Influenza

What is influenza?

Influenza (also called "the flu") is a viral infection in the nose, throat and lungs. About 10% to 20% of Americans get the flu each year. Some people can get very sick from the flu. Each year, about 200,000 people go to a hospital with the flu, and 36,000 people die because of the flu and complications.

The flu may cause fever, cough, sore throat, a runny or stuffy nose, headache, muscle aches and tiredness. Most people feel better after 1 or 2 weeks, but for some people, the flu leads to serious diseases, such as pneumonia. The influenza vaccine (the flu shot) can help protect you from getting the flu.

Who is at higher risk?

Some people have a higher risk of flu complications, like pneumonia. If you are in any of these groups, you should get the flu vaccine every year:
- All children aged 6 months up to 19 years
- All adults aged 50 years and older
- All women who are or will be pregnant during the flu season
- People who are living in nursing homes or long-term care facilities
- Individuals who have long-term health problems
- Health care workers who have direct contact with patients
- Caregivers and household contacts of children less than 6 months of age


How can I avoid getting the flu?

The best way to avoid getting the flu is to get the influenza vaccine. You should get the vaccine when it becomes available each fall (in October or November), but you can also get it any time throughout the flu season (into December, January and beyond). The vaccine is available by shot or by nasal spray. The vaccines work by exposing your immune system to the flu virus. Your body will build up antibodies to the virus to protect you from getting the flu. The flu shot contains dead viruses. The nasal-spray vaccine contains live but weakened viruses. You cannot get the flu from the flu shot or the nasal-spray vaccine.

You can also reduce your risk of catching the flu by washing your hands frequently, which stops the spread of germs. Eating healthy, exercising and getting enough sleep also play a part in preventing the flu because they help boost your immune system. 

If you are sick, make sure that you cover your mouth when you cough and wash your hands often to prevent giving the flu to others.

Some people who get the vaccine will still get the flu, but they will usually get a milder case than people who aren't vaccinated. The vaccine is especially recommended for people who are more likely to get really sick from flu-related complications.

Is there anyone who shouldn't get the flu shot?

Yes. The following people should talk to their doctor before getting the flu shot:
- People who have had an allergic reaction to a flu shot in the past
- People with an allergy to eggs
- People who previously developed Guillain-Barré Syndrome (a reversible reaction that causes partial or complete loss of movement of muscles, weakness or a tingling sensation in the body) within 6 weeks of getting a flu shot
- Children less than 6 months of age
- People who have a moderate or severe illness with a fever should wait until they feel better before receiving the flu shot

Is there anyone who shouldn't get the nasal-spray vaccine?

Yes. The following people should talk to their doctor before getting the nasal-spray vaccine:
- Children less than 2 years of age
- Adults 50 years of age and older
- People with long-term health problems
- People with weakened immune systems
- Children or adolescents who are on long-term aspirin therapy
- People with diabetes, kidney disease, heart disease or lung disease
- People with a history of Guillain-Barré syndrome
- Pregnant women
- People who have had an allergic reaction to a flu vaccine in the past or who are allergic to eggs

If I get the flu vaccine, can I still get the flu?

Yes. Even with a flu vaccine, you aren't 100% protected. Each year, the flu vaccine contains 3 different strains (kinds) of the virus. The strains chosen are those that scientists believe are most likely to show up in the United States that year. If the choice is right, the vaccine is 70% to 90% effective in preventing the flu in healthy adults. If you're older than 65, the vaccine is less likely to prevent the flu. Even if you get the flu after being vaccinated, your flu symptoms should be milder than if you didn't get the vaccine. You'll also be less likely to get complications from the flu.

Is the vaccine safe?

Yes. The flu vaccine is safe. There are very few side effects. If you got the flu shot, your arm may be sore for a few days . You may have a fever, feel tired or have sore muscles for a short time. If you got the nasal-spray vaccine, you may have a runny nose, headache, cough or sore throat.

Can I get the flu vaccine if I am pregnant or nursing?

If you are pregnant during flu season, you cannot get the nasal-spray vaccine. However, it is recommended that women who will be pregnant during flu season get the shot. Pregnancy can increase your risk for complications from the flu.

It is also safe to get the flu shot while breast feeding your baby. The flu shot cannot cause you or your nursing baby to get sick.

What are antiviral flu drugs?

Antiviral flu drugs are prescription medicines that can be used to help prevent and/or treat the flu. There are four antiviral flu drugs: amantadine (one brand name: Symmetrel), oseltamivir (brand name: Tamiflu), rimantadine (brand name: Flumadine) and zanamavir (brand name: Relenza). All 4 of these antiviral drugs have been approved to treat the flu. If you take one of these drugs within 2 days of getting sick, it can lessen your symptoms, decrease the amount of time you are sick and make you less contagious to other people. However, most healthy people who have the flu get better without using an antiviral flu drug. Your doctor will decide whether one of these medicines is right for you.

