Although a growing number of studies suggest interactions between Schistosoma parasites and viral infections, the effects of schistosome infections on the host response to viruses have not been... Show moreAlthough a growing number of studies suggest interactions between Schistosoma parasites and viral infections, the effects of schistosome infections on the host response to viruses have not been evaluated comprehensively. In this systematic review, we investigated how schistosomes impact incidence, virulence, and prevention of viral infections in humans and animals. We also evaluated immune effects of schistosomes in those coinfected with viruses. We screened 4,730 studies and included 103. Schistosomes may increase susceptibility to some viruses, including HIV and Kaposi's sarcoma-associated herpesvirus, and virulence of hepatitis B and C viruses. In contrast, schistosome infection may be protective in chronic HIV, Human T-cell Lymphotropic Virus-Type 1, and respiratory viruses, though further research is needed. Schistosome infections were consistently reported to impair immune responses to hepatitis B and possibly measles vaccines. Understanding the interplay between schistosomes and viruses has ramifications for anti-viral vaccination strategies and global control of viral infections.Author summary Many studies have described the effects of parasitic Schistosoma worm infections on the way that humans and animals respond to a variety of viral infections. Our goal was to evaluate, in a systematic manner, how having a schistosome parasitic infection affects a host's susceptibility to viral infections, the clinical disease course of viral infections, and prevention of viral infections by vaccines. We also assessed the effects of schistosome infection on the host immune response to viruses. We screened 4,730 studies for potential relevance and included 103 of them in this review. Overall, our analysis showed that schistosome infection impairs the host response to many viruses. This includes increasing host susceptibility to HIV and possibly Kaposi's sarcoma-associated herpesvirus, worsening the severity of clinical disease in hepatitis B and C infections, and decreasing immune responses to vaccines for hepatitis B and possibly measles. The studies that we analyzed also suggested that schistosome infection may protect the host against poor clinical outcomes from some viral infections including Human T-cell Lymphotropic Virus-Type 1, respiratory viruses, and chronic HIV. We discuss how these findings might be interpreted, and the additional research needed, in order to improve anti-viral vaccination strategies and control of viral infections globally. Show less
Schistosome infection is recognized as a potentially modifiable risk factor for HIV in women by the World Health Organization. Alterations in cervicovaginal bacteria have been associated with HIV... Show moreSchistosome infection is recognized as a potentially modifiable risk factor for HIV in women by the World Health Organization. Alterations in cervicovaginal bacteria have been associated with HIV acquisition and have not been studied in schistosome infection. We collected cervical swabs from Tanzanian women with and without S. mansoni and S. haematobium to determine effects on cervicovaginal microbiota. Infected women were treated, and follow-up swabs were collected after 3 months. 16S rRNA sequencing was performed on DNA extracted from swabs. We compared 39 women with S. mansoni with 52 uninfected controls, and 16 with S. haematobium with 27 controls. S. mansoni-infected women had increased abundance of Peptostreptococcus (p = 0.026) and presence of Prevotella timonesis (p = 0.048) compared to controls. High-intensity S. haematobium infection was associated with more diverse cervicovaginal bacterial communities than uninfected controls (p = 0.0159). High-intensity S. mansoni infection showed a similar trend (p = 0.154). At follow-up, we observed increased alpha diversity in S. mansoni (2.53 vs. 1.72, p = 0.022) and S. haematobium (2.05 vs. 1.12, p = 0.066) infection groups compared to controls. Modifications in cervicovaginal microbiota, particularly increased diversity and abundance of taxa associated with bacterial vaginosis and HIV (Peptostreptococcus, Prevotella), were associated with schistosome infection. Show less
