Viremia is a medical condition where viruses enter the bloodstream and hence have access to the rest of the body. It is similar to bacteremia, a condition where bacteria enter the bloodstream. The name comes from combining the word 'virus' with the Greek word for 'blood' (haima). It usually lasts for 4 to 5 days in the primary condition. Viremia is a medical condition where viruses enter the bloodstream and hence have access to the rest of the body. It is similar to bacteremia, a condition where bacteria enter the bloodstream. The name comes from combining the word 'virus' with the Greek word for 'blood' (haima). It usually lasts for 4 to 5 days in the primary condition.