Common Cold

More than 200 different viruses can cause colds. Rhinoviruses are responsible for up to a third of all upper respiratory infections.

Congenital Infections

Bacteria, parasites, or viruses can cause congenital infections, which are infections that are present at birth. These infections can be passed to the fetus or newborn in two ways.


Conjunctivitis, is an inflammation of the thin membrane that lines the inside of the eyelids and covers the white surface of the eye. The inflammation can produce redness, burning, or itching of the eyes and sometimes a discharge.

Coxsackieviruses and Other Enteroviruses

There are many different kinds of viruses in the enterovirus family, which cause infections with different symptoms, mostly in children. These viruses make their home in the digestive tract and are related to the viruses that cause poliomyelitis* and hepatitis A*.

Creutzfeldt-Jakob Disease

Creutzfeldt-Jakob disease (CJD) is a very rare disorder that damages the tissues of the brain, causing a rapid decline in mental function and muscle coordination, eventually leading to death.


*trochea (TRAY-kee-uh) is the windpipe, the firm, tubular structure that carries air from the throat to the lungs.

Cytomegalovirus (CMV) Infection

CMV is part of the herpesvirus (her-peez-VY-rus) family, which also includes the viruses that cause herpes*, chicken pox, and mononucleosis*. As with other members of the herpesvirus family, once CMV enters a person's body, it remains there for life.

Dengue Fever

Dengue fever is characterized by a sudden high fever and severe pain in the muscles, joints, and bones. (It originally was named "break-bone fever.") The disease is more likely to cause serious illness in children, and some cases are fatal.


Diphtheria is an infection caused by a bacterium called Corynebacterium diphtheriae (kor-ih-nee-bak-TEER-e-um dif-THEER-e-eye) that infects the upper respiratory tract. As the bacteria infect the nose, throat, or larynx (LAIR-inks, the voicebox), a distinctive thick membrane forms over the site of infection.

Ebola Virus Infection

Ebola appeared without warning in late 2000 in the northern district of Gulu in Uganda, Africa. Health workers responded quickly, caring for people infected with the disease and isolating them so that they would not spread the devastating virus to others.


Caused by an organism once thought to infect only dogs, sheep, cattle, goats, and horses, ehrlichiosis was first discovered in humans in 1953 when researchers in Japan found that Sennetsu fever, an illness that resembles mononucleosis*, was caused by Ehrlichia sennetsu bacteria. Since the 1980s, scientists have identified three additional strains* of Ehrlichia bacteria that cause forms of human ehrlichiosis in the United States: E.


There are several different causes of encephalitis. The most common is infection, usually by a virus.

Endocarditis, Infectious

The heart has four chambers and four valves that regulate the flow of blood through the heart. Each valve is made up of two or three smaller parts, known as leaflets, that swing open and shut.


Epiglottitis, also known as supraglottitis (su-pra-glah-TIE-tis), is characterized by inflammation and swelling of the epiglottis and other upper airway structures. The epiglottis can become dangerously swollen within just a few hours, leading to narrowing of the airway and severe breathing difficulty.

Fifth Disease

Fifth disease, sometimes called slapped-cheek disease, is an infection caused by a virus called human parvovirus B19. Its most characteristic feature is a bright red rash that begins on the face, making the cheeks look as if they have been slapped.


Filariasis is caused by different species of microscopic parasitic* roundworms that are passed to people through the bites of insects, most commonly mosquitoes. Several strains* of these worms, known as filariae (fih-LAIR-e-e), can infect humans, including Wuchereria bancrofti (vooker-E-re-ah ban-CROFT-e).

Fungal Infections

*microbes (MY-krobes) are microscopic living organisms, such as bacteria, viruses and fungi.


Gangrene is not a contagious disease. It is a condition in which living tissue (e.g., skin, muscle, or bone) begins to decay and die because blood flow (and oxygen) to an area is blocked or because harmful bacteria invade the body's tissues after entering through a wound or sore.


*urethra (yoo-REE-thra) is the tube through which urine passes from the bladder to the outside of the body.

Hantavirus Pulmonary Syndrome

Hantavirus pulmonary syndrome, or HPS, is a potentially deadly disease that attacks the lungs. A family of viruses called hantavirus causes HPS.