Effects of schistosomes on host anti-viral immune response and the acquisition, virulence, and prevention of viral infections: A systematic review

Schistosoma mansoni infection and hepatitis B surface antigen carriage rate among school children in Jille Timuga District, Amhara Region, Northeast Ethiopia

BACKGROUND

Hepatitis B virus (HBV) is highly prevalent and a major health problem in developing countries. Controversial findings are reported on the effect of schistosomiasis and HBV infection. This study aimed to describe the association of S. mansoni infection with Hepatitis B surface antigen (HBsAg) carriage rate in schistosome endemic setting.

METHODS

A cross-sectional study was conducted from January to March 2024 among school children aged 7-14 years old in two primary schools of Jille Timuga district of Oromo special zone, Amhara region, Ethiopia. Demographic and health related data was collected by Kobo collect tool. Blood and stool specimens were collected to test Hepatitis B infection using rapid test kit and S.mansoni infection by kato-katz method respectively. The data was analyzed by STATA version 17 statistical software. A descriptive statistic, bivariate and multivariate logistic regression analysis was used to identify associated factors. P-value of <0.05 was used as a cut-off in reporting statistical significance.

RESULTS

A total of 300 children participated in the study with a mean age of 10.5 years (±2) ranging from 7 to 14 years. Eighty-nine (29.6%) children were infected with S. mansoni and the sero-prevalence of hepatitis B surface antigen was 0.3%; no co-infection was observed. Children who had taken praziquantel mass treatment recently (<6 month) had higher infection rate at 34%. Likewise, highest prevalence of S. mansoni infection (39.8%) was found among 11-12 years age group. A significant association of sex with higher S.mansoni infection rate was observed where males had 2.07 increased odds of infection.

CONCLUSIONS

The observed prevalence of S. mansoni infection (29.6%) was high in view of the ongoing preventive chemotherapy using praziquantel. The low, 0.3%, prevalence of HBV in the setting of higher S.mansoni prevalence underscore non well defined association of HBSAg carriage with schistosomiasis. However, a larger, well-controlled further research is recommended. The infection rate of S. mansoni was higher among children who recently took praziquantel which highlight the limitations of mass drug administration (MDA) program and possibility of re-infection. These emphasize the need for integrated schistosomiasis control programs, combining mass drug administration with other supportive intervention measures such as snail control.

Impact of Schistosoma mansoni Infection on the Gut Microbiome and Hepatitis B Vaccine Immune Response in Fishing Communities of Lake Victoria, Uganda

OBJECTIVE

Schistosoma mansoni (S. mansoni) infection is endemic in Ugandan fishing communities. We investigated its potential impact on Hepatitis B (Hep B) vaccine responses and its role in mediating the association between the gut microbiome and long-term effectiveness of the vaccine.

METHODS

Participants were tested for S. mansoni infections at baseline and received the Hep B vaccine at baseline, month 1, and month 6. Those with infections were treated. Stool samples were collected at baseline and analyzed using 16S rRNA sequencing. The Wilcoxon rank-sum test was used to compare alpha diversity between groups. A linear regression model was applied to estimate the association between one-year Hep B vaccine responses and the baseline gut microbiome by infection status, adjusting for age and sex.

RESULTS

A total of 107 participants were included (44 from the fishing community and 63 from the Kampala community). There was no significant difference in microbiome composition by location or infection status at baseline or discharge. In the linear regression analysis, S. mansoni infection (β = 1.24, p = 0.025) and a higher alpha diversity (β = 0.001, p = 0.07) were associated with higher Hep B vaccine responses, while older age was associated with a lower Hep B vaccine response (β = -0.06, p = 0.0013).

CONCLUSIONS

S. mansoni infection status before vaccination may modify the association between the gut microbiome and Hep B vaccine response. Potential interventions could focus on infection control as well as improving microbiome richness before implementing vaccine programs in fishing communities.

Effects of Schistosoma haematobium infection and treatment on the systemic and mucosal immune phenotype, gene expression and microbiome: A systematic review

BACKGROUND

Urogenital schistosomiasis caused by Schistosoma haematobium affects approximately 110 million people globally, with the majority of cases in low- and middle-income countries. Schistosome infections have been shown to impact the host immune system, gene expression, and microbiome composition. Studies have demonstrated variations in pathology between schistosome subspecies. In the case of S. haematobium, infection has been associated with HIV acquisition and bladder cancer. However, the underlying pathophysiology has been understudied compared to other schistosome species. This systematic review comprehensively investigates and assimilates the effects of S. haematobium infection on systemic and local host mucosal immunity, cellular gene expression and microbiome.

