Asbestos is a natural mineral product that's resistant to heat and corrosion. It was used extensively in the past in products such as insulation, cement and some floor tiles.

Most people with asbestosis acquired it on the job before the federal government began regulating the use of asbestos and asbestos products in the 1970s. Today, its handling is strictly regulated. Acquiring asbestosis is extremely unlikely if you follow your employer's safety procedures. Treatment focuses on relieving your symptoms.

As asbestosis progresses, more and more lung tissue becomes scarred. Eventually, your lung tissue becomes so stiff that it can't contract and expand normally.

Smoking appears to increase the retention of asbestos fibers in the lungs, and often results in a faster progression of the disease.

For some people, asthma is a minor nuisance. For others, it can be a major problem that interferes with daily activities and may lead to a life-threatening asthma attack.

Asthma can't be cured, but its symptoms can be controlled. Because asthma often changes over time, it's important that you work with your doctor to track your signs and symptoms and adjust your treatment as needed.

Exposure to various irritants and substances that trigger allergies (allergens) can trigger signs and symptoms of asthma. Asthma triggers are different from person to person and can include:

Asthma signs and symptoms include:

Signs that your asthma is probably worsening include:

For some people, asthma signs and symptoms flare up in certain situations:

See your doctor:

Proper treatment makes a big difference in preventing both short-term and long-term complications caused by asthma.

Risk of asbestosis is generally related to the amount and the duration of exposure to asbestos. The greater the exposure is, the greater the risk is of lung damage.

Secondhand exposure is possible for household members of exposed workers, as asbestos fibers may be carried home on clothing. People living close to mines may also be exposed to asbestos fibers released into the air.

In general, it's safe to be around materials that are made with asbestos as long as the asbestos fibers are contained. This prevents them from getting into the air and being inhaled.

Many homes, schools and other buildings built before the 1970s have materials such as pipes and floor tiles that contain asbestos. Generally, there's no risk of exposure as long as the asbestos is enclosed and undisturbed. It's when materials containing asbestos are damaged that there's a danger of asbestos fibers being released into the air and inhaled.

The severity of symptoms can vary widely. Some people have only a few symptoms that do not appear often, while others have wide-ranging daily symptoms.

The symptoms tend to get worse if you develop an infection in your lungs.

Your lungs are continually exposed to germs, so your body has sophisticated defence mechanisms designed to keep the lungs free of infection.

If a foreign substance (such as bacteria or a virus) gets past these defences, your immune system will attempt to stop the spread of any infection by sending white blood cells to the location of the infection.

These cells release chemicals to fight the infection, which can cause the surrounding tissue to become inflamed.

For most people, this inflammation will pass without causing any further problems.

But bronchiectasis can occur if the inflammation permanently destroys the elastic-like tissue and muscles surrounding the bronchi (airways), causing them to widen.

The abnormal bronchi then become filled with excess mucus, which can trigger persistent coughing and make the lungs more vulnerable to infection.

If the lungs become infected again, this can result in further inflammation and further widening of the bronchi.

As this cycle is repeated, the damage to the lungs gets progressively worse.

How quickly bronchiectasis progresses can vary significantly. For some people, the condition will get worse quickly, but for many the progression is slow.

Common causesIn around half of all cases of bronchiectasis, no obvious cause can be found. Some of the more common triggers that have been identified are described below.Childhood infectionsAround a third of cases of bronchiectasis in adults are associated with a severe lung infection in childhood, such as:

But as there are now vaccinations available for these infections, it's expected that childhood infections will become a less common cause of bronchiectasis in the future.

Some cases of bronchiectasis occur because a person has a weakened immune system, which makes their lungs more vulnerable to tissue damage.

The medical term for having a weakened immune system is immunodeficiency.

Some people are born with an immunodeficiency because of problems with the genes they inherit from their parents.

It's also possible to acquire an immunodeficiency after an infection such as HIV.

Some people with bronchiectasis develop the condition as a complication of an allergic condition known as allergic bronchopulmonary aspergillosis (ABPA).

People with ABPA have an allergy to a type of fungi known as aspergillus, which is found in a wide range of different environments across the world.

If a person with ABPA breathes in fungal spores, it can trigger an allergic reaction and persistent inflammation, which in turn can progress to bronchiectasis.  

Aspiration is the medical term for stomach contents accidentally passing into your lungs, rather than down into your gastrointestinal tract.

The lungs are very sensitive to the presence of foreign objects, such as small samples of food or even stomach acids, so this can trigger inflammation leading to bronchiectasis.

Cystic fibrosis is a relatively common genetic disorder, where the lungs become clogged up with mucus.

The mucus then provides an ideal environment for a bacterial infection to take place, leading to the symptoms of bronchiectasis.

Cilia are the tiny hair-like structures that line the airways in the lungs. They're designed to protect the airways and help move away any excess mucus.

Bronchiectasis can develop if there's a problem with the cilia that means they're unable to effectively clear mucus from the airways.

Conditions that can cause problems with the cilia include:

But as the regulations regarding the use of mercury are now much stricter than they were in the past, it's expected that Young's syndrome will become a much less common cause of bronchiectasis in the future.  

Certain conditions that cause inflammation in other areas of the body are sometimes associated with bronchiectasis.

These include:

These conditions are usually thought to be caused by a problem with the immune system, where it mistakenly attacks healthy tissue.

The phlegm can be clear, pale yellow or yellow-greenish in colour. Other people may only occasionally cough up small amounts of phlegm, or none at all.

Other symptoms may include:

While persistent coughing may not necessarily be the result of bronchiectasis, it requires further investigation.

If you have been diagnosed with bronchiectasis previously and begin to experience symptoms that suggest you have a lung infection, contact a GP.

You'll usually need treatment with antibiotics.

Some people with bronchiectasis are given a stock of antibiotics as a precaution in case they suddenly develop a lung infection.

Some people with bronchiectasis develop a severe lung infection that may need to be treated in hospital.Signs and symptoms of a serious lung infection include:

If you experience any of the above, phone the healthcare professional in charge of your care immediately.

This may be a GP, a doctor who specialises in lung conditions (pulmonologist), or a specialist nurse.

If this is not possible, call NHS 111 or your local out-of-hours service.

It can affect anyone at any age, but symptoms do not usually develop until middle age.

A rare, but serious, complication of bronchiectasis is coughing up large amounts of blood (the medical term for this is massive haemoptysis).This can occur when a section of one of the blood vessels supplying the lungs suddenly splits open.Symptoms that may indicate massive haemoptysis include:

Massive haemoptysis is a medical emergency. If you think someone is experiencing massive haemoptysis, call 999 for an ambulance.

A person with massive haemoptysis needs to be admitted to hospital. A tube may need to be placed into their throat to assist them with their breathing.

A procedure called a bronchial artery embolisation (BAE) will be required to stop the bleeding.

During a BAE, a special dye is injected into your arteries so they show up clearly on X-rays.

