Which one of the following diseases is caused by virus ?

Influenza, commonly known as the flu, is a contagious respiratory disease caused by the influenza virus [c2][t1]. It primarily affects the respiratory tract, leading to symptoms like fever, cough, and body ache [c2]. In contrast, the other options are bacterial infections. Tuberculosis is caused by the bacterium Mycobacterium tuberculosis, which typically affects the lungs [c1][t1][t7]. Typhoid fever is caused by the bacterium Salmonella Typhi, often spreading through contaminated food and water [c3][t1]. Diphtheria is an acute bacterial disease caused by Corynebacterium diphtheriae, which produces toxins that can damage heart and nerve tissues [t1][t5]. Therefore, among the given choices, only influenza is a viral disease, while tuberculosis, typhoid, and diphtheria are bacterial in origin.

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 12: Animal Diversity of India > 12,7. W ILDLIF E DISEASES > p. 193
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > Activity 3.4: Let us find out > p. 33
3. [3] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > Activity 3.4: Let us find out > p. 34
4. [4] https://www.cda.gov.sg/public/diseases/
5. [5] https://www.ncbi.nlm.nih.gov/books/NBK20370/