Three of the antiviral flu drugs have also been approved to prevent the flu. These drugs are not a substitute for the influenza vaccine. They are most often used for flu prevention in institutions where people at high risk for flu complications are in close contact with each other, such as nursing homes or hospitals. For example, during a flu outbreak in a nursing home, residents and staff might be given the flu vaccine and an antiviral drug to prevent the flu until the vaccine takes effect.

Asthma

What is Asthma?

Asthma is a disease affecting the airways that carry air to and from your lungs. People who suffer from this chronic condition (long-lasting or recurrent) are said to be asthmatic.
 

The inside walls of an asthmatic's airways are swollen or inflamed. This swelling or inflammation makes the airways extremely sensitive to irritations and increases your susceptibility to an allergic reaction.

As inflammation causes the airways to become narrower, less air can pass through them, both to and from the lungs. Symptoms of the narrowing include wheezing (a hissing sound while breathing), chest tightness, breathing problems, and coughing. Asthmatics usually experience these symptoms most frequently during the night and the early morning.

For information on the different causes of asthma (allergy, colds, stress, exercise, etc) please see page 4 (causes of asthma). 
Asthma is Incurable

Asthma is an incurable illness. However, with good treatment and management there is no reason why a person with asthma cannot live a normal and active life.
What is an Asthma Episode / Attack?

An asthma episode, or an asthma attack, is when symptoms are worse than usual. They can come on suddenly and can be mild, moderate or severe. 

What happens during an asthma attack? 

The muscles around your airways tighten up, narrowing the airway.
Less air is able to flow through the airway.
Inflammation of the airways increases, further narrowing the airway.

More mucus is produced in the airways, undermining the flow of air even more.

Asthma Attacks Vary

 In some asthma attacks, the airways are blocked such that oxygen fails to enter the lungs. This also prevents oxygen from entering the blood stream and traveling to the body's vital organs. Asthma attacks of this type can be fatal, and the patient may require urgent hospitalization. 

Asthma attacks can be mild, moderate, severe and very severe. At onset, an asthma attack does allow enough air to get into the lungs, but it does not let the carbon dioxide leave the lungs at a fast enough rate. Carbon dioxide - poisonous if not expelled - can build up in the lungs during a prolonged attack, lowering the amount of oxygen getting into your bloodstream.

See Your Doctor

If you suffer from asthma you should see your doctor. He/she will help you find out what triggers your asthma symptoms and how to avoid them. You will also be prescribed medications which will help you manage your asthma.

With experience you will learn to keep away from things that irritate your airways, know when to take your medication, and better control your asthma. Effective asthma control allows you to take part in normal everyday activities.

Consequences of Not Controlling Your Asthma

If you don't control your asthma you will miss school or work more often and you will be less likely to be able to take part in some activities you enjoy. In the USA and Western Europe, asthma is one of the leading causes of school absenteeism.

Types of Asthma

Child-Onset Asthma
 
Asthma that begins during childhood is called child-onset asthma. This type of asthma happens because a child becomes sensitized to common allergens in the environment - most likely due to genetic reasons. The child is atopic - a genetically determined state of hypersensitivity to environmental allergens.

Allergens are any substances that the body will treat as a foreign body, triggering an immune response. These vary widely between individuals and often include animal proteins, fungi, pollen, house-dust mites and some kind of dust. The airway cells are sensitive to particular materials making an asthmatic response more likely if the child is exposed to a certain amount of an allergen.

Adult-Onset Asthma

This term is used when a person develops asthma after reaching 20 years of age. Adult-onset asthma affects women more than men, and it is also much less common than child-onset asthma.

It can also be triggered by some allergic material or an allergy. It is estimated that up to perhaps 50% of adult-onset asthmas are linked to allergies. However, a substantial proportion of adult-onset asthma does not seem to be triggered by exposure to allergen(s); this is called non-allergic adult-onset asthma. This non-allergic type of adult onset asthma is also known as intrinsic asthma. Exposure to a particle or chemical in certain plastics, metals, medications, or wood dust can also be a cause of adult-onset asthma. 

Exercise-Induced Asthma

If you cough, wheeze or feel out of breath during or after exercise, you could be suffering from exercise-induced asthma. Obviously, your level of fitness is also a factor - a person who is unfit and runs fast for ten minutes is going to be out of breath. However, if your coughing, wheezing or panting does not make sense, this could be an indication of exercise-induced asthma.

As with other types of asthma, a person with exercise-induced asthma will experience difficulty in getting air in and out of the lungs because of inflammation of the bronchial tubes (airways) and extra mucus. 

