Funny you should say that because I did pull out my dictionary(.com) and looked at the definition. I think perhaps the researcher meant this first definition:

1. a disordered or incorrectly functioning organ, part, structure, or system of the body resulting from the effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavorable environmental factors; illness; sickness; ailment.

Which is not necessarily my traditional understanding of the word. But one could make the argument for the third definition:

3. any harmful, depraved, or morbid condition, as of the mind or society: His fascination with executions is a disease.

Fun with semantics!

Pull out your dictionaries. For many years, obesity has been called an epidemic. But until there is evidence that obesity is somehow transmitted from one person to the next, I’ll avoid using that term.

As to disease, well, it seems that only your researcher knows for sure.

Regards
ed