Prevalence of human T-lymphotropic virus type 1 (HTLV-1) infection among patients attending a dermatology clinic in Northeastern Brazil.

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus with a worldwide distribution, infecting approximately 10 to 20 million people. It is associated with serious diseases such as adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In addition to neurological and hematological manifestations, HTLV-1 is associated with dermatological manifestations, notably HTLV-1-associated infectious dermatitis (IDH), frequently described in children but also present in adults. Previous studies demonstrate a higher frequency of dermatological manifestations in HTLV-1 seropositive individuals, especially in populations from endemic areas and in socioeconomically disadvantaged contexts. In Brazil, it is estimated that 800,000 to 2.5 million individuals are infected with HTLV-1; particularly in the Northeastern region, including the states of Bahia and Pernambuco. Despite the high endemicity, there is underreporting of the infection and underdiagnosis of cutaneous manifestations, limiting the adequate characterization of these alterations in patients with HTLV-1 infection in specialized dermatological services. Therefore, the aim of this study was to estimate the prevalence of HTLV-1/2 infection and to describe the sociodemographic, socioeconomic, and behavioral factors of patients treated at a dermatology clinic in Northeastern Brazil. A cross-sectional study was conducted from February to December 2025, in which sociodemographic, socioeconomic, and behavioral data were collected through interviews and medical records. Patients underwent serological screening using an enzyme-linked immunosorbent assay (ELISA) with the Murex HTLV-I+II kit (DiaSorin, UK). From samples with positive or indeterminate ELISA results, HTLV DNA was extracted using the HiPurA Blood Genomic DNA Miniprep Purification kit (Himedia Laboratories, India), followed by polymerase chain reaction (PCR) to confirm the diagnosis of infection and determine the viral type. HTLV-1 infection was identified in 0.99 % (5/504) of patients with dermatologic manifestations. In the five cases testing positive for HTLV-1, the age range was 19 to 81 years, with a predominance of women and individuals of mixed race, with low levels of education and income. All had a history of breastfeeding, and one patient had received a blood transfusion. No single characteristic pattern was observed regarding the skin manifestations. In conclusion, although the prevalence of HTLV-1 infection among patients with dermatologic manifestations was low, it is epidemiologically relevant and highlights the importance of HTLV-1 infection screening in dermatology outpatient settings to reduce underdiagnosis of this infection.