METHODS

We conducted a systematic review assessing the reported effects of S. haematobium infections and anthelmintic treatment on the immune system, gene expression and microbiome in humans and animal models. This review followed PRISMA guidelines and was registered prospectively in PROSPERO (CRD42022372607). Randomized clinical trials, cohort, cross-sectional, case-control, experimental ex vivo, and animal studies were included. Two reviewers performed screening independently.

RESULTS

We screened 3,177 studies and included 94. S. haematobium was reported to lead to: (i) a mixed immune response with a predominant type 2 immune phenotype, increased T and B regulatory cells, and select pro-inflammatory cytokines; (ii) distinct molecular alterations that would compromise epithelial integrity, such as increased metalloproteinase expression, and promote immunological changes and cellular transformation, specifically upregulation of genes p53 and Bcl-2; and (iii) microbiome dysbiosis in the urinary, intestinal, and genital tracts.

CONCLUSION

S. haematobium induces distinct alterations in the host's immune system, molecular profile, and microbiome. This leads to a diverse range of inflammatory and anti-inflammatory responses and impaired integrity of the local mucosal epithelial barrier, elevating the risks of secondary infections. Further, S. haematobium promotes cellular transformation with oncogenic potential and disrupts the microbiome, further influencing the immune system and genetic makeup. Understanding the pathophysiology of these interactions can improve outcomes for the sequelae of this devastating parasitic infection.

Clinical and Demographic Factors Associated With Kaposi Sarcoma-Associated Herpesvirus Shedding in Saliva or Cervical Secretions in a Cohort of Tanzanian Women

Background

Reasons for the high prevalence of Kaposi sarcoma-associated herpesvirus (KSHV) in sub-Saharan Africa, and risk factors leading to viral reactivation and shedding, remain largely undefined. Preliminary studies have suggested that schistosome infection, which has been associated with impaired viral control, is associated with KSHV. In this study we sought to determine the relationship between active Schistosoma mansoni or Schistosoma haematobium infection and KSHV shedding.

Methods

We quantified KSHV DNA in saliva and cervical swabs from 2 cohorts of women living in northwestern Tanzanian communities endemic for S mansoni or S haematobium by real-time polymerase chain reaction. χ2 and Fisher exact tests were used to determine differences in clinical and demographic factors between those who were and were not shedding KSHV.

Results

Among 139 total women, 44.6% were KSHV seropositive. Six percent of those with S mansoni and 17.1% of those with S haematobium were actively shedding KSHV in saliva and none in cervical samples. Women from the S mansoni cohort who were shedding virus reported infertility more frequently (80% vs 19.5%, P = .009). There was no difference in frequency of KSHV salivary shedding between schistosome-infected and -uninfected women.

Conclusions

In an area with high KSHV seroprevalence and endemic schistosome infections, we provide the first report with data demonstrating no association between schistosome infection and salivary or cervical herpesvirus shedding. KSHV salivary shedding was associated with infertility, a known effect of another herpesvirus, human herpesvirus 6.

Beyond schistosomiasis: unraveling co-infections and altered immunity

Schistosomiasis is a neglected tropical disease caused by the helminth Schistosoma spp. and has the second highest global impact of all parasites. Schistosoma are transmitted through contact with contaminated fresh water predominantly in Africa, Asia, the Middle East, and South America. Due to the widespread prevalence of Schistosoma, co-infection with other infectious agents is common but often poorly described. Herein, we review recent literature describing the impact of Schistosoma co-infection between species and Schistosoma co-infection with blood-borne protozoa, soil-transmitted helminths, various intestinal protozoa, Mycobacterium, Salmonella, various urinary tract infection-causing agents, and viral pathogens. In each case, disease severity and, of particular interest, the immune landscape, are altered as a consequence of co-infection. Understanding the impact of schistosomiasis co-infections will be important when considering treatment strategies and vaccine development moving forward.

Single-cell RNA sequencing reveals a peripheral landscape of immune cells in Schistosomiasis japonica

BACKGROUND

Schistosomiasis, also known as bilharzia, is a devastating parasitic disease. This progressive and debilitating helminth disease is often associated with poverty and can lead to chronic poor health. Despite ongoing research, there is currently no effective vaccine for schistosomiasis, and praziquantel remains the only available treatment option. According to the progression of schistosomiasis, infections caused by schistosomes are classified into three distinct clinical phases: acute, chronic and advanced schistosomiasis. However, the underlying immune mechanism involved in the progression of schistosomiasis remains poorly understood.