Then, using X-ray scans as a guide, the source of the bleeding is located and injected with tiny particles, around the size of a grain of sand, that will help clog the vessel up and stop the bleeding.

In most cases, treatment involves a combination of medication, exercises you can learn, and devices to help clear your airways. Surgery for bronchiectasis is rare.

There are a number of things you can do to help relieve the symptoms of bronchiectasis and stop the condition getting worse.

These include:

There are a range of exercises, known as airway clearance techniques, that can help remove mucus from your lungs. This can often help improve coughing and breathlessness in people with bronchiectasis. You can be referred to a physiotherapist, who can teach you these techniques.

The most widely used technique in the UK is called active cycle of breathing techniques (ACBT). It involves repeating a cycle made up of a number of different steps. These include a period of normal breathing, followed by deep breaths to loosen the mucus and force it up, then coughing the mucus out. The cycle is then repeated for 20 to 30 minutes. Don't attempt ACBT if you haven't first been taught the steps by a suitably trained physiotherapist, as performing the techniques incorrectly could damage your lungs. If you're otherwise in good health, you'll probably only need to perform ACBT once or twice a day. If you develop a lung infection, you may need to perform ACBT on a more frequent basis.

Changing your position can also make it easier to remove mucus from your lungs. This is known as postural drainage. Each technique can involve several complex steps, but most techniques involve leaning or lying down while the physiotherapist or a caretaker uses their hands to vibrate certain sections of your lungs as you go through a series of "huffing" and coughing.

There are also a number of handheld devices that can help remove mucus from your lungs. Although these devices look different, most work in a similar way. Generally, they use a combination of vibrations and air pressure to make it easier to cough out any mucus. Examples of these devices include the flutter, the RC cornet and the Acapella. But these devices aren't always available on the NHS, so you may have to pay for one yourself. They usually cost £45 to £60.

In some cases, medications to make breathing or clearing your lungs easier may be prescribed.

Occasionally, medication inhaled through a device called a nebulizer may be recommended to help make it easier for you to clear your lungs. Nebulizers are devices consisting of a face mask or mouthpiece, a chamber to convert the medication into a fine mist, and a compressor to pump the medication into your lungs. A number of different medications can be administered using a nebulizer, including salt water solutions. These medications help reduce the thickness of your phlegm so it's easier to cough it out. Nebulizers can also be used to administer antibiotics, if necessary. But while the medications used with a nebulizer can be provided on prescription, the nebulizer device itself isn't always available on the NHS. In some areas, a local respiratory service may provide the device without charge, but if this isn't an option, you may have to pay for a device.

If you have a particularly severe flare-up of symptoms, you may be prescribed bronchodilator medications on a short-term basis. Bronchodilators are inhaled medications that help make breathing easier by relaxing the muscles in the lungs. Examples of this type of medication include beta 2-adrenergic agonist, anticholinergics and theophylline.

If you experience a worsening of symptoms because of a bacterial infection (infective exacerbation), you'll need to be treated with antibiotics. A sample of phlegm will be taken to determine what type of bacteria is causing the infection, although you'll be initially treated with an antibiotic known to be effective against a number of different bacteria (a broad spectrum antibiotic) because it can take a few days to get the test results. Depending on the test results, you may be prescribed a different antibiotic, or in some cases a combination of antibiotics known to be effective against the specific bacteria causing the infection. If you're well enough to be treated at home, you'll probably be prescribed 2 to 3 antibiotic tablets a day for 10 to 14 days. It's important to finish the course even if you feel better, as stopping the course prematurely could cause the infection to recur quickly. If your symptoms are more severe, you may need to be admitted to hospital and treated with antibiotic injections.

If you have 3 or more infective exacerbations in any one year or your symptoms during an infective exacerbation were particularly severe, it may be recommended that you take antibiotics on a long-term basis. This can help prevent further infections and give your lungs the chance to recover. This could involve taking low-dose antibiotic tablets to minimize the risk of side effects, or using an antibiotic nebulizer. Using antibiotics in this way increases the risk that one or more types of bacteria will develop a resistance to the antibiotic. You may be asked to give regular phlegm samples to check for any resistance. If bacteria do show signs of developing a resistance, your antibiotic may need to be changed.

Surgery is usually only recommended where bronchiectasis is only affecting a single section of your lung, your symptoms aren't responding to other treatment, and you don't have an underlying condition that could cause bronchiectasis to recur. The lungs are made up of sections known as lobes – the left lung has 2 lobes and the right lung has 3 lobes. Surgery for focal bronchiectasis would usually involve removing the lobe affected by the bronchiectasis in a type of operation known as a lobectomy. Surgery won't be used if more than one lobe is affected, as it's too dangerous to remove so much lung tissue.

The most common cause of chronic bronchitis is cigarette smoking. Air pollution and dust or toxic gases in the environment or workplace also can contribute to the condition.

If you have acute bronchitis, you might have cold symptoms, such as a mild headache or body aches. While these symptoms usually improve in about a week, you may have a nagging cough that lingers for several weeks.

Chronic bronchitis is defined as a productive cough that lasts at least three months, with recurring bouts occurring for at least two consecutive years.

If you have chronic bronchitis, you're likely to have periods when your cough or other symptoms worsen. At those times, you may have an acute infection on top of chronic bronchitis.

A chronic cough is more than just an annoyance. A chronic cough can interrupt your sleep and leave you feeling exhausted. Severe cases of chronic cough can cause vomiting, lightheadedness and even rib fractures.

While it can sometimes be difficult to pinpoint the problem that's triggering a chronic cough, the most common causes are tobacco use, postnasal drip, asthma and acid reflux. Fortunately, chronic cough typically disappears once the underlying problem is treated.

However, a cough that persists for weeks is usually the result of a medical problem. In many cases, more than one cause is involved.

The following causes, alone or in combination, are responsible for the majority of cases of chronic cough:

Less commonly, chronic cough may be caused by:

Children younger than 6 are at greatest risk of colds, but healthy adults can also expect to have two or three colds annually.

Most people recover from a common cold in a week or 10 days. Symptoms might last longer in people who smoke. If symptoms don't improve, see your doctor.

A cold virus enters your body through your mouth, eyes or nose. The virus can spread through droplets in the air when someone who is sick coughs, sneezes or talks.

It also spreads by hand-to-hand contact with someone who has a cold or by sharing contaminated objects, such as utensils, towels, toys or telephones. If you touch your eyes, nose or mouth after such contact or exposure, you're likely to catch a cold.

The discharge from your nose may become thicker and yellow or green in color as a common cold runs its course. This isn't an indication of a bacterial infection.

For children — in general, your child doesn't need to see the doctor for a common cold. But seek medical attention right away if your child has any of the following:

Emphysema and chronic bronchitis are the two most common conditions that contribute to COPD. These two conditions usually occur together and can vary in severity among individuals with COPD.

