What causes acne?
Acne is not caused by having dirty skin or by eating the "wrong" foods. Instead, it is caused by the actions of the body's hormones, which stimulate the glands of acne-prone skin to produce oil. Pores in the skin become plugged, and bacteria growing in the blocked pores may lead to redness, swelling, and pus-filled bumps. Simple things such as pressure from a headband or a football helmet can make this condition worse.

Who is most likely to have acne?
People aged 15 to 25 years are most likely to get acne. Although acne usually clears up by early adulthood, women often experience this problem for the first time when they reach middle age. You are more likely to have acne if your parents or other family members also had it.

How is acne treated?
Skin with acne should be washed several times a day with soap and water applied with the hands. Soap brands such as Dial, Irish Spring, Ivory, or Zest are just as good as brands that cost more. If dry skin is also a problem, you may use a light moisturizer. Touching your face often, squeezing pimples, or scrubbing your skin can make acne worse.

If you wear makeup, wear as little as possible. While most nonoily cosmetics are relatively safe, none are helpful for skin with acne. Remove all makeup at bedtime.

For mild acne, you may want to try one of the many over-the-counter acne soaps or washes. Check the label to see if the soap or wash contains ingredients helpful in fighting acne, such as benzoyl peroxide, salicylic acid, or sulfur.

If you have a lot of acne, your doctor may prescribe a special soap, wash, lotion, gel, or cream. These treatments commonly contain an antibiotic (for example, clindamycin or erythromycin), azelaic acid, benzoyl peroxide, sodium sulfacetamide, or sulfur. Medications made from vitamin A, which are called retinoids, are prescribed to target blackheads and whiteheads. The most commonly used retinoid is tretinoin, available in generic form or under the brand name Retin-A or Avita.

Acne medications applied to the skin generally are used once or twice a day. However, several weeks may pass before you see results. There may even be an initial period in which your acne becomes worse. During treatment, especially with a retinoid, the skin may become dry and scaly. Spending time in the sun may increase this dryness.

Your doctor may also prescribe pills to use with or without a cream or lotion. Typical acne drugs taken by mouth include the antibiotics tetracycline, doxycycline, and minocycline. Other oral antibiotics that are used less commonly for acne include clindamycin, erythromycin, fluoroquinolones, sulfonamides, and a trimethoprim-sulfamethoxazole combination. Acne medications taken by mouth may cause stomach problems, dizziness, yeast infections, or skin redness after being in the sun.

The retinoid isotretinoin, sold under the brand name Accutane, is given only to people with severe acne that cannot be treated any other way. This drug can cause serious problems, including birth defects, and people who take it must use birth control to avoid pregnancy.

Some people benefit from using a new form of light therapy that can be done in their doctor's office. In addition, certain types of birth control pills as well as drugs that affect male hormones may help control acne in some women.

This information is not a substitute for medical treatment.

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What is Alzheimer's disease?
Dementia is a deterioration of your ability to think, learn, and remember as clearly and as quickly as you once did. The most common form of dementia is Alzheimer's disease, which in its middle and late stages also includes behavioral symptoms and personality changes. Most cases of Alzheimer's disease are caused by a complex combination of genetic factors and increasing age. Lower education levels and serious head injuries may also be risk factors.

Although Alzheimer's disease is one of the medical conditions most feared by older adults, it occurs in only about 3% of people between the ages of 65 and 74. The incidence then goes up until nearly half of those over age 85 may be affected.

What are the symptoms of Alzheimer's disease?
Although some memory loss may be normal as you age, a defining characteristic of Alzheimer's disease is significant, progressive loss of memory, judgment, and other mental skills. Eventually this can limit your ability to handle everyday activities. Behavioral symptoms may include anxiety, irritability, restlessness, aggression, and wandering and tend to vary widely from patient to patient. Impaired judgment is often a serious concern.

What should I do if I notice symptoms?
Never assume that poor judgment, difficulty concentrating, disorientation, or memory loss is normal. Be sure to tell your doctor about any symptoms you notice. Some causes of these problems are reversible, such as anemia or drug interactions. In other patients, symptoms may be a result of treatable conditions, such as depression, thyroid problems, certain vitamin deficiencies, and Parkinson's disease.

