Cockroaches pose a severe risk to humans because they can carry the bacteria and diseases that lead to human food poisoning. Cockroaches can often be found in drains and sewers, before they migrate to human habitats, which is where they can spread dirt and illness. 

Cockroaches must be dealt with swiftly to avoid illness within a home, or risk closure of a business. To ensure that the problem is properly dealt with, a professional should be called in.