An infection occurs when a microorganism — such as bacteria, fungi, or a virus — enters a person’s body and begins multiplying. Infections can have a variety of effects, ranging from mild to severe.

Fungi are microorganisms with a substance in their cell walls called chitin. Some, like mushrooms, are edible, while others, like Aspergillus, can be dangerous. Infections include athlete’s foot and ...

Vaginal yeast infections (candidiasis) are common. Over-the-counter treatment options may alleviate your symptoms within a few days. In severe cases, prescription medication may be necessary to clear ...