In retirement, my mom volunteers her time teaching English as a second language.
My student and I discussed (briefly) the inconsistent use of articles before the names of diseases/ailments/injuries:
a cold, a broken arm, a headache
the flu, the measles, the mumps
cancer, pneumonia, pleurisy, shingles
What’s the reason? Maybe temporary, easily curable diseases/ailments/injuries get an “a,” the ones that land you in bed for a few days get “the,” and the killers get neither. Or symptoms may get “a” (a sore throat) and the actual disease earns some more powerful linguistic designation. Or anything in the plural (swollen glands, clogged arteries) gets no article.
But I’m sure that there are many variations (a heart attack, for example). Since you’re in the health care biz, maybe you know.
No, I don’t know. Do you?