not long ago, these tests would not have been needed. They will be testing for Zika soon
“Not long ago,” these tests didn’t exist.
There have been people in France from North Africa, Sub-Saharan Africa, and the Francophone Caribbean ... the French colonial empire ... for centuries. Probably quite a few, especially in the latter two groups, carried the sickle-cell trait. However, there was no particular reason to track it, since it is not a communicable disease and there was no good treatment for the symptoms.