Cancers

Cancer Type

AIDS and HIV

What is HIV?

The Human Immunodeficiency Virus (HIV) is the virus that leads to AIDS. HIV belongs to a subset of retroviruses called lentiviruses (or slow viruses), which means that there is an interval -- sometimes years -- between the initial infection and the onset of symptoms. Upon entering the bloodstream -- through mucous membranes or blood-to-blood contact -- HIV infects the CD4+T cells and begins to replicate rapidly.
Scientists believe that when the virus enters the body, HIV begins to disable the body's immune system by using the body's aggressive immune responses to the virus to infect, replicate and kill immune system cells. Gradual deterioration of immune function and eventual destruction of lymphoid and immunologic organs is central to triggering the immunosuppression that leads to AIDS.

What is AIDS?

Acquired Immunodeficiency Syndrome (AIDS) is the final stage of HIV infection. The Centers for Disease Control establish the definition of AIDS, which occurs in HIV-infected persons with fewer than 200 CD4+T cells and/or persons with HIV who develop certain opportunistic infections. In 1992, the CDC redefined AIDS to include 26 CDC-defined AIDS indicator illnesses and clinical conditions that affect persons with advanced HIV.

What is a retrovirus?

A retrovirus is any of a group of viruses that contain two single-strand linear RNA molecules per virion, which means it carries its genetic blueprint in the form of ribonucleic acid (RNA) instead of deoxyribonucleic acid (DNA). Additionally, the enzyme reverse transcriptase is employed to copy its genome into the DNA of the host cell's chromosomes. Usually the cellular process involves transcription of DNA into RNA. Reverse transcriptase makes it possible for genetic material to become permanently incorporated into the DNA genome of an infected cell.

What is the distinction between HIV and AIDS?

AIDS is a disease developed by a person living with HIV, which is a viral organism. The term AIDS applies to the most advanced stages of HIV infection. Although an HIV-positive test result does not mean that a person has AIDS, most people will develop AIDS as a result of their HIV infection.
There are four main stages in the progression of an HIV infected person developing AIDS. The period following the initial HIV infection is called the window period. It is called this because this period reflects the window of time between infection with the virus and when HIV antibodies develop in the bloodstream. An HIV test that looks for antibodies taken during this time can result in a false negative, though antibodies usually appear within six months of the initial infection.
Seroconversion refers to the period of time during which your body is busy producing HIV antibodies, trying to protect itself against the virus. This is the period after the initial infection when many people experience flu-like symptoms and swollen lymph nodes � this is a highly infectious stage.
After most people seroconvert, they usually experience a symptom-free period or asymptomatic period. This stage can last anywhere from 6 months to over 10 years, varying from person to person. Although the person with HIV is experiencing no symptoms, the virus is still replicating inside the body and weakening the immune system.
After this period, severe CD4+T cell loss leads to the symptomatic period, in which the body experiences the symptoms associated with HIV. This is the final stage before developing AIDS.

What are CD4+T cells?

CD4+T cells are the immune system's key infection fighters and the entity that allows HIV to enter, attach and infect the body's immune system. The CD4+T cells (also called T4 cells) are disabled and destroyed by the virus, often with no symptoms, causing a significant decrease in the blood levels of T4 cells. In the advanced stages of HIV, the body may have fewer than 200 T4 cells, while a healthy adult's count is 1,000 or more. In this way, the body's immune system is continuously weakened from the moment of infection and the inability of the immune system to fight infection opens the door to opportunistic infections.

What are opportunistic infections?

According to the CDC, AIDS-defining opportunistic illnesses are the major cause of morbidity and mortality among human immunodeficiency virus (HIV)-infected persons. Opportunistic infections are a result of the weakened immune system present in persons with HIV/AIDS. An infection takes the "opportunity" provided by the weakened immune system to cause an illness that is usually controlled by a healthy immune system. These infections are sometimes life-threatening and require medical intervention to prevent or treat serious illnesses. Persons living with advanced HIV infection suffer opportunistic infections of the lungs, brain, eyes and other organs. The 26 CDC-defined AIDS indicator illnesses are opportunistic infections. There are medical treatments that can slow the rate at which the immune system is weakened and early detection offers more options for treatment and preventative care.

How is HIV transmitted?

HIV infection most commonly occurs through sexual contact. However, the virus can also be spread through blood-to-blood contact -- such as sharing needles or blood transfusions involving unscreened blood. Studies have shown that HIV is not transmitted through casual contact such as touching or sharing towels, bedding, utensils, telephones, swimming pools, or toilet seats. Scientists have also found no evidence of transmission through kissing, sweat, tears, urine or feces. It is important to acknowledge that it is not sex that transmits HIV, but certain bodily fluids: blood, semen (including "pre-cum"), vaginal secretions and breast milk. High-risk behaviors that can result in HIV transmission are sharing needles for drugs, tattoos, body piercing, vitamins or steroids with an HIV-infected person and/or engaging in unprotected anal, vaginal or oral sex with a person who is HIV infected. The virus also can be transmitted from an HIV-infected mother to her child through pregnancy, birth or breastfeeding.
It does appear that persons already infected with a sexually transmitted disease are more susceptible to acquiring HIV during sex with an infected partner. Mucous membranes, a weak point in the skin, include the lips, mouth, vagina, vulva, penis or rectum. Because mucous membranes are porous and viruses and other pathogens are able to pass through, these areas are rich in immune cells. When a person already has a sexually transmitted disease, sex organs may be flooded with CD4+T cells, making it much easier for HIV to infect.
The only way to determine HIV infection is to be tested for the virus. It is not unusual for HIV-infected persons to experience symptoms years after the initial infection; some may be symptom free for over 10 years. However, during the asymptomatic period, the virus is actively multiplying and destroying cells in the immune system, weakening the body's ability to fight infection. The effect is most keenly observed in the decline of the immune system's key infection fighters in the blood, the CD4+T cells. There are medical treatments that can reduce the rate at which HIV disables the immune system; early detection offers more options for treatment and preventative care. As a matter of safety, people who engage in high-risk behaviors -- such as intravenous drug use or having unprotected sex with multiple partners -- should be tested regularly.

