When there is a disease either the functioning or the appearance of one or more systems of the body will change for the worse. These changes give rise to symptoms and signs of disease. Symptoms of disease are the things we feel as being wrong. Different symptoms which could be established during the diseased condition include headache cough loose motion and wounds with pus. These symptoms indicate there may be a disease but they don’t indicate what the disease is.

Doesn't look like fun. The flu is caused by an influenza virus. And usually a slightly different virus every season.

Viruses cause many human diseases. In addition to the flu and HIV, viruses cause rabies, measles, diarrheal diseases, hepatitis, polio, cold sores, and other diseases. Viral diseases range from mild to fatal. Viruses cause disease by causing host cells to burst open and die. Viruses may also cause disease without killing host cells. They may cause illness by disrupting homeostasis in host cells.

Let us now think a little more about the disease. The tissue makes up a physiological system and organ system that carry out body functions. Each of the body organs systems carries out body functions. Each organ system has a specific organ as its parts, and it has particular functions. So the digestive system has the stomach and intestine and it helps to digest food taken in from outside the body. The musculoskeletal system which is made up of bones and muscles holds the body part and helps to move the body.

 When there is a disease either the functioning of one or more systems of the body will change for the worse. These changes give rise to symptoms as a sign of disease. Symptoms o disease are the things we feel as being wrong. So we had a headache we have a cough we have loose motion we have a wound with pus these are all symptoms. These indicate that there may be a disease but they do not indicate what the disease is. For example, a headache may mean just examination stress, or very rarely it may mean meningitis or one of a dozen different diseases. Signs of disease are what physicians will look for based on the symptoms. Signs will give a little more definite indication of the presence of a particular disease. Physicians will also get laboratory tests done to pinpoint the disease further.

There are two types of disease:-

• Acute conditions are often caused by a virus or an infection, but can also be caused by an injury resulting from a fall or an automobile accident, or by the misuse of drugs or medications. Acute diseases come on rapidly and are accompanied by distinct symptoms that require urgent or short-term care, and get better once they are treated.
• Chronic conditions are often caused by unhealthy behaviors that increase the risk of disease—poor nutrition, inadequate physical activity, overuse of alcohol, or smoking. Social, emotional, environmental, and genetic factors also play a role. Chronic conditions are slower to develop, may progress over time, and may have any number of warning signs or no signs at all
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