Enteropathogens and chronic illness in returning travelers

The Discovery of Phages in the Substantia Nigra and Its Implication for Parkinson's Disease

Background: A century ago, a mystery between a virus and Parkinson's disease (PD) was described. Owing to the limitation of human brain biopsy and the challenge of electron microscopy in observing virions in human brain tissue, it has been difficult to study the viral etiology of PD. Recent discovery of virobiota reveals that viruses coexist with humans as symbionts. Newly developed transcriptomic sequencing and novel bioinformatic approaches for mining the encrypted virome in human transcriptome make it possible to study the relationship between symbiotic viruses and PD. Nevertheless, whether viruses exist in the human substantia nigra (SN) and whether symbiotic viruses underlie PD pathogenesis remain unknown. Methods: We collected current worldwide human SN transcriptomic datasets from the United States, the United Kingdom, the Netherlands, and Switzerland. We used bioinformatic approaches including viruSITE and the Viral-Track to identify the existence of viruses in the SN of patients. The comprehensive RNA sequencing-based virome analysis pipeline was used to characterize the virobiota in the SN. The Pearson's correlation analysis was used to examine the association between the viral RNA fragment counts (VRFCs) and PD-related human gene sequencing reads in the SN. The differentially expressed genes (DEGs) in the SN between PD patients and non-PD individuals were used to examine the molecular signatures of PD and also evaluate the impact of symbiotic viruses on the SN. Findings: We observed the existence of viruses in the human SN. A dysbiosis of virobiota was found in the SN of PD patients. A marked correlation between VRFC and PD-related human gene expression was detected in the SN of PD patients. These PD-related human genes correlated to VRFC were named as the virus-correlated PD-related genes (VPGs). We identified 3 bacteriophages (phages), including the Proteus phage VB_PmiS-Isfahan, the Escherichia phage phiX174, and the Lactobacillus phage Sha1, that might impair the gene expression of neural cells in the SN of PD patients. The Proteus phage VB_PmiS-Isfahan was a common virus in the SN of patients from the United Kingdom, the Netherlands, and Switzerland. VPGs and DEGs together highlighted that the phages might dampen dopamine biosynthesis and weaken the cGAS-STING function. Interpretation: This is the first study to discover the involvement of phages in PD pathogenesis. A lifelong low symbiotic viral load in the SN may be a contributor to PD pathogenesis. Our findings unlocked the black box between brain virobiota and PD, providing a novel insight into PD etiology from the perspective of phage-human symbiosis.

Development of a Novel mRNA Vaccine Against Shigella Pathotypes Causing Widespread Shigellosis Endemic: An In-Silico Immunoinformatic Approach

Shigellosis remains a major global health concern, particularly in regions with poor sanitation and limited access to clean water. This study used immunoinformatics and reverse vaccinology to design a potential mRNA vaccine targeting Shigella pathotypes out of 4071 proteins from Shigella sonnei str. Ss046, 4 key antigenic candidates were identified: putative outer membrane protein (Q3YZL0), PapC-like porin protein (Q3YZM5), putative fimbrial-like protein (Q3Z3I2), and lipopolysaccharide (LPS)-assembly protein LptD (Q3Z5V5), ensuring broad pathotype coverage. A multitope vaccine was designed incorporating cytotoxic T lymphocyte, helper T lymphocyte, and B-cell epitopes, linked with suitable linkers and adjuvants to enhance immunogenicity. Computational analyses predicted vaccine's favorable antigenicity, solubility, and stability, while molecular docking and dynamic simulations demonstrated strong binding affinity and stability with Toll-like receptor 4 (TLR-4), indicating potential for robust immune activation. Immune simulations predicted strong humoral and cellular immune responses, characterized by significant cytokine production and long-term immune memory. Structural evaluations of the complex, including radius of gyration, root mean square deviation, root mean square fluctuation, and solvent accessibility, confirmed the vaccine's structural integrity, and stability under physiological conditions. This research contributes to the ongoing effort to alleviate the global burden of Shigella infections, providing a foundation for future wet laboratory investigations aimed at vaccine development.

Impact of the SARS-CoV-2 Pandemic on the Prevalence and Incidence of Enteric Protozoa in a Spanish Tertiary-Care Hospital and a Referral Center for Tropical Diseases, 2019-2023

OBJETIVE

The aim of this study was to describe the impact of non-pharmaceutical interventions (NPIs) against SARS-CoV-2 in patients with symptoms of enteric protozoa (EP), including Blastocystis spp., Dientamoeba fragilis, Giardia lamblia, Cryptosporidium spp., Entamoeba histolytica, and Cyclospora cayetanensis, in the overall population and in patients who were consulted at a National Referral Center for Imported Tropical Diseases (NRCITD patients) from a healthcare area in Madrid (Spain).

METHOD

Data on patients with positive RT-PCR results for EP were collected. The periods analyzed were prepandemic (P0, 1 April 2019-31 March 2020), and the first (P1, 1 April 2020-31 March 2021), second (P2, 1 April 2021-31 March 2022), and third (P3, 1 April 2022-31 March 2023) pandemic years. We compared the prevalence, median age, absolute incidence (EP per 100,000 population of each period), and patient profile (NRCITD vs. non-NRCITD) during the study periods using Fisher's test (p < 0.05) and the T-test (p < 0.001).

RESULTS

During P0, 24.8%, [95% CI: 23.9-25.6] of patients tested for EP RT-PCR were positive, 22.6% [95% CI: 21.5-23.7] were positive in P1, 20.4%, [95% CI: 19.5-21.3] were positive during P2, and 20% [95% CI: 19.2-20.9] of patients tested during P3 were positive. During the study, there was no difference in the median ages. The prevalence and absolute incidence of EP showed a decreasing trend during the pandemic for the NRCITD and non-NRCITD patients (p < 0.05).

CONCLUSION

Blastocystis spp. and D. fragilis showed a lower decrease in prevalence during P1 (p > 0.05) due to the higher detection of colonized patients during the SARS-CoV-2 pandemic. However, G. lamblia and Cryptosporidium spp. showed the highest decrease in prevalence and absolute incidence during P2 (p < 0.05) because of the NPIs implemented during the SARS-CoV-2 pandemic. The NTRCID patients showed a higher prevalence of Blastocystis spp. than the non-NTRCID patients during every period studied (p < 0.001). E. histolytica and C. cayetanensis showed a homogeneous trend.

Giardiasis and diarrhea in dogs: Does the microbiome matter?

BACKGROUND

Giardia duodenalis (Gd) causes intestinal parasitosis. The involvement of the intestinal microbiome in determining the infection's clinical phenotype is unknown.

OBJECTIVE

Investigate the fecal microbiome features in dogs with giardiasis.

ANIMALS AND METHODS

Cross-sectional study, including fecal samples of kenneled dogs with Gd diagnosed by fecal Giardia antigen dot ELISA. The fecal microbial compositional characteristics and dysbiosis index (DI) were compared between diarrheic and nondiarrheic dogs.

RESULTS

Fecal samples of 38 Gd-infected dogs (diarrheic, 21; nondiarrheic, 17) were included. No differences were found in Faith's phylogenic diversity and beta diversity (weighted UniFrac distances) and in specific taxa abundances at the phylum, genus, and species levels, as well as in alpha and beta diversities between diarrheic and nondiarrheic dogs, and also when divided by sex or age. Among diarrheic dogs, alpha diversity was higher in males than in females (pairwise Kruskal-Wallis, q = 0.01). Among males, fecal abundances of the genus Clostridium (W = 19) and Clostridium spiroforme species (W = 33) were higher in diarrheic compared to nondiarrheic dogs. In diarrheic dog fecal samples, Proteobacteria were more prevalent (W = 1), whereas Verrucomicrobia were less prevalent in dogs <1 year of age than in older dogs. The fecal sample DI of 19 diarrheic and 19 nondiarrheic dogs was similar (median, -0.2; range, -4.3 to 4.5 and median, -1.0; range, -4.3 to 5.8, respectively).