How are foodborne diseases treated

How are foodborne diseases treated? 
There are many different kinds of foodborne diseases and they may require different treatments, depending on the symptoms they cause.  Illnesses that are primarily diarrhea or vomiting can lead to dehydration if the person loses more body fluids and salts (electrolytes) than they take in.  Replacing the lost fluids and electrolytes and keeping up with fluid intake are important.  If diarrhea is severe, oral rehydration solution such as Ceralyte*, Pedialyte* or Oralyte*, should be drunk to replace the fluid losses and prevent dehydration.  Sports drinks such as Gatorade* do not replace the losses correctly and should not be used for the treatment of diarrheal illness.  Preparations of bismuth subsalicylate (e.g., Pepto-Bismol)* can reduce the duration and severity of simple diarrhea.   If diarrhea and cramps occur, without bloody stools or fever, taking an antidiarrheal medication may provide symptomatic relief, but these medications should be avoided if there is high fever or blood in the stools because they may make the illness worse. 

Foodborne disease

What is foodborne disease? 
Foodborne disease is caused by consuming contaminated foods or beverages.  Many different disease-causing microbes, or pathogens, can contaminate foods, so there are many different foodborne infections.  In addition, poisonous chemicals, or other harmful substances can cause foodborne diseases if they are present in food. 
More than 250 different foodborne diseases have been described.  Most of these diseases are infections, caused by a variety of bacteria, viruses, and parasites that can be foodborne.  Other diseases are poisonings, caused by harmful toxins or chemicals that have contaminated the food, for example, poisonous mushrooms.   These different diseases have many different symptoms, so there is no one "syndrome" that is foodborne illness.  However, the microbe or toxin enters the body through the gastrointestinal tract, and often causes the first symptoms there, so nausea, vomiting, abdominal cramps and diarrhea are common symptoms in many foodborne diseases. 
Many microbes can spread in more than one way, so we cannot always know that a disease is foodborne.  The distinction matters, because public health authorities need to know how a particular disease is spreading to take the appropriate steps to stop it.  For example, Escherichia coli O157:H7 infections can spread through contaminated food, contaminated drinking water, contaminated swimming water, and from toddler to toddler at a day care center.  Depending on which means of spread caused a case, the measures to stop other cases from occurring could range from removing contaminated food from stores, chlorinating a swimming pool, or closing a child day care center. 

What are the most common foodborne diseases? 
The most commonly recognized foodborne infections are those caused by the bacteria Campylobacter, Salmonella, and E. coli O157:H7, and by a group of viruses called calicivirus, also known as the Norwalk and Norwalk-like viruses. 
Campylobacter is a bacterial pathogen that causes fever, diarrhea, and abdominal cramps.  It is the most commonly identified bacterial cause of diarrheal illness in the world.  These bacteria live in the intestines of healthy birds, and most raw poultry meat has Campylobacter on it.  Eating undercooked chicken, or other food that has been contaminated with juices dripping from raw chicken is the most frequent source of this  infection. 
Salmonella is also a bacterium that is widespread in the intestines of birds, reptiles and mammals.  It can spread to humans via a variety of different foods of animal origin.  The illness it causes, salmonellosis, typically includes fever, diarrhea and abdominal cramps.  In persons with poor underlying health or weakened immune systems, it can invade the bloodstream and cause life-threatening infections. 
E. coli O157:H7 is a bacterial pathogen that has a reservoir in cattle and other similar animals.  Human illness typically follows consumption of food or water that has been contaminated with microscopic amounts of cow feces.  The illness it causes is often a severe and bloody diarrhea and painful abdominal cramps, without much fever.   In 3% to 5% of cases, a complication called hemolytic uremic syndrome (HUS) can occur several weeks after the initial symptoms.  This severe complication includes temporary anemia, profuse bleeding, and kidney failure. 
Calicivirus, or Norwalk-like virus is an extremely common cause of foodborne illness, though it is rarely diagnosed, because the laboratory test is not widely available.  It causes an acute gastrointestinal illness, usually with more vomiting than diarrhea, that resolves within two days.  Unlike many foodborne pathogens that have animal reservoirs, it is believed that Norwalk-like viruses spread primarily from one infected person to another.  Infected kitchen workers can contaminate a salad or sandwich as they prepare it, if they have the virus on their hands.  Infected fishermen have contaminated oysters as they harvested them. 
Some common diseases are occasionally foodborne, even though they are usually transmitted by other routes.  These include infections caused by Shigella, hepatitis A, and the parasites Giardia lamblia and Cryptosporidia.  Even strep throats have been transmitted occasionally through food. 
In addition to disease caused by direct infection, some foodborne diseases are caused by the presence of a toxin in the food that was produced by a microbe in the food.  For example, the bacterium Staphylococcus aureus can grow in some foods and produce a toxin that causes intense vomiting.  The rare but deadly disease botulism occurs when the bacterium Clostridium botulinum grows and produces a powerful paralytic toxin in foods.  These toxins can produce illness even if the microbes that produced them are no longer there. 
Other toxins and poisonous chemicals can cause foodborne illness.  People can become ill if a pesticide is inadvertently added to a food, or if naturally poisonous substances are used to prepare a meal.  Every year, people become ill after mistaking poisonous mushrooms for safe species, or after eating poisonous reef fishes.


Are the types of foodborne diseases changing?  




The spectrum of foodborne diseases is constantly changing.  A century ago, typhoid fever, tuberculosis and cholera were common foodborne diseases.   Improvements in food safety, such as pasteurization of milk, safe canning, and disinfection of water supplies have conquered those diseases.  Today other foodborne infections have taken their place, including some that have only recently been discovered.  For example, in 1996, the parasite Cyclospora suddenly appeared as a cause of diarrheal illness related to Guatemalan raspberries.  These berries had just started to be grown commercially in Guatemala, and somehow became contaminated in the field there with this unusual parasite.  In 1998, a new strain of the bacterium Vibrio parahemolyticus contaminated oyster beds in Galveston Bay and caused an epidemic of diarrheal illness in persons eating the oysters raw. The affected oyster beds were near the shipping lanes, which suggested that the bacterium arrived in the ballast water of freighters and tankers coming into the harbor from distant ports.  Newly recognized microbes emerge as public health problems for several reasons: microbes can easily spread around the world, new microbes can evolve, the environment and ecology are changing, food production practices and consumption habits change, and because better laboratory tests can now identify microbes that were previously unrecognized. 
 In the last 15 years, several important diseases of unknown cause have turned out to be complications of foodborne infections.  For example, we now know that the Guillain-Barre syndrome can be caused by Campylobacter infection, and that the most common cause of acute kidney failure in children, hemolytic uremic syndrome, is caused by infection with E. coli O157:H7 and related bacteria.  In the future, other diseases whose origins are currently unknown may turn out be related to foodborne infections.




