Diseases & Conditions
The human body is a remarkable structure. It's designed to efficiently manage the wear and tear of everyday life and fend off all sorts of threats. Most of us are healthy for most of our lives. But we're also susceptible to hundreds of injuries, diseases, and conditions. Some are quite common, others are extremely rare. Here are some of the most common conditions that affect humans.
Diseases & Conditions Articles
Get health tips from the faculty physicians of Harvard Medical School. Each video is one to three minutes in length and the video library covers a broad variety of topics related to health and wellness.
The bacteria that cause disease are remarkably resilient and can develop ways to evade the drugs meant to kill or weaken them. This phenomenon is called antibiotic resistance and it is due largely to the growing, and often careless, use of antibiotics.
Today, bacterial infections in the United States and throughout the world are becoming resistant to the drugs we rely on to treat them. Antibiotic resistance has been called one of the world's most pressing public health problems. The smart use of antibiotics is the key to controlling the spread of antibiotic resistant bacteria and the rise of superbugs—bacteria that cause infections that are difficult if not impossible to treat.
Osgood-Schlatter disease is a common, temporary condition that causes knee pain in older children and teenagers, especially those who play sports.
During activities that include a lot of jumping and bending — hockey, basketball, volleyball, soccer, skating, gymnastics, or ballet — the quadriceps muscle (thigh muscle) pulls tightly against the kneecap and the kneecap's anchor, the patellar tendon. The fibers of the patellar tendon are attached to the shinbone (tibia). With repeated pulling against these fiber connections, the tendon can become inflamed at or near its bone attachment. The result is pain and swelling at the tibial tuberosity, which is a raised area at the top of the shinbone. The tibial tuberosity is where the patellar tendon attaches to the bone.
Psoriatic arthritis is a chronic (long-lasting) disease in which a person with psoriasis develops the symptoms and signs of arthritis joint pain, stiffness and swelling. Psoriasis is a common, inherited skin condition that causes grayish-white scaling over a pink or dull-red skin rash.
Psoriasis can develop before or after the arthritis, but psoriasis develops first in about 75% of cases. A person may begin to get morning joint stiffness before the arthritis is recognized. People who have psoriasis that involves the nails, especially nail pitting, are much more likely to develop arthritis than those without this problem (50% versus 10%).
The cause of psoriatic arthritis is unknown. There is some evidence that infection or trauma can play a role in the development of the disease. For example, psoriatic arthritis seems to flare up in people whose immune systems are affected by human immunodeficiency virus (HIV) infection. Also, heredity seems to play a role. Up to 40% of people with psoriatic arthritis have a family history of skin or joint disease. Certain genes seem to be involved in certain types of psoriatic arthritis. For example, the gene HLA-B27 has been associated with psoriatic spondylitis.
A normal spine has several front-to-back curves between the neck and the pelvis. In scoliosis, the spine curves abnormally to the side or twists. Although scoliosis seems to run in some families, most cases appear for unknown reasons in children and adolescents who previously had a straight spine. Scoliosis without a known cause is called idiopathic scoliosis. Girls and boys are affected equally by idiopathic scoliosis, but girls with this condition are more likely to develop curves that get big enough to require treatment.
A sprain is a tear of ligaments, the tough bands of fibrous tissue that connect bones to one another at a joint. Normally, ligaments stabilize a joint, keep the joint's bones aligned and limit the motion of a joint to the normal range. When a joint is sprained, its torn or stretched ligaments can lose part or all of their ability to reinforce the joint and to keep it moving normally. In severe cases, the sprained joint can become unstable and loose, bones can move out of alignment and the joint may extend beyond its normal range of motion.
Although ligaments can be sprained in a variety of ways, the actual ligament damage is usually caused by at least one of the following:
Flexing (bending), extending (stretching out) or twisting a joint beyond its normal range of motion — This injury is a common cause of wrist sprains in skiers. If a skier falls with a ski pole still strapped to the wrist, the attached pole can twist the wrist beyond its normal limits and cause a sprain.
Suddenly increasing the tension (strain or pull) on a ligament to the point that it snaps in two — This type of injury can happen in the knee joint if you suddenly stop short while running. The extreme tension of the braking force actually tears one of the knee ligaments in two, often causing a pop that can be felt or even heard when the ligament snaps.
Hitting the joint directly or hitting one of the bones near the joint — This type of sprain often happens in contact sports, especially when a shoulder or knee joint takes the full impact of a collision between two athletes.