CONCLUSIONS

The fecal microbial composition of symptomatic and asymptomatic dogs with giardiasis is similar. Based on fecal DI, giardiasis is not characterized by prominent dysbiosis. Other host and parasite characteristics might determine the severity of giardiasis in dogs.

GMP manufacture of Shigella flexneri 2a Artificial Invaplex (InvaplexAR) and evaluation in a Phase 1 Open-label, dose escalating study administered intranasally to healthy, adult volunteers

Shigella species cause severe disease among travelers to, and children living in, endemic countries. Although significant efforts have been made to improve sanitation, increased antibiotic resistance and other factors suggest an effective vaccine is a critical need. Artificial Invaplex (InvaplexAR) is a subunit vaccine approach complexing Shigella LPS with invasion plasmid antigens. In pre-clinical studies, the InvaplexAR vaccine demonstrated increased immunogenicity as compared to the first generation product and was subsequently manufactured under cGMP for clinical testing in a first-in-human Phase 1 study. The primary objective of this study was the safety of S. flexneri 2a InvaplexAR given by intranasal (IN) immunization (without adjuvant) in a single-center, open-label, dose-escalating Phase 1 trial and secondarily to assess immunogenicity to identify a dose of InvaplexAR for subsequent clinical evaluations. Subjects received three IN immunizations of InvaplexAR, two weeks apart, in increasing dose cohorts (10 µg, 50 µg, 250 µg, and 500 μg). Adverse events were monitored using symptom surveillance, memory aids, and targeted physical exams. Samples were collected throughout the study to investigate vaccine-induced systemic and mucosal immune responses. There were no adverse events that met vaccination-stopping criteria. The majority (96%) of vaccine-related adverse events were mild in severity (most commonly nasal congestion, rhinorrhea, and post-nasal drip). Vaccination with InvaplexAR induced anti-LPS serum IgG responses and anti-Invaplex IgA and IgG antibody secreting cell (ASC) responses at vaccine doses ≥250 µg. Additionally, mucosal immune responses and functional antibody responses were seen from the serum bactericidal assay measurements. Notably, the responder rates and the kinetics of ASCs and antibody lymphocyte secretion (ALS) were similar, suggesting that either assay may be employed to identify IgG and IgA secreting cells. Further studies with InvaplexAR will evaluate alternative immunization routes, vaccination schedules and formulations to further optimize immunogenicity. (Clinical Trial Registry Number NCT02445963).

Tritrichomonas foetus Cell Division Involves DNA Endoreplication and Multiple Fissions

Tritrichomonas foetus and Trichomonas vaginalis are extracellular flagellated parasites that inhabit animals and humans, respectively. Cell division is a crucial process in most living organisms that leads to the formation of 2 daughter cells from a single mother cell. It has been assumed that T. vaginalis and T. foetus modes of reproduction are exclusively by binary fission. However, here, we showed that multinuclearity is a phenomenon regularly observed in different T. foetus and T. vaginalis strains in standard culture conditions. Additionally, we revealed that nutritional depletion or nutritional deprivation led to different dormant phenotypes. Although multinucleated T. foetus are mostly observed during nutritional depletion, numerous cells with 1 larger nucleus have been observed under nutritional deprivation conditions. In both cases, when the standard culture media conditions are restored, the cytoplasm of these multinucleated cells separates, and numerous parasites are generated in a short period of time by the fission multiple. We also revealed that DNA endoreplication occurs both in large and multiple nuclei of parasites under nutritional deprivation and depletion conditions, suggesting an important function in stress nutritional situations. These results provide valuable data about the cell division process of these extracellular parasites. IMPORTANCE Nowadays, it's known that T. foetus and T. vaginalis generate daughter cells by binary fission. Here, we report that both parasites are also capable of dividing by multiple fission under stress conditions. We also demonstrated, for the first time, that T. foetus can increase its DNA content per parasite without concluding the cytokinesis process (endoreplication) under stress conditions, which represents an efficient strategy for subsequent fast multiplication when the context becomes favorable. Additionally, we revealed the existence of novel dormant forms of resistance (multinucleated or mononucleated polyploid parasites), different than the previously described pseudocysts, that are formed under stress conditions. Thus, it is necessary to evaluate the role of these structures in the parasites' transmission in the future.

Portal vein-variceal anastomosis for portal vein inflow reconstruction in orthotopic liver transplantation: A case report and review of literature

BACKGROUND

Portal vein thrombosis (PVT) is a frequent complication occurring in 5% to 26% of cirrhotic patients candidates for liver transplantation (LT). In cases of extensive portal and or mesenteric vein thrombosis, complex vascular reconstruction of the portal inflow may become necessary for a successful orthotopic LT (OLT).

CASE SUMMARY

A 54-year-old male with history of cirrhosis secondary to schistosomiasis complicated with extensive portal and mesenteric vein thrombosis and severe portal hypertension who underwent OLT with portal vein-left gastric vein anastomosis.

CONCLUSION

We review the various types of PVT, the portal venous inflow reconstruction techniques.

Persistent abdominal symptoms in returning travellers: clinical and molecular findings

BACKGROUND

Persistent abdominal symptoms (PAS) are the leading cause of post-travel morbidity although there is a paucity of evidence concerning the aetiology of this condition. Recently molecular methods for protozoa detection in stool have been introduced. Herein, we describe the clinical aspects and the prevalence of gastrointestinal protozoa in returning travellers with PAS.

METHODS

From 2017 to 2019, clinical information and stool specimens from returning travellers with PAS were analysed for the presence of parasites using the Allplex-GI-Parasite-assay. Stool findings from symptomatic patients without a travel history were used as a comparator.

RESULTS

During the 2-year study, 203 stool specimens from returning travellers were analysed. The median duration of symptoms before seeking care was 6 months, the most common symptoms were fatigue (79.2%), abdominal pain (75.7%) and loose stool (70.8%).Most of travellers had returned from Asia (57.6%), mainly from the Indian-subcontinent and only 52.6% were backpackers. Altogether, 36.9% samples were positive for protozoa, with Blastocystis hominis being the most common (26.6%) in samples, followed by Dientamoeba fragilis (18.7%), Giardia lamblia (3.0%) and Cryptosporidium spp (0.5%). The former two were dominant in all regions. In all cases but one, G. lamblia was acquired, but one were acquired in the Indian subcontinent (odds ratios 16.9; 95% confidence intervals: 1.9-148.3). Entamoeba histolytica was not detected. The demographic characterization of the 1359 non-travellers was comparable with the travellers. Among them D. fragilis was the most common followed by B. hominis, which was significantly less frequent compared among the travellers (16.7% vs 26.6%, P < 0.001). Average Cycle threshold values for each stool parasites were comparable between the two groups.

CONCLUSION

Among returning travellers with PAS, more than one-third were positive for gastrointestinal protozoa. A low rate of giardia was found and no E. histolytica while B. hominis followed by D. fragilis were the dominant findings. Further studies are required to better understand the role of these protozoa in PAS.

Persistent abdominal symptoms: a persistently neglected topic in travel medicine

Persistent abdominal symptoms are a common complaint in returning travellers; yet, there is very sparse evidence to support the causes and potential aetiologies. New molecular stool-testing techniques and accurate clinical studies may shed light on this gap in our knowledge, paving ways for more successful management of this common and difficult problem.