What happens in the body after the microbes that produce illness are swallowed? 
 After they are swallowed, there is a delay, called the incubation period, before the symptoms of illness begin.  This delay may range from hours to days, depending on the organism, and on how many of them were swallowed.  During the incubation period, the microbes pass through the stomach into the intestine, attach to the cells lining the intestinal walls, and begin to multiply there.  Some types of microbes stay in the intestine, some produce a toxin that is absorbed into the bloodstream, and some can directly invade the deeper body tissues.  The symptoms produced depend greatly on the type of microbe. Numerous organisms cause similar symptoms, especially diarrhea, abdominal cramps, and nausea.  There is so much overlap that it is rarely possible to say which microbe is likely to be causing a given illness unless laboratory tests are done to identify the microbe, or unless the illness is part of a recognized outbreak.


How are foodborne diseases diagnosed? 
 The infection is usually diagnosed by specific laboratory tests that identify the causative organism.  Bacteria such as Campylobacter, Salmonella, E. coli O157 are found by culturing stool samples in the laboratory and identifying the bacteria that grow on the agar or other culture medium.  Parasites can be identified by examining stools under the microscope.  Viruses are more difficult to identify, as they are too small to see under a light microscope and are difficult to culture.  Viruses are usually identified by testing stool samples for genetic markers that indicate a specific virus is present. 
Many foodborne infections are not identified by routine laboratory procedures and require specialized, experimental, and/or expensive tests that are not generally available.  If the diagnosis is to be made, the patient has to seek medical attention, the physician must decide to order diagnostic tests, and the laboratory must use the appropriate procedures.  Because many ill persons to not seek attention, and of those that do, many are not tested, many cases of foodborne illness go undiagnosed.  For example, CDC estimates that 38 cases of salmonellosis actually occur for every case that is actually diagnosed and reported to public health authorities. 

Diastolic blood pressure and Systolic blood pressure

Blood pressure is a measurement of the force applied to the walls of the arteries as the heart pumps blood through the body. The pressure is determined by the force and amount of blood pumped, and the size and flexibility of the arteries.
Blood pressure is continually changing depending on activity, temperature, diet, emotional state, posture, physical state, and medication use.

How the Test is Performed

Blood pressure is usually measured while you are seated with your arm resting on a table. Your arm should be slightly bent so that it is at the same level as your heart. Your upper arm should be bare, with your sleeve comfortably rolled up.
Blood pressure readings are measured in millimeters of mercury (mmHg) and are given as two numbers. For example, 110 over 70 (written as 110/70).

• The top number is the systolic blood pressure reading. It represents the maximum pressure exerted when the heart contracts.
• The bottom number is the diastolic blood pressure reading. It represents the minimum pressure in the arteries when the heart is at rest.

To obtain your blood pressure measurement, your health care provider will wrap the blood pressure cuff snugly around your upper arm, positioning it so that the lower edge of the cuff is 1 inch above the bend of the elbow.
The health care provider will locate the large artery on the inside of the elbow by feeling for the pulse and will place the head of the stethoscope over this artery, below the cuff. It should not rub the cuff or any clothing because these noises may block out the pulse sounds. Correct positioning of the stethoscope is important to get an accurate recording.
Your health care provider will close the valve on the rubber inflating bulb and then will squeeze it rapidly to inflate the cuff until the dial or column of mercury reads 30 mmHg higher than the usual systolic pressure. If the usual systolic pressure is unknown, the cuff is inflated to about 210 mmHg.
Next, the valve is opened slightly, allowing the pressure to fall gradually (2 to 3 mmHg per second). As the pressure falls, the level on the dial or mercury tube at which the sound of blood pulsing is first heard is recorded. This is the systolic pressure.
As the air continues to be let out, the sounds will disappear. The point at which the sound disappears is recorded. This is the diastolic pressure (the lowest amount of pressure in the arteries as the heart rests).
The procedure may be performed two or more times.

How to Prepare for the Test

The test may be done at any time with your arm supported and held at the level of your heart. When your doctor needs to compare the current reading to previous ones, the test is usually done after you rest for at least 5 minutes.
All you need to perform a blood pressure measurement is a cuff and a device (stethoscope or microphone) to detect the sound of the pulse in the artery.

How the Test Will Feel

You will feel the pressure of the cuff on your arm. If the test is repeated a few times, you may feel temporary numbness or tingling in your hand.

Why the Test is Performed

The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends screening adults for high blood pressure every 2 years if their blood pressure is normally less than 120/80 mmHg.
Adults with high blood pressure or prehypertension should have their blood pressure checked every year or more often.
Most people cannot tell if their blood pressure is high because there are usually no symptoms.
High blood pressure increases the risk of heart failure, heart attack, stroke, and kidney failure.
If you have high blood pressure, blood pressure measurements can help determine if your medicine and diet changes are working.
Low blood pressure may be a sign of a variety of illnesses, including heart failure, infection, gland disorders, and dehydration.

Normal Results

In adults, the ideal top number (systolic pressure) should be less than 120 mmHg. The bottom number (diastolic pressure) should be less than 80 mmHg.

What Abnormal Results Mean

Prehypertension:

• Top number is consistently 120 to 139 or the bottom number reads 80 to 89.

Stage 1: Mild high blood pressure:

• Top number is consistently 140 to 159 or the bottom number reads 90 to 99.

Stage 2: Moderate to severe high blood pressure:

• Top number is consistently 160 or over or the bottom number reads 100 or over.

Low blood pressure (hypotension):

• Top number reading lower than 90 or pressure 25 mmHg lower than usual

Blood pressure readings may be affected by many different conditions, including:

• Cardiovascular disorders
• Neurological conditions
• Kidney and urological disorders
• Pre-eclampsia in pregnant women
• Psychological factors such as stress, anger, or fear
• Various medications
• "White coat hypertension" may occur if the medical visit itself produces anxiety

Risks

There are no significant risks associated with checking blood pressure.
If you have vascular access (shunt) for kidney dialysis on your arm, you should not have your blood pressure checked in that arm.

Considerations

Repeated measurements are important. A single high measurement does not necessarily mean you have high blood pressure. On the other hand, a single normal measurement does not necessarily mean that you don't have high blood pressure.
Blood pressure readings taken at home can provide important information to your doctor. Such readings may be a better measure of your current blood pressure than those taken at your doctor's office, as long as you make sure your machine is accurate. You can ask your health care provider to compare readings in the office. Many people become nervous at the doctor's office and have higher readings that they normally would at home. This is called white coat hypertension.
Consult your provider if your blood pressure measurements are consistently high or low or if you have symptoms at the same time as the high or low reading.

