Epidemiologia da infecção pelo HTLV-1/2 na região metropolitana de Manaus e avaliação de estratégias minimamente invasivas para diagnóstico e monitoramento do perfil inflamatório

Abstract

Introduction: HTLV-1/2 infection has a global distribution, with prevalence rates varying by region. In Brazil, an estimated 2 million individuals are infected; however, epidemiological studies remain scarce, and most do not accurately reflect the true prevalence of the infection, particularly in the Amazon region. Moreover, the lack of accessible diagnostic tools hampers both detection and the implementation of preventive measures. This study aimed to estimate the prevalence and perform molecular characterization of HTLV-1/2 infection in the metropolitan region of Manaus, as well as to evaluate the use of minimally invasive sampling methods (saliva and DBS/DPS) as alternatives to conventional venous blood collection. Methods: A total of 1,604 individuals residing in the Manaus metropolitan area were recruited and screened for HTLV-1/2 infection using an enzlyme-linked immunosorbent asslay (ELISA). Reactive samples were confirmed by Western blot or INNO-LIA. Molecular characterization was conducted lusing nested PCR, sequencing, and phylogenetic analysis. Sociodemographic data and potential risk factors were obtained through an epidemiological questionnaire. For the evaluation of minimally invasive methods, patients from Saint Mary’s Hospital, United Kingdom, were also recruited. Results: The prevalence of HTLV infection in Manaus was found to be 0.3% (4/1.314), with higher frequency in women compared to men. Potential risk factors identified among infected individuals included having tattoos, receiving blood transfusions, being breastfed, and not using condoms. Among the infected individuals, three were positive for HTLV-1 and one for HTLV-2. Phylogenetic analyses revealed the presence of HTLV-1aA (n=2), HTLV-1aC (n=1), and HTLV 2c (n=1) subtypes. Regarding the use of minimally invasive samples, anti-HTLV 1 IgG was successfully detected in saliva, and both anti-HTLV-1/2 IgG and the inflammatory biomarker neopterin were detected in DBS and DPS samples. Conclusion: The findings of this study revealed the emergence of the HTLV-1aC subtype in the Brazilian Amazon, an unprecedented finding in Brazil, and validated the use of alternative and accessible sampling methods (DBS/DPS) for monitoring inflammatory markers in PVHTLV. These results enhance the epidemiological surveillance of HTLV-1/2 in Brazil, broaden the understanding of viral diversity in the region, and offer practical and feasible tools for the diagnosis and follow-up of infection in populations living in remote areas with limited access to healthcare.