Any unusual force across a joint can cause a sprain. Among athletes, more than any other group, sprains are common. Knee sprains and shoulder sprains are common among those who participate in football, basketball, soccer, rugby, wrestling, gymnastics and skiing. Foot sprains are a danger for ballet dancers, snowboarders, windsurfers, equestrians and competitive divers. Wrist sprains are common in skiing, football, basketball, baseball, roller hockey, boxing, basketball, volleyball and weightlifting. The specific joint that tends to be sprained during a particular sport is usually related to the kinds of joint movements that the sport requires or to the types of impact or collision that can happen. For example, many knee sprains in football players are caused by the extreme knee stress of cutting moves and sharp turns. Others are caused by the direct impact of tackles.
Off the playing field, sprains often occur because of high-impact accidents — for example, striking the knee on the dashboard during a car crash or slipping on a patch of ice and landing on a wrist or shoulder. Sprains are also common in the workplace.
A deep venous thrombosis (DVT) is a blood clot (thrombus) that forms inside deep veins in your legs or pelvis. The clot blocks blood flow and causes pressure to build up in the vein. Part of the clot can break away and move through your bloodstream to your lungs.
A person with somatization disorder is chronically preoccupied with numerous "somatic" (physical) symptoms over many years. These symptoms, however, cannot be explained fully by a non-psychiatric diagnosis. Nonetheless, the symptoms cause significant distress or impair the person's ability to function.
The person is not "faking." Somatization disorder is a medical problem. The disorder, however, is probably related to brain functioning or emotional regulation rather than the area of the body that has become the focus of the patient's attention. The symptoms are real and are not under the person's conscious control.
People with somatization disorder report multiple medical problems over many years, involving several different areas of the body. For example, the same person might have back pain, headaches, chest discomfort, and stomach or urinary distress. Women often report irregular periods. Men may report erectile dysfunction (impotence). The person may:
Describe symptoms in dramatic and emotional terms
Seek care from more than one physician at the same time
Describe symptoms in vague terms
Lack signs of defined medical illness
Have complaints that medical tests fail to support
People with somatization disorder do get diagnosable medical illnesses, too, so doctors must be careful not to dismiss symptoms too easily.
A person with somatization disorder also may have symptoms of anxiety and depression. He or she may begin to feel hopeless and attempt suicide, or may have trouble adapting to the stresses of life. The person may abuse alcohol or drugs, including prescription medications.
Spouses and other family members may become distressed because the person's symptoms continue for long periods of time and no medical treatment seems to help.
Symptoms of somatization disorder vary by culture, sometimes depending on how illness or "sick roles" are viewed in a given culture. Cultural factors also affect the proportions of men and women with the disorder.
Female relatives of people with somatization disorder are more likely to develop the disorder. Male relatives are more likely to develop alcoholism and personality disorder.
Scientists do not know the cause of the symptoms reported by people with somatization disorder, but researchers have some theories. It is possible, for example, that people with this disorder perceive bodily sensations in an unusual way. Or they may describe feelings in physical (rather than mental or emotional) terms. Trauma or stress may cause a person's physical sensations to change.
Laryngitis is an inflammation of the larynx, the "voice box" that contains the vocal cords in the upper portion of the neck. Laryngitis occurs in two forms, acute and chronic. Acute laryngitis typically is a brief illness producing hoarseness and a sore throat. In most cases, an upper respiratory tract infection causes it. Chronic laryngitis is a more persistent disorder that produces lingering hoarseness and other voice changes. It usually is painless and has no significant sign of infection.
What Is It?
Young children and, sometimes, older children and adults may swallow toys, coins, safety pins, buttons, bones, wood, glass, magnets, batteries or other foreign objects. These objects often pass all the way through the digestive tract in 24 to 48 hours and cause no harm.
But problems may arise when objects are stuck for a long time, are sharp, or contain corrosive materials. Complications can include tears in the esophagus (the tube that connects the mouth and stomach), movement of the object into the tissue of the esophagus, and infection. Small magnets can pose a special problem. If more than one is swallowed, they can stick together and erode through tissue.
Three areas of the esophagus are the most likely places for objects to lodge:
At the level of the collarbones (clavicles) — the most common place
At the center of the chest
Just before the esophagus meets the stomach, near the bottom of the rib cage
Objects also may get stuck in any part of the esophagus that has been injured previously.