Alternative Names

Diastolic blood pressure; Systolic blood pressure

Whey protein may help keep your blood pressure in check, suggests a new study from the International Dairy Journal.
For the study, 71 adults (ages 18 to 26) drank a beverage containing 28 grams of whey protein every day for six weeks. While whey protein did not lower blood pressure in participants with normal blood pressure levels, it did lead to significant drops in both systolic and diastolic blood pressure among subjects who had elevated blood pressure at the start of the study. What's more, whey protein appeared to cut cholesterol levels.
A protein complex derived from milk, whey protein has been found to act as an antioxidant in past research. Some studies show that whey protein may also reduce levels of C-reactive protein (a marker of inflammation) and triglycerides (blood fats known to raise risk of heart disease when present at elevated levels).

Osteoarthritis

What is osteoarthritis?

Osteoarthritis is a type of arthritis that is caused by the breakdown and eventual loss of the cartilage of one or more joints. Cartilage is a protein substance that serves as a "cushion" between the bones of the joints. Osteoarthritis is also known as degenerative arthritis. Among the over 100 different types of arthritis conditions, osteoarthritis is the most common, affecting over 20 million people in the United States. Osteoarthritis occurs more frequently as we age. Before age 45, osteoarthritis occurs more frequently in males. After 55 years of age, it occurs more frequently in females. In the United States, all races appear equally affected. A higher incidence of osteoarthritis exists in the Japanese population, while South-African blacks, East Indians, and Southern Chinese have lower rates.
Osteoarthritis commonly affects the hands, feet, spine, and large weight-bearing joints, such as the hips and knees. Most cases of osteoarthritis have no known cause and are referred to as primary osteoarthritis. When the cause of the osteoarthritis is known, the condition is referred to as secondary osteoarthritis. Osteoarthritis is sometimes abbreviated OA.

What causes osteoarthritis?

Primary osteoarthritis is mostly related to aging. With aging, the water content of the cartilage increases, and the protein makeup of cartilage degenerates. Eventually, cartilage begins to degenerate by flaking or forming tiny crevasses. In advanced cases, there is a total loss of cartilage cushion between the bones of the joints. Repetitive use of the worn joints over the years can irritate and inflame the cartilage, causing joint pain and swelling. Loss of the cartilage cushion causes friction between the bones, leading to pain and limitation of joint mobility. Inflammation of the cartilage can also stimulate new bone outgrowths (spurs, also referred to as osteophytes) to form around the joints. Osteoarthritis occasionally can develop in multiple members of the same family, implying a hereditary (genetic) basis for this condition.
Secondary osteoarthritis is caused by another disease or condition. Conditions that can lead to secondary osteoarthritis include obesity, repeated trauma or surgery to the joint structures, abnormal joints at birth (congenital abnormalities), gout, diabetes, and other hormone disorders.
Obesity causes osteoarthritis by increasing the mechanical stress on the cartilage. In fact, next to aging, obesity is the most powerful risk factor for osteoarthritis of the knees. The early development of osteoarthritis of the knees among weight lifters is believed to be in part due to their high body weight. Repeated trauma to joint tissues (ligaments, bones, and cartilage) is believed to lead to early osteoarthritis of the knees in soccer players. Interestingly, studies have not found an increased risk of osteoarthritis in long-distance runners.
Crystal deposits in the cartilage can cause cartilage degeneration and osteoarthritis. Uric acid crystals cause arthritis in gout, while calcium pyrophosphate crystals cause arthritis in pseudogout.
Some people are born with abnormally formed joints (congenital abnormalities) that are vulnerable to mechanical wear, causing early degeneration and loss of joint cartilage. Osteoarthritis of the hip joints is commonly related to structural abnormalities of these joints that had been present since birth.
Hormone disturbances, such as diabetes and growth hormone disorders, are also associated with early cartilage wear and secondary osteoarthritis

Garlic May Thwart Osteoarthritis

Garlic might help shield your hips from osteoarthritis, according to recent research. Published in the journal BMC Musculoskeletal Disorders, the new study shows that women with a diet rich in allium vegetables (including onions and leeks) may have lower levels of hip osteoarthritis.
The study focused on 1,086 female twins (ages 46 to 77), many of whom had no symptoms of arthritis. Looking at x-ray images and data on the participants' dietary patterns, researchers found that those who followed a healthy diet high in fruits and vegetables (especially alliums) showed fewer signs of early osteoarthritis in the hip joint. The researchers also investigated certain compounds in garlic, finding that a substance called diallyl disulphide may eliminate enzymes known to damage cartilage.
Past research suggests that garlic may guard against a host of other health conditions, including high cholesterol and high blood pressure. There's also some evidence that garlic may aid in cold prevention.

 

Polycystic Ovary Syndrome

Definition

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Polycystic ovary syndrome (PCOS) is the most common hormonal disorder among women of reproductive age. The name of the condition comes from the appearance of the ovaries in most, but not all, women with the disorder — enlarged and containing numerous small cysts located along the outer edge of each ovary (polycystic appearance).
Infrequent or prolonged menstrual periods, excess hair growth, acne and obesity can all occur in women with polycystic ovary syndrome. Menstrual abnormality may signal the condition in adolescence, or PCOS may become apparent later following weight gain or difficulty becoming pregnant.
The exact cause of polycystic ovary syndrome is unknown. Women with polycystic ovary syndrome may have trouble becoming pregnant due to infrequent or lack of ovulation. Early diagnosis and treatment of polycystic ovary syndrome can help reduce the risk of long-term complications, such as type 2 diabetes, heart disease and stroke.

Mushrooms May Fight Polycystic Ovary Syndrome

Maitake may help treat polycystic ovary syndrome (PCOS), suggests a new study from the Journal of Alternative and Complementary Medicine.
A condition marked by multiple small cysts in the ovaries, PCOS is often linked to insulin resistance and lack of ovulation. Since maitake is known to improve insulin resistance, researchers tested the medicinal mushroom's effects on 57 women with PCOS. After up to 12 weeks of treatment, 20 out of 26 study participants given maitake extract experienced ovulation (compared with 29 out of the 31 participants given the ovulation-inducing medication clomiphene). According to the study's authors, these findings indicate that maitake may be useful for PCOS patients who fail to respond to clomiphene.
Past research shows that acupuncture may also help improve insulin resistance, regulate menstrual cycles and reduce levels of male hormones in women with PCOS.

Asthma

What Is Asthma?