Chronic bronchitis is inflammation of the lining of the bronchial tubes, which carry air to and from the air sacs (alveoli) of the lungs. It's characterized by daily cough and mucus (sputum) production.

Emphysema is a condition in which the alveoli at the end of the smallest air passages (bronchioles) of the lungs are destroyed as a result of damaging exposure to cigarette smoke and other irritating gases and particulate matter.

Although COPD is a progressive disease that gets worse over time, COPD is treatable. With proper management, most people with COPD can achieve good symptom control and quality of life, as well as reduced risk of other associated conditions.

Only some chronic smokers develop clinically apparent COPD, although many smokers with long smoking histories may develop reduced lung function. Some smokers develop less common lung conditions. They may be misdiagnosed as having COPD until a more thorough evaluation is performed.

Air travels down your windpipe (trachea) and into your lungs through two large tubes (bronchi). Inside your lungs, these tubes divide many times — like the branches of a tree — into many smaller tubes (bronchioles) that end in clusters of tiny air sacs (alveoli).

The air sacs have very thin walls full of tiny blood vessels (capillaries). The oxygen in the air you inhale passes into these blood vessels and enters your bloodstream. At the same time, carbon dioxide — a gas that is a waste product of metabolism — is exhaled.

Your lungs rely on the natural elasticity of the bronchial tubes and air sacs to force air out of your body. COPD causes them to lose their elasticity and over-expand, which leaves some air trapped in your lungs when you exhale.

Causes of airway obstruction include:

In the vast majority of people with COPD, the lung damage that leads to COPD is caused by long-term cigarette smoking. But there are likely other factors at play in the development of COPD, such as a genetic susceptibility to the disease, because not all smokers develop COPD.

Other irritants can cause COPD, including cigar smoke, secondhand smoke, pipe smoke, air pollution, and workplace exposure to dust, smoke or fumes.

In about 1% of people with COPD, the disease results from a genetic disorder that causes low levels of a protein called alpha-1-antitrypsin (AAt). AAt is made in the liver and secreted into the bloodstream to help protect the lungs. Alpha-1-antitrypsin deficiency can cause liver disease, lung disease or both.

For adults with COPD related to AAt deficiency, treatment options include those used for people with more-common types of COPD. In addition, some people can be treated by replacing the missing AAt protein, which may prevent further damage to the lungs.

Signs and symptoms of COPD may include:

People with COPD are also likely to experience episodes called exacerbations, during which their symptoms become worse than the usual day-to-day variation and persist for at least several days.

Seek immediate medical care if you can't catch your breath, if you experience severe blueness of your lips or fingernail beds (cyanosis) or a rapid heartbeat, or if you feel foggy and have trouble concentrating.

If you're a longtime smoker, these simple statements may not seem so simple, especially if you've tried quitting — once, twice or many times before. But keep trying to quit. It's critical to find a tobacco cessation program that can help you quit for good. It's your best chance for reducing damage to your lungs.

Occupational exposure to chemical fumes and dusts is another risk factor for COPD. If you work with these types of lung irritants, talk to your supervisor about the best ways to protect yourself, such as using respiratory protective equipment.

Here are some steps you can take to help prevent complications associated with COPD:

The virus is now known as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease it causes is called coronavirus disease 2019 (COVID-19). In March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a pandemic.

Public health groups, including the U.S. Centers for Disease Control and Prevention (CDC) and WHO, are monitoring the pandemic and posting updates on their websites. These groups have also issued recommendations for preventing and treating the illness.

The virus appears to spread easily among people, and more continues to be discovered over time about how it spreads. Data has shown that it spreads from person to person among those in close contact (within about 6 feet, or 2 meters). The virus spreads by respiratory droplets released when someone with the virus coughs, sneezes or talks. These droplets can be inhaled or land in the mouth or nose of a person nearby.

It can also spread if a person touches a surface with the virus on it and then touches his or her mouth, nose or eyes, although this isn't considered to be a main way it spreads.

Early symptoms of COVID-19 may include a loss of taste or smell.

Other symptoms can include:

This list is not all inclusive. Other less common symptoms have been reported, such as rash, nausea, vomiting and diarrhea. Children have similar symptoms to adults and generally have mild illness.

The severity of COVID-19 symptoms can range from very mild to severe. Some people may have only a few symptoms, and some people may have no symptoms at all. Some people may experience worsened symptoms, such as worsened shortness of breath and pneumonia, about a week after symptoms start.

People who are older have a higher risk of serious illness from COVID-19, and the risk increases with age. People who have existing chronic medical conditions also may have a higher risk of serious illness. Serious medical conditions that increase the risk of serious illness from COVID-19 include:

Other conditions may increase the risk of serious illness, such as:

This list is not all inclusive. Other underlying medical conditions may increase your risk of serious illness from COVID-19.

If you have emergency COVID-19 signs and symptoms, seek care immediately. Emergency signs and symptoms can include:

If you have signs or symptoms of COVID-19, contact your doctor or clinic for guidance. Let your doctor know if you have other chronic medical conditions, such as heart disease or lung disease. During the pandemic, it's important to make sure health care is available for those in greatest need.

Complications can include:

If you have a chronic medical condition and may have a higher risk of serious illness, check with your doctor about other ways to protect yourself.

If you're planning to travel, first check the CDC and WHO websites for updates and advice. Also look for any health advisories that may be in place where you plan to travel. You may also want to talk with your doctor if you have health conditions that make you more susceptible to respiratory infections and complications.

The cough and other signs and symptoms of croup are the result of swelling around the voice box (larynx), windpipe (trachea) and bronchial tubes (bronchi). When a cough forces air through this narrowed passageway, the swollen vocal cords produce a noise similar to a seal barking. Likewise, taking a breath often produces a high-pitched whistling sound (stridor).

Croup typically occurs in younger children. Croup usually isn't serious and most children can be treated at home.

Your child may contract a virus by breathing infected respiratory droplets coughed or sneezed into the air. Virus particles in these droplets may also survive on toys and other surfaces. If your child touches a contaminated surface and then touches his or her eyes, nose or mouth, an infection may follow.

Symptoms of croup are typically worse at night and usually last for three to five days.

Seek immediate medical attention if your child:

Only a small number of children seen in the emergency room for croup require hospitalization.

To stave off more-serious infections, keep your child's vaccinations current. The diphtheria and Haemophilus influenza type b (Hib) vaccines offer protection from some of the rarest — but most dangerous — upper airway infections. There isn't a vaccine yet that protects against parainfluenza viruses.

Cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. These secreted fluids are normally thin and slippery. But in people with CF, a defective gene causes the secretions to become sticky and thick. Instead of acting as lubricants, the secretions plug up tubes, ducts and passageways, especially in the lungs and pancreas.

Although cystic fibrosis is progressive and requires daily care, people with CF are usually able to attend school and work. They often have a better quality of life than people with CF had in previous decades. Improvements in screening and treatments mean that people with CF now may live into their mid- to late 30s or 40s, and some are living into their 50s.

