There are certain “Presumptions” that the VA and Congress allow when considering some illnesses and diseases incurred. This is not an inclusive list for the illnesses and diseases the VA will accept, but it is a list of particular illnesses and diseases that can be linked to war many years after discharge. As defined in U.S. Code Title 38 and on the VA’s website, these presumptions include but are not limited to: Former Prisoners of War, Exposure to Agent Orange (Vietnam Veterans), Exposure to Radiation (Atomic Veterans), and Gulf War Veterans with undiagnosed illness.
To see if you may qualify for one of these “Presumptions,” each of the items are further broken down into qualifications and explanations at the VA website hyperlinked above. For even more information on this topic please look at USC title 38, chapter 11.
http://www.vba.va.gov/VBA/benefits/factsheets/serviceconnected/presumptive.doc