Asthma (AZ-ma) is a chronic (long-term) lung disease that inflames and narrows the airways. Asthma causes recurring periods of wheezing (a whistling sound when you breathe), chest tightness, shortness of breath, and coughing. The coughing often occurs at night or early in the morning.
Asthma affects people of all ages, but it most often starts in childhood. In the United States, more than 22 million people are known to have asthma. Nearly 6 million of these people are children.

Overview

The airways are tubes that carry air into and out of your lungs. People who have asthma have inflamed airways. This makes the airways swollen and very sensitive. They tend to react strongly to certain substances that are breathed in.
When the airways react, the muscles around them tighten. This causes the airways to narrow, and less air flows to your lungs. The swelling also can worsen, making the airways even narrower. Cells in the airways may make more mucus than normal. Mucus is a sticky, thick liquid that can further narrow your airways.
This chain reaction can result in asthma symptoms. Symptoms can happen each time the airways are irritated.

Asthma

Figure A shows the location of the lungs and airways in the body. Figure B shows a cross-section of a normal airway. Figure C shows a cross-section of an airway during asthma symptoms.

Sometimes symptoms are mild and go away on their own or after minimal treatment with an asthma medicine. At other times, symptoms continue to get worse. When symptoms get more intense and/or additional symptoms appear, this is an asthma attack. Asthma attacks also are called flareups or exacerbations.
It's important to treat symptoms when you first notice them. This will help prevent the symptoms from worsening and causing a severe asthma attack. Severe asthma attacks may require emergency care, and they can cause death.

Outlook

Asthma can't be cured. Even when you feel fine, you still have the disease and it can flare up at any time.
But with today's knowledge and treatments, most people who have asthma are able to manage the disease. They have few, if any, symptoms. They can live normal, active lives and sleep through the night without interruption from asthma.
For successful, comprehensive, and ongoing treatment, take an active role in managing your disease. Build strong partnerships with your doctor and other clinicians on your health care team.

Alternative Medicine: Risky for Kids with Asthma?

 


If you've got a child with asthma, take caution when using alternative medicine. In a recent study from the Canadian Respiratory Journal, researchers found that asthmatic children treated with alternative therapies were twice as likely to have poor asthma control (compared to kids not treated with alternative therapies).
For the study, more than 2,000 families with asthmatic children completed questionnaires about their strategies for asthma management. About 13 percent of parents reported using alternative therapies to treat their children's asthma. The most commonly used alternative therapies included dietary supplements, homeopathy, and acupuncture.
In past research, a number of alternative therapies (such as omega-3 fatty acid supplements) have been found to aid in asthma management. However, the recent study's authors warn that use of alternative therapies may interfere with conventional asthma treatment (by causing harmful interactions with medication, for instance). If you're considering the use of alternative medicine to control of your child's asthma, make sure to consult his or her physician before beginning treatment.

anthrax

Introduction to How Anthrax Works

Anthrax is a bacteria that could be used as a biological weapon.

­ The threat of anthrax as a biological weapon has become a ­real concern for everyone. Anthrax is a disease caused not by a virus, but rather by bacteria. There aren't any known cases of anthrax passing from one person to another, so it is considered to be noncontagious. It is still a large threat, however, because if it isn't recognized and treated quickly enough it can be deadly. Bacillus anthracis is the bacterium that causes the disease anthrax. It has historically affected herbivores like cattle, sheep or other grazing herds, but has also been a threat to humans who work with these animals and their by-products.

While in the ground or on a surface, anthrax spores are relatively harmless, but once they come into contact with the right environment they begin to germinate. They need an environment that is rich in amino acids, nucleosides and glucose -- like those elements found in blood and other tissues in humans or animals. Once there, a series of changes takes place that can make these bacteria deadly to its host.
In this edition of HowStuffWorks, we'll look at what anthrax is and how it affects the body. We'll also discuss new research and ideas for treatment and prevention of the anthrax disease.

Where Does it Come From?

Anthrax is found all over the world. It contaminates the ground when an affected animal dies. It spreads when grazing animals pick it up from contaminated dirt or through contaminated food sources such as bone meal that may have been made from contaminated carcasses. There appears to be an increase in the cases of anthrax among grazing animals during droughts, when they tend to graze closer to the ground and consume more dirt with the grass.
Anthrax may also spread when carnivorous animals, such as vultures or even insects, feed on affected herbivores. The bacteria are then transferred to other areas by the host and contaminate the ground when that animal dies. As the animal decays, the bacteria are exposed to oxygen and turn back into the spores that contaminate the soil. The anthrax spores have a very tough outer casing and can remain viable in the ground for decades.

Anthrax cycle.

Many diagnostic laboratories around the world have anthrax samples for use in research and for the identification of anthrax. Anthrax can be grown in laboratories from these existing spores. In the wrong hands, these spores can be grown, dried and milled for use in biological weapons.

How Does it Spread?

Anthrax spores can enter the body through:

• Inhalation into the lungs (inhalation anthrax) - The spores can be inhaled in contaminated soil or other particles containing the spores. The spores have no smell, taste or color, so a person would not notice anything had happened unless the spores had been mixed into a substance that could be readily seen, smelled or tasted. In order to enter the lungs, where they can germinate, the spores have to be very small -- from 1 to 5 microns (millionths of a meter). According to an anthrax report published by the American Medical Association, at least 2,500 spores have to be inhaled to cause an infection.

Inhaled anthrax

• Entry into a cut or opening in the skin (cutaneous or skin anthrax) - Open cuts and scrapes can allow entry of the spores into the body to an environment in which they can germinate. This type of anthrax may also be spread by biting insects that have fed on infected hosts. The head, arms and hands are most often affected. People who handle contaminated animal products such as leather, hair (particularly goat hair) and wool are often exposed to the anthrax bacteria. Cutaneous anthrax accounts for about 95 percent of cases worldwide. If untreated, it has a fatality rate of five to 20 percent. If treated with antibiotics, it rarely leads to death.

Cutaneous anthrax

• Entry through the gastrointestinal tract (gastrointestinal anthrax) - Eating undercooked meat that is infected with the anthrax bacteria, or drinking unchlorinated water that harbors the spores, can introduce the bacteria into the gastrointestinal tract. Infection can occur in either the upper or lower GI tract. This form of anthrax is rare.

Gastrointestinal anthrax

What Happens When it Enters the Body?

When viewed at the cellular level, an anthrax bacterium looks like a jointed bamboo rod. When it enters the body and finds the environment it needs, it moves to the lymph nodes. From there it begins to multiply and produce a toxin that attacks human cells resulting in hemorrhaging, swelling, a drop in blood pressure and ultimately death.

