Epidemiology Health Channel

	Feature Article Illustrations for this article Click on an image below to enlarge Tuberculosis in the lung Kaposi's sarcoma - lesion on the foot Show all 19 photos AIDS Definition AIDS (Acquired Immune Deficiency Syndrome) is the final and most serious stage of HIV disease, which causes severe damage to the immune system. According to the Centers for Disease Control and Prevention, AIDS begins when a person with HIV infection has a CD4 cell count below 200. CD4 cells are also called "T-cells" or "helper cells"; they are a type of immune cell. AIDS is also defined by numerous opportunistic infections and cancers that occur in the presence of HIV infection. Alternative Names Acquired immune deficiency syndrome Causes, incidence, and risk factors AIDS is the fifth leading cause of death among persons between ages 25 and 44 in the United States, down from number one in 1995. About 25 million people worldwide have died from this infection since the start of the epidemic, and 40.3 million people are currently living with HIV/AIDS globally Human immunodeficiency virus (HIV) causes AIDS. The virus attacks the immune system and leaves the body vulnerable to a variety of life-threatening infections and cancers. Common bacteria, yeast, parasites, and viruses that ordinarily do not cause serious disease in people with healthy immune systems can cause fatal illnesses in people with AIDS. HIV has been found in saliva, tears, nervous system tissue and spinal fluid, blood, semen (including pre-seminal fluid), vaginal fluid, and breast milk. However, only blood, semen, vaginal secretions, and breast milk generally transmit infection to others. Transmission of the virus occurs: Through sexual contact -- including oral, vaginal, and anal sex Through blood -- via blood transfusions (now extremely rare in the U.S) or needle sharing From mother to child -- a pregnant woman can transmit the virus to her fetus through their shared blood circulation, or a nursing mother can transmit it to her baby in her milk Other transmission methods are rare and include accidental needle injury, artificial insemination with donated semen, and organ transplants. HIV infection is not spread by casual contact such as hugging, by touching items previously touched by a person infected with the virus, during participation in sports, or by mosquitoes. It is not transmitted to a person who DONATES blood or organs. Those who donate organs are not in direct contact with those who receive them. Likewise, a person who donates blood is not in contact with the person receiving it. Continue reading this article

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Pulmonary tuberculosis (9 Images) Average Rating: (Doctor-Reviewed information)
Pulmonary tuberculosis (TB) is a contagious bacterial infection that mainly involves the lungs, but may spread to other organs. Reviewer: Allen J. Blaivas, DO, Pulmonary, Critical Care, and Sleep Medicine, Department of Veteran Affairs, VA New Jersey Health Care System, East Orange, NJ. Review provided by VeriMed Healthcare Network.Date: 08/03/2007
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Encephalitis (1 Video) (Doctor-Reviewed information)
Encephalitis is an inflammation (irritation and swelling) of the brain, usually caused by infections. See also meningitis. Reviewer: Kenneth Gross, M.D., Neurology, North Miami, FL. Review provided by VeriMed Healthcare Network.Date: 09/07/2006
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Meningitis - meningococcal (1 Image) (Doctor-Reviewed information)
Meningococcal meningitis is an infection that causes inflammation of the membranes covering the brain and spinal cord. Reviewer: Hilary M. Babcock, M.D., Medical Director of Occupational Infection Control, Barnes-Jewish and St. Louis Children's Hospitals; Instructor of Medicine, Infectious Disease Division, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.Date: 08/15/2006
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Cholera (2 Images) (Doctor-Reviewed information)
Cholera is an infection of the small intestine caused by the bacterium Vibrio cholerae. It¿causes a large amount of¿watery diarrhea. Reviewer: Arnold L. Lentnek, MD, Division of Infectious Disease, Kennestone Hospital, Marietta, GA. Review provided by VeriMed Healthcare Network.Date: 08/16/2007
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Severe acute respiratory syndrome (SARS) (2 Images) (Doctor-Reviewed information)
Severe acute respiratory syndrome (SARS) is a serious form of pneumonia, caused by a virus isolated in 2003. Infection with the SARS virus results in acute respiratory distress (severe breathing diffculty) and sometimes death. It is a dramatic example of how quickly world travel can spread a disease. It is also an example of how quickly a networked health system can respond to an emerging threat. Background Information: This contagious respiratory infection was first described on Feb. 26, 2003. SARS was identified as a new disease by World Health Organization (WHO) physician Dr. Carlo Urbani. He diagnosed it in a 48-year-old businessman who had traveled from the Guangdong province of China, through Hong Kong, to Hanoi, Vietnam. The businessman died from the illness. Dr. Urbani subsequently died from SARS on March 29, 2003, at the age of 46. In the meantime, SARS was spreading, and within 6 weeks of its discovery, it had infected thousands of people around the world, including people in Asia, Australia, Europe, Africa, and North and South America. Schools had closed throughout Hong Kong and Singapore. National economies were affected. The WHO had identified SARS as a global health threat, and issued an unprecedented travel advisory. Daily WHO updates tracked the spread of SARS seven days a week. It wasn't clear whether SARS would become a global pandemic, or would settle into a less aggressive pattern. The rapid, global public health response helped to stem the spread of the virus, and by June 2003, the epidemic had subsided to the degree that on June 7 the WHO backed off from its daily reports. Nevertheless, even as the number of new cases dwindled, and travel advisories began to be lifted, the sober truth remained: every new case had the potential to spark another outbreak. SARS appears to be here to stay, and to have changed the way that the world responds to infectious diseases in the era of widespread international travel. Reviewer: D. Scott Smith, M.D., MSc, DTM&H, Chief of Infectious Disease & Geographic Medicine, Kaiser Redwood City, CA & Adjunct Assistant Professor, Stanford University. Review provided by VeriMed Healthcare Network.Date: 01/29/2007
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