This paper addresses the problem of controlling interleaved dc-dc boost converters (IBC) associated to fuel cell (FC) energy generators. The FC-IBC association is powering a, possibly unknown and time-varying, load of resistance type. Furthermore, all IBC parallel cells are not equipped with current sensors. The control objective is twofold: (i) the IBC output voltage must be tightly regulated; (ii) the total current carried by the IBC must be equally shared between the different parallel branches. The complexity of the control problem lies in: (i) the system nonlinearity and instability of its zero-dynamics with respect to the output voltage; (ii) the load uncertainty; (iii) the inaccessibility to measurements of all currents. The instability of the output voltage zero-dynamics is coped by reformulating all control objectives in term of current regulation in the different converter cells. The resulting current regulation problem is dealt with by developing an adaptive output feedback controller. The latter includes a collection of adaptive current regulators and a battery of current estimators. The regulator parameter adaptation feature is used to compensate for the load uncertainty and variation. It is formally shown, using Lyapunov stability tools, that the proposed output feedback adaptive controller actually meets its objectives. This theoretical analysis is confirmed by numerical simulations showing that the controller enjoys additional robustness features.