Dalrymple declares his pride at having caught pneumonia at the tender age of 27, and shares the results of a recent study on the disease:

I was rather surprised by the frequency, or rather the infrequency, with which a causative organism for the pneumonia was found…The investigators found evidence of at least one pathogenic organism in only 38 percent of cases: they found viruses in 27 percent of cases and bacteria in 14. Obviously, then, there were some patients with both.

…But still, the figure of 62 percent of indeterminate cause surprises me.

The triumph of medicine over infectious disease is perhaps the greatest of its achievements. But evidently there is still much to learn – as there always will be.