Human T-lymphotropic Virus Type 1 and 2 (HTLV-1/HTLV-2):
HTLV-1 and HTLV-2 are enveloped, single-stranded RNA retroviruses of the Deltaretrovirus genus, related to HIV. These viruses primarily infect human CD4+ T-lymphocytes. They are transmitted mainly through breastfeeding, sexual contact, and contaminated blood products.

Diseases caused by Human T-lymphotropic Virus:
The majority of infected individuals remain asymptomatic carriers. HTLV-1 is highly pathogenic, with 2–10% of those infected developing severe conditions over their lifetime, most notably Adult T-cell Leukemia/Lymphoma (ATL), a highly aggressive malignancy, and HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP), a chronic progressive neurological disorder. HTLV-2 has a lower pathogenic potential but has been occasionally linked to chronic neurological disorders and pulmonary infections.

Detection and Diagnosis of Human T-lymphotropic Virus:
Screening for HTLV infection involves immunoassays that detect antibodies to HTLV-1 and HTLV-2 in the blood, such as an ELISA-based assay like the assays available here. Due to potential cross-reactivity and false positives, a positive screening test must be confirmed. Confirmatory tests include Western blot or, most definitively, molecular assays like PCR to detect the proviral DNA in the patient’s cells and to differentiate between HTLV-1 and HTLV-2.