West nile virus is an arbovirus that can be transmitted by birds because they develop viremia when infected. in contrast, infected humans cannot spread the disease because they do not develop viremia. why is viremia associated with the ability to transmit the disease? a. if there are no (or only very few) viral particles in the blood, then they are not picked up by vectors feeding on the blood in sufficient amounts to cause infection. b. the virus is only found within red blood cells if there is no viremia, so it cannot be spread by mosquitoes that do not consume those cells. c. direct contact with blood is required for infection. if there are no viral particles in the blood, then infection can't occur using this mechanism. d. because white blood cells are found in the blood, any virus in the blood would be attacked by the immune system. with no viral particles available for the immune system to attack, the virus cannot be spread.