This 3 sentence summary provides the key points from the document: Environmental contamination after disasters can increase the spread of disease-causing microorganisms, as floods allow mosquitoes and flies to proliferate and transmit pathogens to humans. Various animals also carry disease-causing microorganisms both inside and outside homes through waste. People can get infected by microorganisms through contaminated air, food, water or direct contact with insects, animals or their waste in dirty environments.