Some people only experience asthma symptoms during physical exertion. The good news is that with proper treatment, a person who suffers from exercise-induced asthma does not have to limit his/her athletic goals. With proper asthma management, one can exercise as much as desired. Mark Spitz won nine swimming gold medals during the 1972 Olympics and he suffered from exercise-induced asthma. 

Eighty percent of people with other types of asthma may have symptoms during exercise, but many people with exercise-induced asthma never have symptoms while they are not physically exerting themselves.

Cough-Induced Asthma

Cough-induced asthma is one of the most difficult asthmas to diagnose. The doctor has to eliminate other possibilities, such as chronic bronchitis, post nasal drip due to hay fever, or sinus disease. In this case the coughing can occur alone, without other asthma-type symptoms being present. The coughing can happen at any time of day or night. If it happens at night it can disrupt sleep. 

Occupational Asthma

This type of asthma is triggered by something in the patient's place of work. Factors such as chemicals, vapors, gases, smoke, dust, fumes, or other particles can trigger asthma. It can also be caused by a virus (flu), molds, animal products, pollen, humidity and temperature. Another trigger may be stress. Occupational asthma tends to occur soon after the patients starts a new job and disappears not long after leaving that job.

Nocturnal Asthma

Nocturnal asthma occurs between midnight and 8 AM. It is triggered by allergens in the home such as dust and pet dander or is caused by sinus conditions. Nocturnal or nighttime asthma may occur without any daytime symptoms recognized by the patient. The patient may have wheezing or short breath when lying down and may not notice these symptoms until awoken by them in the middle of the night - usually between 2 and 4 AM. 

Nocturnal asthma may occur only once in a while or frequently during the week. Nighttime symptoms may also be a common problem in those with daytime asthma as well. However, when there are no daytime symptoms to suggest asthma is an underlying cause of the nighttime cough, this type of asthma will be more difficult to recognize - usually delaying proper therapy. The causes of this phenomenon are unknown, although many possibilities are under investigation.

Steroid-Resistant Asthma (Severe Asthma)

While the majority of patients respond to regular inhaled glucocorticoid (steroid) therapy, some are steroid resistant. Airway inflammation and immune activation play an important role in chronic asthma. Current guidelines of asthma therapy have therefore focused on the use of anti-inflammatory therapy, particularly inhaled glucocorticoids (GCs). By reducing airway inflammation and immune activation, glucocorticoids are used to treat asthma. However, patients with steroid resistant asthma have higher levels of immune activation in their airways than do patients with steroid sensitive (SS) asthma. 

Furthermore, glucocorticoids do not reduce the eosinophilia (high concentration of eosinophil granulocytes in the blood) or T cell activation found in steroid resistant asthmatics. This persistent immune activation is associated with high levels of the immune system molecules IL-2 (interleukin 2), IL-4 and IL-5 in the airways of these patients.

What Causes Asthma?
 
According to recent estimates, asthma affects 300 million people in the world and more than 22 million in the United States. Although people of all ages suffer from the disease, it most often starts in childhood, currently affecting 6 million children in the US. Asthma kills about 255,000 people worldwide every year.
Children at Risk

Asthma is the most common chronic disease among children - especially children who have low birth weight, are exposed to tobacco smoke, are black, and are raised in a low-income environment. Most children first present symptoms around 5 years of age, generally beginning as frequent episodes of wheezing with respiratory infections. Additional risk factors for children include having allergies, the allergic skin condition eczema, or parents with asthma.

Young boys are more likely to develop asthma than young girls, but this trend reverses during adulthood. Researchers hypothesize that this is due to the smaller size of a young male's airway compared to a young female's airway, leading to a higher risk of wheezing after a viral infection.
Allergies

Almost all asthma sufferers have allergies. In fact, over 25% of people who have hay fever (allergic rhinitis) also develop asthma. Allergic reactions triggered by antibodies in the blood often lead to the airway inflammation that is associated with asthma.

Common sources of indoor allergens include animal proteins (mostly cat and dog allergens), dust mites, cockroaches, and fungi. It is possible that the push towards energy-efficient homes has increased exposure to these causes of asthma. 

Tobacco Smoke

Tobacco smoke has been linked to a higher risk of asthma as well as a higher risk of death due to asthma, wheezing, and respiratory infections. In addition, children of mothers who smoke - and other people exposed to second-hand smoke - have a higher risk of asthma prevalence. Adolescent smoking has also been associated with increases in asthma risk.
Environmental Factors

Allergic reactions and asthma symptoms are often the result of indoor air pollution from mold or noxious fumes from household cleaners and paints. Other indoor environmental factors associated with asthma include nitrogen oxide from gas stoves. In fact, people who cook with gas are more likely to have symptoms such as wheezing, breathlessness, asthma attacks, and hay fever. 
 