Photo courtesy Public Health Image Library Anthrax bacteria (Bacillus anthracis), stained

The way it attacks the cells and exactly what it does was in question for many years. Research that began in the mid 1980s has revealed some interesting facts about the behavior of the anthrax bacterium when it finds a host.
Researchers found that there are three proteins that are created by the anthrax bacteria. These proteins are harmless individually, but together can be deadly. These proteins are referred to as:

• Protective antigen (PA)
• Edema factor (EF)
• Lethal factor (LF)

When these proteins are released, the protective antigen binds to the cell surface and forms a type of channel in the cell membrane that allows the edema factor and lethal factor to enter the cell. The edema factor, when combined with the protective antigen, forms a toxin known as the edema toxin. The lethal factor, when combined with the protective antigen, forms a toxin known as the lethal toxin. It is the lethal toxin that does the most damage within the cell.
Research in 1998, by George Vande Woude at the National Cancer Institute in Frederick, MD, revealed clues to what the lethal toxin does to the cells. He found that the lethal factor cuts enzymes in two -- the enzymes that are responsible for transmitting signals within the cells. He also identified the enzyme in question. He was studying the mitogen-activated protein kinase (MAPK) pathway, which helps control cell growth, embryonic development and the way oocytes (eggs) mature. He was specifically looking for information about what the pathway actually did in the oocyte maturation cycle, so he searched for compounds that blocked the activity of the MAPK. A database search lead him to the lethal factor.
It is still not completely understood why disrupting the signal transmission within the cell results in the symptoms anthrax generates, but research continues. Research is also being done to find ways to alter the protective antigen to disable its ability to allow the entry of the lethal and edema toxins into cells.

The Symptoms of Anthrax

In its bacterial state, anthrax survives outside of a proper host environment for only about 24 hours. But inside the body, where it gets the nutrients it needs to grow, anthrax germinates and spreads rapidly.
Inhalation Anthrax
Inhaled anthrax typically begins showing symptoms in seven to 10 days, although it could be as early as two to three days. It can take as long as 60 days after exposure to the anthrax spores for the disease to surface, however, and once the germination begins, the disease progresses very rapidly. It appears to come in two stages:

1. It begins with fever, cough, headache, vomiting, chills, weakness, abdominal pain, shortness of breath and chest pain. This first stage may last from a few hours to a few days. Then there may be a brief break in symptoms.
2. The second stage of the disease lasts anywhere from two to four days. The symptoms for the second stage include fever, difficulty breathing, sweating, a bluish discoloration of the skin, shock, and finally death.

Cutaneous Anthrax
Cutaneous anthrax, which occurs when the anthrax spore is deposited into a break in the skin, may occur as late as 12 days after exposure. The germination of the bacteria results in local swelling of the skin -- a small papule (bump) will appear. The following day the bump will enlarge into an ulcer and begin discharging a clear fluid. Then, a painless, depressed black scab will form that will dry and fall off within one to two weeks. Treatment with antibiotics may not change the appearance or formation of the bumps, but they decrease the chances that the disease will become systemic.
Gastrointestinal Anthrax
The gastrointestinal form of anthrax, which occurs from eating or drinking infected meats or water, brings about symptoms that include nausea, vomiting blood, abdominal pain, bloody diarrhea, and weakness. Death occurs in 25 to 60 percent of these cases.

Diagnosis and Treatment

According to an article in the Journal of the American Medical Association, a blood sample is taken from the patient and cultured for six to 24 hours. At this point, a "Gram stain" can be done. The Gram stain highlights the bacteria.

Photo courtesy Public Health Image Library Anthrax bacteria in Gram stain

The Gram stain takes about 10 to 15 minutes and can identify whether the bacteria come from the anthrax category. At that point, biochemical testing can be done to find the specific anthrax bacteria, which takes another 12 to 24 hours. Usually, the specimens have to be sent to national reference laboratories for comparison with stock anthrax samples.
Treatment
Anthrax is treated with the antibiotics penicillin, ciprofloxacin or doxycycline. The antibiotic most often used is ciprofloxacin, partly because of rumors that the Soviet Union had developed a penicillin-resistant form of anthrax for use in biological warfare. It is also specifically recommended by the U.S. Food and Drug Administration (FDA) for use in treating anthrax.
Treatment of inhaled anthrax has to start very early in the progression of symptoms. If treatment is begun after the symptoms have progressed too far, then the bacteria may be killed but the toxins remain in the body.

Vaccine and Treatment Research

The vaccine that was developed in the 1950s (licensed in 1970), is currently only given to military personnel, people who work directly with anthrax in research labs, and those who work with animals and animal by-products that may be infected with anthrax. The vaccine uses the anthrax protective antigen to make the body create immunity to the disease. It is created from a strain of anthrax that does not cause the disease, and doesn't use any live or dead whole bacteria. There is a separate vaccine for use in animals. (That vaccine can't be used in humans.)
The side effects of the anthrax vaccine include:

• Mild local reactions at the site of the injection (like with many other vaccinations)
• Occasional, moderate local reactions that include redness, swelling and tenderness, often at the site of the injection and extending up to 5 inches (13 cm) across the area
• Large local reactions larger than 5 inches, including swelling of the forearm and at the injection site
• Muscle aches, joint aches, headaches, rash, chills, fever, nausea, loss of appetite, and weakness for a few days after the vaccination (experienced in up to 35 percent of people who get the vaccine)
• A severe allergic reaction (appears once in every 100,000 doses)
• A severe reaction that requires hospitalization (appears once in every 200,000 doses)

cholera

Definition

Cholera is a bacterial disease which affects the intestines. This disease is found in Indonesia, Asia, Eastern Europe, and Africa. Some of the symptoms of Cholera include vomiting, diarrhea, and dehydration.
There are several things you can do to avoid getting Cholera. There is a vaccine you can get before you travel that is at least 50 percent affective. Another thing you can do to avoid getting cholera is to avoid eating uncooked food and to boil all your drinking water.