Strongyloides stercoralis Infection in Immunocompromised Host

Strongyloides stercoralis is a soil-dwelling roundworm that causes an intestinal infection, Strongyloidiasis. In the United States, this helminth generally causes chronic asymptomatic infection, and severe symptomatic infections are reported in immunocompromised hosts like patients undergoing chemotherapy, receiving long-term corticosteroids, transplant patients, or patients with HIV. The clinicians should have a high index of suspicion to diagnose this infection, as the exposure is usually remote and symptoms are non-specific. The treatment is simple, with oral anti-helminthic drugs like ivermectin and albendazole.

Epidemiological and clinical profile of adult patients with diarrhoea after international travel attended in an International Health referral center

BACKGROUND

The aim of the study is to describe the epidemiological, clinical, and microbiological characteristics of patients with diarrhoea after their return from a trip to tropical and subtropical areas.

METHODS

Retrospective study of patients with travel-related diarrhoea attended International Health referral center. Travel diarrhoea was defined as the presence of three or more liquid stools per day, or liquid stools more often than is normal for the individual, during travel or within two weeks after returning. Epidemiological, clinical and microbiological variables were collected.

RESULTS

669 patients were included, 393 (58.7%) were female, with a mean age of 33 (SD 10.7) years. Abdominal pain was present in 59.6% (n = 399), and fever in 44.7% (n = 299). In 43% (n = 280) cases the etiological agent was found. Giardia duodenalis, Enteropathogenic Escherichia coli, and Enterotoxigenic Escherichia coli were the most frequent identified causative agents. Parasitic cause of the diarrhoea was associated to a longer duration of the travel, longer duration of symptoms, and having received pre-travel counseling.

CONCLUSIONS

In our cohort, that represents a group of travellers presenting prolonged symptoms after travel, the most frequent causes of diarrhoea were parasitic infections being the most prevalent Giardia duodenalis. This information could be relevant in order to improve travel-related diarrhoea management protocols in this type of patients.

Sodium butyrate ameliorates Schistosoma japonicum-induced liver fibrosis by inhibiting HMGB1 expression

Schistosomiasis is a prevalent zoonotic parasitic disease caused by schistosomes. Its main threat to human health is hepatic granuloma and fibrosis due to worm eggs. Praziquantel remains the first choice for the treatment of schistosomiasis but has limited benefit in treating liver fibrosis. Therefore, the need to develop effective drugs for treating schistosomiasis-induced hepatic fibrosis is urgent. High-mobility group box 1 protein (HMGB1) is a potential immune mediator that is highly associated with the development of some fibrotic diseases and may be involved in the liver pathology of schistosomiasis. We speculated that HMGB1 inhibitors could have an anti-fibrotic effect. Sodium butyrate (SB), a potent inhibitor of HMGB1, has shown anti-inflammatory activity in some animal disease models. In this study, we evaluated the effects of SB on a murine schistosomiasis model. Mice were percutaneously infected with 20 ± 2 cercariae of Schistosoma japonicum. SB (500 mg/kg/day) was administered every 3 days for the entire experiment period. The activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), liver histopathology, HMGB1 expression, and the levels of interferon gamma (IFN-γ), transforming growth factor-β1 (TGF-β1), and interleukin-6 (IL-6) in serum were analyzed. SB reduced hepatic granuloma and fibrosis of schistosomiasis, reflected by the decreased levels of ALT and AST in serum and the reduced expression of pro-inflammatory and fibrogenic cytokines (IFN-γ, TGF-β1, and IL-6). The protective effect could be attributable to the inhibition of the expression of HMGB1 and release by SB.

Chronic diarrhea and parasitic infections: Diagnostic challenges

BACKGROUND

Diarrhea is among the top ten global causes of death. Chronic diarrhea may have destructive impact on physical and mental health of patients and is also associated with high risk of mortality in children. Parasitic intestinal infections remain an important cause of chronic diarrhea especially in the developing part of the world.

OBJECTIVE

To study the parasitic causes of chronic diarrhea and highlight the challenges faced in the diagnosis of chronic diarrhea caused due to parasitic infections.

CONTENT

Due to non-specific symptoms, insensitive available diagnostic techniques, asymptomatic carriage and transmission, recurrent infections in endemic areas, pose a challenge for diagnosis of the parasitic infections and thus delay the treatment. Conventional techniques like microscopy, though cheaper are not very sensitive. Advanced techniques like molecular methods are more sensitive but expensive and are not readily available in resource limited settings. Newer cost-effective diagnostic techniques with higher sensitivity and specificity are required to detect the infectious agent and for appropriate management.

Rise of informal slums and the next global pandemic

Informal slums are growing exponentially in the developing world and these will serve as the breeding ground for a future global pandemic. Virtually every sustainable development goal is unmet in slums around the globe thus we must act now to divert a global humanitarian crisis.

Lipocalin 2 Is a Regulator During Macrophage Polarization Induced by Soluble Worm Antigens

Caused by schistosomes, the human schistosomiasis is a tropical zoonotic parasitic disease. Pathologically, it occurs most often in the intestines and the liver, the sites of Schistosoma japonicum egg accumulation. The parasites' produced eggs cause the main pathology in patients. Deposited parasite eggs in the liver induce the production of multiple cytokines that mediate the immune response, which in turn leads to granulomatous responses and liver fibrosis. These impact the hosts' quality of life and health status, resulting in severe morbidity and even mortality. In this study, differentially expressed genes (DEGs) between ordinary samples and three 6- week infected mice were mined from microarray analysis based on the limma package. In total, we excavated the differential expression LCN2 was exhibited high expressions profile in GSE59276, GSE61376 demonstrated the result. Furthermore, CIBERSORT suggested detailed analysis of the immune subtype distribution pattern. In vivo experiments like real-time quantitative PCR, immunohistochemical (IHC) staining, and immunofluorescence (IF) demonstrated the expressions of LCN2 was significantly upregulated in S. japonicum-infected mice liver tissues and located in macrophages. Previous studies have shown that macrophages act as the first line of defense during schistosome infection and are an important part of liver granuloma. We used S. japonicum soluble worm antigens (SWA) to induce RAW264.7 cells to construct an in vitro inflammatory model. The current study aimed to investigate whether the NF-κB signaling network is involved in LCN2 upregulation induced by SWA and whether LCN2 can promote M1 polarization of macrophages under SWA treatment. Our research work suggests that LCN2 is significant in the development of early infection caused by S. japonicum and is of great value for further exploration. Collectively, the findings indicated that SWA promoted the expression of LCN2 and promoted M1 polarization of macrophages via the upregulation of NF-κB signaling pathway. Our findings demonstrate that NF-κB/LCN2 is necessary for migration and phagocytosis of M1 macrophages in response to SWA infection. Our study highlights the essential role of NF-κB/LCN2 in early innate immune response to infection.

Immune Response to the Enteric Parasite Entamoeba histolytica

Entamoeba histolytica is a protozoan parasite responsible for amoebiasis, a disease with a high prevalence in developing countries. Establishing an amoebic infection involves interplay between pathogenic factors for invasion and tissue damage, and immune responses for protecting the host. Here, we review the pathogenicity of E. histolytica and summarize the latest knowledge on immune response and immune evasion mechanisms during amoebiasis.

Predictors of aetiology and outcomes of acute gastrointestinal illness in returning travellers: a retrospective cohort analysis

BACKGROUND

Gastrointestinal illness is a major cause of morbidity in travellers and is a common reason for presentation to healthcare services on return. Whilst the aetiology of imported gastrointestinal disease is predominantly infectious, outcomes are variable due to a range of phenomena such as post-infectious irritable bowel syndrome, drug resistance and occult pathology (both infectious and non-infectious). Previous studies have focussed on predictors of aetiology of gastrointestinal disease in travellers; we present a retrospective study combining both aetiological and early outcome data in a large cohort of returned travellers.

METHOD

We identified 1450 patients who attended our post-travel walk-in clinic with gastrointestinal symptoms between 2010 and 2016. Demographic, travel, clinical and laboratory data was collected through case note review. Logistic regression analysis to examine correlates of aetiology and outcome were performed in R (CRAN Project 2017).

