Type | Description | Examples | Some Disorders That Can Result |
---|---|---|---|
Bacteria are microscopic, single-celled organisms without a nucleus. | Streptococcus pyogenes | ||
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 | Chickenpox Chickenpox Chickenpox is a highly contagious viral infection with the varicella-zoster virus that causes a characteristic itchy rash, consisting of small, raised, blistered, or crusted spots. Chickenpox... read more and shingles Shingles Shingles is a painful skin rash caused by a viral infection that results from reactivation of the varicella-zoster virus, the virus that causes chickenpox. What causes the virus to reactivate... read more | |
Rhinovirus | |||
Fungi are neither plants nor 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). | |||
Plasmodium falciparum (a species of protozoa) |