Many different defects can occur in the gene. The type of gene mutation is associated with the severity of the condition.

Children need to inherit one copy of the gene from each parent in order to have the disease. If children inherit only one copy, they won't develop cystic fibrosis. However, they will be carriers and could pass the gene to their own children.

Cystic fibrosis signs and symptoms vary, depending on the severity of the disease. Even in the same person, symptoms may worsen or improve as time passes. Some people may not experience symptoms until their teenage years or adulthood. People who are not diagnosed until adulthood usually have milder disease and are more likely to have atypical symptoms, such as recurring bouts of an inflamed pancreas (pancreatitis), infertility and recurring pneumonia.

People with cystic fibrosis have a higher than normal level of salt in their sweat. Parents often can taste the salt when they kiss their children. Most of the other signs and symptoms of CF affect the respiratory system and digestive system.

The thick and sticky mucus associated with cystic fibrosis clogs the tubes that carry air in and out of your lungs. This can cause signs and symptoms such as:

The thick mucus can also block tubes that carry digestive enzymes from your pancreas to your small intestine. Without these digestive enzymes, your intestines aren't able to completely absorb the nutrients in the food you eat. The result is often:

Cystic fibrosis requires consistent, regular follow-up with your doctor, at least every three months. Contact you doctor if you experience new or worsening symptoms, such as more mucus than usual or a change in the mucus color, lack of energy, weight loss, or severe constipation.

Seek immediate medical care if you're coughing up blood, have chest pain or difficulty breathing, or have severe stomach pain and distention.

If you're already pregnant and the genetic test shows that your baby may be at risk of cystic fibrosis, your doctor can conduct additional tests on your developing child.

Genetic testing isn't for everyone. Before you decide to be tested, you should talk to a genetic counselor about the psychological impact the test results might carry.

When you exhale, the damaged alveoli don't work properly and old air becomes trapped, leaving no room for fresh, oxygen-rich air to enter.

Most people with emphysema also have chronic bronchitis. Chronic bronchitis is inflammation of the tubes that carry air to your lungs (bronchial tubes), which leads to a persistent cough.

Emphysema and chronic bronchitis are two conditions that make up chronic obstructive pulmonary disease (COPD). Smoking is the leading cause of COPD. Treatment may slow the progression of COPD, but it can't reverse the damage.

Rarely, emphysema is caused by an inherited deficiency of a protein that protects the elastic structures in the lungs. It's called alpha-1-antitrypsin deficiency emphysema.

You may start avoiding activities that cause you to be short of breath, so the symptom doesn't become a problem until it starts interfering with daily tasks. Emphysema eventually causes shortness of breath even while you're at rest.

Several types of hantaviruses can cause hantavirus pulmonary syndrome. They are carried by several types of rodents, particularly the deer mouse. You become infected primarily by breathing air infected with hantaviruses that are shed in rodent urine and droppings.

Because treatment options are limited, the best protection against hantavirus pulmonary syndrome is to avoid rodents and their habitats.

Hantaviruses are transmitted to people primarily through the aerosolization of viruses shed in infected rodents' droppings, urine or saliva. Aerosolization occurs when a virus is kicked up into the air, making it easy for you to inhale. For example, a broom used to clean up mouse droppings in an attic may nudge into the air tiny particles of feces containing hantaviruses, which you can then easily inhale.

After you inhale hantaviruses, they reach your lungs and begin to invade tiny blood vessels called capillaries, eventually causing them to leak. Your lungs then flood with fluid, which can trigger any of the respiratory problems associated with hantavirus pulmonary syndrome.

People who become infected with the North American strain of hantavirus pulmonary syndrome aren't contagious to other people. However, certain outbreaks in South America have shown evidence of being transmitted from person to person, which illustrates variation across strains in different regions.

In its early stages, hantavirus infection is difficult to distinguish from influenza, pneumonia or other viral conditions. After four to 10 days, more-serious signs and symptoms begin. They typically include:

The chance of developing hantavirus pulmonary syndrome is greater for people who work, live or play in spaces where rodents live. Factors and activities that increase the risk include:

Wet down dead rodents and areas where rodents have been with alcohol, household disinfectants or bleach. This kills the virus and helps prevent infected dust from being stirred up into the air. Once everything is wet, use a damp towel to pick up the contaminated material. Then mop or sponge the area with disinfectant.

Take special precautions, such as wearing a respirator, when cleaning buildings with heavy rodent infestations.

For most people, the flu resolves on its own. But sometimes, influenza and its complications can be deadly. People at higher risk of developing flu complications include:

Though the annual influenza vaccine isn't 100% effective, it's still your best defense against the flu.

People with the virus are likely contagious from about a day before symptoms appear until about five days after they start. Children and people with weakened immune systems may be contagious for a slightly longer time.

Influenza viruses are constantly changing, with new strains appearing regularly. If you've had influenza in the past, your body has already made antibodies to fight that specific strain of the virus. If future influenza viruses are similar to those you've encountered before, either by having the disease or by getting vaccinated, those antibodies may prevent infection or lessen its severity. But antibody levels may decline over time.

Also, antibodies against influenza viruses you've encountered in the past may not protect you from new influenza strains that can be very different viruses from what you had before.

Common signs and symptoms of the flu include:

If you have flu symptoms and are at risk of complications, see your doctor right away. Taking antiviral drugs may reduce the length of your illness and help prevent more-serious problems.

If you have emergency signs and symptoms of the flu, get medical care right away. For adults, emergency signs and symptoms can include:

Emergency signs and symptoms in children can include:

Pneumonia is one of the most serious complications. For older adults and people with a chronic illness, pneumonia can be deadly.

Flu vaccination is especially important this season because the flu and coronavirus disease 2019 (COVID-19) cause similar symptoms. Flu vaccination could reduce symptoms that might be confused with those caused by COVID-19. Preventing the flu and reducing the severity of flu illness and hospitalizations could also lessen the number of people needing to stay in the hospital.

Each year's seasonal flu vaccine provides protection from the three or four influenza viruses that are expected to be the most common during that year's flu season. This year, the vaccine will be available as an injection and as a nasal spray.

In recent years, there was concern that the nasal spray vaccine wasn't effective enough against certain types of flu. However, the nasal spray vaccine is expected to be effective in the 2020-2021 season. The nasal spray still isn't recommended for some groups, such as pregnant women, children between 2 and 4 years old with asthma or wheezing, and people who have compromised immune systems.

If you have an egg allergy, you can still get a flu vaccine.

Controlling the spread of infection

The influenza vaccine isn't 100% effective, so it's also important to take several measures to reduce the spread of infection, including:

During the COVID-19 pandemic, both COVID-19 and the flu may be spreading at the same time. Your local health department and the CDC may suggest other precautions to reduce your risk of COVID-19 or the flu. For example, you may need to practice social distancing (physical distancing) and stay at least 6 feet (2 meters) from others outside your household. You may also need to wear a cloth face mask when around people outside your household.

