However, subsequent studies
carried out on
small numbers (20 — 30)
of CFS
patients, failed to confirm evidence for HTLV (type 1 or 11)[22]--[25] or other retroviruses, including the closely - related simian T lymphotropic virus type l, the prototype foamy virus, simian retrovirus, bovine and feline leukaemia viruses [26] and HIV - 1 [23].