Types of Infectious Organisms
Type | Description | Examples | Some Disorders That Can Result |
|---|---|---|---|
Bacteria are microscopic, single-celled organisms without a nucleus. | Streptococcus pyogenes | Pharyngitis (strep throat) | |
Escherichia coli | |||
Viruses are small infectious organisms—much smaller than a fungus or bacterium. They cannot reproduce on their own. They must invade a living cell and use that cell’s machinery to reproduce. | Varicella-zoster virus | Chickenpox and shingles | |
Rhinovirus | The common cold | ||
Fungi are living organisms, but they are not plants or animals. Their size ranges from microscopic to easily seen with the naked eye. They include yeasts, molds, and mushrooms. | Candida albicans | ||
Trichophyton | |||
Parasites are organisms that survive by living inside another usually much larger organism (the host). They include worms and single-celled organisms called protozoa (which, unlike bacteria, have a nucleus). | Enterobius vermicularis (a species of pinworm) | ||
Plasmodium falciparum (a species of protozoa) |