The scarring associated with pulmonary fibrosis can be caused by a multitude of factors. But in most cases, doctors can't pinpoint what's causing the problem. When a cause can't be found, the condition is termed idiopathic pulmonary fibrosis.

The lung damage caused by pulmonary fibrosis can't be repaired, but medications and therapies can sometimes help ease symptoms and improve quality of life. For some people, a lung transplant might be appropriate.

Long-term exposure to a number of toxins and pollutants can damage your lungs. These include:

Some people who receive radiation therapy for lung or breast cancer show signs of lung damage months or sometimes years after the initial treatment. The severity of the damage may depend on:

Many drugs can damage your lungs, especially medications such as:

Lung damage can also result from a number of conditions, including:

Many substances and conditions can lead to pulmonary fibrosis. Even so, in most cases, the cause is never found. Pulmonary fibrosis with no known cause is called idiopathic pulmonary fibrosis.

Researchers have several theories about what might trigger idiopathic pulmonary fibrosis, including viruses and exposure to tobacco smoke. Also, some forms of idiopathic pulmonary fibrosis run in families, and heredity may play a role in idiopathic pulmonary fibrosis.

Many people with idiopathic pulmonary fibrosis may also have gastroesophageal reflux disease (GERD) — a condition that occurs when acid from your stomach flows back into your esophagus. Ongoing research is evaluating if GERD may be a risk factor for idiopathic pulmonary fibrosis, or if GERD may lead to a more rapid progression of the condition. However, more research is needed to determine the association between idiopathic pulmonary fibrosis and GERD.

The course of pulmonary fibrosis — and the severity of symptoms — can vary considerably from person to person. Some people become ill very quickly with severe disease. Others have moderate symptoms that worsen more slowly, over months or years.

Some people may experience a rapid worsening of their symptoms (acute exacerbation), such as severe shortness of breath, that may last for several days to weeks. People who have acute exacerbations may be placed on a mechanical ventilator. Doctors may also prescribe antibiotics, corticosteroid medications or other medications to treat an acute exacerbation.

You may also be at risk of having or developing other conditions such as gastroesophageal reflux disease and heart disease. Gastroesophageal reflux disease affects 9 out of 10 people.

It is best to go see a doctor before things get worse.

Coping and support

Pulmonary fibrosis is a chronic, progressive disease, meaning it worsens over time. Learning more about the disease can help you and your family cope. Attending pulmonary rehabilitation can help you manage your symptoms and improve your daily functioning.

Having pulmonary fibrosis can cause fear and stress. Spend time with family and friends and let them know how they can support and help you. Talk to your doctor about your condition and how you feel. If you're depressed, your doctor may recommend you see a mental health professional.

Participating in a support group with people who have pulmonary fibrosis may be helpful. It can help to talk to other people who have had similar symptoms or treatments and discuss coping strategies.

As your condition progresses, your doctor may advise you and your family to discuss end-of-life issues and plan advance directives.

Lung cancer is the leading cause of cancer deaths worldwide.

People who smoke have the greatest risk of lung cancer, though lung cancer can also occur in people who have never smoked. The risk of lung cancer increases with the length of time and number of cigarettes you've smoked. If you quit smoking, even after smoking for many years, you can significantly reduce your chances of developing lung cancer.

Types of lung cancer

Doctors divide lung cancer into two major types based on the appearance of lung cancer cells under the microscope. Your doctor makes treatment decisions based on which major type of lung cancer you have.

The two general types of lung cancer include:

Doctors believe smoking causes lung cancer by damaging the cells that line the lungs. When you inhale cigarette smoke, which is full of cancer-causing substances (carcinogens), changes in the lung tissue begin almost immediately.

At first your body may be able to repair this damage. But with each repeated exposure, normal cells that line your lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop.

Signs and symptoms of lung cancer may include:

If you smoke and have been unable to quit, make an appointment with your doctor. Your doctor can recommend strategies for quitting smoking, such as counseling, medications and nicotine replacement products.

Risk factors for lung cancer include:

Despite the fact that the 1918 flu wasn’t isolated to one place, it became known around the world as the Spanish flu, as Spain was hit hard by the disease and was not subject to the wartime news blackouts that affected other European countries. (Even Spain's king, Alfonso XIII, reportedly contracted the flu.)

One unusual aspect of the 1918 flu was that it struck down many previously healthy, young people—a group normally resistant to this type of infectious illness—including a number of World War I servicemen.

In fact, more U.S. soldiers died from the 1918 flu than were killed in battle during the war. Forty percent of the U.S. Navy was hit with the flu, while 36 percent of the Army became ill, and troops moving around the world in crowded ships and trains helped to spread the killer virus.

Although the death toll attributed to the Spanish flu is often estimated at 20 million to 50 million victims worldwide, other estimates run as high as 100 million victims—around 3 percent of the world’s population. The exact numbers are impossible to know due to a lack of medical record-keeping in many places.

What is known, however, is that few locations were immune to the 1918 flu—in America, victims ranged from residents of major cities to those of remote Alaskan communities. Even President Woodrow Wilson reportedly contracted the flu in early 1919 while negotiating the Treaty of Versailles, which ended World War I.

However, a second, highly contagious wave of influenza appeared with a vengeance in the fall of that same year. Victims died within hours or days of developing symptoms, their skin turning blue and their lungs filling with fluid that caused them to suffocate. In just one year, 1918, the average life expectancy in America plummeted by a dozen years.

The flu was also detrimental to the economy. In the United States, businesses were forced to shut down because so many employees were sick. Basic services such as mail delivery and garbage collection were hindered due to flu-stricken workers.

In some places there weren’t enough farm workers to harvest crops. Even state and local health departments closed for business, hampering efforts to chronicle the spread of the 1918 flu and provide the public with answers about it.

St. Louis, Missouri, was different: Schools and movie theaters closed and public gatherings were banned. Consequently, the peak mortality rate in St. Louis was just one-eighth of Philadelphia’s death rate during the peak of the pandemic.

Citizens in San Francisco were fined $5—a significant sum at the time—if they were caught in public without masks and charged with disturbing the peace.

Almost 90 years later, in 2008, researchers announced they’d discovered what made the 1918 flu so deadly: A group of three genes enabled the virus to weaken a victim’s bronchial tubes and lungs and clear the way for bacterial pneumonia.

Since 1918, there have been several other influenza pandemics, although none as deadly. A flu pandemic from 1957 to 1958 killed around 2 million people worldwide, including some 70,000 people in the United States, and a pandemic from 1968 to 1969 killed approximately 1 million people, including some 34,000 Americans.

More than 12,000 Americans perished during the H1N1 (or “swine flu”) pandemic that occurred from 2009 to 2010. The novel coronavirus pandemic of 2020 is spreading around the world as countries race to find a cure for COVID-19 and citizens shelter in place in an attempt to avoid spreading the disease, which is particularly deadly because many carriers are asymptomatic for days before realizing they are infected.