Pollution, sulfur dioxide, nitrogen oxide, ozone, cold temperatures, and high humidity have all been shown to trigger asthma in some individuals.

During periods of heavy air pollution, there tend to be increases in asthma symptoms and hospital admissions. Smoggy conditions release the destructive ingredient known as ozone, causing coughing, shortness of breath, and even chest pain. These same conditions emit sulfur dioxide, which also results in asthma attacks by constricting airways.

Weather changes have also been known to stimulate asthma attacks. Cold air can lead to airway congestion, bronchoconstriction (airways constriction), secretions, and decreased mucociliary clearance (another type of airway inefficiency). In some populations, humidity causes breathing difficulties as well.

Obesity

Overweight adults - those with a body mass index (BMI) between 25 and 30 - are 38% more likely to have asthma compared to adults who are not overweight. Obese adults - those with a BMI of 30 or greater - have twice the risk of asthma. According to some researchers, the risk may be greater for nonallergic asthma than allergic asthma.

Pregnancy

The way you enter the world seems to impact your susceptibility to asthma. Babies born by Caesarean sections have a 20% increase in asthma prevalence compared to babies born by vaginal birth. It is possible that immune system-modifying infections from bacterial exposure during Cesarean sections are responsible for this difference. 

When mothers smoke during pregnancy, their children have lower pulmonary function. This may pose additional asthma risks. Research has also shown that premature birth is a risk factor for developing asthma.

Stress

People who undergo stress have higher asthma rates. Part of this may be explained by increases in asthma-related behaviors such as smoking that are encouraged by stress. However, recent research has suggested that the immune system is modified by stress as well.
Genes

It is possible that some 100 genes are linked to asthma - 25 of which have been associated with separate populations as of 2005.
 

Genes linked to asthma also play roles in managing the immune system and inflammation. There have not, however, been consistent results from genetic studies across populations - so further investigations are required to figure out the complex interactions that cause asthma. 

Mom and Dad may be partially to blame for asthma, since three-fifths of all asthma cases are hereditary. The Centers for Disease Control (USA) say that having a parent with asthma increases a person's risk by three to six times.

Genetics may also be interacting with environmental factors. For example, exposure to the bacterial product endotoxin and having the genetic trait CD14 (single nucleotide polymorphism (SNP) C-159T) have remained a well-replicated example of a gene-environment interaction that is associated with asthma.

Airway Hyperreactivity

Researchers are not sure why airway hyperreactivity is another risk factor for asthma, but allergens or cold air may trigger hyperreactive airways to become inflamed. Some people do not develop asthma from airway hyperreactivity, but hyperreactivity still appears to increase the risk of asthma.

Atopy

Atopy - such as eczema (atopic dermatitis), allergic rhinitis (hay fever), allergic conjunctivitis (an eye condition) - is a general class of allergic hypersensitivity that affects different parts of the body that do not come in contact with allergens. Atopy is a risk factor for developing asthma.

Some 40% to 50% of children with atopic dermatitis also develop asthma, and it is probable that children with atopic dermatitis have more severe and persistent asthma as adults.

Treatment for Asthma
 
Asthma is not so much "treated" as it is "controlled". As a chronic, long-term disease, there is no cure. However, there are tools and medicines to help you control asthma as well as benchmarks to gauge your progress.

The Peak Flow Meter

A peak flow meter is a simple, small, hand-held tool that can help you maintain control of asthma by providing a measurement of how well air moves out of the lungs.

After blowing into the device, the meter reveals your peak flow number. A physician will indicate how often to test as well as how to interpret the result to determine the amount of medication to take. Some people record scores every morning while others use the peak flow meter intermittently. 

Often, each test with the peak flow meter will be judged against your "personal best" peak flow number (found during 2 to 3 weeks of good asthma control). If peak flow tests begin to decline - even before other symptoms are present - it may indicate a looming asthma attack. After taking asthma medication, the peak flow meter can be used to test the effectiveness of drug therapy.

Good Control

Asthma is considered "well-controlled" if:
Chronic and troublesome symptoms (coughing and shortness of breath) are prevented and occur no more than 2 days per week.
There is little need for quick-relief medicines or they are needed less than 2 days per week.
You maintain good lung function.
Your activity level remains normal.
Your sleep level remains normal and symptoms do not wake you from sleep more than 1 to 2 nights per month.
You do not need emergency medical treatment.
You have no more than one asthma attack each year that requires inhalation of corticosteroids.
Your peak flow stays above 80% of your personal best number.

These benchmarks can be obtained by working with a doctor and avoiding factors that can make your asthma flare up. Also be sure to treat other conditions that may interfere with asthma management.

