Helminthic infection and the risk of neurologic disease progression in HTLV-1

Abstract

Background Infection with the human T-cell lymphotropic virus, type 1 (HTLV-1) has been associated with an increased Th1 response. Interestingly, a higher prevalence of helminthic coinfection has been observed among infected individuals, and subsequent modulation of the immune response typically associated with helminths may influence clinical outcomes among HTLV-1 coinfected individuals. Objective This study was conducted to elucidate the association between helminthic coinfection and the development of clinically characterized neurologic disease that occurs in HTLV-1 infection. Study design In a cohort analysis, incidence of HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP) was recorded. Incidence of clinical outcomes and disease-free survival of several neurologic outcomes associated with HTLV-1 were estimated using the Kaplan–Meier method with log-rank tests. The relationships between helminthic infection and risk of HTLV-1 neurologic outcomes were assessed by Cox proportional hazard modeling. Results Seventy-four coinfected and 79 non-coinfected patients were followed, with 92 helminthic infections observed in the coinfected group. One patient per group developed HAM/TSP and the risk of progression to neurologic disease outcomes did not differ among those with and without helminthic coinfection (p > 0.45). A significant difference was noted in the prevalence of neurologic disease outcomes among all patients at the conclusion of the study (p < 0.01). Conclusions These data suggest that treated helminthic infection does not affect risk of development of neurologic disease in HTLV-1 infection, and reinforce that treatment of helminths does not adversely affect patients with HTLV-1. Importantly, among all patients, an overall progression of neurologic disease was observed.