Deer that survive a particular strain of EHD do build up an immunity to THAT strain. Problem is there are at least five known strains of EHD in Alabama and different strains can hit the same herd in the same year. The storms out of south Fla brought a new strain into Alabama year before last that killed a lot of deer. Southern deer that have evolved over time do not die at the same high rate that northern deer do that have recently been exposed to EHD

historically EHD outbreaks IN A SMALL AREA do run a seven year+/- cycle. EHD does kill deer all over Alabama EVERY YEAR, but usually NOT the same small locations. The mutation of the virus may be changing that cycle some.