It shows how the disease can be better understood in times of crisis
Explanation:
Give.
Cholera gets a foothold when natural disaster strikes or when war or instability pushes a large number of people into crammed refugee camps.
The phrase gets a foothold as used in the SENTENCE above, explains how cholera finds strength and the ease at which it could spread easily within congested areas. Get a Foothold literally means to take control or start to take charge of a situation or circumstance. Hence, it could be concluded that it's usage in the sentence means starts to spread.
The effect of using the phrase in the sentence shows how the disease can be better understood in times of crisis. It shows the accompanying effect of war or civil distruptions.
