Cough

Definition

A cough is a forceful release of air from the lungs that can be heard. Coughing protects the respiratory system by clearing it of irritants and secretions.

Description

While people can generally cough voluntarily, a cough is usually a reflex triggered when an irritant stimulates one or more of the cough receptors found at different points in the respiratory system.

These receptors then send a message to the cough center in the brain, which in turn tells the body to cough. A cough begins with a deep breath in, at which point the opening between the vocal cords at the upper part of the larynx (glottis) shuts, trapping the air in the lungs. As the diaphragm and other muscles involved in breathing press against the lungs, the glottis suddenly opens, producing an explosive outflow of air at speeds greater than 100 mi (160 km) per hour.

cryptococcosis

Definition

Cryptococcosis is an infection caused by inhaling the fungus Cryptococcus neoformans. It is one of the diseases most often affecting AIDS patients. Cryptococcosis may be limited to the lungs, but frequently spreads throughout the body. Although almost any organ can be infected, the fungus is often fatal if it infects the nervous system where it causes an inflammation of the membranes covering the brain and spinal cord (meningitis).

Description

The fungus causing cryptococcis, C. neoformans, is found worldwide in soil contaminated with pigeon or other bird droppings. It has also been found on unwashed raw fruit. Cryptococcosis is a rare disease in healthy individuals, but is the most common fungal infection affecting people with AIDS.

People with Hodgkin's disease or who are taking large doses of drugs that suppress the functioning of the immune system (corticosteroids, chemotherapy drugs) are also more susceptible to cryptococcal infection. Cryptococcosis is also called cryptococcal meningitis (when the brain is infected), BusseBuschke disease, European blastomycosis, torular meningitis, or torulosis.

Avian Tuberculosis

A strain of tuberculosis in birds, caused by Mycobacterium avium. Birds consistently shed large amounts of the bacteria into the environment via feces. The organism is also pathogenic in humans and is especially problematic in the immunocompromised, such as those with human immunodeficiency virus infection.

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Tuberculosis [too-ber´ku-lo´sis]

An infectious, inflammatory, reportable disease that is chronic in nature and usually affects the lungs (pulmonary tuberculosis), although it may occur in almost any part of the body. The causative agent is Mycobacterium tuberculosis (also known as the tubercle bacillus). Formerly, the only other species of Mycobacterium thought to be pathogenic to humans were M. bovis and M. avium. It is now known that other species can produce diseases similar to true tuberculosis, including M. intracellulare, M. kansasii, M. simiae, and M. szulgai.

The most common mode of transmission of tuberculosis in the United States is inhalation of infected droplet nuclei. In some other parts of the world bovine tuberculosis, which is carried by unpasteurized milk and other dairy products from tuberculous cattle, is more prevalent. A rare mode of transmission is by infected urine, especially for young children using the same toilet facilities. Tuberculosis is also seen as an opportunistic infection in human immunodeficiency virus (HIV) infection.