Human T-cell Leukemia Virus Type 1 and Strongyloides stercoralis: Partners in Pathogenesis.

Adam Dykie,Sydney Wilson,Christian Farinas,David Abraham,Arnold B Rabson,Kiran Madugula,Pooja Jain,Tharaka Wijesinghe

doi:10.3390/pathogens9110904

Abstract

Infection with human T-cell leukemia/lymphoma virus type 1 (HTLV-1) has been associated with various clinical syndromes including co-infection with Strongyloides stercoralis, which is an intestinal parasitic nematode and the leading cause of strongyloidiasis in humans. Interestingly, HTLV-1 endemic areas coincide with regions citing high prevalence of S. stercoralis infection, making these communities optimal for elucidating the pathogenesis of co-infection and its clinical significance. HTLV-1 co-infection with S. stercoralis has been observed for decades in a number of published patient cases and case series; however, the implications of this co-infection remain elusive. Thus far, data suggest that S. stercoralis increases proviral load in patients co-infected with HTLV-1 compared to HTLV-1 infection alone. Furthermore, co-infection with HTLV-1 has been associated with shifting the immune response from Th2 to Th1, affecting the ability of the immune system to address the helminth infection. Thus, despite this well-known association, further research is required to fully elucidate the impact of each pathogen on disease manifestations in co-infected patients. This review provides an analytical view of studies that have evaluated the variation within HTLV-1 patients in susceptibility to S. stercoralis infection, as well as the effects of strongyloidiasis on HTLV-1 pathogenesis. Further, it provides a compilation of available clinical reports on the epidemiology and pathology of HTLV-1 with parasitic co-infection as well as data from mechanistic studies suggesting possible immunopathogenic mechanisms. Furthermore, specific areas of potential future research have been highlighted to facilitate advancing understanding of the complex interactions between these two pathogens.

Highlights

A well-characterized disease manifestation associated with human T-cell leukemia/lymphoma virus type 1 (HTLV-1) is the co-infection with Strongyloides stercoralis
HTLV-1 exhibits a wide variety of disease manifestations, most infected individuals remain asymptomatic carriers
It is common for the co-infection to manifest many years after exposure to HTLV-1

Summary

Introduction

A well-characterized disease manifestation associated with human T-cell leukemia/lymphoma virus type 1 (HTLV-1) is the co-infection with Strongyloides stercoralis. As a soil transmitted helminth (STH), the infection is initiated through populations with a high infectious burden of HTLV-1 and S. stercoralis Analysis of these by the invasion of the skin by the infective third stage larvae (L3). Hyperinfection due to stercoralis multiple potential autoinfective third stage larvae without leaving theS.host, with results the L3ainreinfecting the same clinical with consequences resulting in female mortality rates of up to at. The result is not an increase in the number associated, given the prevalence of the co-infection and theinfections apparent clinical association ofclosely adult worms in the intestine, but rather extremely long-term in the host, causedofby. Characterizing the co-infection will require exploring the epidemiology of HTLV and S. stercoralis individually and considering each pathogen’s biology

The Clinical Spectrum of HTLV-1 Infection

Findings

Conclusions and Future Perspectives