Impact of initial seeds in cooperative contagion processes

Many types of contagion phenomena are often strongly influenced by cooperative effects among multiple pathogens. When a node has been infected with one of the diseases, the probability of the second disease’s transmission grows, compared to single pathogen spreading. It remains unclear how to predict epidemic outbreaks from the location of the initial seeds. In this work, we modulate the probability of infection depending on the state of nodes taking into account the cooperativity between different pathogens. Defining the transmission probabilities of the first and of the second infecting disease, we derive message-passing equations for cooperative contagion processes. By using the message-passing equations, we assess the impact of seeds in cooperative coinfections and also provide explanation how cooperative epidemic occurs.