Can Alzheimer's disease be treated?
A great deal of research is going on in the field of Alzheimer's disease, and some encouraging treatments are being investigated. This is sure to be a major area of study as the US population ages, so feel free to ask your doctor about new advances.

Right now, there is no way to cure Alzheimer's disease or to stop its course. However, certain medications may temporarily slow its progression in some patients in early or middle stages of the disease. Medications are available to treat the behavioral problems of Alzheimer's disease, too, although changing the patient's surroundings to suit his or her needs is often a more effective strategy.

If you are caring for a loved one with Alzheimer's disease, you can do a great deal to minimize the patient's stresses and hazards. A calm environment and structured daily routine seem to work best. However, keep in mind that these patients should be gently encouraged to help themselves as much as possible in order to keep their brain active and functioning.

Can Alzheimer's disease be prevented?
Scientists are searching for ways to prevent Alzheimer's disease, but to date, no treatments, drugs, or other measures have proven to be effective. Nevertheless, many experts agree that a "brain healthy" lifestyle may help:

• Engage in intellectually stimulating activities.
• Stay socially active.
• Eat a healthy diet.
• Exercise regularly.
• Avoid tobacco totally, and avoid excessive alcohol consumption.
• Maintain healthy blood pressure and cholesterol levels.
• Control diabetes.

Taking care of the caregiver
If someone in your family has Alzheimer's disease, you may feel overwhelmed. These tips might help you:

• Talk with others who understand. Join a support group or ask for support from family and friends. You might also want to find a support group for the Alzheimer's patient.
• Keep your loved one involved. Social activities are important, and many patients can stay involved in normal family life. Scheduling regular outings is helpful for some patients.
• Simplify tasks. Lower your expectations when needed to match your loved one's abilities. If managing a checkbook becomes too complex, change the focus to something that is more manageable.
• Hang on to your personal interests and hobbies. Stay involved in the hobbies or activities that refresh you and add to your physical and mental strength.
• Take a break. Check out respite care, adult day care, or other community services that can free you from your responsibilities occasionally.

For more information

Many resources are available to help both patients and caregivers who are living with Alzheimer's disease.

Alzheimer's Association
225 N Michigan Ave, 17th Floor
Chicago, IL 60601
800-272-3900
www.alz.org

Alzheimer's Disease Education and Referral Center
PO Box 8250
Silver Spring, MD 20907
800-438-4380
www.alzheimers.org

Alzheimer's Foundation of America
322 8th Ave, 6th Floor
New York, NY 10001
866-232-8484
www.alzfdn.org

National Institute of Neurological Disorders and Stroke
PO Box 5801
Bethesda, MD 20824
800-352-9424
www.ninds.nih.gov

This information is not a substitute for medical treatment.

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What does angina feel like?
Angina is a squeezing or crushing pain in the chest, although it is sometimes described as pressure, tightness, or burning. It has been likened to a vise around or a heavy weight on the chest. Occasionally the pain or discomfort is felt in the neck, arm (especially the left), jaw, lower teeth, back, or upper abdomen. The pain may be accompanied by shortness of breath, nausea, sweating, or dizziness. Sharp chest pain that lasts less than a minute is usually not angina.

When is angina most likely to occur?
Usually angina occurs when blood vessels that carry oxygen to the heart become narrowed or develop spasm, limiting the supply of oxygen to the heart, but other factors may play a role. It is felt most often during exertion, such as walking, climbing stairs, carrying a heavy load, or performing any activity that increases the oxygen demand on your heart. Sometimes, little or no exertion is needed to provoke an attack, such as after meals, when exposed to cold winds, or during excitement or stress.

When should you see your doctor?
Angina rarely lasts longer than 3 to 5 minutes. It is relieved by rest but can recur several times within a short period. Pain or discomfort that lasts longer than this may signal a heart attack. Rather than take chances, seek medical attention immediately.

How is angina treated?
Angina can be treated with drugs that affect the supply of blood to the heart muscle or medications that lower the heart's workload.