Good control also means avoiding things that trigger asthma or asthma symptoms such as allergens. This may mean limiting time spent outdoors when pollen levels or air pollution levels are highest and limiting contact with animals. Asthma linked to allergies can also be suppressed by getting the necessary allergy shots.

Preventive Checkups

Part of good asthma control is seeing a doctor every 2 to 6 weeks for regular checkups until it is under control. Then checkups may be reduced to once a month or twice a year. 

It is a good habit to keep track of asthma symptoms and attacks and diagnostic numbers such as the peak flow measurement. Doctors and nurses will ask about these and about daily activities in order to gauge the status of your asthma control.

Medicine

 
Medication for asthma is broadly categorized as either quick-relief medicine or long-term control medicine. Reducing airway inflammation and preventing asthma symptoms is the goal of long-term control medicines, where as immediate relief of asthma symptoms is the goal of quick-relief or "rescue" medicines.

Medications can be ingested in pill form, but most are powders or mists taken orally using a device known as an inhaler. Inhalers permit medicines to travel efficiently through the airways to the lungs.

Inhaler

Medication may also be administered using a nebulizer, providing a larger, continuous dose. Nebulizers vaporize a dose of medication in a saline solution into a steady stream of foggy vapor that is inhaled by the patient.

Long-Term Control

Long-term control medicines are taken every day and are designed to prevent asthma symptom such as airway inflammation. Inhaled corticosteroids are the most effective long-term control medicine - the best at relieving airway inflammation and swelling. They are usually taken daily to greatly reduce the inflammation that initiates the chain reaction of the asthma attack.

Even if taken every day, inhaled corticosteroids are not habit-forming. However, the medicines do have side effects such as the mouth infection known as "thrush". Thrush occurs when the corticosteroids land in your throat or mouth. Spacers or holding chambers have been developed to help avoid this. Thrush can also be avoided by rinsing the mouth out after inhalation. 

Inhaled corticosteroids also increase the risk of cataracts (clouding of the eye's lens) and osteoporosis (weakening of the bones) if taken for long periods of time. 

There are other long-term control medicines available that doctors may prescribe. Most of them are taken by mouth and are designed to open the airways and prevent airway inflammation. Examples include inhaled long-acting B2-agonists (used with low-dose inhaled corticosteroids), leukotriene modifiers, cromolyn and nedocromil, and theophylline.

Quick-Relief Medicines

Quick-relief medicines relieve asthma symptoms when they occur. The most common of these are inhaled short-acting B2-agonists - bronchodilators that quickly relax tight muscles around the airways, allowing air to flow through them. 

The quick-relief inhaler should be used when asthma symptoms are first noticed, but should not be used more than 2 days a week. Most people carry the quick-relief inhaler with them at all times. Quick-relief medicines usually do not reduce inflammation and therefore should not be used as a replacement for long-term control medicines.

Emergency Care

 
If your medicines do not relieve an asthma attack or your peak flow is less than half of what it normally is, emergency medicine may be necessary. Call 911 or have someone take you to the emergency room if you cannot walk because you are out of breath or if you have blue lips or fingernails. 

Lifesaving treatments at the hospital will consist of direct oxygen (to alleviate hypoxia) and higher doses of medicines. Emergency personnel will likely administer a cocktail of short-acting B-2 agonists, systemic oral or intravenous steroids, other bronchodilators, nonspecific injected or inhaled B-2 agonists, anticholinergics, inhalation anesthetics, the dissociative anesthetic ketamine, and intravenous magnesium sulfate.

Intubation (a breathing tube down one's throat) and mechanical ventilation may also be used in patients undergoing respiratory arrest.
Children 

Although quick-relief medicines can relieve wheezing in young children, long-term control medicines will be used to treat infants and young children if symptoms are likely to persist after 6 years of age. 

Like adults, children are treated with inhaled corticosteroids, montelukast, or cromolyn. Often, treatments will be tried for 4 to 6 weeks and stopped if the desired outcome is not seen. Inhaled corticosteroids carry the side-effect of slowed growth, but the effect is generally small and is only apparent for the first few months of treatment.

Elderly

Elderly asthma care may require adjustments to prevent interactions between medicines. Beta blockers, aspirin, pain relievers, and anti-inflammatory medicines can prevent asthma medicines from working correctly and may worsen symptoms. In addition, it may be difficult for older persons to hold their breath for 10 seconds after inhalation of medicines, but spacers have been developed to help this issue.

The increased osteoporosis risk brought on by inhaled corticosteroids may be magnified in older adults with weak bones. It is common to take calcium and vitamin D pills, among other therapies, to keep bones healthy.

