Four more bodies lay at the other end of the pipes. All black men, one had his brains blown out, another man had been decapitated, his dreadlocked head lying beside his torso.

Researchers from the Johns Hopkins School of Medicine compared nuns with normal cognitive function at the end of life with those who had mild dementia or full-blown Alzheimer’s.

That could mean bird flu will remain a dead end, infecting the occasional unlucky person but never turning into a full-blown pandemic.