Skin and Soft Tissue Infections
Viruses, bacteria, and fungi generally cause skin and soft tissue infections by entering the body at a spot where a cut, scrape, bite, or other wound has broken the skin; some infections are even the result of bacteria that normally live on the body. These infections can affect the layers of the skin or deeper tissues, such as muscle and connective tissue (the interlacing framework of tissue that forms ligaments, tendons, and other supporting structures of the body), and they may bring about symptoms in other parts of the body.
Parasites live off other living things (including people), often living, feeding, and reproducing on them. Some parasites thrive on human blood and cannot live long without it.
What do Queen Mary II of England, King Louis XV of France, and Czar Peter II of Russia have in common? Other than being royalty, they all died from smallpox, one of the deadliest diseases in history.
A sore throat can be a symptom of many infectious diseases. Viral infections such as the common cold, influenza*, adenovirus* infection, and infectious mononucleosis* cause most sore throats.
They cannot be seen with the naked eye, but bacteria cover the skin's surface. Staphylococcus aureus bacteria, also called staph bacteria, often live on people's skin, particularly around openings such as the nose, mouth, genitals*, and rectum* and sometimes inside the nose and mouth, without causing disease.
Streptococci (strep-tuh-KAH-kye) are common bacteria that live in the human body, including the nose, skin, and genital tract. These bacteria can destroy red blood cells, damage them, or cause no damage at all.
Syphilis is a disease that is caused by the bacterium Treponema pallidum (treh-puh-NEE-muh PAL-ih-dum). The disease develops in three distinct phases.
Tetanus is a disease caused by infection with Clostridium tetani (klos-TRIH-dee-um teh-TAH-nye) bacteria, which are found all over the world in soil, dust, and some animal feces (FEE-seez, or bowel movements) and even on human skin. The bacteria can enter the body through any type of wound, such as a scratch or deep cut.
Ticks can spread bacteria or parasites through their bites. A tick becomes infected when it bites an animal, and then the tick can pass the infection to humans when it bites them.
The parasite Toxoplasma gondii, the organism behind toxoplasmosis, is found in soil and can infect humans and many species of animals. It is often found in cats, and is passed in cat feces (FEE-seez, or bowel movements).
When travelers go abroad, they may be exposed to many bacterial, viral, parasitic, and fungal infections that they would not come into contact with in the United States. With different climates, sanitation, and hygiene practices (such as bathing and urinating in the same water source), some diseases that are rarely or never seen in the United States are common in other parts of the world.
Also called trichinellosis (trih-kih-neh-LO-sis), trichinosis can occur when people eat meat that is infected with the larvae* of Trichinella roundworms (also called nematodes, NEE-muh-todes); Trichinella spiralis (spy-RAL-is) is the most common species that causes trichinosis. People can become infected only by eating infected meat; the disease is not spread through human contact.
Trichomoniasis (also known as "trich") is an infection caused by the parasite Trichomonas vaginalis (trih-koh-MO-nas vah-jih-NAL-is). It usually affects the urethra* in men and the vagina or urethra in women.
Trypanosomiasis refers to three types of infections caused by protozoa* and spread to humans through insect bites. There are two kinds of African trypanosomiasis, East African and West African.
A germ known as Mycobacterium (my-ko-bak-TEER-e-um) tuberculosis causes tuberculosis (TB). Being infected with the bacterium and actually having the disease tuberculosis are very different.
Tularemia is caused by the bacterium Francisella tularensis (fran-sih-SEL-uh too-lah-REN-sis). Most cases in the United States come from contact with infected rabbits and deer, although the bacterium also lives in other small mammals and birds, and it can be found in soil.
Urinary Tract Infections
A UTI usually is caused by bacteria. The bacterium most often responsible for UTIs is Escherichia coli (eh-sher-IH-she-ah KOH-lye).
Varicella (Chicken Pox) and Herpes Zoster (Shingles)
This highly contagious disease is characterized by the appearance of crops of red, itchy spots on the skin. The spots progress to blisters and eventually develop crusts and heal.
Warts are small areas of hardened skin that can grow on almost any part of the body. They are caused by human papilloma (pah-pih-LO-mah) viruses, or HPV.
West Nile Fever
West Nile fever (WNF) is caused by West Nile virus (WNV), which is part of the flavivirus family*. First discovered in Africa, WNV can infect animals and humans, although animals (mainly birds, but also horses, cats, and bats) are the primary hosts* for the virus.
Yellow fever is a disease caused by yellow fever virus, a member of the flavivirus (FLAY-vih-vy-rus) group of viruses. The disease gets its name because it often causes jaundice*, which tints the skin yellow, and a high fever.
Zoonoses are infections caused by parasites, bacteria, or viruses that are passed from animals to humans. Most people contract zoonotic (zoh-uh-NAH-tik) infections from animals with which they have a lot of contact, such as pets or farm animals.