RESULTS

Of 1450 patients in our cohort 153 reported bloody diarrhoea and 1081 (74.6%) reported non-bloody diarrhoea. A definitive microbiological diagnosis was made in 310 (20.8%) of which 137 (9.4%) had a parasite identified and 111 (7.7%) had a bacterial cause identified. Factors associated with a parasitological diagnosis included history of travel to South Asia (aOR = 2.55; 95%CI 1.75-3.70, p < 0.0001) and absence of bloody diarrhoea (aOR = 0.22; 95%CI 0.066-0.53, p < 0.005). Factors associated with a bacteriological diagnosis included male gender (aOR = 1.69; 95%CI 1.10-2.62, p < 0.05), an age < 37 years on presentation (aOR = 2.04; 95%CI 1.25-3.43, p < 0.01), white cells on stool microscopy (aOR = 3.52; 95%CI 2.09-5.86, p < 0.0001) and a C-reactive protein level of >5iu/dL (aOR = 4.68; 95%CI 2.91-7.72, p < 0.0001). The majority (1235/1450, 82.6%) reported full symptomatic resolution by the first follow up visit; factors associated with lack of symptomatic resolution included female gender (aOR = 1.45 95%CI 1.06-1.99, p < 0.05), dysenteric diarrhoea (aOR = 2.14 (95%CI 1.38-3.25, p < 0.0005) and elevated peripheral leukocyte count (aOR = 1.58 95%CI 1.02-2.40, p < 0.05).

CONCLUSIONS

In a cohort of returned travellers, we were able to identify multiple factors that are correlated with both aetiology and outcome of imported gastrointestinal syndromes. We predict these data will be valuable in the development of diagnostic and therapeutic pathways for patients with imported gastrointestinal infections.

Neutrophils vs. amoebas: Immunity against the protozoan parasite Entamoeba histolytica

Entamoeba histolytica is a protozoan parasite with high prevalence in developing countries, and causes amoebiasis. This disease affects the intestine and the liver, and is the third leading cause of human deaths among parasite infections. E. histolytica infection of the intestine or liver is associated with a strong inflammation characterized by a large number of infiltrating neutrophils. Consequently, several reports suggest that neutrophils play a protective role in amoebiasis. However, other reports indicate that amoebas making direct contact with neutrophils provoke lysis of these leukocytes, resulting in the release of their lytic enzymes, which in turn provoke tissue damage. Therefore, the role of neutrophils in this parasitic infection remains controversial. Neutrophils migrate from the circulation to sites of infection, where they display several antimicrobial functions, including phagocytosis, degranulation, and formation of neutrophil extracellular traps (NET). Recently, it was found that E. histolytica trophozoites are capable of inducing NET formation. Neutrophils in touch with amoebas launched NET in an explosive manner around the amoebas and completely covered them in nebulous DNA and cell aggregates where parasites got immobilized and killed. In addition, the phenotype of neutrophils can be modified by the microbiome resulting in protection against amoebas. This review describes the mechanisms of E. histolytica infection and discusses the novel view of how neutrophils are involved in innate immunity defense against amoebiasis. Also, the mechanisms on how the microbiome modulates neutrophil function are described.

Risk factors for and management of metronidazole-refractory giardiasis in international travellers: A retrospective analysis

BACKGROUND

Giardia lamblia is a common cause of diarrhoea in returning travellers. Failure of the recommended first-line treatment, metronidazole, has frequently been observed. Recommendations for treatment of metronidazole-refractory giardiasis lack clarity and evidence.

METHODS

We conducted a retrospective data analysis of returned travellers with confirmed giardiasis at the Bernhard-Nocht-Clinic in Hamburg, Germany, between 2007 and 2016.

RESULTS

We identified 339 cases of giardiasis, mostly acquired in South Asia (n = 157). 308 patients received metronidazole as first-line treatment, leading to treatment failure in 93 cases. Statistical analysis suggested by far the highest risk of metronidazole treatment failure for travellers returning from South Asia (Odds Ratio 8.73). Second-line therapy consisted of various different therapy regimens. Combination therapy as second-line treatment seemed to be more effective than monotherapy. A repeat course of metronidazole proved to be futile.

CONCLUSION

This study reveals a strikingly low effectiveness of metronidazole, especially in patients returning from South Asia. Second-line treatment showed inconsistency of regimens and yielded unsatisfactory results. These findings require reconsideration of treatment strategies for giardiasis. Large prospective trials are urgently needed to assess new first-line treatment options and to help implement advice for effective, agreed second-line treatment strategies. Translational projects should be created to link the understanding of resistance mechanisms with epidemiological data and clinical outcome.

An atypical cause of right lower abdominal pain: amoebiasis, a family cluster

In this case report we present a family cluster of amoebiasis in a nonendemic region. A 46-year-old women, diagnosed with Crohn's disease for which she received no maintenance therapy, was evaluated for the suspicion of a flare. At colonoscopy however, atypical findings for Crohn's disease were seen. Histopathologic examination revealed micro-organisms compatible with amoebiasis. Interestingly, 4 years before this event she started a new relationship with a 38-year-old man who was diagnosed with liver-amoebiasis 3 months after the start of their relationship. On top of this, her 18-year-old daughter was diagnosed with amoebiasis 2 years after her diagnosis. The source of the infection remains unknown, but we speculate that the infection was transmitted feco-orally between the different members of this family. These cases illustrate that we should be aware of parasitological causes of colitis, especially in patients with atypical endoscopic images or when a close "relative" is diagnosed with amoebiasis.

Outbreak of Cyclosporiasis in Korean Travelers Returning from Nepal

Cyclospora cayetanensis is an apicomplexan protozoan and is one of the most common pathogens causing chronic diarrhea worldwide. Eight stool samples with diarrheal symptom out of 18 Korean residents who traveled to Nepal were obtained, and examined for 25 enteropathogens including 16 bacterial species, 5 viral species, and 4 protozoans in stool samples as causative agents of water-borne and food-borne disease. Only C. cayetanensis was detected by nested PCR, and 3 PCR-positive samples were sequenced to confirm species identification. However, the oocysts of C. cayetanensis in fecal samples could not be detected by direct microscopy of the stained sample. As far as we know, this is the first report of a group infection with C. cayetanensis from a traveler visiting Nepal, and the second report of a traveler’s diarrhea by C. cayetanensis imported in Korea.

Entamoeba histolytica DNA Detection in Serum from Patients with Suspected Amoebic Liver Abscess

Amoebic liver abscess (ALA) is regularly seen in travelers or immigrants from tropical countries. The diagnosis relies on liver imaging that is not specific and on the detection of anti-Entamoeba histolytica antibodies, which cannot distinguish an acute from a former infection. We tested whether E. histolytica DNA detection in serum can improve the diagnosis of ALA. We retrospectively tested available serum samples taken from patients with ALA and non-ALA space-occupying lesions of the liver between 1 January 2010 and 30 November 2019. The quantitative PCR (qPCR) assay tested specifically amplifies a 99-bp fragment of the small-subunit rRNA gene of E. histolytica We analyzed 76 samples (19 ALA and 57 non-ALA samples) collected from 76 patients within 6 days before and after the antiamoebic treatment. Serum qPCR results were positive for 17 of 19 ALA patients and for none of the control patients (sensitivity and specificity were 89.5% and 100%, respectively). In parallel, the sensitivity and specificity of anti-E. histolytica antibody detection were 100% and 89.5%, respectively. The two false-negative qPCR results may be explained by ongoing metronidazole treatment or a possible persistent seropositivity that was not caused by the current liver abscess. Additionally, of 12 abscess pus aspirates (5 from ALA and 7 from non-ALA samples) tested, 5 were qPCR positive and 7 were qPCR negative, with concordant results in serum. This study demonstrates that cell-free circulating E. histolytica DNA can be detected in serum in ALA. This may assist in both positive diagnoses and treatment efficacy follow-up. The origin of this circulating DNA remains to be investigated.