Cholera in Haiti

the Haitian Ministry of Public Health and Population (MSPP) reported 60 240 cumulative cholera cases including 1 415 deaths at the national level. The case fatality rate in hospitals at the national level is 2.3%, with 67% of the deaths occurring at health services level and 33% at community level.
In Port-au-prince and metropolitan area (Carrefour, Cite Soleil, Delmas, Kenscoff, Petion Ville, Tabarre and Croix des Bouquets), 5 778 cases, including 95 deaths have been reported.
On 19 November, the Ministry of Health of the Dominican Republic reported two cases tested positive for cholera. One person is hospitalized and the other is receiving treatment at his residence in the province of Santo Domingo.
WHO/PAHO and partners, including the GOARN (Global Outbreak Alert and Response Network) continue to support the Haitian MSPP in the response to the outbreak. Civil unrest since 15 November has slowed down several activities, including delivery of supplies for prevention and treatment of patients, particularly in the Northern city of Cap Haitian. Trainings on cholera treatment and initiatives to chlorinate water for 300 000 people had to be postponed.
The National Cholera Response Plan identifies the need to urgently scale-up Oral Rehydration Centres at the community level to provide services to non-life threatening cases and serve as a contact point for referring non severe patients to Cholera Treatment Units (CTUs) and severe patients to Cholera Treatment Centres (CTCs). The plan states the essential need to scale-up CTUs, which are attached to or near existing health centres, to provide essential treatment and triage patients with severe symptoms to CTCs. Nationwide, CTCs with a total capacity of 2 830 beds have been established in Haiti.

Recommendation

WHO does not recommend restrictions to international travel or trade due to the cholera outbreak in Haiti. For further information, please refer to the "WHO statement relating to international travel and trade to and from countries experiencing outbreaks of cholera" below.

Botulism

   The  meaning 

 Definition

Botulism is caused by botulinum toxin, a natural poison produced by certain bacteria in the Clostridium genus. Exposure to the botulinum toxin occurs mostly from eating contaminated food, or in infants, from certain clostridia growing in the intestine. Botulinum toxin blocks motor nerves' ability to release acetylcho-line, the neurotransmitter that relays nerve signals to muscles, and flaccid paralysis occurs.
As botulism progresses, the muscles that control the airway and breathing fail.


Description

Botulism occurs rarely, but it causes concern because of its high fatality rate. Clinical descriptions of botulism possibly reach as far back in history as ancient Rome and Greece. However, the relationship between contaminated food and botulism wasn't defined until the late 1700s. In 1793 the German physician, Justinius Kerner, deduced that a substance in spoiled sausages, which he called wurstgift (German for sausage poison), caused botulism. The toxin's origin and identity remained elusive until Emile von Ermengem, a Belgian professor, isolated Clostridium botulinum in 1895 and identified it as the poison source.
Three types of botulism have been identified: foodborne, wound, and infant botulism. The main difference between types hinges on the route of exposure to the toxin. In the United States, there are approximately 110 cases of botulism reported annually. Food-borne botulism accounts for 25% of all botulism cases and usually can be traced to eating contaminated home-preserved food. Infant botulism accounts for 72% of all cases, but the recovery rate is good (about 98%) with proper treatment. From 1990 to 2000, 263 cases of food-borne cases were reported in the United States, most of them in Alaska. Though most were related to home canning, two restaurant-associated outbreaks affected 25 people.
Though domestic food poisoning is a problem world-wide, there has been a growing concern regarding the use of botulism toxin in biological warfare and terrorist acts. The Iraqi government admitted in 1995 that it had loaded 11,200 liters of botulinum toxin into SCUD missiles during the Gulf War. Luckily, these special missiles were never used. As of 1999, there were 17 countries known to be developing biological weapons, including the culture of botulism toxins.


Causes and symptoms


Toxin produced by the bacterium Clostridium botulinum is the main culprit in botulism. Other members of the clostridium genus can produce botulinum toxin, namely C. argentinense, C. butyricum, and C. baratii, but they are minor sources. To grow, these bacteria require a low-acid, oxygen-free environment that is warm (40-120°F or 4.4-48.8°C) and moist. Lacking these conditions, the bacteria transform themselves into spores that, like plant seeds, can remain dormant for years. Clostridia and their spores exist all over the world, especially in soil and aquatic sediments. They do not threaten human or animal health until the spores encounter an environment that favors growth. The spores then germinate, and the growing bacteria produce the deadly botulism toxin.
Scientists have discovered that clostridia can produce at least seven types of botulism toxin, identified as A, B, C, D, E, F, and G. Humans are usually affected by A, B, E, and very rarely F. Domesticated animals such as dogs, cattle, and mink are affected by botulism C toxin, which also affects birds and has caused massive die-offs in domestic bird flocks and wild waterfowl. Botulism D toxin can cause illness in cattle, and horses succumb to botulism A, B, and C toxin. There have been no confirmed human or animal botulism cases linked to the G toxin.
In humans, botulinum toxin latches onto specific proteins in nerve endings and irreversibly destroys them. These proteins control the release of acetylcholine, a neurotransmitter that stimulates muscle cells. With acetylcholine release blocked, nerves are not able to stimulate muscles. Ironically, botulinum toxin has found a beneficial niche in the world of medicine due to this action. Certain medical disorders are characterized by involuntary and uncontrollable muscle contractions. Medical researchers have discovered that injecting a strictly controlled dose of botulinum toxin into affected muscles inhibits excessive muscle contractions. The muscle is partially paralyzed and normal movement is retained. This is commonly referred to as Botox injection.
The three types of human botulism include the following symptoms:

    * Food-borne. Food that has been improperly preserved or stored can harbor botulinum toxin-producing clostridia. Botulism symptoms typically appear within 18-36 hours of eating contaminated food, with extremes of four hours to eight days. Initial symptoms include blurred or double vision and difficulty swallowing and speaking. Possible gastrointestinal problems include constipation, nausea, and vomiting. As botulism progresses, the victim experiences weakness or paralysis, starting with the head muscles and progressing down the body. Breathing becomes increasingly difficult. Without medical care, respiratory failure and death are very likely.
    * Infant. Infant botulism was first described in 1976. Unlike adults, infants younger than 12 months are vulnerable to C. botulinum colonizing the intestine. Infants ingest spores in honey or simply by swallowing spore-containing dust. The spores germinate in the large intestine and, as the bacteria grow, they produce botulinum toxin that is absorbed into the infant's body. The first symptoms include constipation, lethargy, and poor feeding. As infant botulism progresses, sucking and swallowing (thus eating) become difficult. A nursing mother will often notice breast engorgement as the first sign of her infant's illness. The baby suffers overall weakness and cannot control head movements. Because of the flaccid paralysis of the muscles, the baby appears "floppy." Breathing is impaired, and death from respiratory failure is a very real danger.
    * Wound. Confirmed cases of wound botulism have been linked to trauma such as severe crush injuries to the extremities, surgery, and illegal drug use. Wound botulism occurs when clostridia colonize an infected wound and produce botulinum toxin. The symptoms usually appear four to 18 days after an injury occurs and are similar to food-borne botulism, although gastrointestinal symptoms may be absent.

