Which one of the following is a bacterium that causes disease in the human body?

Salmonella typhi is the bacterium responsible for causing typhoid fever in humans [2]. Pathogens are classified into various categories including bacteria, viruses, and protozoa [1]. Among the other options provided, Varicella zoster is a virus that causes chickenpox and shingles. Trypanosoma gambiense (specifically Trypanosoma brucei gambiense) is a protozoan parasite transmitted by the tsetse fly, leading to African Sleeping Sickness. Similarly, Plasmodium falciparum is a protozoan parasite belonging to the genus Plasmodium, which is the primary cause of malaria in humans. While all these organisms are pathogens that cause disease, only Salmonella typhi is classified as a bacterium [2]. Understanding these distinctions is crucial for diagnosis and treatment, as bacterial infections are typically treated with antibiotics, whereas viral and protozoan infections require different medical interventions [1].

Sources

1. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > z. Effects on human health: > p. 75
2. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > 3.4 Diseases: What Are the Causes and Types? > p. 32