  We give a precise definition of BPS vortex loops in 3D non-abelian gauge
theories with ${\cal N}=2$ SUSY by the path integral over fields with a
prescribed singular behavior. We compute the expectation value of a BPS vortex
loop on an ellipsoid. Using the result we revisit the known equivalence between
Wilson and vortex loops in pure Chern-Simons theory. Naive computations of
expectation values in ${\cal N}=2$ theory leads to an unwanted shift of
parameters in the rule of correspondence. We resolve the problem by relating
the shift to the global anomaly of ${\cal N}=2$ SUSY quantum mechanics. For
theories with $U(N)$ gauge group we also develop an alternative description of
vortex loops in terms of 1D ${\cal N}=2$ SUSY quantum mechanics on their
worldline. For vortex loops in ${\cal N}=4$ theories, our construction
reproduces some of the quiver GLSMs of Assel and Gomis.