Infant Botulism Risk From Honey

Infant Botulism Risk From Honey

Although it is a rare illness, infant botulism is incredibly serious.  For this reason, parents of newborns are being reminded to refrain from feeding honey, even the smallest amount, to any child under the age of 1.

If the botulism spores are ingested, they begin to multiply in the infant's gastrointestinal tract, producing a toxin.  The toxin interferes with muscle control and nerve pathways, and can lead to paralysis and possible death.

Why risk it?  Be safe, and just wait until your child is over the age 1 and has developed sufficient "good" bacteria in his or her gastrointestinal tract to fight off the potentially lethal toxin.

Avian influenza Avian Influenza in Poultry

A few facts about Avian Influenza

Introduction

Avian Influenza (AI) is a contagious viral infection which can affect all species of birds. In intensive poultry rearing systems young fattening turkeys and laying hens are usually the most affected species.

Free-living birds may carry influenza viruses without becoming ill due to a natural resistance. It is known that wild waterfowl present a natural reservoir for these viruses and can be responsible for the primary introduction of infection into domestic poultry.

Causative agent

The virus causing avian influenza is an Influenzavirus A virus of the family Orthomyxoviridae. Several virus subtypes exist, which are divided on the bases of the antigenic relationships in the virus glycoproteins haemoagglutinin (H) and neuraminidase (N). At present 15 H subtypes have been recognised (H1-H15) and nine neuraminidase subtypes (N1- N9).

Influenza A viruses infecting poultry can also be divided on the basis of their pathogenicity (ability to cause disease).

The very virulent viruses cause highly pathogenic avian influenza (HPAI) with mortality in poultry as high as 100%. In the whole world there have been only 19 reported primary isolates of such viruses from domestic poultry since 1959. A severe epidemic occurred in Italy in 1999/2000 causing 413 outbreaks with 16 Million birds affected.

Other AI viruses cause a much milder disease (low pathogenic avian influenza, LPAI). Clinical signs are much less evident or even absent and mortality is much lower.

Sometimes secondary infections or environmental conditions may cause exacerbation of LPAI infections leading to more serious disease. Evidence suggests that certain avian influenza virus subtypes of low pathogenicity may, after circulation for some time in a poultry population, mutate into highly pathogenic virus strains.

To date only viruses of H5 and H7 subtype have been shown to cause HPAI in susceptible species, but not all H5 and H7 viruses are highly pathogenic.

Clinical symptoms

The main symptoms of HPAI in poultry are depression, loss of appetite, cessation of egg laying, nervous signs, swelling and blue discoloration of combs and wattles due to disturbance of blood circulation, coughing, sneezing and diarrhoea. Sudden death can occur without any previous signs. The mortality rate may reach up to 100% depending on the species, their age, the virus type involved and environmental factors like concurrent bacterial infections.

Clinical signs of LPAI consist primarily of mild respiratory disease, depression and drop in egg production in laying birds.

The incubation periods for these viruses range from as short as a few hours to 3 days in individual birds and up to 14 days to spread throughout a flock.

Transmission and spread

All the available evidence suggests that the most common primary introduction of AI viruses into an area is by wild birds, usually waterfowl, but gulls and shorebirds have also been implicated. Direct contact between wild bird and poultry is not always necessary for introduction of virus into poultry farms, as infected waterfowl may spread AI viruses by infective faeces into an area and these may then be introduced to poultry farms by a variety of mechanisms that may transfer the virus mechanically. If contaminated with influenza viruses, surface water used as drinking water may also be a source of infection. Poultry kept in free range or poultry which have access to surface water are at specific risk. AI is transmitted within a farm by direct contact of infected animals with healthy animals, or indirect contacts with contaminated equipment or farm staff.

Spread of AI viruses from farm to farm is mainly by mechanical transfer of infective faeces, in which virus may be present at high concentrations and may survive for considerable periods. Shared water or food may also become contaminated.

However, man is a very important cause of secondary spread of AI for domestic poultry. Caretakers, farmers, workers, trucks and drivers visiting farms, moving birds or delivering food have caused the spread of AI virus both on to and within farms.

Legislation and basic disease control measures

The O.I.E (Office International des Epizooties, the World Organisation for Animal Health) has classified HPAI as a "list A" disease, signifying a rapidly spreading animal disease of major economic importance, such as Foot and mouth disease or classical swine fever.

EU legislation to control avian influenza is laid down in Council Directive 92/40/EEC. All suspected cases of AI must be investigated and appropriate measures taken in case of confirmation of HPAI. To limit the spread, infected poultry must be killed in a humane way and disposed off safely. Feedingstuffs, contaminated equipment and manure must be destroyed or treated to inactivate the virus.

To prevent further spread of disease the veterinary authorities are required to immediately put in place movement restrictions on the affected holdings and on all farms in a radius of at least 10-km around these holdings, the so called surveillance zone. If necessary, stamping-out measures can also be extended to poultry farms in the vicinity of or which have had dangerous contacts with infected farms.

In accordance with Community legislation, all Member States have AI contingency plans in place to ensure that the most appropriate measures are immediately implemented.

At farm level preventive hygienic measures such as cleaning and disinfection are crucial. Disease awareness amongst farmers and cooperation by all people in the poultry sector must ensure that the strictest biosecurity measures are applied to prevent disease spread.

Vaccination

The existence of a large number of virus subtypes together with the known variation of different strains within a subtype pose serious problems when selecting strains to produce influenza vaccines and to use vaccination as a routine tool for disease prevention.

In accordance with Directive 92/40/EEC, vaccination against AI may be used to supplement the control measures carried out after confirmation of disease. Birds vaccinated against the HA subtype corresponding to the one which is circulating are protected against the worst effects of AI. The decision to introduce vaccination may be taken by the Member State concerned, with or without prior approval by the Commission. Such steps must be accompanied by further disease control measures, including trade restrictions, in accordance with the Standing Committee procedures(1). Following confirmation of LPAI, vaccination against AI is currently being applied in some regions of Italy, pursuant to Commission Decision 2002/975/EC(2). This vaccination strategy developed and applied in Italy makes use of a heterologous vaccine, allowing discrimination between vaccinated and infected poultry(3). This strategy was adopted for the first time in the world in 2001 by Commission Decision 2001/847/EC(4) and allowed certain trade restrictions on the meat of vaccinated poultry to be lifted.

However, the immunity induced by vaccination may not be sufficiently rapid to stop farm-to-farm spread of HPAI. Furthermore, emergency vaccination is also hindered by practical difficulties related to the administration of the vaccine (each single bird must be injected).