Health Science

Health science



Health science

1. Infectious Diseases

Infectious disease is a disease caused by bacterial, viral, fungal, or protozoan infection. Though some infectious diseases are not contagious, others may be transmitted from animal to person (bird flu and cat scratch disease) or from person to person (MRSA, HIV, and other STDs). Get the facts on the various types of infectious diseases, and read the latest statistics and news about emerging infections.

Also called: Communicable diseases

Diphtheria

This bacterial infection can cause a membrane to form at the back of the throat, or lower down in the airways in the lungs, and prevents an infected person from breathing properly. The toxin produced by the diphtheria bacteria may also damage the heart and the nervous system. Once the infection has taken hold, there is no specific treatment and the illness has to run its course.

HIV/AIDS

HIV (human immunodeficiency virus) infection has now spread to every country in the world. Approximately 40 million people are currently living with HIV infection, and an estimated 25 million have died from this disease. The scourge of HIV has been particularly devastating in sub-Saharan Africa, but infection rates in other countries remain high. In the United States, approximately 1 million people are currently infected. Here are a few key points about the disease:

Globally, 85% of HIV transmission is heterosexual.

In the United States, approximately one-third of new diagnoses appear to be related to heterosexual transmission. Male-to-male sexual contact still accounts for approximately half of new diagnoses in the U.S. Intravenous drug use contributes to the remaining cases. Because the diagnosis may occur years after infection, it is likely that a higher proportion of recent infections are due to heterosexual transmission.

Infections in women are increasing. Worldwide, 42% of people with HIV are women. In the United States, approximately 25% of new diagnoses are in women, and the proportion is rising.

There is good news on one front: New HIV infections in U.S. children have fallen dramatically, with only 38 cases reported in 2006. This is largely a result of testing and treating infected mothers, as well as establishing uniform testing guidelines for blood products.

2. Non-infectious diseases

Heart disease is a general term that refers to a variety of acute and chronic medical conditions that affect one or more of the components of the heart. The heart is a muscular, fist-sized organ that is located in the left side of the chest cavity. It continuously pumps blood, beating as many as 100,000 times a day. The blood that the heart moves carries oxygen and nutrients throughout the body and transports carbon dioxide and other wastes to the lungs, kidneys, and liver for removal. The heart ensures its own oxygen supply through a set of coronary arteries and veins. The heart is also an endocrine organ that produces the hormones atrial natriuretic hormone (ANP) and B-type natriuretic peptide (BNP), which coordinate heart function with blood vessels and the kidneys.

Internally, the heart is essentially hollow. It is divided vertically into two halves by a septum, and each side of ...