Delayed cytokinesis generates multinuclearity and potential advantages in the amoeba Acanthamoeba castellanii Neff strain

Multinuclearity is a widespread phenomenon across the living world, yet how it is achieved, and the potential related advantages, are not systematically understood. In this study, we investigate multinuclearity in amoebae. We observe that non-adherent amoebae are giant multinucleate cells compared to adherent ones. The cells solve their multinuclearity by a stretchy cytokinesis process with cytosolic bridge formation when adherence resumes. After initial adhesion to a new substrate, the progeny of the multinucleate cells is more numerous than the sibling cells generated from uninucleate amoebae. Hence, multinucleate amoebae show an advantage for population growth when the number of cells is quantified over time. Multiple nuclei per cell are observed in different amoeba species, and the lack of adhesion induces multinuclearity in diverse protists such as Acanthamoeba castellanii, Vermamoeba vermiformis, Naegleria gruberi and Hartmannella rhysodes. In this study, we observe that agitation induces a cytokinesis delay, which promotes multinuclearity. Hence, we propose the hypothesis that multinuclearity represents a physiological adaptation under non-adherent conditions that can lead to biologically relevant advantages.

First steps in the formulation of praziquantel nanosuspensions for pharmaceutical applications

Praziquantel (PZQ), a broad spectrum anthelmintic drug, cannot be found in acceptable dosage forms for elderly patients, paediatric patients, and for veterinary use. In fact, very little has been done up to now in the formulation of liquid dosage forms, being they always formulated for parenteral administration. To beat this important challenge, it was accomplished a comprehensive analysis of the influence of two elementary physicochemical aspects, i.e. surface thermodynamic and electrokinetic properties, on the colloidal stability of PZQ nanosuspensions. The hydrophobic character of the drug, intensely determining the flocculation curves, was confirmed by the thermodynamic characterization. The electrophoretic characterization, in combination with the sedimentation and relative absorbance versus time curves, highlighted that the electrical double layer thickness and the surface charge can play an essential role in the stability of the pharmaceutical colloid. Finally, it was demonstrated that controlling the pH values and the incorporation of electrolytes can help in formulating PZQ aqueous nanosuspensions with appropriate stability and redispersibility behaviours for pharmaceutical use.

Ethnopharmacological evaluation of schistosomicidal and cercaricidal activities of some selected medicinal plants from Ghana

Background

The adulticidal and cercaricidal activities of five Ghanaian medicinal plants, namely, Phyllanthus amarus, Vernonia amygdalina, Azadirachta indica, Morinda lucida and Nauclea latifolia against S. mansoni were evaluated in this study. Six weeks old ICR mice (n = 25) were percutaneously infected with S. mansoni cercariae. Nine weeks later, infected mice (n = 5) were anaesthetised and perfused for adult S. mansoni. Cercariae were treated with different concentrations (1000, 500, 250, 125, 62.5, 31.25 μg/mL) of methanolic extracts of the experimenting plants in triplicates. Adult S. mansoni incopula were also treated with same concentrations of each extract or 20 μg/mL praziquantel. The cercariae and adult worms were observed at time intervals for 180 min and 120 h to assess mortality and viability respectively. Additionally, 9-week cercariae-infected mice (4 groups of 5 mice) were treated with either 500 mg/kg po A. indica or V. amygdalina, 400 mg/kg po praziquantel or distilled water for 14 days. The mice were euthanized after adult worms were recovered from them. The liver was processed and histologically examined for granuloma formations.

Results

All the plants exhibited varying cercaricidal and adulticidal activities against S. mansoni in a time and concentration-dependent manner. A. indica (3 h IC₅₀ = 27.62 μg/mL) and V. amygdalina (3 h IC₅₀ = 35.84 μg/mL) exerted the highest cercaricidal activity. Worm recovery after treatment with V. amygdalina, A. indica and praziquantel in vivo was 48.8%, 85.1 % and 59.9 % respectively (p < 0.05). A. indica and V. amydalina-treated mice recorded lesser mean liver and spleen weights compared to untreated groups (p < 0.05).

Conclusion

A. indica demonstrated the highest cercaricidal and alduticidal activities in vitro, whereas V. amygdalina exhibited the most potent aldulticidal activity in vivo. This study could provide baseline information which can be used to develop plant-based alternative commercial drugs against S. mansoni.

Pathogenesis and post-infectious complications in giardiasis

Giardia is an important cause of diarrhoea, and results in post-infectious and extra-intestinal complications. This chapter presents a state-of-the art of our understanding of how this parasite may cause such abnormalities, which appear to develop at least in part in Assemblage-dependent manner. Findings from prospective longitudinal cohort studies indicate that Giardia is one of the four most prevalent enteropathogens in early life, and represents a risk factor for stunting at 2 years of age. This may occur independently of diarrheal disease, in strong support of the pathophysiological significance of the intestinal abnormalities induced by this parasite. These include epithelial malabsorption and maldigestion, increased transit, mucus depletion, and disruptions of the commensal microbiota. Giardia increases epithelial permeability and facilitates the invasion of gut bacteria. Loss of intestinal barrier function is at the core of the acute and post-infectious complications associated with this infection. Recent findings demonstrate that the majority of the pathophysiological responses triggered by this parasite can be recapitulated by the effects of its membrane-bound and secreted cysteine proteases.

A meta-analysis of infection rates of Schistosoma japonicum in sentinel mice associated with infectious waters in mainland China over last 40 years

BACKGROUND

Schistosomiasis japonica is a zoonotic parasitic disease. After nearly 70 years of control efforts in China, Schistosomiasis transmission has been reduced to a much lower level. The absence or near absence of infections in humans or livestock, based on traditional fecal and serological tests, has made the targets and priorities of future control efforts difficult to determine. However, detection of schistosome cercariae in waters using sentinel mice could be an alternative way of identifying remaining foci of infection, or even serve as a tool for evaluation of control efficacy. This method has been employed in China over last forty years. We therefore performed a meta-analysis of the relevant research to investigate if infections in sentinel mice mirror the ongoing trend of schistosomiasis transmission in China.

METHODS

We conducted a meta-analysis of studies reporting infection rates of S. japonicum in sentinel mice in China before Sep 1, 2018 in accordance with the PRISMA guidelines. We retrieved all relative studies based on five databases (CNKI, WanFang, VIP, PubMed and Web of Science) and the reference lists of resulting articles. For each individual study, the infection rate in sentinel mice is presented together with its 95% confidence interval (CI). Point estimates of the overall infection rates and their 95% CIs were calculated. Subgroup analyses were performed according to study periods, seasons or regions.

RESULTS

We identified 90 articles, including 290 studies covering eight endemic provinces. The overall rate in sentinel mice was 12.31% (95% CI: 10.14-14.65%) from 1980 to 2018. The value of 3.66% (95% CI: 2.62-4.85%) estimated in 2004 to 2018 was significantly lower than in 1980 to 2003 (22.96%, 95% CI: 19.25-26.89%). The estimate was significantly higher in the middle and lower reaches than in the upper reaches of the Yangtze River. The highest estimates were obtained in Hunan (30.11%, 95% CI: 25.64-34.77%) followed by Anhui (26.34%, 95% CI: 12.88-42.44%) and then Jiangxi (13.73%, 95% CI: 6.71-22.56%). Unlike the other provinces in the middle and lower reaches, no significant reduction was seen in Hubei after 2003. Even in Hubei two studies carried out after 2014 reported infections in sentinel mice, although no infected snails were reported across the province. Infections were most found in April (17.40%, 95% CI: 1.13-45.49%), July (24.98%, 95% CI: 15.64-35.62%) and October (17.08%, 95% CI 5.94-32.05%). High degrees of heterogeneity were observed.

