Leprosy is caused by

Leprosy, also known as Hansen's disease, is a chronic infectious disease caused by the slow-growing bacteria Mycobacterium leprae and Mycobacterium lepromatosis [4]. These organisms are obligate intracellular pathogens that primarily target the skin and peripheral nerves [4]. The disease was historically stigmatized, but it was scientifically proven to be a bacterial infection by Dr. Gerhard H.A. Hansen in 1873, which disproved earlier theories that it was hereditary [1]. Because it is a bacterial disease, it is treated with antibiotics, which are specifically designed to target bacterial cell structures that differ from human cells [5]. Unlike viral infections or those caused by protozoa, leprosy requires long-term multidrug therapy to eliminate the causative bacilli [2]. It is not caused by a virus, protozoa, or retrovirus [3].

Sources

1. [1] https://www.dshs.texas.gov/hansens-disease-leprosy
2. [3] https://www.cdc.gov/leprosy/about/index.html
3. [4] https://www.ncbi.nlm.nih.gov/books/NBK559307/
4. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > 3.5.1 Treatment of diseases > p. 39
5. [5] https://researchonline.lshtm.ac.uk/4653727/1/2010_ITD-PhD_Walker_S.pdf