The mathematical model of the infectious disease modified to take into account the impect of diffuse perturbations on the infectious disease dynamics under conditions of a temperature reaction of the body. The solution of a singularly perturbed model problem with a delay is reduced to a sequence of solutions of problems without delay, for which the sought functions are obtained in the asymptotic expansions form as perturbations of solutions of the corresponding degenerate problems. Using computer simulations, we present results that show influences of diffusion “redistributions” on infection disease dynamics in the conditions of temperature reaction of organism. They illustrate that decrease of model antigen concentrations in the infection locus to a non-critical level caused by diffusion "redistribution" for a relatively short period may contribute to their further neutralization by presence antibodies in the organism or require injection with a lower concentration of donor antibodies.