CONCLUSION

This meta-analysis provides a comprehensive analysis of schistosome infection in sentinel mice across China. The estimates largely mirror the ongoing trends of transmission in terms of periods and regions. Infections were most likely to occur in April, July and October. In areas where no infected snails were reported infections in sentinel mice were still observed. Due to the presence of snails and infected wildlife, detection of schistosomes in waters using such a highly sensitive method as the deployment of sentinel mice, remains of importance in schistosomiasis monitoring. We would suggest the current criteria for transmission interruption or elimination of schistosomiasis in China be adjusted by integrating the results of sentinel mice based surveys.

Co-parasitism of intestinal protozoa and Schistosoma japonicum in a rural community in the Philippines

Background

Co-parasitism is a frequent occurrence in impoverished communities in the tropics resulting in a considerable disease burden. While there are extensive reports of intestinal helminthiases, including schistosomiasis japonica, the occurrence and extent of diseases caused by intestinal protozoa (IP) have yet to be investigated in depth in the Philippines. We present a detailed analysis of polyparasitism in a rural community of Northern Samar, focusing on co-infections of IP with Schistosoma japonicum.

Methods

A descriptive cross sectional study was carried out in 2015 across 18 barangays (villages) endemic for S. japonicum in Northern Samar, the Philippines to assess the burden of human schistosomiasis and IP infections. Faecal samples collected from 412 participants from the 18 barangays were included in the final molecular analysis. A multiplex quantitative PCR assay was developed and used for the detection of Blastocystis spp., Entamoeba histolytica, Cryptosporidium spp. and Giardia duodenalis in stool samples. The findings were combined with previous results of droplet digital PCR diagnosis of individuals from the same 18 barangays infected with S. japonicum determined using the same stool samples for analysis.

Results

Mean age of the study participants was 40.3 years (95% CI: 38.8–41.8) with 53% (n = 218) being males. Prevalence of S. japonicum (74.5%) and Blastocystis spp. (58.7%) was significantly higher compared to other infections, with E. histolytica having the lowest prevalence (12.1%). A majority of individuals were infected with more than one parasite with two infections being most common (n = 175, 42.5%). The prevalence of individuals with two parasites was significantly higher than all others with 27.9% (n = 115) subjects harbouring a single parasite species. Of individuals with two infections, S. japonicum and Blastocystis spp. were the most common combination (n = 110, 62.9%). Examining age within the population, 58.5% (n = 38) of school-aged children and 60.1% (n = 14) of women of child bearing age harboured at least two parasite species.

Conclusions

The study revealed that polyparasitism with IP infections and schistosomiasis japonica is highly prevalent in individuals in Northern Samar which likely contributes to the significant public health and socio-economic burden suffered by this population. More generally, the findings are of relevance when considering implementation of integrated control strategies for intestinal parasites.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0504-6) contains supplementary material, which is available to authorized users.

A 12-Year Retrospective Study of Invasive Amoebiasis in Western Sydney: Evidence of Local Acquisition

In Australia, amoebiasis is thought to occur in travellers, immigrants from endemic areas, and among men who have sex with men. Prevalence of amoebiasis in communities with immigrants from Entamoeba histolytica-endemic countries is unknown. The present study is a retrospective case series analysis of patients with laboratory-confirmed amoebiasis from Western Sydney Local Health District, Australia, between years 2005 and 2016. Forty-nine patients with amoebiasis were identified, resulting in an estimated annual incidence of up to 1.1 cases per 100,000 adults. Many were born in Australia (15/47) and India (12/47). Three patients (3/37) had no history of overseas travel, two others had not travelled to an endemic country, and an additional two had a very remote history of overseas travel; one died of fulminant amoebic colitis. Three patients (3/16) were employed in the food industry and one had a history of colonic irrigation in an Australian ‘wellness clinic’. Patients had invasive amoebiasis with either liver abscess (41/48) or colitis (7/48), diagnosed most commonly by serology. Invasive procedures were common, including aspiration of liver abscess (28/41), colonoscopy (11/49), and partial hepatectomy (1/49). Although rare, local acquisition of amoebiasis occurs in Western Sydney and contributes to significant morbidity and hospital admissions.

Beyond O&P Times Three

Although examination of the stool for ova and parasites times three (O&P ×3) is routinely performed in the United States (US) for the evaluation of persistent and/or chronic diarrhea, the result is almost always negative. This has contributed to the perception that parasitic diseases are nearly non-existent in the country unless there is a history of travel to an endemic area. The increasing number of immigrants from third-world countries, tourists, and students who present with symptoms of parasitic diseases are often misdiagnosed as having irritable bowel syndrome or inflammatory bowel disease. The consequences of such misdiagnosis need no explanation. However, certain parasitic diseases are endemic to the US and other developed nations and affect both immunocompetent and immunocompromised patients. Testing for parasitic diseases either with O&P or with other diagnostic tests, followed by the recommended treatment, is quite rewarding when appropriate. Most parasitic diseases are easily treatable and should not be confused with other chronic gastrointestinal (GI) disorders. In this review, we critically evaluate the symptomatology of luminal parasitic diseases, their differential diagnoses, appropriate diagnostic tests, and management.

In silico analysis to identify vaccine candidates common to multiple serotypes of Shigella and evaluation of their immunogenicity

Shigellosis or bacillary dysentery is an important cause of diarrhea, with the majority of the cases occurring in developing countries. Considering the high disease burden, increasing antibiotic resistance, serotype-specific immunity and the post-infectious sequelae associated with shigellosis, there is a pressing need of an effective vaccine against multiple serotypes of the pathogen. In the present study, we used bio-informatics approach to identify antigens shared among multiple serotypes of Shigella spp. This approach led to the identification of many immunogenic peptides. The five most promising peptides based on MHC binding efficiency were a putative lipoprotein (EL PGI I), a putative heat shock protein (EL PGI II), Spa32 (EL PGI III), IcsB (EL PGI IV) and a hypothetical protein (EL PGI V). These peptides were synthesized and the immunogenicity was evaluated in BALB/c mice by ELISA and cytokine assays. The putative heat shock protein (HSP) and the hypothetical protein elicited good humoral response, whereas putative lipoprotein, Spa32 and IcsB elicited good T-cell response as revealed by increased IFN-γ and TNF-α cytokine levels. The patient sera from confirmed cases of shigellosis were also evaluated for the presence of peptide specific antibodies with significant IgG and IgA antibodies against the HSP and the hypothetical protein, bestowing them as potential future vaccine candidates. The antigens reported in this study are novel and have not been tested as vaccine candidates against Shigella. This study offers time and cost-effective way of identifying unprecedented immunogenic antigens to be used as potential vaccine candidates. Moreover, this approach should easily be extendable to find new potential vaccine candidates for other pathogenic bacteria.

Review: chronic and persistent diarrhea with a focus in the returning traveler

Background

Travelers’ diarrhea is a common malady afflicting up to 50% of travelers after a 2-week travel period. An appreciable percentage of these cases will become persistent or chronic. We summarized the published literature reporting persistent/chronic diarrhea in travelers elucidating current understanding of disease incidence, etiology and regional variability.

Methods

We searched electronic databases (Medline, Embase, and Cochrane database of clinical trials) from 1990 to 2015 using the following terms: “chronic or persistent diarrh* and (returning) travel* or enteropathogen, GeoSentinel, and travel-associated infection. Included studies published in the English language on adult returning travelers (duration < 3-months) reporting denominator data. Point estimates and standard 95% confidence intervals were calculated for incidence using a random-effects model. Study incidence heterogeneity rates were assessed using x² heterogeneity statistics, graphically represented with Forest plots.