Drugs called coronary vasodilators help the blood vessels relax and open up to allow greater blood flow. More oxygen and other nutrients can then reach the heart muscle. Nitroglycerin is the vasodilator used most often. Medicines called beta blockers or calcium channel blockers also help relieve angina. Aspirin and cholesterol-lowering medicines can help prevent recurrence of heart problems.

When pain is clearly caused by heart disease and medication doesn't work, a procedure called angioplasty is sometimes needed. A tiny balloon is inflated in the blood vessel to open blocked areas. A small mesh tube called a stent may be inserted into the vessel to keep it open.

Bypass surgery is sometimes used to treat heart pain. Veins or arteries from the legs are sewn into the arteries of the heart to carry blood around a blockage. A bypass is usually done when angioplasty isn't possible or when the results are likely to be better than with a balloon or stent.

Pay attention to chest pain
Heart disease often can be managed through proper treatment, lifestyle changes, and exercise. Your doctor will guide you, but you need to be alert to changes that might be clues to the need to adjust your treatment plan. If you have any unusual chest pain that lasts more than a few minutes or that doesn't go away with rest or after taking nitroglycerin, go to the nearest emergency department right away.

Lowering your risk of heart disease
Here are some of the things you can do to reduce your chance of having a heart attack.

• If you smoke, quit.
• If you are overweight, trim down.
• If you have high blood pressure or diabetes, follow the program prescribed to bring it under control.
• Eat a healthful diet and avoid fatty foods, especially those high in saturated fats, such as butter, ice cream, fried foods, and fatty meats.
• Develop a reasonable and realistic exercise program.
• Get regular medical checkups, including cholesterol tests.
• Follow the medication and exercise plan developed for you.

What does angina feel like?

Angina is pain usually caused by blockages in coronary arteries. Symptoms may include:

• Chest pain or pressure under the breastbone in the middle of the chest or slightly to the left
• Pain that travels to the shoulder, arm, jaw, neck, back, or other areas
• Tightness, squeezing, crushing, burning, choking, or aching sensations
• Discomfort that mimics gas pains or indigestion
• Chest pain that occurs after activity or exertion or that is related to stress
• Episodes of pain that are of short duration, usually 1 to 15 minutes

When is chest pain an emergency?

Go to your nearest hospital immediately if you have chest pain or discomfort that:

• Is very bad, gets worse, and lasts longer than 20 minutes
• Is associated with weakness, feeling sick to your stomach, or fainting
• Does not go away when you take three nitroglycerin tablets 5 minutes apart
• Is worse than any pain you have had before

Call 911 immediately if you think you may be having a heart attack. If an ambulance is not available quickly, have someone drive you to the nearest hospital. Do not drive yourself.

This information is not a substitute for medical treatment.

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What are NSAIDs?
The term is short for "nonsteroidal anti-inflammatory drugs." It is used to distinguish these inflammation-reducing drugs from those that contain corticosteroids. Many mild NSAIDs can be purchased in drugstores. Stronger NSAIDs and medications containing corticosteroids usually require a prescription.

NSAIDs reduce the swelling, pain, and heat that result from injury to tissues, muscles, or ligaments, such as after minor surgery or an accident. Also, they help relieve the symptoms of arthritis and menstrual pain. NSAIDs ease pain and fever but are usually recommended when you have a problem that includes swelling, such as back pain.

How are NSAIDs different from aspirin?
Aspirin is an NSAID. Like the others, it reduces inflammation, pain, and fever. But it is often considered to be in a class of its own, called "salicylates," or agents made up of acetylsalicylic acid. Aspirin has an added effect--it hinders the clotting mechanism of the blood. ("Aspirin substitutes" are another class. They contain acetaminophen and reduce pain and fever but not inflammation.)

Are NSAIDs safe?
When you follow directions, yes. But as with all drugs, taking the smallest amount for the shortest time possible is best. Taking too much can increase your risk of gastrointestinal pain and bleeding as well as kidney problems. People with ulcers, aspirin sensitivity, or kidney disease should not take NSAIDs. To avoid stomach irritation, it's a good idea to take them with food. Aspirin should not be given to children or teenagers who may have chickenpox or influenza. Reye's syndrome is a rare but serious disorder that may be related to aspirin use during these viral infections.

