And some diseases should not even have symptoms, as there are diseases in the real world where you dont actually feel the affect for another 5 years or dont feel, or get anything physically abnormal ever.
At ABove I never did that, just kill em and cure the disease. ANyways if you block them but the matter still gts on your shield and you touch your shield then you could still get it.
As well you should be able to get Prions from zombies.