Translation guide
In Japanese, expressing 'be infected' depends on what is being infected—a person, a wound, a computer, or an emotion. The most common and versatile verb is 感染する (kansen suru), used for diseases and computer viruses. For wounds becoming infected, 化膿する (kanō suru) is used. There are also specific terms for plant diseases and figurative 'infection' by ideas or emotions.
To become infected with a pathogen, such as a virus or bacteria, leading to illness.
The standard verb for 'to be infected' with a disease. It is an intransitive verb, so the disease is marked with に (ni).
彼はインフルエンザに感染した。
He was infected with the flu.
Many people are infected with the virus.
A formal, written term meaning 'to suffer from/contract a disease'. Often used in medical contexts or news reports.
彼は重い病気に罹患した。
He contracted a serious illness.
An intransitive verb meaning 'to be transmitted/caught' (of a disease). Used when the focus is on the disease spreading to someone. The person is marked with に (ni).
風邪がうつった。
I caught a cold (from someone).
子供に水疱瘡がうつった。
The child caught chickenpox.
When a cut or injury gets infected, often with pus formation.
Specifically means 'to fester/suppurate', i.e., a wound becomes infected and produces pus.
傷が化膿した。
The wound became infected.
Can also be used for wounds, but is less specific than 化膿する. It simply means the wound has become infected by bacteria.
傷口が感染した。
The wound got infected.
When a computer, smartphone, or other device is infected by a virus or malicious software.
The same verb as for diseases. The device is the subject, and the virus is marked with に (ni).
パソコンがウイルスに感染した。
My computer was infected with a virus.
When a plant is infected by a pathogen.
Used for plants as well. The disease is marked with に (ni).
トマトが疫病に感染した。
The tomatoes were infected with blight.
A technical term used in agriculture and botany meaning 'to contract a disease' (for plants).
稲がいもち病に罹病した。
The rice plants were infected with blast disease.
To be 'infected' by an idea, enthusiasm, fear, etc., in a metaphorical sense.
Used metaphorically for emotions or ideas that spread like a disease. Often used with 熱 (netsu, 'fever/enthusiasm') or 恐怖 (kyōfu, 'fear').
彼の熱意に感染した。
I was infected by his enthusiasm.
群衆は恐怖に感染した。
The crowd was infected with fear.
Literally 'to be contagious', but also used figuratively for things like laughter or panic spreading. Often intransitive.
あくびが伝染した。
The yawn was contagious (I caught the yawn).
感染する is a more formal, clinical term for 'be infected'. うつる is a casual, everyday word meaning 'to catch (a disease from someone)' or 'to be contagious'. Use うつる when emphasizing transmission from person to person.
風邪がうつった。
I caught a cold.
インフルエンザに感染した。
I was infected with influenza.
For food poisoning, use 食中毒になる (shokuchūdoku ni naru) or あたる (ataru), not 感染する.
食中毒になった。
I got food poisoning.