Which disease is caused by a bacterium?

Strep throat is caused by the bacterium Streptococcus pyogenes. This bacterium is known to infect the throat and can lead to a range of symptoms, including a sore throat, fever, and swollen lymph nodes. Strep throat is a common infection, particularly in children and adolescents, and is diagnosed through a throat culture or rapid strep test.

In contrast to strep throat, HIV/AIDS is caused by a virus (the Human Immunodeficiency Virus), meaning it is not a bacterial infection. Malaria is also not caused by bacteria; it is an infectious disease caused by Plasmodium parasites, which are transmitted to humans through the bites of infected mosquitoes. Influenza is another viral infection, caused by the influenza virus, that affects the respiratory system. This highlights the distinct differences between bacterial infections and those caused by viruses or parasites, underlining why strep throat is the correct answer in this context.