A method for preventing or treating an active Norwalk-Like Virus (NLV) infection in the gastrointestinal (GI) tract of a host, comprising the step of administering orally a fucosyl α1→2 carbohydrate compound to the host, the compound having a binding specificity of the antigenic determinant of a human histo-blood group antigen and competitively binds with a NLV at the determinant binding site of the NLV. The compound inhibits binding of the NLV in vivo to a histo-blood group antigen of the host, thereby inhibiting the active infection or preventing infection of the GI tract of the host by the NLV.
