Translation guide
Describes something spreading widely and uncontrollably, often with negative connotations. Covers disease, crime, weeds, rumors, and other undesirable things that are prevalent or out of control.
To say that an illness is spreading rapidly and affecting many people.
General term for something (especially disease) becoming prevalent or going around.
インフルエンザが流行している。
The flu is rampant.
Stronger than 流行, implies spreading uncontrollably, often used for infectious diseases.
感染症が蔓延している。
Infectious diseases are rampant.
Literally 'wield fierce power', used for diseases or natural disasters causing widespread damage.
新型ウイルスが猛威を振るっている。
The new virus is rampant.
To say that crime, corruption, or bad behavior is common and uncontrolled.
Specifically for bad behavior or crime being rampant; implies it's happening openly.
この地域では窃盗が横行している。
Theft is rampant in this area.
Often used for negative things like crime or weeds spreading; can have a nuance of being hard to eradicate.
悪徳商法が蔓延っている。
Unscrupulous business practices are rampant.
Commonly used in conversation and writing for something undesirable spreading.
偽情報がネットにはびこっている。
Misinformation is rampant online.
To say that weeds or unwanted plants are spreading everywhere.
Often used for weeds taking over a garden or area.
庭に雑草が蔓延っている。
Weeds are rampant in the garden.
Describes plants growing thickly and luxuriantly, often unwanted.
To say that rumors, beliefs, or trends are spreading quickly among people.
General term for something spreading (information, rumors, ideas).
デマが広まっている。
False rumors are rampant.
More formal, often used for rumors or information circulating widely.
誤った情報が流布している。
Misinformation is rampant.
Literally 'fly about', used for rumors or gossip being exchanged actively.
蔓延する implies a more serious, uncontrolled spread, often with negative consequences. 流行する is neutral and can be used for fashion or trends as well as disease.
風邪が流行している。
Colds are going around. (neutral)
感染症が蔓延している。
Infectious disease is rampant. (serious)
蔓延る (habikoru) has a strong negative connotation. Do not use it for desirable spreading like popularity or good ideas.
空き地に草が生い茂っている。
Weeds are rampant in the vacant lot.
様々な噂が飛び交っている。
All sorts of rumors are rampant.