What happens when invading organisms escape from a localized area?

When invading organisms escape from a localized area, they can lead to septicemia, which refers to the presence of infectious agents in the bloodstream. This condition can occur when pathogens bypass local defenses and enter the circulatory system, potentially leading to a systemic infection that can affect multiple organs and lead to severe complications. Septicemia often triggers a systemic inflammatory response, which can be detrimental and requires prompt medical attention.

The other options describe potential effects or responses but do not directly address the central consequence of organisms escaping a localized infection. For instance, while fever may accompany infections, it doesn't specifically result from the escape of pathogens from a localized area. Lymph nodes act as a filtration system and often contain infections; however, their primary role is to support the immune response rather than to entirely prevent organisms from spreading. Furthermore, while spreading to nearby tissues is a possibility, it does not encompass the full severity of the systemic complications that can arise from septicemia.