A possible origin population of pathogenic intestinal nematodes, Strongyloides stercoralis, unveiled by molecular phylogeny.

Humans and dogs are the two major hosts of Strongyloides stercoralis, an intestinal parasitic nematode. To better understand the phylogenetic relationships among S. stercoralis isolates infecting humans and dogs and to assess the zoonotic potential of this parasite, we analyzed mitochondrial Cox1, nuclear 18S rDNA, 28S rDNA, and a major sperm protein domain-containing protein genes. Overall, our analyses indicated the presence of two distinct lineages of S. stercoralis (referred to as type A and type B). While type A parasites were isolated both from humans and dogs in different countries, type B parasites were found exclusively in dogs, indicating that the type B has not adapted to infect humans. These epidemiological data, together with the close phylogenetic relationship of S. stercoralis with S. procyonis, a Strongyloides parasite of raccoons, possibly indicates that S. stercoralis originally evolved as a canid parasite, and later spread into humans. The inability to infect humans might be an ancestral character of this species and the type B might be surmised to be an origin population from which human-infecting strains are derived.

Normal serum IgE levels and eosinophil counts exhibited during Strongyloides stercoralis infection.

Infections with parasites, such as Strongyloides stercoralis, typically cause elevated levels of serum immunoglobulin E (IgE) and eosinophils; however, co-infection with human T cell lymphotropic virus type 1 (HTLV-1) can cause lower levels of serum IgE during S. stercoralis infection. We conducted this study to determine whether serum IgE levels and eosinophil counts could also be related to other patient characteristics or symptoms. Between 1991 and 2014, we measured and compared the symptoms of 237 patients and evaluated serum IgE levels and eosinophil counts of 199 patients who were infected with S. stercoralis at the Ryukyu University Hospital and the Nishizaki Hospital. Medical records were reviewed and blood samples were taken before treatment with the anthelminthic, ivermectin, 2weeks following the first dosage, and 2weeks following the second dosage. Commonly reported symptoms included abdominal pain, diarrhea, and general fatigue. Serum IgE levels were found to be normal in patients co-infected with HTLV-1. Additionally, females and patients younger than 70years old exhibited normal serum IgE levels when infected with S. stercoralis. No factor included in our analysis was found to affect eosinophil counts. Serum IgE levels can remain within the normal range for some patients infected with S. stercoralis. Therefore, physicians should not eliminate S. stercoralis infection from the differential diagnosis solely according to findings of normal or low IgE levels.

Genome-Wide Analyses of Individual Strongyloides stercoralis (Nematoda: Rhabditoidea) Provide Insights into Population Structure and Reproductive Life Cycles.

The helminth Strongyloides stercoralis, which is transmitted through soil, infects 30-100 million people worldwide. S. stercoralis reproduces sexually outside the host as well as asexually within the host, which causes a life-long infection. To understand the population structure and transmission patterns of this parasite, we re-sequenced the genomes of 33 individual S. stercoralis nematodes collected in Myanmar (prevalent region) and Japan (non-prevalent region). We utilised a method combining whole genome amplification and next-generation sequencing techniques to detect 298,202 variant positions (0.6% of the genome) compared with the reference genome. Phylogenetic analyses of SNP data revealed an unambiguous geographical separation and sub-populations that correlated with the host geographical origin, particularly for the Myanmar samples. The relatively higher heterozygosity in the genomes of the Japanese samples can possibly be explained by the independent evolution of two haplotypes of diploid genomes through asexual reproduction during the auto-infection cycle, suggesting that analysing heterozygosity is useful and necessary to infer infection history and geographical prevalence.

Factors associated with visceral fat accumulation in the general population in Okinawa, Japan.

AIM: To investigate the clinical and biochemical factors associated with visceral fat accumulation in the general population. METHODS: We enrolled 1004 subjects who underwent a medical health checkup between April 2008 and March 2009. The medical health checkup included the following tests: Height, body weight, waist circumference (WC), systolic blood pressure, diastolic blood pressure, urinalysis, blood-cell counts, blood chemistry, electrocardiography, chest radiography, and abdominal computed tomography (CT) for visceral fat accumulation. The patients' medical history and lifestyle factors were collected privately by nurses using a self-administered questionnaire, and they included questions regarding physical activity, sleep duration, dietary habits, smoking, and alcohol consumption. Visceral fat area (VFA) was defined as the sum of the intraperitoneal fat area at the level of the umbilicus with CT density in the range of -150 to -50 Hounsfield units. RESULTS: The mean age and body mass index (BMI) of the study subjects were 57.0 years and 24.4 kg/m(2). In both male and females, VFA was significantly and positively correlated with WC (r = 0.532, P < 0.01; r = 0.612, P < 0.01). Subjects with high levels of VFA were primarily male with significantly higher age, height, body weight, BMI, systolic blood pressure (BP), diastolic BP, and hemoglobin in all subjects (P < 0.05). A multivariate logistic regression analysis revealed that VFA had a positive relationship with age ≥ 56, BMI ≥ 25 kg/m(2), and triglyceride level ≥ 149 in males (P < 0.05), whereas it had a positive relationship with age ≥ 58, BMI ≥ 24.4 kg/m(2), high-density lipoprotein cholesterol level < 40 mg/dL, and current drinking in females (P < 0.05). CONCLUSION: These results suggest that gender differences exist in the clinical and biochemical parameters associated with visceral fat accumulation.

Relationship Among Strongyloides stercoralis Infection, Human T-Cell Lymphotropic Virus Type 1 Infection, and Cancer: A 24-Year Cohort Inpatient Study in Okinawa, Japan.

This study evaluated the prevalence of Strongyloides stercoralis infection and human T-cell lymphotropic virus type 1 (HTLV-1) infection in the population. In addition, this study investigated the relationship between S. stercoralis infection or HTLV-1 infection and a patient's risk of developing related cancers. This is a retrospective cohort study of 5,209 patients. The prevalence of S. stercoralis infection was 5.2% among all patients. The prevalence among men (6.3%) was significantly higher than among women (3.6%, P < 0.001). The prevalence of HTLV-1 infection among this population was 13.6% and the prevalence among women (15.5%) was significantly higher than that of men (12.3%, P < 0.001). HTLV-1 seroprevalence was higher in patients with liver cancer (P = 0.003, odds ratio [OR]: 1.91, 95% confidence interval [CI]: 1.24, 2.95) and in those with lymphoma other than adult T-cell leukemia/lymphoma (ATLL) (P = 0.005, adjusted OR: 2.76, 95% CI: 1.36, 5.62) if compared with patients without any neoplasm. The prevalence of both S. stercoralis and HTLV-1 in the Okinawan population has been steadily decreasing over the past 24 years. HTLV-1 infection significantly increases the odds of developing liver cancer and lymphomas other than ATLL.