How do I choose an NSAID?
No one knows why, but a certain agent may work well in one person and not as well in another. So you may have to try more than one. Luckily, there are several to choose from. Generic names of NSAIDs that are available without prescription include ibuprofen, ketoprofen, and naproxen.

This information is not a substitute for medical treatment.

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How antibiotic resistance develops

There are four main reasons why antibiotic resistance develops:

• Demand for and use of antibiotics when antibiotics are not appropriate. Researchers at the Centers for Disease Control and Prevention estimate that one third of all outpatient prescriptions for antibiotics are unnecessary. Antibiotics do not harm viruses. When you take antibiotics for viral illnesses, such as a cold or the "flu," they primarily attack the "good" bacteria that live in your body naturally. When you have fewer of these "good" bacteria, your body provides favorable conditions for "bad" bacteria to thrive.
• Failure to finish an antibiotic prescription. Even though an antibiotic is effective in attacking susceptible bacteria, some resistant ones may survive, especially if you don't take enough of the medication to do the job. These surviving resistant bacteria multiply as a resistant strain, or group, and are more difficult to treat. The drug-resistant bacteria can also spread from one person to another.
• Misuse and overuse of antibiotics in livestock and agriculture. Sometimes antibiotics are mixed into livestock feed in an effort to help the animals grow. Although the amounts are too little to treat infection in livestock, they may be just enough to keep resistant bacteria going strong. In addition, antibiotics may be sprayed on plants and trees to destroy bacteria on produce. The antibiotic residues left on these fruits and vegetables may attack the good bacteria in our intestines--and let the more powerful, resistant, and harmful strains survive.
• Availability of antibiotics without a prescription in some countries. Many people have taken antibiotics for colds and other minor "bugs," not knowing that the medication works only on bacterial infections. This overuse has led to the production of more drug-resistant strains of bacteria.

Treating resistant bacteria

If resistance develops to one antibiotic, your doctor will prescribe a different antibiotic in order to fight the infection. However, many bacteria are resistant to more than one antibiotic. In fact, infections involving a few kinds of resistant bacteria are untreatable.

Preventing antibiotic resistance

• Talk to your healthcare provider about how bacteria are different from viruses and when antibiotics should and shouldn't be used (see box on this page). Don't pressure your doctor to prescribe antibiotics to treat viral infections such as a cold or the flu. Instead, be open to remedies that may help relieve your symptoms. Let your cold run its course. It takes time to recover from a cold or the flu. Call your doctor if your illness lasts longer than 2 weeks.
• When given antibiotics, take them exactly as directed and complete the full course, even if you are feeling better. If you stop using the medication early, the surviving bacteria may come back stronger than ever.

Preventing the need for antibiotics

• Wash your hands thoroughly with soap and warm water before preparing or eating food and after using the toilet.
• Wash fruits and vegetables to remove any resistant bacteria or residue from antibiotic sprays.
• Avoid eating raw eggs and undercooked meat, especially in ground form.

When to use antibiotics

Illnesses that are caused by bacteria and can be treated with antibiotics:

• Some ear infections
• Sinus infections. Antibiotics should be used only for severe infections or infections that last longer than 2 weeks. Keep in mind that a runny nose plus discolored mucus does not always mean that you need an antibiotic.
• Strep throat. Your healthcare provider will do a throat swab to determine if you have this illness, which is caused by Streptococcus bacteria.
• Urinary tract infections
• Some coughs or bronchitis. If you have a problem with your lungs or an illness that lasts longer than usual, bacteria may be the cause. In this case, your doctor may prescribe an antibiotic.

Illnesses that are caused by viruses and cannot be treated with antibiotics:

• All colds and "flu"
• Most sore throats
• Some ear infections
• Most coughs or bronchitis

This information is not a substitute for medical treatment.

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What causes appendicitis?

The appendix is a "dead end." When something (such as a hard pellet of stool, a foreign body, a seed or other piece of undigested food) blocks the only opening from the colon, inflammation soon sets in. In other instances, infection from bacteria in the intestinal tract causes swelling that gradually closes the opening. There is no way to predict or prevent appendicitis. It can occur in anyone. However, it is most common in adolescents and young adults and rare in children under age 2.

