Interaction of Schistosoma japonicum with Salmonellae and other gram-negative bacteria

Schistosoma japonicum Associated Colorectal Cancer and Its Management

BACKGROUND

An association between Schistosoma japonicum and colorectal cancer in humans has been known since a long time; however, this association remains understudied and lacks comprehensive experimentation support.

OBJECTIVE

Various epidemiological and pathological studies have established the role of chronic inflammation as a major factor behind the induction of colorectal cancer. The aim of this review is to present the current knowledge on the association of Schistosoma japonicum with colorectal cancer.

RESULT

Mechanisms which lead to induction and progression of colorectal cancer are highlighted along with diagnosis and treatment for the same. Further, various methodologies, including mass drug administration, use of new drugs and vaccines, role of apoptosis, and histone-modifying enzymes, have been described which can either prevent the schistosomal infection itself or can check it from reaching an advanced stage.

CONCLUSIONS

Epidemiological, clinical, pathological and surgical studies suggest that Schistosoma japonicum is responsible for induction of colorectal cancer. However, thorough clinical studies are required to support and globally accept this notion. Further, methodologies highlighted in this work can be employed in order to take care of schistosomal infection or address the cancer induction and progression.

Non-typhoidal Salmonella intestinal carriage in a Schistosoma mansoni endemic community in a rural area of the Democratic Republic of Congo

BACKGROUND

Clinical observations and animal studies have suggested that Salmonella intestinal carriage is promoted by concurrent Schistosoma infection. The present study assessed association of Salmonella intestinal carriage and Schistosoma mansoni infection among individuals in a Schistosoma endemic area in sub-Saharan Africa.

METHODS

From November 2015 to March 2016, a cross-sectional community-wide study was conducted in Kifua II, a rural village in Kongo Central Province, Democratic Republic of Congo. Stool samples were collected and analyzed for Salmonella intestinal carriage (culture) and Schistosoma mansoni infection (Kato Katz microscopy with determination of egg load). Salmonella Typhimurium and Enteritidis isolates were assessed for genetic similarity with blood culture isolates obtained during the same period in a neighboring hospital using multi-locus variable-numbers tandem repeat analysis (MLVA).

RESULTS

A total of 1,108 participants were included (median age 15 years (IQR: 7-36), male-to-female ratio of 1:1.1). The overall prevalence of Schistosoma mansoni infection and non-typhoidal Salmonella carriage was 51.2% (95% CI: 48.2-54.1) and 3.4% (95% CI: 2.5-4.7) respectively, with 2.2% (95% CI: 1.5-3.2) of participants coinfected. The proportion of Salmonella carriage tended to be higher among Schistosoma mansoni infected participants compared to non-infected participants but this difference did not reach statistical significance (4.2% versus 2.6%, p = 0.132). However, the proportion of Salmonella carriage among participants with a heavy Schistosoma mansoni infection was significantly higher compared to those with a light and moderate infection (8.7% versus 3.2%, p = 0.012) and compared to Schistosoma mansoni negatives (8.7% versus 2.6%, p = 0.002). The 38 Salmonella isolates comprised five and four Enteritidis and Typhimurium serotypes respectively, the majority of them had MLVA types identical or similar to those observed among blood culture isolates.

CONCLUSION

Salmonella intestinal carriage was associated with a heavy intensity of Schistosoma mansoni infection. Further studies are needed to address causation.

Schistosoma japonicum-Associated Colorectal Cancer: A Review

Schistosoma japonicum is a digenetic blood fluke that has been implicated in the carcinogenesis of several human malignancies, notably liver and colorectal cancer (CRC). Schistosoma japonicum-associated colorectal cancer (SACC) is a distinct subtype with biological behavior analogous to colitis-induced CRC. The clinicopathological characteristics of SACC include young age at diagnosis, predominance among males, a strong predilection for the sigmoid colon and rectum, multifocal distribution, frequent mucinous histology, and poor prognosis. In addition to chronic inflammation, immunomodulation, and schistosomal toxins, bacterial coinfection appears to play an important role in the carcinogenic process. The present review provides the most recent updates on epidemiology, pathobiology, and clinical and prognostic features pertaining to SACC.

Symbiotic bacteria of helminths: what role may they play in ecosystems under anthropogenic stress?

Symbiotic bacteria are a common feature of many animals, particularly invertebrates, from both aquatic and terrestrial habitats. These bacteria have increasingly been recognized as performing an important role in maintaining invertebrate health. Both ecto- and endoparasitic helminths have also been found to harbour a range of bacterial species which provide a similar function. The part symbiotic bacteria play in sustaining homeostasis of free-living invertebrates exposed to anthropogenic pressure (climate change, pollution), and the consequences to invertebrate populations when their symbionts succumb to poor environmental conditions, are increasingly important areas of research. Helminths are also susceptible to environmental stress and their symbiotic bacteria may be a key aspect of their responses to deteriorating conditions. This article summarizes the ecophysiological relationship helminths have with symbiotic bacteria and the role they play in maintaining a healthy parasite and the relevance of specific changes that occur in free-living invertebrate-bacteria interactions under anthropogenic pressure to helminths and their bacterial communities. It also discusses the importance of understanding the mechanistic sensitivity of helminth-bacteria relationships to environmental stress for comprehending the responses of parasites to challenging conditions.

