Which of the following diseases is categorized under bacteria in water contamination?

Typhoid is a disease caused by the bacterium Salmonella typhi, which can contaminate water supplies, particularly in areas with poor sanitation and hygiene practices. When individuals consume contaminated water or food, they can contract typhoid fever, leading to symptoms such as prolonged fever, weakness, and abdominal pain. Understanding the transmission route of typhoid through contaminated water underscores the importance of maintaining safe drinking water sources and proper sanitation practices to prevent outbreaks.

In contrast, the flu, AIDS, and COVID-19 are caused by viruses, not bacteria. The flu is caused by influenza viruses, AIDS is caused by the human immunodeficiency virus (HIV), and COVID-19 is caused by the coronavirus SARS-CoV-2. While these diseases can spread through various means, they do not fall under the category of bacterial water contamination, which is why typhoid stands out as the correct answer in this context.