Each of these modern day pandemics brings renewed interest in and attention to the Spanish Flu, or “forgotten pandemic,” so-named because its spread was overshadowed by the deadliness of WWI and covered up by news blackouts and poor record-keeping.

The best way to protect against pertussis is by getting vaccinated.

Transmission

Pertussis is a very contagious disease only found in humans. Pertussis spreads from person to person. People with pertussis usually spread the disease to another person by coughing or sneezing or when spending a lot of time near one another where you share breathing space. Many babies who get pertussis are infected by older siblings, parents, or caregivers who might not even know they have the disease.

Infected people are most contagious up to about 2 weeks after the cough begins. Antibiotics may shorten the amount of time someone is contagious.

While pertussis vaccines are the most effective tool to prevent this disease, no vaccine is 100% effective. When pertussis circulates in the community, there is a chance that a fully vaccinated person, of any age, can catch this disease. If you have gotten the pertussis vaccine but still get sick, the infection is usually not as bad.

Early Symptoms

The disease usually starts with cold-like symptoms and maybe a mild cough or fever. In babies, the cough can be minimal or not even there. Babies may have a symptom known as “apnea.” Apnea is a pause in the child’s breathing pattern. Pertussis is most dangerous for babies. About half of babies younger than 1 year who get the disease need care in the hospital. Learn more about pertussis complications.

Early symptoms can last for 1 to 2 weeks and usually include:

Pertussis in its early stages appears to be nothing more than the common cold. Therefore, healthcare professionals often do not suspect or diagnose it until the more severe symptoms appear.

Later-stage Symptoms

After 1 to 2 weeks and as the disease progresses, the traditional symptoms of pertussis may appear and include:

Pertussis can cause violent and rapid coughing, over and over, until the air is gone from your lungs. When there is no more air in the lungs, you are forced to inhale with a loud “whooping” sound. This extreme coughing can cause you to throw up and be very tired. Although you are often exhausted after a coughing fit, you usually appear fairly well in-between. Coughing fits generally become more common and bad as the illness continues, and can occur more often at night. The coughing fits can go on for up to 10 weeks or more. In China, pertussis is known as the “100 day cough.”

The “whoop” is often not there if you have milder (less serious) disease. The infection is generally milder in teens and adults, especially those who have gotten the pertussis vaccine.

Less than 1 out of 20 (5%) teens and adults with pertussis needed care in the hospital. Healthcare professionals diagnosed pneumonia (lung infection) in 1 out of 50 (2%) of those patients. The most common complications in another study were:

The best way to prevent pertussis (whooping cough) among babies, children, teens, pregnant women, and adults is to get vaccinated. Also, keep babies and other people at high risk for pertussis complications away from infected people.

Two vaccines in the United States help prevent whooping cough: DTaP and Tdap. These vaccines also provide protection against tetanus and diphtheria. Learn who needs a pertussis vaccine and when.

Infection

If your doctor confirms that you have pertussis, your body will have a natural defense (immunity) to future pertussis infections. Some observational studies suggest that pertussis infection can provide immunity for 4 to 20 years. Since this immunity fades and does not offer lifelong protection, CDC still recommends pertussis vaccination.

Antibiotics

If you or a member of your household has been diagnosed with pertussis, your doctor or local health department may recommend preventive antibiotics (medications that can help prevent diseases caused by bacteria) to other members of the household to help prevent the spread of disease. Additionally, they may recommend preventive antibiotics to some other people outside the household who have been exposed to a person with pertussis, including

Babies younger than 1 year old are most at risk for serious complications from pertussis. Pregnant women are not at increased risk for serious disease. However, experts consider those in their third trimester to be at increased risk since they could expose their newborn to pertussis. You should discuss whether or not you need preventative antibiotics with your doctor. This is especially important if there is a baby or pregnant woman in your household. It is also important if you plan to have contact with a baby or pregnant woman.

Hygiene

Like many respiratory illnesses, pertussis spreads by coughing and sneezing while in close contact with others, who then breathe in the bacteria. CDC recommends practicing good hygiene to prevent the spread of respiratory illnesses. To practice good hygiene you should:

Depending on the cause, the excess fluid may be either protein-poor (transudative) or protein-rich (exudative). These two categories help physicians determine the cause of the pleural effusion.

Certain medications, abdominal surgery and radiation therapy may also cause pleural effusions. Pleural effusion may occur with several types of cancer including lung cancer, breast cancer and lymphoma. In some cases, the fluid itself may be malignant (cancerous), or may be a direct result of chemotherapy.

Depending on the cause, the excess fluid may be either protein-poor (transudative) or protein-rich (exudative).

Pleural effusions that cannot be managed through drainage or pleural sclerosis may require surgical treatment.

The two types of surgery include:

A minimally-invasive approach that is completed through 1 to 3 small (approximately ½ -inch) incisions in the chest. Also known as thoracoscopic surgery, this procedure is effective in managing pleural effusions that are difficult to drain or recur due to malignancy. Sterile talc or an antibiotic may be inserted at the time of surgery to prevent the recurrence of fluid build-up.

A thoracotomy is performed through a 6- to 8-inch incision in the chest and is recommended for pleural effusions when infection is present. A thoracotomy is performed to remove all of the fibrous tissue and aids in evacuating the infection from the pleural space. Patients will require chest tubes for 2 days to 2 weeks after surgery to continue draining fluid.

Your surgeon will carefully evaluate you to determine the safest treatment option and will discuss the possible risks and benefits of each treatment option.

One pleural layer of tissue wraps around the outside of the lungs. The other pleural layer lines the inner chest wall. Between these two layers is a small space (pleural space) that's usually filled with a very small amount of liquid. Normally, these layers act like two pieces of smooth satin gliding past each other, allowing your lungs to expand and contract when you breathe.

If you have pleurisy, these tissues swell and become inflamed. As a result, the two layers of the pleural membrane rub against each other like two pieces of sandpaper, producing pain when you inhale and exhale. The pleuritic pain lessens or stops when you hold your breath.

Treatment of pleurisy involves pain control and treating the underlying condition.

Pain caused by pleurisy might worsen with movement of your upper body and can radiate to your shoulders or back.

Pneumonia can range in seriousness from mild to life-threatening. It is most serious for infants and young children, people older than age 65, and people with health problems or weakened immune systems.

Pneumonia is classified according to the types of germs that cause it and where you got the infection.

Community-acquired pneumonia is the most common type of pneumonia. It occurs outside of hospitals or other health care facilities. It may be caused by:

Some people catch pneumonia during a hospital stay for another illness. Hospital-acquired pneumonia can be serious because the bacteria causing it may be more resistant to antibiotics and because the people who get it are already sick. People who are on breathing machines (ventilators), often used in intensive care units, are at higher risk of this type of pneumonia.

