<Li> Developmental transmission: The agent undergoes some development in the transmission vehicle . </Li> <Li> Fecal - oral transmission: The infectious agent is shed by the infected host in feces and acquired by the susceptible host through ingestion of contaminated material . </Li> <Li> Horizontal transmission: Lateral spread to others in the same group and at the same time; spread to contemporaries . </Li> <Li> Mechanical transmission: The transmitter is not infected in that tissues are not invaded and the agent does not multiply . </Li>

When is an area declared free of epidemic