Pregnant Women

Proper asthma control is necessary for pregnant women in order to ensure a good supply of oxygen to the fetus. Babies born of asthmatic mothers have a higher chance of premature birth and lower birth weight. For pregnant women, the risks associated with having an asthma attack outweigh any risks associated with asthma medicines. 

Non-medical Treatments

Some people treat asthma using unconventional alternative therapies, but there is little formal data to support the effectiveness of these methods. There is research, however, that has found acupuncture, air ionizers, and dust mite control measures, to have little or no effect on asthma symptoms or lung function. Evidence is inconclusive to support or reject osteopathic, chiropractic, physiotherapeutic, and respiratory therapeutic techniques. Homeopathy may mildly reduce the intensity of symptoms, but this finding is not robust.

Avian Influenza

Avian influenza viruses are found chiefly in birds, but rare infections can occur in humans. Symptoms are generally mild, and include cough and sore throat, but more serious symptoms are possible. Because of concerns over a possible pandemic, researchers are currently studying ways of not only creating a vaccine against avian influenza, but also creating large quantities quickly.

What Is Avian Influenza?

Avian influenza -- commonly called "bird flu" or "avian flu" -- is an infection caused by influenza viruses that occur naturally in birds.
 

Avian Influenza in Birds

Wild birds can carry the avian influenza virus in their intestines, but usually do not get sick from it. The condition can be highly contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, sick and even kill them. Infected birds shed the virus in their saliva, nasal secretions, and feces.
 
Susceptible birds become infected when they have contact with contaminated secretions, excretions, or with surfaces that are contaminated with secretions or excretions from infected birds. Domesticated birds may become infected with avian influenza virus through:
 
Direct contact with infected waterfowl or other infected poultry 
Contact with infected surfaces (such as dirt or cages) 
Materials (such as water or feed) that have been contaminated with the virus. 
 
Infection with the avian influenza virus in domestic poultry causes two main forms of the disease that are distinguished by low and high extremes of virulence. The "low pathogenic" form may go undetected, and usually causes only mild symptoms (such as ruffled feathers and a drop in egg production). However, the highly pathogenic form spreads more rapidly through flocks of poultry. This form may cause disease that affects multiple internal organs, and has a mortality rate that can reach 90 to 100 percent, often within 48 hours.
 
One strain of avian influenza, the H5N1 virus, is endemic in much of Asia and has recently spread into Europe. Avian H5N1 infections have recently killed poultry and other birds in a number of countries.

Avian Influenza in Humans

There are many different subtypes of type A influenza viruses. These subtypes differ because of changes in certain proteins on the surface of the influenza A virus, which includes hemagglutinin (HA) and neuraminidase (NA) proteins.
 
There are 16 known HA subtypes and 9 known NA subtypes of influenza A viruses. Many different combinations of HA and NA proteins are possible. Each combination represents a different subtype, and all known subtypes of influenza A viruses can be found in birds.
 
Usually, the term "avian influenza virus" refers to influenza A viruses found chiefly in birds, but infections with these viruses can occur in humans. The risk from the disease is generally low in most people, because the viruses do not usually infect humans. However, confirmed cases of human infection from several subtypes of avian influenza infection have been reported since 1997.
 
Most cases of infection in humans have resulted from contact with infected poultry (domesticated chicken, ducks, and turkeys) or with surfaces contaminated with secretions/excretions from infected birds. The spread of the avian influenza virus from one ill person to another has been reported only rarely, and transmission has not been observed to continue beyond one person.
 
During an outbreak of avian influenza among poultry, there is a possible risk to people who have contact with infected birds or with surfaces that have been contaminated with secretions or excretions from infected birds. Avian influenza H5N1 in humans is currently limited and not a pandemic flu.
 
Human H5N1 influenza infection was first recognized in 1997, when this virus infected 18 people in Hong Kong, causing six deaths. Since 2003, more than 100 human H5N1 flu cases have been diagnosed in Thailand, Vietnam, Cambodia, Indonesia, and China. Of those cases, more than half have died as a result of avian influenza.

Pandemic Versus Seasonal Outbreak of Avian Influenza

Scientists are worried that avian influenza could become an influenza pandemic. An influenza pandemic is different from a seasonal outbreak, or epidemic, of influenza. Seasonal outbreaks are caused by subtypes of influenza viruses that already circulate among people, whereas pandemic outbreaks are caused by:
 

New subtypes 

Subtypes that have never circulated among people 
Subtypes that have not circulated among people for a long time. 
 
Past influenza pandemics have led to high levels of illness, death, social disruption, and economic loss.
 

Human Symptoms of Avian Influenza

Symptoms of avian influenza in humans have ranged from typical influenza-like symptoms (fever, cough, sore throat, and muscle aches) to eye infections, pneumonia, severe respiratory diseases (such as acute respiratory distress), and other severe and life-threatening complications. The symptoms may depend on which virus caused the infection.
 

