Viruses

HTLV-1 and HTLV-2 infections are associated with various neurological manifestations, particularly HTLV-1-associated myelopathy (HAM). This descriptive, cross-sectional observational study aimed to investigate and analyze the neurological manifestations in patients treated at the Service for the Care of People Living with HTLV (Serviço de Atendimento à Pessoa Vivendo com HTLV-SAPEVH) at the Federal University of Pará. A cohort of 957 individuals underwent screening for HTLV-1/2 infection using enzyme-linked immunosorbent assay (ELISA), with seropositive samples subsequently confirmed via Western blotting or quantitative polymerase chain reaction (qPCR). HTLV-1/2 infection was confirmed in 69 individuals. Of these, fifteen individuals—diagnosed with HTLV-1 (n = 11) or HTLV-2 (n = 4) infection—who presented with neurological complaints at the first nursing consultation, were referred to a neurologist for clinical evaluation of neurological signs and symptoms. Most of the patients were female (13), ranging from 33 to 80 years of age. Neurological symptoms were present in 86.7%, and included spasticity, paraparesis, chronic pain, both motor and sensory deficits, as well as urinary disorders, predominantly affecting the thoracic spinal cord and lower limbs. Urinary symptoms were observed in 77% of symptomatic patients, often preceding other neurological signs that suggest a role as “sentinel symptoms” in the clinical screening of HTLV carriers. The results demonstrated the presence of neurological impairment in patients infected with both HTLV-1 and HTLV-2, with motor symptoms ranging from moderate to advanced. In addition, cases of cranial nerve and upper limb involvement were reported, a finding that is rarely described in the literature. The study highlights the importance of neurological assessment as early as possible in patients infected with either HTLV-1 or HTLV-2 and suggests that sphincter dysfunctions can serve as early clinical markers of future neurological impairment.

Co-infection with human T-cell lymphotropic virus types 1 and 2 (HTLV-1/2) and HIV is not routinely screened for, yet it may significantly influence clinical progression, mortality, and quality of life in affected individuals. This study aimed to estimate the prevalence of HTLV-1/2 co-infection among adults living with HIV and to identify associated epidemiological factors in the Peruvian Amazon. A cross-sectional study was conducted including patients receiving antiretroviral therapy through the multidisciplinary TARGA program in Iquitos, Peru, during the second quarter of 2013. Screening for HTLV-1/2 antibodies was performed using enzyme-linked immunosorbent assay, with reactive samples confirmed by Line Immunoassay. Demographic and behavioral variables were collected, and prevalence odds ratios with 95% confidence intervals were estimated using logistic regression models. Among the 284 patients included, 28 were co-infected with HIV and HTLV-1/2, resulting in a prevalence of 10% with a 95% confidence interval of 6.5 to 14.1. In multivariable analysis, age over 35 years and having more than 10 lifetime sexual partners were independently associated with co-infection, with prevalence odds ratios of 12.4 and 3.6, respectively. HTLV-1/2 co-infection was highly prevalent among people living with HIV in the Peruvian Amazon, and the main risk factors identified suggest that cumulative exposure and sexual behavior play a significant role in the joint transmission of both retroviruses, supporting the need to consider systematic HTLV screening in endemic settings.

Highly pathogenic influenza A viruses of the H5 subtype continue to diversify worldwide through mutation and genetic reassortment, generating novel variants with unpredictable consequences under the One Health approach. Between 2024 and 2025, five outbreaks of avian influenza A viruses were detected in backyard poultry across Michoacán, Estado de México, and Ciudad de México. We conducted molecular and genetic characterization of five highly pathogenic H5N2 viruses isolated from these events. All cases tested positive for influenza A virus and the H5 hemagglutinin, exhibiting high pathogenicity with intravenous pathogenicity index values ranging from 2.88 to 3.0. Whole-genome sequencing revealed novel reassortants containing hemagglutinin from Eurasian H5N1 clade 2.3.4.4b and neuraminidase from the endemic Mexican H5N2 lineage. The viral genome of the isolate from Michoacán contained six segments derived from Eurasian H5N1 viruses introduced into North America in 2021–2022, while nucleoprotein and neuraminidase originated from Mexican H5N2 viruses. In contrast, viruses from Estado de México and Ciudad de México contained five H5N1-derived segments and incorporated polymerase basic protein 1, nucleoprotein, and neuraminidase from low-pathogenic H5N2 viruses circulating in 2024. Phylogenetic analyses confirmed the emergence of a distinct H5N2 Mexican sublineage, providing evidence of active viral reassortment and local evolutionary processes in Mexico.