Results

We identified 19 studies meeting the inclusion criteria (all published after 1999). 18 studies reported upon the incidence of persistent/chronic diarrhea as a syndromic diagnosis in returning travelers; one study reported adequate denominator data from which to assess pathogen specific etiology. Giardiasis comprise an appreicaible percentage of infectious mediated persistent/chronic diarrhea in returning travelers. The overall estimate of persistent/chronic diarrhea incidence was 6% (0.05–0.07) in 321,454, travelers; with significant heterogeniety observed across regions. The total number of regional travelers, and point estimates for incidence (95% CI) for Latin American, African, and Asian travelers were [15816 (0.09 [0.07–0.11]), 42290 (0.06 [0.05–0.07]), and 27433 (0.07 [0.06–0.09])] respectively. We identified lower published rates of chronic diarrhea from Sub-Saharan Africa relative to [North Africa, South Central Asia, and Central America]. Persistent/chronic diarrhea ranked fourth as a syndromic diagnosis in all regions.

Conclusions

Persistent/Chronic diarrhea is a leading syndromic diagnosis in returning travelers across all regions. The 6% incidence [proportionate morbidity (PM) of 60] observed in over >300,000 global travelers is comparable to prior estimates. We identified lower published rates of chronic diarrhea from Sub-Saharan Africa relative to [North Africa, South Central Asia, and Central America]. Giardiasis comprises an appreciabile percentatge of travel-associated infectious mediated persistent/chronic diarrhea. There’s a dearth of published data characterizing the incidence of specific enteropathogenic etiologies for persistent/chronic diarrhea in returning travelers.

Crohn's disease and schistosomiasis: a rare association

Schistosomiasis is a chronic enteropathogenic disease caused by blood flukes of the genus Schistosoma. Coexistence of schistosomiasis with Crohn's disease is very rare. To the best of our knowledge, this association has been described in literature only once. A 20-year-old male patient with a past medical history of appendectomy and ileocecal Crohn's disease, presented with abdominal pain and vomiting. Ileocolonoscopy showed an ulcerated and congested appearance of the upper rectum and sigmoid. Computed tomography scan revealed a circumferential thickening of the terminal ileum with luminal stenosis. Histopathological examination of the biopsy specimens revealed a focally ulcerated colonic epithelium. The lamina propria was fibrous harbouring a polymorphic inflammatory infiltrate including lymphocytes and plasma cells organized in lymphoid follicles admixed with eosinophils and neutrophils. In the submucosa, there were two well-preserved schistosoma eggs surrounded by a thick shell with a barely visible terminal spine. The final pathological diagnosis was colonic schistosomiasis associated with Crohn's disease. The patient underwent an ileocecal resection for stenosis of the terminal ileum complicated with enterocutaneous fistula. The postoperative course was uneventful. A stool examination and serology tests were planned for this patient who was lost to follow-up.

A novel duplex ddPCR assay for the diagnosis of schistosomiasis japonica: proof of concept in an experimental mouse model

The current World Health Organization strategic plan targets the elimination of schistosomiasis as a public health problem by 2025 and accurate diagnostics will play a pivotal role in achieving this goal. DNA-based detection methods provide a viable alternative to some of the commonly used tests, notably microscopy and serology, for the diagnosis of schistosomiasis. The detection of parasite cell-free DNA in different clinical samples is a recent valuable advance, which provides significant benefits for accurate disease diagnosis. Here we validated a novel duplex droplet digital PCR assay for the diagnosis of Chinese (SjC) and Philippine (SjP) strains of Schistosoma japonicum infection in a mouse model. The assay proved applicable for both SjC and SjP infections and capable of detecting infection at a very early intra-mammalian stage in conveniently obtainable samples (urine and saliva) as well as in serum and feces. The target DNA copy numbers obtained in the assay showed a positive correlation with the infection burden assessed by direct traditional parasitology. The potential to detect parasite DNA in urine and saliva has important practical implications for large-scale epidemiological screening programmes in the future, particularly in terms of logistical convenience, and the assay has the potential to be a valuable additional tool for the diagnosis of schistosomiasis japonica.

Safety and Immunogenicity of a Candidate Bioconjugate Vaccine against Shigella flexneri 2a Administered to Healthy Adults: a Single-Blind, Randomized Phase I Study

Several candidate vaccines against Shigella spp. are in development, but the lack of a clear correlate of protection from challenge with the induction of adequate immune responses among the youngest age groups in the developing world has hampered Shigella vaccine development over the past several decades. Bioconjugation technology, exploited here for an Shigella flexneri 2a candidate vaccine, offers a novel and potentially cost-effective way to develop and produce vaccines against a major pathogen of global health importance. Flexyn2a, a novel S. flexneri 2a bioconjugate vaccine made of the polysaccharide component of the S. flexneri 2a O-antigen, conjugated to the exotoxin protein A of Pseudomonas aeruginosa (EPA), was evaluated for safety and immunogenicity among healthy adults in a single-blind, phase I study with a staggered randomization approach. Thirty subjects (12 receiving 10 μg Flexyn2a, 12 receiving Flexyn2a with aluminum adjuvant, and 6 receiving placebo) were administered two injections 4 weeks apart and were followed for 168 days. Flexyn2a was well-tolerated, independently of the adjuvant and number of injections. The Flexyn2a vaccine elicited statistically significant S. flexneri 2a lipopolysaccharide (LPS)-specific humoral responses at all time points postimmunization in all groups that received the vaccine. Elicited serum antibodies were functional, as evidenced by bactericidal activity against S. flexneri 2a. The bioconjugate candidate vaccine Flexyn2a has a satisfactory safety profile and elicited a robust humoral response to S. flexneri 2a LPS with or without inclusion of an adjuvant. Moreover, the bioconjugate also induced functional antibodies, showing the technology's features in producing a promising candidate vaccine. (This study has been registered at ClinicalTrials.gov under registration no. NCT02388009.).

Diseases affecting patients returning from abroad: Experience of a travel clinic in Japan from 2004 to 2014

The number of patients returning from or staying abroad is likely to increase in the future. We performed a retrospective study of patients returning from abroad in our travel clinic in Japan. All patients presenting within 6 months of traveling abroad between 2004 and 2014 were included in the present study. A total of 2374 (mean age, 35 years) patients were seen by doctors specializing in treating infectious diseases. Of these, 918 were females and 87 of them lived abroad. Diagnoses and exposure regions were recorded for all patients. The most frequent region visited before attending our clinic was Southeast Asia (n = 1050, 44%), with a median duration for staying abroad of 8 days. The major purposes for overseas travel were tourism (n = 1302, 55%) and business (n = 684, 29%). Of the 2399 individual diagnoses made, the most frequent were diseases of the gastrointestinal system (n = 1083, 45%), skin and soft tissue (n = 440, 18%), systemic febrile disease without specific systems (419, 18%), and the respiratory system (353, 15%). The relative incidences of specific diseases changed drastically due to significant disease outbreaks, such as pandemic influenza in 2009. Exposure regions remained relatively constant throughout the study period, except for Japan. Vaccine-preventable diseases accounted for 5.3% of all the diseases, and 402 (26%) patients received pre-travel consultation and prophylaxis with vaccines and/or anti-malarial drug. We should make an effort to make more people notice the risk of travel and properly perform prophylaxis.

Recent Advances in Antimicrobial Polymers: A Mini-Review

Human safety and well-being is threatened by microbes causing numerous infectious diseases resulting in a large number of deaths every year. Despite substantial progress in antimicrobial drugs, many infectious diseases remain difficult to treat. Antimicrobial polymers offer a promising antimicrobial strategy for fighting pathogens and have received considerable attention in both academic and industrial research. This mini-review presents the advances made in antimicrobial polymers since 2013. Antimicrobial mechanisms exhibiting either passive or active action and polymer material types containing bound or leaching antimicrobials are introduced. This article also addresses the applications of these antimicrobial polymers in the medical, food, and textile industries.

