Directly transmitted infections modeling considering an age-structured contact rate - Epidemiological analysis

Many directly transmitted diseases present a strong age dependent pattern o f infection. Such dependency is analyzed by a mathematical model encompassi ng an age-structured pattern of contacts. From an age-structured contact ra te modeling, we estimate the parameters related to the contact rate based o n the age dependent force of infection calculated from a seroprevalence dat a obtained from a nonimmunized population. This model, with parameters completely determined, is used to assess the ef fects of vaccination strategies. This is done by calculating the new equili brium age dependent force of infection and its correlated variables: the av erage age of the acquisition of the first infection, the rate of new cases of infection, and the risk of Congenital Rubella Syndrome. Also, we present a rough estimation of the basic reproduction ratio and the vaccination rat e at which the disease can be considered eradicated (threshold). (C) 1999 E lsevier Science Ltd. Ail rights reserved.