Which one of the following diseases is non-infectious?

Elephantiasis

The correct answer is Option (4) → Elephantiasis

NCERT:  Diseases can be broadly grouped into infectious and non-infectious. Diseases which are easily transmitted from one person to another, are called infectious diseases. Infectious diseases are very common and every one of us suffers from these at sometime or other. Some of the infectious diseases like AIDS are fatal. Among non-infectious diseases, cancer is the major cause of death. Drug and alcohol abuse also affect our health adversely.

Thus, A non-infectious disease is one that cannot be spread from person to person and is caused by genetics, lifestyle, or environmental factors (like cancer or diabetes).

• Cholera: Infectious disease caused by the bacterium Vibrio cholerae. It spreads through contaminated water or food.

• Pneumonia: Infectious disease caused by bacteria or viruses and spreads through droplets from coughs or sneezes.

• Tuberculosis: Infectious disease caused by Mycobacterium tuberculosis and spreads through airborne droplets.

Elephantiasis: It is caused by parasitic worms (Wuchereria bancrofti) and is transmitted through the bite of infected mosquitoes. Scientifically, it is also an infectious disease, but it does not spread directly from person to person; it requires a vector (mosquito) for transmission.

Therefore, strictly speaking, all the diseases listed are infectious. However, Elephantiasis is not directly communicable between humans, which is why it is treated as the non-infectious option in this question.