Neurological aspects of HTLV-1 infection: symptoms in apparently asymptomatic carriers.

Human T-lymphotropic virus type 1 (HTLV-1) is classically associated with the HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), although the mechanisms of this neurological disorder remain unclear. In addition, some patients who develop "minor" neurological signs that do not meet diagnostic criteria for HAM/TSP are classified as asymptomatic carriers. This study aims to demonstrate the neurological symptoms of Brazilian patients living with HTLV-1 classified as not-HAM.TSP. This observational study evaluated patients treated in an HTLV reference center in Bahia, Brazil, between February 2022 and July 2023. The data were obtained through the analysis of medical records and neurological consultation. Those individuals classified as HAM/ TSP were excluded from this study. 74 patients were submitted to a careful neurological evaluation: 23 HAM/TSP, 22 were classified with intermediate syndrome (IS), and 29 were oligosymptomatic. Self-reported symptoms were significantly more common in the IS group, including urinary symptoms such as nocturia, urgency, incontinence, dysuria, weakness, paresthesia, lumbar pain, xerostomia, and xerophthalmia. Physical examination findings consistent with reduced vibratory and tactile sensitivity were more common in the IS group (p = 0.017 and p = 0.013). Alterations in the V and VIII cranial nerves were present in both groups. HTLV-1 can lead to the development of important neurological signs and symptoms in apparently asymptomatic individuals. This data highlights the need for more research into the neurological aspects of HTLV-1 infection and emphasizes the importance of early diagnosis, treatment, and support for individuals living with this virus.

Role of the Microbiome in Aedes spp. Vector Competence: What Do We Know?

Aedes aegypti and Aedes albopictus are the vectors of important arboviruses: dengue fever, chikungunya, Zika, and yellow fever. Female mosquitoes acquire arboviruses by feeding on the infected host blood, thus being able to transmit it to their offspring. The intrinsic ability of a vector to infect itself and transmit a pathogen is known as vector competence. Several factors influence the susceptibility of these females to be infected by these arboviruses, such as the activation of the innate immune system through the Toll, immunodeficiency (Imd), JAK-STAT pathways, and the interference of specific antiviral response pathways of RNAi. It is also believed that the presence of non-pathogenic microorganisms in the microbiota of these arthropods could influence this immune response, as it provides a baseline activation of the innate immune system, which may generate resistance against arboviruses. In addition, this microbiome has direct action against arboviruses, mainly due to the ability of Wolbachia spp. to block viral genome replication, added to the competition for resources within the mosquito organism. Despite major advances in the area, studies are still needed to evaluate the microbiota profiles of Aedes spp. and their vector competence, as well as further exploration of the individual roles of microbiome components in activating the innate immune system.