Health care-acquired pneumonia is a bacterial infection that occurs in people who live in long-term care facilities or who receive care in outpatient clinics, including kidney dialysis centers. Like hospital-acquired pneumonia, health care-acquired pneumonia can be caused by bacteria that are more resistant to antibiotics.

Aspiration pneumonia occurs when you inhale food, drink, vomit or saliva into your lungs. Aspiration is more likely if something disturbs your normal gag reflex, such as a brain injury or swallowing problem, or excessive use of alcohol or drugs.

Signs and symptoms of pneumonia may include:

Newborns and infants may not show any sign of the infection. Or they may vomit, have a fever and cough, appear restless or tired and without energy, or have difficulty breathing and eating.

It's especially important that people in these high-risk groups see a doctor:

For some older adults and people with heart failure or chronic lung problems, pneumonia can quickly become a life-threatening condition.

Other risk factors include:

Because the clots block blood flow to the lungs, pulmonary embolism can be life-threatening. However, prompt treatment greatly reduces the risk of death. Taking measures to prevent blood clots in your legs will help protect you against pulmonary embolism.

In many cases, multiple clots are involved in pulmonary embolism. The portions of lung served by each blocked artery are robbed of blood and may die. This is known as pulmonary infarction. This makes it more difficult for your lungs to provide oxygen to the rest of your body.

Occasionally, blockages in the blood vessels are caused by substances other than blood clots, such as:

Common signs and symptoms include:

Other signs and symptoms that can occur with pulmonary embolism include:

You're at higher risk if you or any of your family members have had venous blood clots or pulmonary embolism in the past.

In addition, some medical conditions and treatments put you at risk, such as:

Blood clots are more likely to form during periods of inactivity, such as:

Pulmonary embolism can also lead to pulmonary hypertension, a condition in which the blood pressure in your lungs and in the right side of the heart is too high. When you have obstructions in the arteries inside your lungs, your heart must work harder to push blood through those vessels, which increases blood pressure and eventually weakens your heart.

In rare cases, small emboli occur frequently and develop over time, resulting in chronic pulmonary hypertension, also known as chronic thromboembolic pulmonary hypertension.

The risk of blood clots developing while traveling is low, but increases as long-haul travel increases. If you have risk factors for blood clots and you're concerned about travel, talk with your doctor.

Your doctor might suggest the following to help prevent blood clots during travel:

In one form of pulmonary hypertension, called pulmonary arterial hypertension (PAH), blood vessels in your lungs are narrowed, blocked or destroyed. The damage slows blood flow through your lungs, and blood pressure in the lung arteries rises. Your heart must work harder to pump blood through your lungs. The extra effort eventually causes your heart muscle to become weak and fail.

In some people, pulmonary hypertension slowly gets worse and can be life-threatening. Although there's no cure for some types of pulmonary hypertension, treatment can help reduce symptoms and improve your quality of life.

In your lungs, the blood releases carbon dioxide and picks up oxygen. The blood normally flows easily through blood vessels in your lungs (pulmonary arteries, capillaries and veins) to the left side of your heart.

However, changes in the cells that line your pulmonary arteries can cause the walls of the arteries to become stiff, swollen and thick. These changes may slow down or block blood flow through the lungs, causing pulmonary hypertension.

Pulmonary hypertension is classified into five groups, depending on the cause.

Causes include:

Causes include:

Causes include:

Causes include:

Causes include:

Eisenmenger syndrome is a type of congenital heart disease that causes pulmonary hypertension. It's most commonly caused by a large hole in your heart between the two lower heart chambers (ventricles), called a ventricular septal defect.

This hole in your heart causes blood to flow incorrectly in your heart. Oxygen-carrying blood (red blood) mixes with oxygen-poor blood (blue blood). The blood then returns to your lungs — instead of going to the rest of your body — increasing the pressure in the pulmonary arteries and causing pulmonary hypertension.

Pulmonary hypertension symptoms include:

Other things that can raise your risk of pulmonary hypertension include:

In adults and older, healthy children, RSV symptoms are mild and typically mimic the common cold. Self-care measures are usually all that's needed to relieve any discomfort.

RSV can cause severe infection in some people, especially premature babies, older adults, infants and adults with heart and lung disease, or anyone with a very weak immune system (immunocompromised).

The virus can live for hours on hard objects such as countertops, crib rails and toys. Touch your mouth, nose or eyes after touching a contaminated object and you're likely to pick up the virus.

An infected person is most contagious in the first few days after infection. However, the virus may continue to spread for up to a few weeks.

Respiratory syncytial virus infection can spread to the lower respiratory tract, causing pneumonia or bronchiolitis — inflammation of the small airway passages entering the lungs. Signs and symptoms may include:

Infants are most severely affected by RSV. You may notice your child's chest muscles and skin pull inward with each breath. This is a sign that he or she is struggling to breathe. Other signs and symptoms of severe RSV infection in infants include:

Most children and adults recover in one to two weeks, although some might have repeated wheezing. Severe or life-threatening infection requiring a hospital stay may occur in premature babies or infants and adults who have chronic heart or lung problems.

People at increased risk of severe or sometimes life-threatening RSV infections include:

The medication palivizumab (Synagis) can help protect certain children who are at high risk of serious complications of RSV. The medication is recommended for infants under age 1 who were born prematurely (before 29 weeks gestation). It's not recommended for healthy preemies born after 29 weeks.

The medication is also recommended for the following children:

The medication is given monthly for five months during peak RSV season. It only helps prevent RSV infection. It doesn't help treat it once symptoms develop.

Scientists are working to find a nasal-spray vaccine to protect against the respiratory syncytial virus.

The cause of sarcoidosis is unknown, but experts think it results from the body's immune system responding to an unknown substance. Some research suggests that infectious agents, chemicals, dust and a potential abnormal reaction to the body's own proteins (self-proteins) could be responsible for the formation of granulomas in people who are genetically predisposed.

There is no cure for sarcoidosis, but most people do very well with no treatment or only modest treatment. In some cases, sarcoidosis goes away on its own. However, sarcoidosis may last for years and may cause organ damage.

This triggers an overreaction of your immune system, and immune cells begin to collect in a pattern of inflammation called granulomas. As granulomas build up in an organ, the function of that organ can be affected.

Sarcoidosis can begin with these signs and symptoms:

Sarcoidosis most often affects the lungs and may cause lung problems, such as:

Sarcoidosis may cause skin problems, which may include:

Sarcoidosis can affect the eyes without causing any symptoms, so it's important to have your eyes checked regularly. When eye signs and symptoms do occur, they may include:

Heart symptoms

Signs and symptoms related to cardiac sarcoidosis may include:

Sarcoidosis can also affect calcium metabolism, the nervous system, the liver and spleen, muscles, bones and joints, the kidneys, lymph nodes, or any other organ.

