  Chemotaxis along helical paths towards a target releasing a chemoattractant
is found in sperm cells and many microorganisms. We discuss the stochastic
differential geometry of the noisy helical swimming path of a chiral swimmer. A
chiral swimmer equipped with a simple feedback system can navigate in a
concentration gradient of chemoattractant. We derive an effective equation for
the alignment of helical paths with a concentration gradient which is related
to the alignment of a dipole in an external field. We discuss the chemotaxis
index in the presence of fluctuations.