Coinfection of Schistosoma (Trematoda) with bacteria, protozoa and helminths

This review examines coinfection of selected species of Schistosoma with bacteria, protozoa and helminths and focuses on the effects of the coinfection on the hosts. The review is based mainly on tables that contain the salient information on the coinfecting organisms in vertebrate hosts. Further explanation and clarification of the tables are given in the text. A table is also provided that gives synoptic information on the 37 species in the 19 genera considered in this review. Coinfection studies with Schistosoma species and the other organisms were considered in six tables plus the accompanying text. Considerations of the Schistosoma interactions with another species of organism include studies on coinfection with Plasmodium, with protozoa other than Plasmodium; with Salmonella, with bacteria other than Salmonella; and with Fasciola, with helminths other than Fasciola. Numerous factors were found to influence the effects of coinfection on the vertebrate host, including organisms and hosts used in the studies, order and time interval between the first and the second infection, studies on natural versus experimental hosts, dosage of the infectious agents, strains and pedigrees of the parasites, age of hosts at time of exposure to the infectious agents and age of hosts at the time of necropsy. Overall, a prior infection with Schistosoma, particularly a patent infection, often has an effect on the subsequent infection by a protozoan, bacterium or other helminth. In relatively few cases, a prior infection with Schistosoma decreased the severity of the subsequent infection as with Helicobacter pylori, Fasciola hepatica, Echinostoma or Plasmodium, the latter only exhibiting this behaviour when coinfected with Schistosoma haematobium. More often, however, a prior infection with Schistosoma increased the severity of the second infection as with Leishmania, Toxoplasma gondii, Entamoeba histolytica, Staphylococcus aureus or Salmonella. In some of these coinfection studies, the increased severity of the subsequent infection was associated with a specific, prolonged form of the disease in humans, which has implications for patient treatment and recovery. Additional research is needed, particularly on Schistosoma coinfections which currently have a small body of research and are current problems in human populations. Examples of such Schistosoma interactions include the genera of Mycobacteria, Leishmania, Staphylococcus, Necator and Strongyloides. Hopefully, future studies will elucidate valuable new information on the interesting subject of coinfection of Schistosoma with other organisms.

Schistosomiasis and signet ring cell carcinoma of the rectum

A definitive link between Schistosoma hematobium infection and squamous cell carcinoma of the bladder has been identified. A weaker association between S japonicum infection and colorectal neoplasia has been proposed, although reports are limited to case reports, a case series, and epidemiologic studies. Virtually all cases presented in the literature describe intestinal-type adenocarcinoma occurring in association with S japonicum. We here describe a 40-year-old male Filipino patient with signet ring cell carcinoma of the rectum and evidence of infection by S japonicum.

Colorectal carcinoma associated with schistosomiasis: a possible causal relationship

The association between schistosomiasis and colorectal malignancy has long been suggested in the literature, but it is not uniformly accepted. In the Far East, considerable evidence supports an etiological link between Schistosoma japonicum and colorectal cancer. However, the available data regarding the role of Schistosoma mansoni in colorectal carcinogenesis are conflicting and most often do not show causality. We report on a patient with sigmoid colonic cancer coexisting with schistosomiasis, and we provide a comprehensive review of the literature regarding the epidemiology and pathobiology of this association.

The ultrastructure of hypersymbionts on the monogenean Gyrodactylus salaris infecting Atlantic salmon Salmo salar

There is increasing pressure to develop alternative control strategies against the pathogen Gyrodactylus salaris, which has devastated wild Atlantic salmon Salmo salar in Norway. Hyperparasitism is one option for biological control and electron microscopy has revealed two ectosymbionts associated with G. salaris: unidentified rod-shaped bacteria, and the protist, Ichthyobodo necator. No endosymbionts were detected. The flagellate I. necator occurred only occasionally on fish suffering costiosis, whereas bacterial infections on the tegument of G. salaris were observed throughout the year, but at variable densities. Bacteria were seldom observed attached to fish epidermis, even when individuals of G. salaris on the same host were heavily infected. Wounds on salmon epidermis caused by the feeding activity of bacteria-infected G. salaris did not appear to be infected with bacteria. On heavily infected gyrodactylids, bacteria were most abundant anteriorly on the cephalic lobes, including the sensory structures, but no damaged tissue was detected by transmission electron microscopy in the region of bacterial adherence. Furthermore, transmission and survival of infected G. salaris on wild salmon did not appear to be influenced by the bacterial infection. The lack of structural damage and impact on G. salaris biology indicates that these bacteria are not a potential agent for control of gyrodactylosis. However, this may not be the case for all gyrodactylid–bacterial interactions and a review of bacterial infections of platyhelminths is presented.

Morphological variability withinOesophagostomum bifurcumamong different primate species from Ghana

AdultOesophagostomum bifurcum(Nematoda: Strongylida) from human and non-human primates from Ghana were compared in order to investigate the extent of morphological variability within the species. Using analysis of variance and principal component analysis, significant differences in morphological characters (such as parasite length, width, length of the oesophagus and length of spicules) were demonstrated betweenO. bifurcumworms from humans, the Mona, Patas or Green monkey and/or Olive baboons. These findings suggest thatO. bifurcumfrom different species of primate host represent distinct population variants, also supported by recent epidemiological and genetic studies ofO. bifurcumfrom such hosts.