The present invention relates to heavy chain immunoglobulins or fragments thereof of the VHH or VNAR type, or domain antibodies (dAbs) of the heavy or light chains of immunoglobulins or fragments thereof, suitable for use in the management of infections, in particular of the gastrointestinal tract. The present invention also relates to a delivery system comprising these heavy chain immunoglobulins or functional fragments thereof of the VHH or VNAR type, or domain antibodies (dAbs) of the heavy or light chains of immunoglobulins or fragments thereof, and hosts comprising expression vectors encoding for these heavy chain immunoglobulins or functional fragments thereof of the VHH or VNAR type, or domain antibodies (dAbs) of the heavy or light chains of immunoglobulins or fragments thereof. The invention also relates to food products and pharmaceutical preparations comprising the delivery system, and methods for the preparation of food products according to the invention.
