Infections are a cause of encephalopathy. Many types of bacteria, viruses, and fungi can cause encephalitis by infection and inflammation of the brain tissue or of the meninges (meningitis) that line the brain and spinal cord.
A value of zero indicates that there is no relationship between the two variables. If the correlation coefficient of two variables is zero, it signifies that there is no linear relationship between the variables. However, this is only for a linear relationship; it is possible that the variables have a strong curvilinear relationship.
It's always a good idea to read the fine print, and statistics has a lot of fine print. Knowing that two variables are independent will tell you that their correlation coefficient is zero. But knowing the correlation coefficient to be zero does NOT mean the two variables are independent, or otherwise unrelated.