As an adjunct to this question, I vividly recall interviewing prospective student nurses in Zambia in 1971. I asked one if she had ever had any diseases in her lifetime.
'No, Bwana, nothing', she said.
'Oh, surely, you must have had something in your childhood, like mumps or measles perhaps?' I replied.
She threw her hands in horror. 'No, Bwana, I never had the measles, never the measles'
She appeared quite distressed at the thought, so I apologised and went on with the interview. At the end of the interview, I asked if she wished to add anything. She said
'I think I told you a mistruth, Baas. I did have a disease, but it was very little, and I had forgotten about it.'
'Oh yes, what was that?' I enquired.
'I had the smallpox, Baas,'