Widal test is used to diagnose:

The correct answer is Option (1) → Typhoid

Option (1) Typhoid — Correct. Typhoid fever is caused by Salmonella typhi. The Widal test confirms it.

Note: A similar question was also asked in CUET (UG) 2026 on 24-05-2026 (Slot 1), and in CUET (UG) 2025 on 23-05-2025 (Slot 2).

NCERT Extract:
Common Diseases in Humans – “… Salmonella typhi is a pathogenic bacterium which causes typhoid fever in human beings. These pathogens generally enter the small intestine through food and water contaminated with them and migrate to other organs through blood. Sustained high fever (39° to 40°C), weakness, stomach pain, constipation, headache and loss of appetite are some of the common symptoms of this disease. Intestinal perforation and death may occur in severe cases. Typhoid fever could be confirmed by Widal test : A classic case in medicine, that of Mary Mallon nicknamed Typhoid Mary, is worth mentioning here.”