Bacterial and Parasitic Pathogens as Risk Factors for Cancers in the Gastrointestinal Tract: A Review of Current Epidemiological Knowledge

The oncogenic potential of viral infections is well established and documented for many years already. However, the contribution of (commensal) bacteria and parasites to the development and progression of cancers has only recently gained momentum, resulting in a rapid growth of publications on the topic. Indeed, various bacteria and parasites have been suggested to play a role in the development of gastrointestinal cancer in particular. Therefore, an overview of the current epidemiological knowledge on the association between infections with bacteria and parasites and cancers of the gastrointestinal tract is needed. In this review, we summarized the methodological characteristics and main results of epidemiological studies investigating the association of 10 different bacteria (Bacteroides fragilis, Campylobacter spp., Clostridium spp., Enterococcus faecalis, Escherichia coli, Fusobacterium nucleatum, Porphyromonas gingivalis, non-typhoidal Salmonella, Salmonella Typhi, and Streptococcus spp.) and three parasites (Cryptosporidium spp., Schistosoma spp., and Strongyloides stercoralis) with gastrointestinal cancer. While the large body of studies based on microbiome sequencing provides valuable insights into the relative abundance of different bacterial taxa in cancer patients as compared to individuals with pre-malignant conditions or healthy controls, more research is needed to fulfill Koch’s postulates, possibly making use of follow-up data, to assess the complex role of bacterial and parasitic infections in cancer epidemiology. Studies incorporating follow-up time between detection of the bacterium or parasite and cancer diagnosis remain valuable as these allow for estimation of cause-effect relationships.

Parasitic and Vector-Borne Infections in HIV-Positive Patients in Slovakia—Evidence of an Unexpectedly High Occurrence of Anaplasma phagocytophilum

In HIV (human immunodeficiency virus) infected people, the immunodeficiency caused by a reduced level of CD4 (cluster of differentiation 4) T-lymphocytes increases the risk of infectious diseases. Additionally, in individuals with immunologically compromising conditions, tick-borne or some parasitic pathogens may cause chronic, debilitating opportunistic infections and even death. The study aimed at determining the IgG seropositivity of HIV-infected patients to Toxoplasma gondii, Toxocara spp., Echinococcus multilocularis, and E. granulosus s.l. and performing the molecular identification of T. gondii and some tick-borne pathogens, namely, Borrelia spp., Babesia spp., Anaplasma phagocytophilum, Rickettsia spp., and Bartonella spp. Out of 89 HIV-positive patients, specific IgG antibodies to T. gondii were detected in 17 (19.1%) and to Borrelia spp. in 12 (13.5%) individuals. Seropositivity to Toxocara spp., E. multilocularis, and E. granulosus s.l. was not recorded. Molecular approaches showed positivity to T. gondii in two (2.2%) patients, and 11 (12.4%) individuals had positive PCR signal for the msp2 gene of A. phagocytophilum. Relatively high prevalence of A. phagocytophilum in HIV-positive patients suggests that these people are more susceptible to some vector-borne pathogens. The presence of opportunistic infections may pose a health risk for patients with weakened immune systems, and should not be neglected during the regular monitoring of the patient’s health status.

Molecular Detection and Characterization of Intestinal and Blood Parasites in Wild Chimpanzees (Pan troglodytes verus) in Senegal

Wild chimpanzee populations in West Africa (Pan troglodytes verus) have dramatically decreased as a direct consequence of anthropogenic activities and infectious diseases. Little information is currently available on the epidemiology, pathogenic significance, and zoonotic potential of protist species in wild chimpanzees. This study investigates the occurrence and genetic diversity of intestinal and blood protists as well as filariae in faecal samples (n = 234) from wild chimpanzees in the Dindefelo Community Nature Reserve, Senegal. PCR-based results revealed the presence of intestinal potential pathogens (Sarcocystis spp.: 11.5%; Giardia duodenalis: 2.1%; Cryptosporidium hominis: 0.9%), protist of uncertain pathogenicity (Blastocystis sp.: 5.6%), and commensal species (Entamoeba dispar: 18.4%; Troglodytella abrassarti: 5.6%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected. Blood protists including Plasmodium malariae (0.4%), Trypanosoma brucei (1.3%), and Mansonella perstans (9.8%) were also identified. Sanger sequencing analyses revealed host-adapted genetic variants within Blastocystis, but other parasitic pathogens (C. hominis, P. malariae, T. brucei, M. perstans) have zoonotic potential, suggesting that cross-species transmission between wild chimpanzees and humans is possible in areas where both species overlap. Additionally, we explored potential interactions between intestinal/blood protist species and seasonality and climate variables. Chimpanzees seem to play a more complex role on the epidemiology of pathogenic and commensal protist and nematode species than initially anticipated.