Prevention and Treatment of Avian Influenza

Vaccines to protect humans against the H5N1 virus currently are under development. In addition, research is underway on methods to make large quantities of avian influenza vaccine more quickly. Studies done in laboratories suggest that the prescription medicines approved in the United States for human influenza viruses should work in treating avian influenza infection in humans. However, the viruses can become resistant to these drugs, so these medications may not always work. Additional studies are needed to demonstrate the effectiveness of these medicines in the long term.

Typhoid

Typhoid Fever

Typhoid fever, which is caused by the bacterium Salmonella typhi, is common in the developing world; however, only a few hundred cases occur annually in the United States. The life-threatening disease is spread when people accidentally consume the bacteria. When treatment is started early, the prognosis is good; however, 3 to 5 percent of people will continue to carry typhoid fever even after symptoms disappear.

What Is Typhoid Fever?

Typhoid fever is a life-threatening illness caused by the bacterium Salmonella typhi. In the United States, about 400 cases occur each year, and 75 percent of these are acquired while traveling internationally. Typhoid fever is still common in the developing world, where it affects about 21.5 million people each year.
 

What Causes It?

The cause of typhoid fever is an infection with the bacteria known as Salmonella typhi.
 
How Is Typhoid Fever Transmitted?
You can get typhoid fever if you eat food or drink beverages that have been handled by a person who is shedding the Salmonella typhi bacteria or if sewage contaminated with the bacteria gets into the water you use for drinking or washing food.
 

Where Is It Common?

Typhoid fever is common in most parts of the world, except in industrialized regions, such as the United States, Canada, Western Europe, Australia, and Japan. Risk is greatest within the Indian subcontinent and other developing countries in Asia, Africa, the Caribbean, and Central and South America.
 

Symptoms of Typhoid Fever

When a person becomes infected with the bacteria that cause typhoid fever, the bacteria begin to multiply and spread into the bloodstream. After 3 to 60 days, symptoms can occur. This period between becoming infected and the start of symptoms is called the incubation period.
 
Symptoms of typhoid fever vary among individuals. Some will have mild symptoms, while others could have very serious symptoms, including death.
 
Common symptoms include:
 
Fever as high as 103° to 104° F (39° to 40° C). 
Stomach pains 
Headache 
Weakness 
Bloody nose 
Loss of appetite 
Constipation 
Decreased heart rate 
Rash of flat, rose-colored spots.

How Is Typhoid Fever Diagnosed?

In order to make a typhoid fever diagnosis, your doctor will:
 
Ask a number of questions, including about your recent medical and travel history 
Perform a physical exam 
Recommend certain tests. 
 
As part of the diagnostic process, your healthcare provider will rule out conditions with similar symptoms, such as:
 
Viral hepatitis 
Mononucleosis 
Malaria. 
 

What Are the Treatment Options?

Typhoid fever treatment involves antibiotics that can kill the bacteria. Treatment is focused on providing relief of symptoms as the body and antibiotics fight the illness.
 
When appropriate treatment is started early, the prognosis is good. With proper treatment, the mortality rate is generally under 1 percent, and few complications should occur.
 

What Are Typhoid Fever Carriers?

Approximately 3 to 5 percent of people may still carry the typhoid fever bacteria, even if symptoms go away with treatment. These people are known as typhoid fever carriers. The most famous carrier was Mary Mallon, better known as Typhoid Mary. In carriers, it is possible for the illness to return or be passed on to other people.
 

Is There a Vaccine for Typhoid Fever?

One way to prevent typhoid fever is with the typhoid vaccine. There are two types of vaccines. One vaccine contains killed Salmonella typhi bacteria. This vaccine is administered by an injection (shot). The other vaccine contains a live but weakened strain of the Salmonella bacteria. This vaccine is taken by mouth.
 
It may surprise you, but watching what you eat and drink when you travel is as important as being vaccinated. This is because the typhoid vaccines are not completely effective. Avoiding risky foods will also help protect you from other illnesses, including:
 
- Travelers' diarrhea 
- Cholera 
- Dysentery 
- Hepatitis A.

Typhoid Vaccine

There are two vaccines against typhoid fever. One typhoid vaccine contains killed Salmonella typhi bacteria. The other contains a live but weakened strain of the Salmonella bacteria that causes typhoid fever. The typhoid vaccine is recommended for travelers to parts of the world where the disease is common, people in close contact with carriers of the disease, and laboratory workers who work with Salmonella typhi bacteria.

Is There a Typhoid Vaccine?

Typhoid fever is a life-threatening illness caused by the bacterium Salmonella typhi. In the United States, about 400 cases of typhoid fever occur each year, and 75 percent of these are acquired while traveling internationally. Typhoid fever is still common in the developing world, where it affects about 21.5 million people each year.
 
