Are white matter brain lesions associated with HIV or are they the end stage of the AIDS disease? Are they not related to the diseases that follows AIDS? What else can cause them, bacteria infection?

"White matter brain lesions" refers to a disease called progressive multifocal leukoencephalopathy (PML), which is a complication of end-stage AIDS. It is an opportunistic infection caused by the JC virus. PML can also occur in HIV-s, but that happens much less frequently. There are no specific treatments known to treat PML, although some people get better on their own and some HIV+ people get better if they start on potent combination treatment for HIV itself, because their immune systems improve to the point where the JC virus infection can be fought better by the patient.