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).
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.
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).
I caught a cold (from someone).
The child caught chickenpox.
When a cut or injury gets infected, often with pus formation.
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).
My computer was infected with a virus.
When a plant is infected by a pathogen.
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').
I was infected by his enthusiasm.
The crowd was infected with fear.
Literally 'to be contagious', but also used figuratively for things like laughter or panic spreading. Often intransitive.
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.
I caught a cold.
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.
I got food poisoning.