The Question

A review of the initial search for a definition of ‘strain’ during the 1920s-1970s. What are the traits that define a strain?

What we found

Differing severity in malaria infections in different regions led to the idea of defining strains based on the parasites’ attributes. While the historical definition frames current debate, the context of the debate has changed. The genetic basis for resistance development is relatively well understood. Further research is needed to distinguish strains by clinical virulence and immunity.

Why it matters

The search for a definition is not only historically relevant. Sorting and classifying objects of study determines how future is framed and pursued.