Q&A and WordPress comments conflict

Hi,

When Q&A is activated, WP comments disappear (there is a Q&A answer instead, have a look for example here: http://www.oreille-malade.com/2015/01/stimulation-du-nerf-vague-acouphene.html )
When Q&A is deactivated, WP comments work as expected.

Any idea?

Thanks!