What is the suspected source of outbreak? How are people exposed to infectious agent? Are there any hotspots areas? Which human activities that might contribute to the spread? Any environmental contamination? Any interaction with animals?
Environmental assessment is very important in understanding contributing factors of disease spread. Let us answer the following questions:
Is there a specific vector or reservoir responsible for transmitting disease? Which control measures implemented and their effectiveness in containing outbreak? Which group of people is vulnerable? Is an outbreak similar to past ones? Any recent climate changes?