Translations:Basic Field Epi: Participants' Workbook/135/en
Infectious agents have developed different ways to survive over time (maintenance). Some agents have a resistant form that can survive in the environment (anthrax spores). Some agents have intermediate forms that survive in other hosts (parasites). Some agents are capable of infecting multiple species (rabies). Some agents form persistent infections or carrier states. Some agents cause little immune response or alter their genetic make up so they can re-infect animals again (influenza).