical Research Network of the Consortium of Thai Medical Schools: MedResNet (Thailand) (identification number: TCTR20180404002 ) Registered 4 April 2018 (retrospectively registered).

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.

An eleven-year retrospective hospital-based study of epidemiological data regarding human strongyloidiasis in northeast Thailand.

BACKGROUND: Human strongyloidiasis is a chronic and persistent gastrointestinal disease caused by infection with soil-transmitted helminths of the genus Strongyloides. The aim of this research was to obtain diagnostic prevalence regarding strongyloidiasis in northeast Thailand through a hospital-based study. METHODS: Patients' demographic data and the results of stool examinations conducted using the formalin ethyl acetate concentration technique were collected from the parasitology laboratory records at Srinagarind Hospital in Khon Kaen, Thailand. The relevant information from years 2004 to 2014 was collected and descriptively analyzed. RESULTS: Of a total of 22,338 patients, 3889 (17.4%) had stool samples that tested positive for Strongyloides larvae. The highest prevalence was 22.8% (95% CI = 19.6-26.2%) in the year 2004. This percentage progressively decreased, reaching 11.2% (95% CI = 10.2-12.4%) in 2013 and remaining stable at 12.9% (95% CI = 11.8-14.1%) in 2014. Males (2741 cases) had double the positivity rate of females (1148 cases). The prevalence of infection was highest (25.9%; 95% CI = 24.5-27.3%) among patients that were 51-60 years of age. CONCLUSIONS: Areas endemic for strongyloidiasis should be emphasized under the national helminth control program and health education campaigns. Nationwide assessments should also be performed regarding Strongyloides infection, including risk factors, treatment, and prevention. The diagnostic laboratory data presented here identify the geographical focus of disease to be the northeastern region of the country. Further targeted surveillance using more sensitive methods will almost certainly reveal a higher individual disease burden than found in this report.

GENETIC SUBTYPES OF BLASTOCYSTIS ISOLATED FROM THAI HOSPITALIZED PATIENTS IN NORTHEASTERN THAILAND.

Blastocystis sp is probably the most common intestinal protozoan of humans. This taxon is known to include more than 17 subtypes, some of which likely cause human disease. We investigated the distribution of Blastocystis subtypes in Thai patients admitted for a variety of conditions at a hospital in northeastern Thailand. Fresh fecal samples, positive for Blastocystis by microscopy, were individually cultured in Jones' medium (n = 20) and each sample was used for amplification and sequencing a fragment of 18S rDNA. BLAST search and phylogenetic analysis demonstrated that Blastocystis subtypes ST1 (20%), ST3 (60%), ST6 (10%) and ST7 (10%) were present. No clear link between gastro-intestinal symptoms and any particular subtype of Blastocystis was apparent. Thus, there is a need to extend the work to evaluate clinical signs and subtypes in a larger cohort of patients.