Infectious diseases and prions

Infectious diseases continue to contribute considerably to the global burden of morbidity, disability, and mortality, especially in low- and middle-income countries. Lower respiratory infections, diarrhoea, and tuberculosis remain among the top ten causes of mortality for all ages and sexes. Moreover, the emergence of many new viral, bacterial, fungal, and parasitic pathogens as well as rising antimicrobial resistance are current challenges. Despite a decline in infectious disease mortality, the growing dangers of antimicrobial resistance and emerging infections pose a critical threat to the health of millions. It is imperative, now more than ever, to scale up interventions for prevention and control of infectious diseases while promoting judicious use of antimicrobials.

722. Parasitic and Non-Parasitic Causes of Eosinophilia in Children Presenting to a Tertiary Care Center in the United States

Background Peripheral eosinophilia can be caused by many underlying conditions, including infectious pathogens, allergic disorders, neoplastic disorders, and immunological disorders. However, uncovering the cause of eosinophilia in children can be challenging due to the wide differential diagnosis. Methods To identify causes and risk factors of eosinophilia in children, we performed a retrospective chart review of children presenting to Texas Children’s Hospital in Houston, TX with peripheral eosinophilia from January 1, 2011 to December 31, 2019. Eosinophilia was classified as mild (absolute eosinophilia count or AEC >500 and < 1500), moderate (AEC >1500 and < 5000) and severe (AEC > 5000). Demographic information in addition to travel history, co-morbid conditions, and diagnostic workup were collected. Results A total of 773 patients under 18 years of age were evaluated. The most common cause of eosinophilia in children was atopy (N=343, 44%), followed by eosinophilia of unknown etiology (N=227, 29%). Infectious pathogens were the etiology in 8% of cases of which all were parasitic pathogens. Helminthic (n=48, 79% of parasitic diseases in total) pathogens were more common than protozoan (n=13, 21% of parasitic diseases in total) and patients with parasitic infections had higher median eosinophilia compared to other subgroups (median = 1661, range 512-17,501) with the majority having moderate to severe eosinophilia (57%). The most common helminth was Toxocara (n=31), followed by Strongyloides (n=15), and, more rarely, pinworms (n=4). The most common protozoa identified was Dientamoeba fragilis (n=9), followed by Giardia species (n=5), Endolimax nana (n=4), Blastocystis species (n=3), and Iodamoeba butschlii (n=1). Many unknown cases had limited workup that did not include investigations for common parasites. Conclusion While atopy and unknown etiology were the most common diagnoses for children presenting with eosinophilia, parasites were relatively common and should be considered in the differential when investigating etiologies for peripheral eosinophilia. Disclosures Joud Hajjar, MD, MS, Baxalta (Grant/Research Support)Horizon (Advisor or Review Panel member)Pharming (Advisor or Review Panel member)

Systematic Review on the Correlation of Quantitative PCR Cycle Threshold Values of Gastrointestinal Pathogens With Patient Clinical Presentation and Outcomes

Background: Quantitative (q) polymerase chain reaction (PCR) cycle threshold (Ct) values represent the number of amplification cycles required for a positive PCR result and are a proxy of pathogen quantity in the tested sample. The clinical utility of Ct values remains unclear for gastrointestinal infections.Objectives: This systematic review assesses the global medical literature for associations between Ct values of gastrointestinal pathogens and patient presentation and clinical outcomes.Data Sources: MEDLINE, EMBASE, Cochrane library databases: searched January 14–17, 2020.Study Eligibility Criteria: Studies reporting on the presence or absence of an association between Ct values and clinical outcomes in adult and pediatric populations were included. Animal studies, reviews, meta-analyses, and non-English language studies were excluded.Participants: Humans infected with gastrointestinal pathogens, detected with qPCR.Interventions: Diagnostics assessing Ct values. Extracted data were reported narratively.Results: Thirty-three eligible studies were identified; the most commonly studied pathogens were Clostridioides difficile (n = 15), norovirus (n = 10), and rotavirus (n = 9). Statistically significant associations between low C. difficile Ct values and increased symptom severity or poor outcome were reported in 4/8 (50%) studies, and increased risk of death in 1/2 (50%) studies; no significant associations were found between Ct value and duration of symptoms or length of hospital stay. Among studies of norovirus, 5/7 (71%), mainly genogroup II, reported symptomatic cases with significantly lower median Ct values than controls. Significantly lower rotavirus Ct values were also observed in symptomatic cases vs. controls in 3/7 (43%) studies, and associated with more severe symptoms in 2/2 studies. Contradictory associations were identified for non-C. difficile bacterial and parasitic pathogens.Conclusions: In conclusion, some studies reported clinically useful associations between Ct values and patient or healthcare outcomes; additional, well-designed, large-scale trials are warranted based on these findings.Systematic Review Registration: [PROSPERO], identifier [CRD42020167239].

