A disease which spreads by contact. Choose the most suitable ‘one word’ for the given expressions -

Contagious (noun)
Meaning: (of a person) having a disease that can be transmitted by contact with other people.
Bengali Meaning: সংক্রামক।
Usage:
Strictly, a contagious disease is one transmitted by physical contact, whereas an infectious one is transmitted via microorganisms in the air or water.
In practice, there is little or no difference in meaning between contagious and infectious when applied to disease or its spread.
In figurative senses, contagious may describe the spread of good things such as laughter and enthusiasm or bad ones such as violence or panic, whereas infectious usually refers to the spread of positive things, such as good humor or optimism

Source: Oxford Dictionary & Bangla Academy Dictionary.