Occasionally there are requirements for the remediation of biological contaminants left behind after a sewage mishap, contaminated flood water, or human/animal feces. These are the dirty jobs that some companies avoid or turn down. Although these incidents, in most cases, are rare, these situations do arise and need to be handled with care. These contaminants may contain infectious organisms, including intestinal bacteria such as E. coli, Salmonella, and Shigella.
Porous building materials are an ideal source for the growth of microorganisms, such as bacteria and fungi.  The growth of these types of organisms can produce toxic substances that can be exposed to humans within indoor environments.  

Signs and symptoms experienced by exposure to such microorganisms are similar, even though they are caused by different pathogens. These symptoms include nausea, vomiting, diarrhea, abdominal cramps, muscle aches, and fever.