Which one of the following diseases is non-infectious?

The correct answer is Option (4) → Elephantiasis

Note 1: The given answer is as per the official NTA Answer Key. However, none of the given options appears to be correct, as explained below. As per NCERT, elephantiasis is an infectious disease, spread by mosquitoes.

An infectious disease is caused by a pathogen, a virus, bacterium, fungus, protozoan or worm, and can be passed from an infected person to a healthy person. A non-infectious disease, such as cancer, is not caused by a pathogen and is not passed on. All four diseases in the options are caused by pathogens.

Why the answer given by NTA is incorrect

Option (1) Cholera — An infectious disease. It is a bacterial infection of the intestine. It spreads through food and water contaminated with the faeces of patients.

Option (2) Pneumonia — An infectious disease. Bacteria such as Streptococcus pneumoniae and Haemophilus influenzae infect the alveoli of the lungs. A healthy person gets it by breathing in the droplets released by an infected person, or by sharing glasses and utensils.

Option (3) Tuberculosis — An infectious disease. It is caused by the bacterium Mycobacterium tuberculosis and spreads through droplets in the air when a patient coughs or sneezes.

Option (4) Elephantiasis — The answer given by NTA, but an infectious disease too. It is caused by the filarial worms Wuchereria, which live in the lymphatic vessels and make the legs swell. The worms reach a healthy person through the bite of an infected female mosquito, so the disease is passed on, only not directly from person to person.

Note 2: The same question was also asked in CUET (UG) 2025 on 03-06-2025 (Slot 1).

NCERT Extract:
Common Diseases in Humans – “… Wuchereria (W. bancrofti and W. malayi), the filarial worms cause a slowly developing chronic inflammation of the organs in which they live for many years, usually the lymphatic vessels of the lower limbs and the disease is called elephantiasis or filariasis (Figure 7.2). The genital organs are also often affected, resulting in gross deformities. The pathogens are transmitted to a healthy person through the bite by the female mosquito vectors.”