There are two main typhoid fever prevention strategies:
 
Getting vaccinated against typhoid fever 
Avoiding risky foods and drinks. 
 
Types of Typhoid Vaccine

There are two types of typhoid vaccines. One vaccine contains killed Salmonella typhi bacteria. This vaccine is administered through a shot. The other vaccine contains a live but weakened strain of the Salmonella bacteria that causes typhoid fever. This typhoid vaccine is taken by mouth.
 
Who Should Get the Typhoid Vaccine?

Routine vaccination against typhoid fever is not recommended in the United States, but typhoid vaccine is recommended for:
 
Travelers to parts of the world where the disease is common 
People in close contact with a typhoid carrier 
Laboratory workers who work with Salmonella typhi bacteria. 
 
How Often Should the Typhoid Vaccine Be Given?

The typhoid vaccine shot schedule varies based on the type of vaccine.
 
Inactivated Typhoid Vaccine (Shot) Schedule
For this typhoid vaccine, one dose provides protection. It should be given at least two weeks before travel to allow the vaccine time to work. A booster dose is needed every two years for people who remain at risk.
 
This typhoid vaccine should not be given to children younger than 2 years of age.


Live Typhoid Vaccine (Oral) Schedule

For this typhoid vaccine, four doses are given two days apart for each dose. The last dose should be given at least one week before travel to allow the vaccine time to work. A booster dose is needed every five years for people who remain at risk.
 
This typhoid vaccine should not be given to children younger than 6 years of age.
 
Who Should Not Get the Typhoid Vaccine?
The following groups of people should not get the typhoid vaccine:
 
Anyone who has had a severe reaction to a previous dose of typhoid vaccine should not get another dose. 
 
Anyone whose immune system is weakened should not get the oral typhoid vaccine. They should get the inactivated typhoid vaccine instead. These people include anyone who: 
o Has HIV/AIDS or another disease that affects the immune system
o Is being treated with drugs that affect the immune system, such as steroids, for two weeks or longer
 
o Has any kind of cancer
 
o Is taking cancer treatment with x-rays or drugs.

The oral typhoid vaccine should not be given within 24 hours of certain antibiotics.
 
Possible Risks of Typhoid Fever Vaccine

Getting typhoid fever is much riskier than getting the typhoid vaccine. However, just like with any medicine, there are potential risks associated with the typhoid vaccine. Most of the problems that can occur are minor, meaning that they go away without treatment or are very easily treated by a healthcare provider. The risk of the typhoid vaccine causing serious harm, or even death, however, is extremely small.

Mild Problems With the Inactivated Typhoid Vaccine (Shot) 
Mild problems that can occur with the typhoid vaccine include but are not limited to:
 
Fever (up to about 1 person per 100). 
Headache (up to about 3 people per 100). 
Redness or swelling at the site of the injection (up to 7 people per 100). 
 
Mild Problems With the Live Typhoid Vaccine (Oral)
Mild problems that can occur with the oral typhoid vaccine include but are not limited to:
 
Fever or headache (up to about 5 people per 100). 
Abdominal discomfort, nausea, vomiting, or rash (rare). 
 
Serious Problems With the Typhoid Vaccine

Serious problems can also happen with either typhoid vaccine. The risk, though, is extremely small. Symptoms that may indicate a serious problem include:
 
- High fever 
- Behavioral changes 
- Difficulty breathing 
- Hoarseness or wheezing 
- Hives 
- Paleness 
- Weakness 
- A fast heartbeat or dizziness. 
 
Call your doctor right away if any of these symptoms occur or if something "just does not feel right."
 
Typhoid Vaccine and Traveling

The typhoid vaccine is not required for international travel, but the Centers for Disease Control and Prevention (CDC) recommends it for travelers to areas where there is a recognized risk of exposure to the bacteria that causes typhoid fever. Risk is greatest for travelers to the Indian subcontinent and other developing countries in Asia, Africa, the Caribbean, and Central and South America.
 
Travelers who are visiting relatives or friends and who may be less likely to eat only safe foods (cooked and served hot) and beverages (carbonated beverages or those made from water that has been boiled) are at greater risk. Typhoid vaccine is particularly recommended for those who will be traveling in smaller cities, villages, and rural areas off the usual tourist itineraries, where food and beverage choices may be more limited.
 
Travelers have been known to acquire typhoid fever even during brief visits of less than a week to countries where the disease is prevalent. While the typhoid vaccine is recommended, travelers should be cautioned that none of the available typhoid vaccines are 100 percent effective, nor do they provide protection against other common causes of gastrointestinal infections. The typhoid vaccine is not a substitute for careful selection of food and drink.