METHODS

We employed single-cell RNA sequencing (scRNA-seq) to profile the immune landscape of Schistosomiasis japonica infection based on peripheral blood mononuclear cells (PBMCs) from a healthy control group (n = 4), chronic schistosomiasis group (n = 4) and advanced schistosomiasis group (n = 2).

RESULTS

Of 89,896 cells, 24 major cell clusters were ultimately included in our analysis. Neutrophils and NK/T cells accounted for the major proportion in the chronic group and the healthy group, and monocytes dominated in the advanced group. A preliminary study showed that NKT cells were increased in patients with schistosomiasis and that CXCR2 + NKT cells were proinflammatory cells. Plasma cells also accounted for a large proportion of B cells in the advanced group. MHC molecules in monocytes were notably lower in the advanced group than in the chronic group or the healthy control group. However, monocytes in the advanced group exhibited high expression of FOLR3 and CCR2.

CONCLUSIONS

Overall, this study enhances our understanding of the immune mechanisms involved in schistosomiasis. It provides a transcriptional atlas of peripheral immune cells that may contribute to elimination of the disease. This preliminary study suggests that the increased presence of CCR2 + monocyte and CXCR2 + NKT cells might participate in the progression of schistosomiasis.

Antigens from the Helminth Fasciola hepatica Exert Antiviral Effects against SARS-CoV-2 In Vitro

SARS-CoV-2, the causal agent of COVID-19, is a new coronavirus that has rapidly spread worldwide and significantly impacted human health by causing a severe acute respiratory syndrome boosted by a pulmonary hyperinflammatory response. Previous data from our lab showed that the newly excysted juveniles of the helminth parasite Fasciola hepatica (FhNEJ) modulate molecular routes within host cells related to vesicle-mediated transport and components of the innate immune response, which could potentially be relevant during viral infections. Therefore, the aim of the present study was to determine whether FhNEJ-derived molecules influence SARS-CoV-2 infection efficiency in Vero cells. Pre-treatment of Vero cells with a tegument-enriched antigenic extract of FhNEJ (FhNEJ-TEG) significantly reduced infection by both vesicular stomatitis virus particles pseudotyped with the SARS-CoV-2 Spike protein (VSV-S2) and live SARS-CoV-2. Pre-treatment of the virus itself with FhNEJ-TEG prior to infection also resulted in reduced infection efficiency similar to that obtained by remdesivir pre-treatment. Remarkably, treatment of Vero cells with FhNEJ-TEG after VSV-S2 entry also resulted in reduced infection efficiency, suggesting that FhNEJ-TEG may also affect post-entry steps of the VSV replication cycle. Altogether, our results could potentially encourage the production of FhNEJ-derived molecules in a safe, synthetic format for their application as therapeutic agents against SARS-CoV-2 and other related respiratory viruses.

Schistosoma mansoni infection alters the host pre-vaccination environment resulting in blunted Hepatitis B vaccination immune responses

Schistosomiasis is a disease caused by parasitic flatworms of the Schistosoma spp., and is increasingly recognized to alter the immune system, and the potential to respond to vaccines. The impact of endemic infections on protective immunity is critical to inform vaccination strategies globally. We assessed the influence of Schistosoma mansoni worm burden on multiple host vaccine-related immune parameters in a Ugandan fishing cohort (n = 75) given three doses of a Hepatitis B (HepB) vaccine at baseline and multiple timepoints post-vaccination. We observed distinct differences in immune responses in instances of higher worm burden, compared to low worm burden or non-infected. Concentrations of pre-vaccination serum schistosome-specific circulating anodic antigen (CAA), linked to worm burden, showed a significant bimodal distribution associated with HepB titers, which was lower in individuals with higher CAA values at month 7 post-vaccination (M7). Comparative chemokine/cytokine responses revealed significant upregulation of CCL19, CXCL9 and CCL17 known to be involved in T cell activation and recruitment, in higher CAA individuals, and CCL17 correlated negatively with HepB titers at month 12 post-vaccination. We show that HepB-specific CD4+ T cell memory responses correlated positively with HepB titers at M7. We further established that those participants with high CAA had significantly lower frequencies of circulating T follicular helper (cTfh) subpopulations pre- and post-vaccination, but higher regulatory T cells (Tregs) post-vaccination, suggesting changes in the immune microenvironment in high CAA could favor Treg recruitment and activation. Additionally, we found that changes in the levels of innate-related cytokines/chemokines CXCL10, IL-1β, and CCL26, involved in driving T helper responses, were associated with increasing CAA concentration. This study provides further insight on pre-vaccination host responses to Schistosoma worm burden which will support our understanding of vaccine responses altered by pathogenic host immune mechanisms and memory function and explain abrogated vaccine responses in communities with endemic infections.

