What i understand from my research is that the virus enters the body ,attacks membrane basically in the respiratory tract and penetrates deep and incubates . Hence depending on the time for incubation the symptoms appear, which can take as fast as 3 days or can take upto a month to show. It then spread to most of the internal organ . How exactly it reaches the brain is not very clear but it looks like the spinal cord makes the way there. On reaching the brain it causes ischemia and thrombosis (stroke) and later encephalitis which can cause a brain lesion.
The main affects include vasculities, encephalitis and neurologic defecits.