title: Population size dependent incidence in models for diseases without immunity.
abstract: Epidemiological models of SIS type are analyzed to determine the thresholds, equilibria, and stability. The incidence term in these models has a contact rate which depends on the total population size. The demographic structures considered are recruitment-death, generalized logistic, decay and growth. The persistence of the disease combined with disease-related deaths and reduced reproduction of infectives can greatly affect the population dynamics. For example, it can cause the population size to decrease to zero or to a new size below its carrying capacity or it can decrease the exponential growth rate constant of the population.
authors: Department of Mathematics, University of Iowa, Iowa City 52242.
authors: J
authors: J
authors: Zhou
authors: H W
authors: HW
authors: Hethcote
mesh_terms: D003710:Demography; D004812:Epidemiologic Methods; D006801:Humans; D007109:Immunity; D015994:Incidence; D008962:Models, Theoretical; D011156:Population Density