Apr 9, 2025 · Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Many organisms live in and on our bodies. They're normally harmless or even helpful. …

Infectious agents come in many shapes and sizes. Bacteria and protozoans are microscopic one-celled organisms. Viruses are even smaller. Fungi grow like plants. Helminths resemble worms.

Mar 5, 2024 · Bacteria Bacteria are one-celled life forms called organisms that can be seen only with a microscope. Not all bacteria are harmful. Some bacteria that live in the body are helpful. For …

Nov 25, 2025 · Bacteria cause bacterial infections. Viruses cause viral infections. Antibiotic medicines kill or keep many bacteria from growing but don't treat viruses. Antiviral medicines help the body …

Apr 8, 2025 · Anti-parasitics Some diseases, including malaria, are caused by tiny parasites. These organisms live in or on host organisms, which can include people. Parasites get their nutrients from …

Sep 20, 2025 · Anthrax is a rare but serious illness caused by a spore-forming bacterium, called Bacillus anthracis. In the body, the spores form poisons that can destroy tissues. Anthrax mainly affects farm …

Dec 22, 2021 · Repetitive douching disrupts the good organisms that live in the vagina and can increase your risk of vaginal infection. Douching won't clear up a vaginal infection.

Nov 14, 2023 · Learn about different tick species and some of the diseases they may carry.

Overview Sexually transmitted diseases (STDs) are caused by sexually transmitted infections (STIs). They are spread mainly by sexual contact. STIs are caused by bacteria, viruses or parasites. A …

May 15, 2024 · Nail fungus is caused by various fungal organisms (fungi). The most common is a type called dermatophyte. Yeast, bacteria and molds also can cause nail infections. The discoloration …