Is appendicitis serious?
When it's not treated, it can be very serious. A completely obstructed appendix becomes more and more inflamed and eventually bursts, casting out its infected contents. The entire lining of the abdominal cavity may become contaminated, causing a life-threatening condition called peritonitis.

What are the symptoms of appendicitis?
Symptoms are usually vague at first, but an early one may be dull, continuous pain in the area around the navel. As inflammation worsens, several of the following symptoms may be noted:

1. Sharper pain that has moved to the right lower part of the abdomen
2. Worsening of pain when the area is touched or with movement, deep breathing, or coughing
3. Loss of appetite, nausea, vomiting
4. Constipation or diarrhea
5. Rapid pulse
6. Slight fever (a degree or two above normal) developing after other symptoms

How is it diagnosed?
Appendicitis can be hard to diagnose because symptoms often resemble those of bladder infection, kidney stones, inflammation of the colon or stomach, or ovarian cysts. Physical examination is usually the first step. By pressing on the right lower part of the abdomen, the doctor may be able to feel a hardened appendix. By letting up quickly, he or she may notice rebound tenderness (pain that is worse after pressure is relieved), which is a sign of appendicitis. Rectal and pelvic examinations often are done to rule out other problems.

Usually, a blood sample is tested for a high white blood cell count indicating infection, and a urine sample is tested for urinary tract infection, which can be confused with appendicitis. An x-ray film may be taken to look for an obstruction, or a thin, lighted telescope called a laparoscope may be inserted into the abdomen to examine the area.

What should I do if I suspect appendicitis?
If you think a youngster may have appendicitis, keep a record of his or her temperature, taken every 2 hours. If there is a sudden rise, pain gets worse, or the child starts vomiting or has blood in the stool, call your doctor right away. Whether you suspect the problem in yourself or someone else, remember the following tips to avoid making the situation worse:

1. Don't take or give laxatives or enemas (may cause rupture)
2. Don't take or give pain medicines (makes diagnosis more difficult)
3. Don't take or give food or drink until talking to your doctor (best to have an empty stomach if surgery is necessary)

How is appendicitis treated?
An inflamed appendix has to be removed, but the operation is simple and usually free of complications. The patient is given a general anesthetic and sometimes an antibiotic to fight infection. A 3- or 4-in. incision is made in the lower abdomen, or if a laparoscope is used for the operation, the incision is even smaller. The appendix is cut away, and the wound in the intestine is closed and cauterized. If there is any fluid or pus present, it is suctioned away, and the abdominal incision is closed with sutures. Patients usually stay in the hospital 3 or 4 days.

After returning home, patients may want to take an over-the-counter pain reliever for a few days. If pain gets worse or if swelling, redness, drainage, or bleeding in the surgical area begins, the doctor should be consulted. Additional symptoms that should be reported are nausea, vomiting, abdominal swelling, and signs of infection (such as headache, muscle aches, dizziness, fever). Most people are back to their normal activities in about 3 weeks.

This information is not a substitute for medical treatment.

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What is asthma?
Asthma is a disease in which a person's airways become inflamed, swollen, and narrowed, making it difficult for air to flow into and out of the lungs. When the airways are swollen, breathlessness and other symptoms of asthma occur.

What are the symptoms of asthma?
People with asthma may have chest tightness, coughing, wheezing, or shortness of breath. Children with asthma may have noisy breathing and may appear very tired after normal play or exercise.

What causes asthma?
No one knows exactly why some people have this condition. What is known is that asthma usually flares up in response to "triggers," which can be ordinary things in the environment at home, school, and work. For example, an asthma attack may occur when someone with asthma comes into contact with a pet, cigarette smoke, or pollen. Other common triggers include dust mites, mold and mildew, paint fumes, chalk dust, and cockroach parts and droppings. Symptoms that occur in asthma sometimes happen in people who have a viral or sinus infection or heartburn. These symptoms can also be caused by emotional stress, exercise, breathing cold air, taking certain drugs, or eating some types of food.

Who is most likely to have asthma?
People who have a parent with asthma are 40% more likely to have asthma. African Americans, Mexican Americans, and people who live in poor neighborhoods are at increased risk for asthma. Also, people who have allergic rhinitis, a condition that is commonly called hay fever, are likely to have asthma.

