Why was Goku the only Z Warrior to contract the Heart Virus? In Trunks' future that had been destroyed by the Androids, Goku died from a Heart Virus.

Even in the alternate timeline caused by Trunks warning the Z Warriors about the Androids, Goku still contracted the Heart Virus but they already had a cure for it given by Trunks. Yet in both timelines out of all the Z Warriors Goku was the only person to contract it.

Why is this? Was it a targeted attack on him by Dr. Gero (given the timing of when it occurred)? Was Goku's diet a factor or was there something Saiyan wise that made him more susceptible which doesn't apply to Vegeta and half-Saiyans?
It is Highly likely that the infection rate of the virus was just exceptionally low. Infection rates vary from virus to virus. Some can only be transmitted in highly populated areas due to their low contraction rate.