Underlying what?

'A woman has died of swine flu. It is believed she had underlying health problems.' 'A man became the latest victim of swine flu yesterday. It is understood he had underlying health problems.' Okay, I get that they died, and the cause was swine flu, but what’s that bit about underlying health problems? What is an underlying health problem? What are we talking here? Something serious? Were they on their last legs anyway? Was death inevitable? Is it a bit like saying ‘A skydiver tragically fell to his death yesterday. It is believed he had forgot to wear a parachute.’ Or ‘A man was fatally run over by a bus last night. Early reports suggest he was lying in the middle of the road disguised as a speed bump at the time.’ What in the name of Jupiter is an underlying health problem? Is ulcerative colitis an underlying health problem? If I died of swine flu would the newspapers say, ‘In London a man of 37 has died of swine flu. Doctors confirm he had underlying health problems.’ Is that what they’ll say? Then some woman sat eating her Sugar Puffs will look up from her paper and say to her husband, “Ere Pete, I see some bloke in London’s been killed by swine flu. Says here he had underlying health problems.” “Down in London, was it?” sniffs the husband, “He probably had AIDS.”