Survey on the Presence of Bacterial and Parasitic Zoonotic Agents in the Feces of Wild Birds

Wild avifauna may act as fecal source of bacterial and parasitic pathogens for other birds and mammals. Most of these pathogens have a relevant impact on human and livestock health which may cause severe disease and economic loss. In the present study, the fecal samples collected from 121 wild birds belonging to 15 species of the genera Anas, Tadorna, Fulica, Arddea, Larus, Falco, Athene, Accipiter, and Columba were submitted to bacteriological and molecular analyses to detect Brucella spp., Coxiella burnetii, Mycobacterium spp., Salmonella spp., Cryptosporidium spp., Giardia spp., and microsporidia. Four (3.3%) animals were positive for one pathogen: one Anas penelope for C. burnetii, one Larus michahellis for S. enterica serovar Coeln, and two Columba livia for Encephalitozoon hellem. Although the prevalence rates found in the present survey were quite low, the obtained results confirm that wild birds would be the a potential fecal source of bacterial and parasitic zoonotic pathogens which sometimes can also represent a severe threat for farm animals.

Evolution of Cellular Immunity Effector Cells; Perspective on Cytotoxic and Phagocytic Cellular Lineages

The immune system has evolved to protect organisms from infections caused by bacteria, viruses, and parasitic pathogens. In addition, it provides regenerative capacities, tissue maintenance, and self/non-self recognition of foreign tissues. Phagocytosis and cytotoxicity are two prominent cellular immune activities positioned at the base of immune effector function in mammals. Although these immune mechanisms have diversified into a wide heterogeneous repertoire of effector cells, it appears that they share some common cellular and molecular features in all animals, but also some interesting convergent mechanisms. In this review, we will explore the current knowledge about the evolution of phagocytic and cytotoxic immune lineages against pathogens, in the clearance of damaged cells, for regeneration, for histocompatibility recognition, and in killing virally infected cells. To this end, we give different immune examples of multicellular organism models, ranging from the roots of bilateral organisms to chordate invertebrates, comparing to vertebrates’ lineages. In this review, we compare cellular lineage homologies at the cellular and molecular levels. We aim to highlight and discuss the diverse function plasticity within the evolved immune effector cells, and even suggest the costs and benefits that it may imply for organisms with the meaning of greater defense against pathogens but less ability to regenerate damaged tissues and organs.

Biology, Taxonomy, and Management of the Root-Knot Nematode (Meloidogyne incognita) in Sweet Potato

Sweet potato is the seventh-ranked food crop produced after wheat, rice, maize, potato, barley, and cassava in the world. It is the most important root tuber crop in temperate, subtropical, and tropical areas of the world. It is grown for food, income-generating, and jobs for farmers and retailers. The important nutritional substances of sweet potatoes are ß-carotene and anthocyanins. However, the production and its valuable products are limited due to root-knot nematode parasitism. One of the most important destructive species of root-knot nematode to this crop is Meloidogyne incognita. The most destructive stage to sweet potato is at its second juvenile stage (J2). At this stage, it invades the roots and tubers of sweet potato highly in warm sandy soil conditions. It is an obligate plant-parasitic nematode. M. incognita caused significant yield loss to sweet potato in terms of quality, quantity, disturbing the process of photosynthesis and nutrient uptake through the formation of galling, establishing of its feeding sites, or induced galls that contain giant-feeding cells, and cracking of tubers and roots directly. It also reduces the market values of the infected tuber of sweet potato by downgrading the production values. The problem of quality and quantity losses to sweet potato by this pest is one of the major problems nowadays. It caused this problem alone or interaction with other plant-parasitic pathogens or through synergistic of fungi, bacteria, viruses, and others. Therefore, this review paper is focused on the sweet potato M. incognita biology, taxonomy, geographical distribution, and management measures.

Occurrence of Intestinal Parasites in Fruits and Vegetables from Markets of Northwest Mexico

Background: Fruits and vegetables are potential vehicle of transmission of intestinal parasites. The main aim of this study was to determine prevalence of intestinal parasitic contamination in fruits and vegetables sampled from Caborca region, Northwest Mexico. Methods: A total of 400 fruit and vegetable samples were collected from unregulated open-air markets and closed (i.e., regulated) markets in Caborca region of Northwest Mexico; including melon, peach, asparagus, and grapes. Faust, Kinyoun, and Enzyme- Linked Immunosorbent Assay (ELISA) techniques were used to detect and identify the genus and species of all parasites found in the examined samples. Data were statistically analyzed using STATA/SE (version 12.0). Results: An overall prevalence (45%) of parasitic contamination was found in the 400 fruit and vegetable samples. Endolimax nana (27.5%) and Entamoeba coli (17.5%) were the most common nonpathogenic parasites, while the most prevalent parasitic pathogens were Cryptosporidium spp. (11.7%), Cyclospora spp., (11.0%), and Blastocystis hominis (9.2%). Asparagus (31%) and grapes (38.9%) had significantly (p<0.05) higher percent- ages of overall and multiple parasitic contamination than melon (10.6%) and peaches (19.4%). The fresh produce from the open-air markets had significantly (p<0.05) higher overall parasitic contamination (53.5%) than those of the closed establishments (36.5%). Conclusion: The parasitic contamination in the fresh produce sold in the Northwest region of Mexico is a serious public health concern.