There is no way to predict the course of a person's asthma. Some children with asthma get better when they reach their teens, but others experience worsening symptoms that continue into adulthood. Some people have their first symptoms of asthma in adulthood.

How is asthma treated?
There is no cure for asthma, but preventive steps and medications can help people breathe easier. The first step is to eliminate or reduce your exposure to asthma triggers, which may involve cleaning your house more often, finding another home for your pet, or quitting smoking. Not only does smoking make existing asthma worse, it can lead to breathing difficulty for children exposed to the smoke.

Your doctor may prescribe an asthma drug. These medications include steroids, bronchodilators, antileukotrienes, and nonsteroidal antiinflammatory drugs in liquid, tablet, or capsule form. Some drugs are taken with a device, such as a metered-dose inhaler or a dry-powder inhaler, a spacer unit that attaches to the inhaler, or a nebulizer that delivers the drug in a mist.

It is important to use asthma drugs exactly as directed. Many of these drugs are made to be used daily--even when you have no symptoms. If you begin having symptoms, take your medication as directed to prevent a serious second attack. Pregnant women with asthma need to carefully follow their doctor's advice to avoid harm to their baby.

If you have moderate or severe asthma, your doctor may recommend that you use a device called a peak flow meter to measure your airflow as you breathe out and that you chart the meter's readings to track your asthma's progress. You and your doctor can use these measurements to find out how well your asthma is being controlled.

If you follow your doctor's directions carefully and still have trouble breathing, tell your doctor. He or she may prescribe a different medication, recommend another way to take your medication, or suggest other steps that can help you breathe easier.

Controlling your asthma

Keeping your home clean and reducing moisture and dust can help control your asthma symptoms. Here are some guidelines to follow:

• Control humidity by using a dehumidifier or air conditioner when the weather is warm.
• Remove wall-to-wall carpet, particularly over concrete floors. Hardwood, tile, or linoleum floors retain less dust than carpet.
• Use zippered plastic covers on pillows and mattresses, and wash bedding in hot water every week.
• Wash throw rugs and curtains often.
• Have someone without asthma vacuum your furniture upholstery and any carpet often using a vacuum cleaner with a high-efficiency particulate air (HEPA) filter.
• To control cockroach infestations, fix leaky pipes and faucets and seal cracks in your home's foundation. If necessary, hire an exterminator.
• Regularly clean and ventilate your basement, bathroom, and kitchen to prevent the growth of mold and mildew.
• If you have a pet, have someone without asthma brush the pet outside, bathe the animal once weekly, change and wash the litter box or cage daily, and wash the pet's bedding once a week in hot water. Keep the animal out of the bedroom.
• Don't allow smoking in your home or around you or your child.

This information is not a substitute for medical treatment.

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How is ADHD diagnosed?
No laboratory test can identify ADHD. The best method is a careful interview with a physician, who looks for a persistent pattern of specific behaviors. Behaviors may be at their worst in a certain setting, such as school, but they must be noticeable in more than one setting, day in and day out, to be ADHD. Certain questionnaires and performance tests can be useful in diagnosis. Disorders that can cause symptoms similar to ADHD (learning disorders, depression, drug use, thyroid abnormalities, fatigue syndromes) must be ruled out.

The problem must have been present in childhood for adults to have ADHD, so parents and childhood report cards may need to be consulted. Many adults and some children do not have hyperactivity but do have other symptoms of ADHD. Most squirmy, high-energy children are just being normal kids. But if a person has several of the following traits, ADHD should be considered:

• Often misses details and makes careless mistakes in work
• Cannot organize chores or follow the steps of a procedure
• Jumps from one unfinished activity to another
• Often does not seem to listen
• Often misplaces and forgets things
• Is easily distracted by other people or activities
• Always seems to be tapping, jiggling, or moving in some way
• Cannot tolerate sitting still for long periods
• Often interrupts, intrudes, finishes the sentences of others, or blurts out answers ahead of time
• Is extremely frustrated by having to wait
• Jumps into situations without thinking

What is the treatment for ADHD?
Patients can be taught to cope with some of their problems, for example, by making lists and establishing a routine to get organized. They may be able to choose activities that involve independence and variation and avoid those that bring out their impatience and impulsiveness. Medications that regulate areas of the brain affecting attention and impulse control are often helpful when taken as prescribed.