Infections Associated with Exotic Cuisine: The Dangers of Delicacies

"Exotic" food dishes are an expression of regional culture, religion, and ethnicity worldwide. With the increase in international travel to remote areas of the world, globalization of the food supply, and changes in food habits, more people are consuming dishes once considered exotic. Such behavioral changes require awareness by consumers and clinicians about the risks of food-borne infections. This chapter addresses pathogens associated with consumption of raw or undercooked seafood including anisakidosis, Diphyllobothrium latum infection, flukes, and other infectious and toxin-mediated diseases. We discuss the geographic distribution of the pathogens, symptomatology, and basic principles of treatment. Food products derived from turtles, snakes, and other reptiles are reviewed, and we address the risk of gnathostomiasis, sparganosis, trichinellosis, and other pathogens. In discussing infections associated with undercooked beef, pork, and bush meat, we address dysentery, amebiasis, toxoplasmosis, Taenia infections, and risks of novel viral infections, among others. We also review infectious risks from poultry, dairy, and other food items, focusing on those organisms encountered less frequently by clinicians in developed countries. The wide range of infectious organisms related to exotic cuisine underscores the importance of educating the adventurous traveler and warrants continued vigilance on the part of the clinician.

Genotyping of Campylobacter coli strains isolated in Brazil suggests possible contamination amongst environmental, human, animal and food sources

Campylobacter coli and Campylobacter jejuni are two of the most common causative agents of food-borne gastroenteritis in numerous countries worldwide. In Brazil, campylobacteriosis is under diagnosed and under-reported, and few studies have molecularly characterized Campylobacter spp. in this country. The current study genotyped 63 C. coli strains isolated from humans (n512), animals (n521), food (n510) and the environment (n520) between 1995 and 2011 in Brazil. The strains were genotyped using pulsed-field gel electrophoresis (PFGE), sequencing the short variable region (SVR) of the flaA gene ( flaA-SVR) and high-resolution melting analysis (HRMA) of the clustered regularly interspaced short palindromic repeat (CRISPR) locus to better understand C. coli genotypic diversity and compare the suitability of these three methods for genotyping this species. Additionally, the discrimination index (DI) of each of these methods was assessed. Some C. coli strains isolated from clinical and non-clinical origins presented ≥80 % genotypic similarity by PFGE and flaA-SVR sequencing. HRMA of the CRISPR locus revealed only four different melting profiles. In total, 22 different flaA-SVR alleles were detected. Of these, seven alleles, comprising gt1647–gt1653, were classified as novel. The most frequent genotypes were gt30 and gt1647. This distribution reveals the diversity of selected Brazilian isolates in comparison with the alleles described in the PubMLST database. The DIs for PFGE, flaA–SVR sequencing and CRISPR-HRMA were 0.986, 0.916 and 0.550, respectively. PFGE and flaA-SVR sequencing were suitable for subtyping C. coli strains, in contrast to CRISPR-HRMA. The high genomic similarity amongst some C. coli strains confirms the hypothesis that environmental and food sources potentially lead to human and animal contamination in Brazil.

How to Diagnose and Treat IBD Mimics in the Refractory IBD Patient Who Does Not Have IBD

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract and includes both Crohn's disease and ulcerative colitis. Patients with IBD often present with abdominal pain, diarrhea, and rectal bleeding but may also have a wide variety of other symptoms such as weight loss, fever, nausea, vomiting, and possibly obstruction. Given that the presentation of IBD is not specific, the differential diagnosis is broad and encompasses a wide spectrum of diseases, many of which can mimic and/or even coexist with IBD. It is important for physicians to differentiate symptoms due to refractory IBD from symptoms due to IBD mimics when a patient is not responding to standard IBD treatment. Many of the various IBD mimics include infectious etiologies (viral, bacterial, mycobacterial, fungal, protozoal, and helminthic infections), vascular causes, other immune causes including autoimmune etiologies, drug-induced processes, radiation-induced, and other etiologies such as small intestinal bacterial overgrowth, diverticulitis, and bile acid malabsorption. Thoughtful consideration and evaluation of these potential etiologies through patient history and physical examination, as well as appropriate tests, endoscopic evaluation, and cross-sectional imaging is required to evaluate any patient presenting with symptoms consistent with IBD.

Incidence rate and risk factors for giardiasis and strongyloidiasis in returning UK travellers

BACKGROUND

Few studies have investigated incidence rate and risk factors for giardiasis and strongyloidiasis in returning UK travellers. The clinical presentations of these two diseases are often similar and difficult to distinguish. This study was conducted to investigate the incidence rate and the risk factors for symptomatic giardiasis and strongyloidiasis in returned tropical travellers.

METHODS

We retrospectively analysed 3306 consecutive attendances presenting to the emergency clinic at the Hospital for Tropical Diseases in London, the UK from September 2008 to May 2010. Odds ratios between the diagnoses and patient variables were analysed by logistic regression.

RESULTS

Giardiasis was diagnosed in 92/3306 cases (2.8%, proportionate morbidity), and the incidence rate per 1000 person-months was 12.5. Multivariate analysis with logistic regression revealed that Caucasian ethnicity (adjusted odds ratio (aOR): 2.37, 95% confidence interval (CI): 1.12-5.03, P value = 0.025), travel length ≥32 days (aOR: 2.63, 95%CI: 1.43-4.83, P = 0.002), travelling to South or South East Asia (aOR: 4.90, 95%CI: 2.03-11.8, P < 0.001, aOR: 3.36, 95%CI: 1.43-7.93, P = 0.006), afebrile presentation (aOR: 2.14, 95%CI: 1.14-4.03, P = 0.018), and presenting with gastro-intestinal symptoms (aOR: 14.6, 95%CI: 6.08-35.0, P < 0.001) were all associated with giardiasis. In contrast, strongyloidiasis was found only in 0.94% (proportionate morbidity) of the cases (31/3306), and the incidence rate per 1000 person-months was 3.1. Multivariate analysis revealed that male sex (aOR: 3.05, 95%CI: 1.36-6.85, P = 0.007), and non-Caucasian ethnicity (aOR: 2.69, 95%CI: 1.32-5.49, P = 0.007) were associated with strongyloidiasis.

CONCLUSIONS

The incidence rate and risk factors for both infectious diseases were identified. The results of this study might guide clinicians to make more accurate and timely diagnoses in returned tropical travellers.

Infectious Risks of Traveling Abroad

A popular leisure activity, international travel can be associated with some infections. The most common travel-related illnesses appear to be gastrointestinal, dermatologic, respiratory, and systemic febrile syndromes. The pretravel medical consultation includes immunizations, malaria chemoprophylaxis, self-treatment for traveler's diarrhea, and advice on the prevention of a myriad of other infectious causes including dengue, chikungunya, rickettsiosis, leptospirosis, schistosomiasis, and strongyloidiasis. Travel to locations experiencing outbreaks such as Ebola virus disease, Middle East respiratory syndrome, avian influenza, and chikungunya call for specific alerts on preventive strategies. After travel, evaluation of an ill traveler must explore details of exposure, including destinations visited; activities; ingestion of contaminated food or drinks; contact with vectors, animals, fresh water, or blood and body fluids; and other potential exposures. Knowledge of the geographic distribution of infectious diseases is important in generating the differential diagnoses and testing accordingly. Empiric treatment is sometimes necessary when suspicion of a certain diagnosis is strong and confirmatory tests are delayed or lacking, particularly for infections that are rapidly progressive (for example, malaria) or for which timing of testing is prolonged (such as leptospirosis).