Coping and support

Although sarcoidosis may go away by itself, some people's lives are forever altered by the disease. If you're having trouble coping, consider talking with a counselor. Participating in a sarcoidosis support group may also be helpful.

Although the cause is unknown, it appears that SIDS might be associated with defects in the portion of an infant's brain that controls breathing and arousal from sleep.

Researchers have discovered some factors that might put babies at extra risk. They've also identified measures you can take to help protect your child from SIDS. Perhaps the most important is placing your baby on his or her back to sleep.

Physical factors associated with SIDS include:

The items in a baby's crib and his or her sleeping position can combine with a baby's physical problems to increase the risk of SIDS. Examples include:

During pregnancy, the mother also affects her baby's risk of SIDS, especially if she:

The main types of sleep apnea are:

If you think you might have sleep apnea, see your doctor. Treatment can ease your symptoms and might help prevent heart problems and other complications.

When the muscles relax, your airway narrows or closes as you breathe in. You can't get enough air, which can lower the oxygen level in your blood. Your brain senses your inability to breathe and briefly rouses you from sleep so that you can reopen your airway. This awakening is usually so brief that you don't remember it.

You might snort, choke or gasp. This pattern can repeat itself five to 30 times or more each hour, all night, impairing your ability to reach the deep, restful phases of sleep.

This less common form of sleep apnea occurs when your brain fails to transmit signals to your breathing muscles. This means that you make no effort to breathe for a short period. You might awaken with shortness of breath or have a difficult time getting to sleep or staying asleep.

Factors that increase the risk of this form of sleep apnea include:

Risk factors for this form of sleep apnea include:

Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS. HIV weakens a person's immune system so it can't fight the TB germs. In the United States, because of stronger control programs, tuberculosis began to decrease again in 1993, but remains a concern.

Many strains of tuberculosis resist the drugs most used to treat the disease. People with active tuberculosis must take several types of medications for many months to eradicate the infection and prevent development of antibiotic resistance.

Although tuberculosis is contagious, it's not easy to catch. You're much more likely to get tuberculosis from someone you live with or work with than from a stranger. Most people with active TB who've had appropriate drug treatment for at least two weeks are no longer contagious.

Since the 1980s, the number of cases of tuberculosis has increased dramatically because of the spread of HIV, the virus that causes AIDS. Infection with HIV suppresses the immune system, making it difficult for the body to control TB bacteria. As a result, people with HIV are many times more likely to get TB and to progress from latent to active disease than are people who aren't HIV positive.

Another reason tuberculosis remains a major killer is the increase in drug-resistant strains of the bacterium. Since the first antibiotics were used to fight tuberculosis more than 60 years ago, some TB germs have developed the ability to survive despite medications, and that ability gets passed on to their descendants.

Drug-resistant strains of tuberculosis emerge when an antibiotic fails to kill all of the bacteria it targets. The surviving bacteria become resistant to that particular drug and frequently other antibiotics as well. Some TB bacteria have developed resistance to the most commonly used treatments, such as isoniazid and rifampin.

Some strains of TB have also developed resistance to drugs less commonly used in TB treatment, such as the antibiotics known as fluoroquinolones, and injectable medications including amikacin and capreomycin (Capastat). These medications are often used to treat infections that are resistant to the more commonly used drugs.

Signs and symptoms of active TB include:

Tuberculosis can also affect other parts of your body, including your kidneys, spine or brain. When TB occurs outside your lungs, signs and symptoms vary according to the organs involved. For example, tuberculosis of the spine may give you back pain, and tuberculosis in your kidneys might cause blood in your urine.

The Centers for Disease Control and Prevention recommends that people who have an increased risk of tuberculosis be screened for latent TB infection. This recommendation includes people who:

A healthy immune system often successfully fights TB bacteria, but your body can't mount an effective defense if your resistance is low. A number of diseases, conditions and medications can weaken your immune system, including:

The risk of contracting tuberculosis is higher for people who live in or travel to areas that have high rates of tuberculosis and drug-resistant tuberculosis, including:

If you have active TB, keep your germs to yourself. It generally takes a few weeks of treatment with TB medications before you're not contagious anymore. Follow these tips to help keep your friends and family from getting sick:

This is the most important step you can take to protect yourself and others from tuberculosis. When you stop treatment early or skip doses, TB bacteria have a chance to develop mutations that allow them to survive the most potent TB drugs. The resulting drug-resistant strains are much more deadly and difficult to treat.

In countries where tuberculosis is more common, infants often are vaccinated with bacillus Calmette-Guerin (BCG) vaccine because it can prevent severe tuberculosis in children. The BCG vaccine isn't recommended for general use in the United States because it isn't very effective in adults. Dozens of new TB vaccines are in various stages of development and testing.

Like other types of asthma, occupational asthma can cause chest tightness, wheezing and shortness of breath. People with allergies or with a family history of allergies are more likely to develop occupational asthma.

Avoidance of occupational triggers is an important part of management. Otherwise, treatment for occupational asthma is similar to treatment for other types of asthma and generally includes taking medications to reduce symptoms. If you already have asthma, sometimes treatment can help it from becoming worse in the workplace.

If it's not correctly diagnosed and you are not protected or able to avoid exposure, occupational asthma can cause permanent lung damage, disability or death.

Asthma symptoms start when your lungs become irritated (inflamed). Inflammation causes several reactions that restrict the airways, making breathing difficult. With occupational asthma, lung inflammation may be triggered by an allergic response to a substance, which usually develops over time. Alternatively, inhaling fumes from a lung irritant, such as chlorine, can trigger immediate asthma symptoms in the absence of allergy.

Other possible accompanying signs and symptoms may include:

Occupational asthma symptoms depend on the substance you're exposed to, how long and how often you're exposed, and other factors. Your symptoms may:

Make an appointment to see a doctor if you have breathing problems, such as coughing, wheezing or shortness of breath. Breathing problems may be a sign of asthma, especially if symptoms seem to be getting worse over time or appear to be aggravated by specific triggers or irritants.

It's possible to develop occupational asthma in almost any workplace. But your risk is higher if you work in certain occupations.

Although you may rely on medications to relieve symptoms and control inflammation associated with occupational asthma, you can do several things on your own to maintain overall health and lessen the possibility of attacks:

If you are in the United States and you have a job in a high-risk profession, your company has legal responsibilities to help protect you from hazardous chemicals. Under guidelines established by the Occupational Safety and Health Administration (OSHA), your employer is required to do the following:

Under OSHA guidelines, your employer is required to keep a material safety data sheet (MSDS) for each hazardous chemical used in your workplace. This is a document that must be submitted by the chemical's manufacturer to your employer. You have a legal right to see and copy such documents. If you suspect you're allergic to a certain substance, show the MSDS to your doctor.

While at work, be alert for unsafe and unhealthy working conditions and report them to your supervisor. If necessary, call OSHA at 800-321-OSHA (800-321-6742) and ask for an on-site inspection. You can do this so that your name won't be revealed to your employer.