This information is not a substitute for medical treatment.

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The number of cases of Giardia infection seems to be increasing in the United States. The parasite, which causes an illness called giardiasis (gee-ar-DYE-a-sis), forms into a cyst that can leave the body in feces (stool). Once outside the body, Giardia organisms live in water and die when dried out. Infection can occur after exposure to just a few organisms--maybe just one, according to some experts. Although symptoms are uncomfortable, giardiasis usually isn't dangerous.

Who is most likely to get giardiasis?
Some people pick up giardiasis from water or food that has been contaminated with the parasite. Others get it from direct contact with contaminated stool, such as when changing diapers or touching soiled clothing of an incontinent person or during other intimate contact with someone who has the infection.

Travelers are at risk throughout the world, and hikers and campers can easily get giardiasis if they drink water from streams or lakes, which may be contaminated no matter how clean the water appears. Other risk factors include:

• Exposure to a family member who has the infection
• Contact through day-care centers, nursing homes, hospitals, or other institutions
• Exposure through sexual or other intimate activity
• Spread through inadequate hand washing

How do you know if you have giardiasis?
Many people--perhaps as many as 60%--never have symptoms after exposure to Giardia organisms. The important thing to remember is that even when infection causes no symptoms, it can still be spread to others. The timing of symptoms can range from 3 to 25 days after exposure, but symptoms usually occur within 7 to 10 days. They often last just a few days, but sometimes they continue for weeks or months--even years. The most common symptoms are:

• Watery diarrhea with foul-smelling stool
• Bloating, stomach pain, cramps, belching, or gassiness
• Frequent bowel movements and intermittent diarrhea
• Nausea, vomiting, weight loss, and loss of appetite

How is giardiasis treated?
Many infections run their course and disappear on their own, but in some cases, drug treatment is needed. The drugs must be prescribed by a physician, who may also want to check a stool sample before and after treatment to make sure the parasite actually goes away. Drinking lots of fluids to replace nutrients lost through diarrhea is another important part of treatment. Infections that last a very long time are more common in adults than in children, and people who have immune disorders, such as AIDS, tend to have a more difficult time recovering from giardiasis. These people may need to try several kinds of treatment before they feel better.

How can you avoid this problem?
Never drink water directly from a stream or lake, and sterilize water that comes from any questionable source by boiling it for 5 minutes. If you are traveling in areas where water supplies may not be safe, drink bottled water or canned carbonated beverages that come sealed. Do not add ice.

Carefully dispose of sewage and diaper wastes so you do not contaminate surface water or groundwater that could spread illness to others. And, of course, wash your hands thoroughly if you come in contact with feces or soiled clothing and after you touch pets or other animals.

Don't forget to wash your hands

When done correctly, hand washing is the single most effective way to prevent spread of disease. Giardiasis and many other infections are passed on through a fecal-oral route. Because disease is spread through ingestion of even the tiniest bit of contaminated material, hand washing after using the toilet cannot be overemphasized.

Correct hand washing is more complicated than many people realize. These steps are important:

• Wet your hands with warm running water, when possible
• Add soap, then rub your hands together, making a soapy lather. Do this away from the running water for about 20 seconds so you don't wash the lather away. Be sure to lather the front and back of your hands and spaces between fingers and under nails.
• Rinse your hands well under warm running water. (Keep hands down so the water runs into the sink instead of down your arms.) Turn off the water with a paper towel and throw that towel away.
• Pat hands dry with a clean paper towel.

It's important to remind children to wash their hands before eating, after using the bathroom, after blowing their noses, and after playing outdoors or touching pets or other animals. Also, don't assume that children know how to wash their hands. (With toddlers, singing "Twinkle, Twinkle, Little Star" while they lather up helps them understand how long to scrub.) Also, wash your own hands as your children wash theirs. Teaching by example is an excellent way to help youngsters establish good hand-washing habits.

This information is not a substitute for medical treatment.

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