Adult T-cell leukemia/lymphoma and cluster of HTLV-1 associated diseases in Brazilian settings

We studied the transmission routes of human T-cell lymphotropic virus type I (HTLV-I) within families of 82 Brazilian patients diagnosed with adult T- cell leukaemia/lymphoma (ATL). Diagnosis of ATL in 43 male and 39 female pa tients was based on clinical and laboratory criteria of T-cell malignancy a nd detection of HTLV-I monoclonal integration. Samples were tested for HTLV antibodies and infection was confirmed as HTLV-I by Western Blot and/or po lymerase chain reaction (PCR) assays. Overall 26/37 (70%) of mothers, 24/37 (65%) of wives, 8/22 (36%) of husbands, 34/112 (30%) of siblings and 10/82 (12%) offspring were HTLV-I infected. In 11 AIL patients, mothers were rep eatedly HTLV-I seronegative, but HTLV-I pol or tax sequences were detected in 2 out of 6 cases tested by PCR. ATL patients with seronegative mothers r elated the following risk factors for HTLV-I infection: 6 were breast-fed b y surrogate mothers with unknown HTLV-I status, 4 had a sexually promiscuou s behaviour and 1 had multiple blood transfusions at a young age. Familial aggregation of ATL and other HTLV-I associated diseases such as HTLV-I myel opathy (HAM/TSP) and or uveitis, ATL in sibling pairs or in multiple genera tions was seen in 9 families. There were 6 families with ATL and TSP siblin g pairs. In 3 families at least one parent had died with lymphoma or presen ting neurological diseases and 2 offspring with ATL. Further to the extent of vertical and horizontal transmission of HTLV-I infection within AIL fami lies, our results demonstrate that mothers who provide surrogate breast-mil k appear to be an important source of HTLV-I transmission and ATL developme nt in Brazil.