Microbiology

Among the diseases listed, Malaria is caused by a protozoan. Malaria is a disease transmitted by the bite of infected Anopheles mosquitoes and is caused by protozoan parasites of the genus Plasmodium. These microscopic single-celled organisms infect and multiply within the host's liver and red blood cells, leading to symptoms such as fever, chills, and anemia.

The other diseases mentioned have different causative agents:

• Tuberculosis: Caused by the bacterium Mycobacterium tuberculosis.
• Typhoid: Caused by the bacterium Salmonella typhi.
• Influenza: Caused by the influenza viruses.

Among the diseases listed, the one that is not caused by bacteria is Dengue. Here’s the breakdown of each disease listed:

• Tuberculosis: Caused by the bacterium Mycobacterium tuberculosis.
• Cholera: Caused by the bacterium Vibrio cholerae.
• Typhoid: Caused by the bacterium Salmonella typhi.
• Dengue: Caused by the dengue virus, which is transmitted by Aedes mosquitoes, making it a viral infection rather than a bacterial one.

Therefore, the correct answer is Dengue.