  We present the first measurement of event-by-event fluctuations in the kaon
sector in Pb-Pb collisions at $\sqrt {s_{\rm NN}}=$ 2.76 TeV with the ALICE
detector at the LHC. The robust fluctuation correlator $\nu_{\rm dyn}$ is used
to evaluate the magnitude of fluctuations of the relative yields of neutral and
charged kaons, as well as the relative yields of charged kaons, as a function
of collision centrality and selected kinematic ranges. While the correlator
$\nu_{\rm dyn}[\rm K^+,\rm K^-]$ exhibits a scaling approximately in inverse
proportion of the charged particle multiplicity, $\nu_{\rm dyn}[\rm K_S^0,\rm
K^{\pm}]$ features a significant deviation from such scaling. Within
uncertainties, the value of $\nu_{\rm dyn}[\rm K_S^0,\rm K^{\pm}]$ is
independent of the selected transverse momentum interval, while it exhibits a
pseudorapidity dependence. The results are compared with HIJING, AMPT and
EPOS-LHC predictions, and are further discussed in the context of the possible
production of disoriented chiral condensates in central Pb-Pb collisions.