Effects of Schistosoma mansoni and praziquantel treatment on the lower gastrointestinal mucosa: A cohort study in Tanzania

Schistosomes infect over 200 million people worldwide, but few studies have characterized the effects of Schistosoma mansoni infection and effective treatment on the lower gastrointestinal mucosa. In this prospective cohort study, we compared the clinical findings on sigmoidoscopy and laboratory measures in Tanzanian adults with and without S. mansoni infection at baseline and 6 months after praziquantel treatment. Grading of the endoscopic findings was done using the Mayo Scoring System for Assessment of Ulcerative Colitis Activity. Schistosome infection was confirmed by stool microscopy and serum circulating anodic antigen (CAA). Baseline comparisons were performed in Stata using Fisher's exact and Wilcoxon rank-sum tests, and pre- and post-treatment comparisons using Wilcoxon matched-pairs signed-rank and McNemar's tests. We investigated the clinical characteristics of 48 individuals: 32 with and 16 without S. mansoni infection. Infected individuals had greater severity of sigmoid and rectal mucosal abnormalities and higher Mayo scores and serum eosinophils (all p < 0.05) than uninfected individuals at initial evaluation. At 6 months, 28 individuals completed repeat blood tests and sigmoidoscopy. Of these, 14 cleared their baseline infection (n = 7) or experienced a greater than 7-fold decrease in serum CAA (n = 7). Follow-up sigmoidoscopies revealed some improvements in sigmoid and rectal mucosal findings, although Mayo scores were not significantly lower. Both the median erythrocyte sedimentation rates (32.5→12.5 mm/hr) and percent of eosinophils (7.1→3.1%) decreased in this group from baseline to follow-up. S. mansoni infection was associated with mild-to-moderate lower gastrointestinal mucosal abnormalities that were grossly visible during sigmoidoscopy, and these improved partially 6 months after effective treatment with praziquantel. Additional studies, of longer duration and focused on both clinical and mucosal immunologic effects of S. mansoni, could provide additional insight.

Schistosoma mansoni Infection Is Associated With Increased Monocytes and Fewer Natural Killer T Cells in the Female Genital Tract

Schistosoma mansoni infection may impair genital mucosal antiviral immunity, but immune cell populations have not been well characterized. We characterized mononuclear cells from cervical brushings of women with and without S mansoni infection. We observed lower frequencies of natural killer T cells and higher frequencies of CD14⁺ monocytes in infected women.

Diarrhoea-causing enteric protist species in intensively and extensively raised pigs (Sus scrofa domesticus) in Southern Spain. Part II: Association with Hepatitis E virus susceptibility

Enteropathogenic parasites can infect a wide range of mammals, including humans, supposing an important zoonotic risk. Hepatitis E virus (HEV) is an emerging foodborne pathogen of increasing public health relevance, affecting both humans and animal populations. Because both microorganisms share faecal-oral transmission route they may constitute an excellent model to evaluate the interplay between them. Thus, we aim to evaluate the viral-parasite interactions at the enteric interface in swine. We included pigs of two different breeds farming in South Spain under different production systems. We compared the HEV prevalence by the presence of Giardia duodenalis, Cryptosporidium spp., Balantioides coli, Blastocystis sp. and Enterocytozoon bieneusi in faecal samples. The HEV prevalence was 13.1 (62 out 475, 95% CI: 10.2-16.4). Those pigs infected with Cryptosporidium spp. showed a higher prevalence of HEV (30.8 vs. 12%; p = .012). In the same way, animals bearing E. bieneusi seem to have a higher rate of HEV infection (24.2 vs. 12.2%; p = .06). According to their location in the gut, animals bearing intracellular enteroparasites showed a higher HEV prevalence than those uninfected (29.6 vs. 12.7%; p = .038), meanwhile those carrying extracellular enteroparasites had a lower likelihood to be infected by HEV than those uninfected (12.1 vs. 23.1%; p = .071). Those animals bearing both types of enteroparasites showed a similar prevalence of HEV infection than those exhibiting negative for both (20.8 vs. 26.1%; p = .763). Our study provides evidence that intracellular and extracellular enteroparasites modulate the susceptibility to HEV infection in pigs. Meanwhile, the presence of extracellular enteroparasites shows a protective effect on the risk of HEV acquisition in swine, whereas intracellular enteroparasites seems to have the opposite effect, favouring the HEV infection.