Impaired humoral immunity following COVID-19 vaccination in HTLV-1 carriers

Trends of changes in human T-cell leukemia virus type 1 epidemiology in Japan and globally

Human T-cell leukemia virus type 1 (HTLV-1) has been identified as a cause of adult T-cell leukemia-lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Despite several HTLV-1 endemic areas being identified, comprehensive investigations have yet to be conducted in all the regions of the world. This review aims to summarize the current reports on HTLV-1. As vertical transmission is known to be a risk factor for ATL development, prevention strategies have been initiated in Japan, and these efforts may be related to the decrease in the estimated number of HTLV-1 carriers in Japan. In numerous HTLV-1 endemic regions, the prevalence of HTLV-1 increases with age, which may be attributed to horizontal infection. However, the incidence of HTLV-1 infection appears to be high among adolescents and young adults in Japan, especially in non-endemic areas. The clinical significance of HTLV-1 infections, other than ATL and HAM/TSP, has recently been documented. Consequently, it is imperative to develop treatment strategies for HTLV-1 infections, including measures to prevent horizontal infections.

Seroprevalence of Strongyloides stercoralis, human T-lymphotropic virus, and Chagas disease in the Peruvian Amazon: a cross-sectional study

Strongyloides stercoralis infections, human T-lymphotropic virus (HTLV) infections, and Chagas diseases occur throughout many regions of Central and South America, including Peru. This study aimed to evaluate the seroprevalence of S. stercoralis, HTLV, and Chagas disease in Iquitos (Peruvian Amazon) and the associated epidemiological conditions for S. stercoralis seroprevalence in Iquitos. A population-based cross-sectional study was conducted from May 1 to June 15, 2020, to assess the seroprevalence of S. stercoralis [lysate antigen ELISA (enzyme linked immunosorbent assay)], HTLV (recombinant antigen ELISA), and Chagas disease (crude and recombinant antigen ELISAs). Of the 396 included individuals, 257 were seropositive for S. stercoralis (a 64.9% prevalence, 95% confidence interval [CI] 60.0% to 69.4%). In the multivariable analysis, seropositivity for S. stercoralis was higher in women (odds ratio [OR] 1.60, 95% CI 1.03 to 2.66) and residents of Punchana (OR 3.47, 95% CI 1.51 to 7.93), whereas residence in Iquitos was associated with lower positivity (OR 0.52, 95% CI 0.32 to 0.85). In total, four individuals were positive for HTLV (1.0% seroprevalence, 95% CI 0.3% to 2.7%), and none were positive for Chagas disease (0.0% seroprevalence, 95% CI 0.0% to 1.2%). The seroprevalence of S. stercoralis in Iquitos is high, particularly among women and residents of Punchana. The presence of HTLV infection indicates that the virus is circulating in Iquitos. This study found no cases of Chagas disease.

Non-cancerous complications in HTLV-1 carriers

INTRODUCTION

Human T-cell leukemia virus type 1 (HTLV-1) carriers may develop adult T-cell leukemia (ATL), or HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). The evidence is limited regarding other diseases potentially associated with HTLV-1, such as HTLV-1-associated autoimmune diseases.

AREA COVERED

We summarized the available information on complications associated with HTLV-1 infection.

EXPERT OPINION

Previous studies showed that HTLV-1 carriers have an increased incidence of collagen diseases including Sjögren's syndrome, as well as dysthyroidism, diabetes mellitus, and atherosclerosis. Furthermore, cognitive deficits are observed in asymptomatic carriers and in symptomatic carriers who develop HAM/TSP. It is hypothesized that altered immunoregulation occurs as a result of persistent HTLV-1 infection. A systematic review and meta-analysis demonstrated that HTLV-1 infection itself has an adverse impact on overall survival. ATL alone cannot entirely explain the adverse impact of HTLV-1 infection on overall mortality, because the incidence is low, and therefore HTLV-1-associated diseases as a whole may contribute to the inferior clinical outcome. However, there are insufficient data to determine the causal relationship between HTLV-1 infection and each complication. While non-cancerous events linked to HTLV-1 infection are not fatal, they are likely to reduce quality of life. Large prospective studies should be conducted by international collaborators.