Severe acute respiratory syndrome (SARS)

Answer 1

Alternative Names

SARS

Definition

Severe acute respiratory syndrome (SARS) is a serious form of pneumonia, caused by a virus isolated in 2003. Infection with the SARS virus results in acute respiratory distress (severe breathing diffculty) and sometimes death. It is a dramatic example of how quickly world travel can spread a disease. It is also an example of how quickly a networked health system can respond to an emerging threat.

Background Information:

This contagious respiratory infection was first described on Feb. 26, 2003. SARS was identified as a new disease by World Health Organization (WHO) physician Dr. Carlo Urbani. He diagnosed it in a 48-year-old businessman who had traveled from the Guangdong province of China, through Hong Kong, to Hanoi, Vietnam. The businessman died from the illness. Dr. Urbani subsequently died from SARS on March 29, 2003, at the age of 46.

In the meantime, SARS was spreading, and within 6 weeks of its discovery, it had infected thousands of people around the world, including people in Asia, Australia, Europe, Africa, and North and South America. Schools had closed throughout Hong Kong and Singapore. National economies were affected.

The WHO had identified SARS as a global health threat, and issued an unprecedented travel advisory. Daily WHO updates tracked the spread of SARS seven days a week. It wasn't clear whether SARS would become a global pandemic, or would settle into a less aggressive pattern.

The rapid, global public health response helped to stem the spread of the virus, and by June 2003, the epidemic had subsided to the degree that on June 7 the WHO backed off from its daily reports. Nevertheless, even as the number of new cases dwindled, and travel advisories began to be lifted, the sober truth remained: every new case had the potential to spark another outbreak. SARS appears to be here to stay, and to have changed the way that the world responds to Infectious Diseases in the era of widespread international travel.

Causes, incidence, and risk factors

SARS is caused by a member of the coronavirus family (the same family that can cause the common cold).

When someone with SARS coughs or sneezes, infected droplets spray into the air. You can catch SARS if you breathe in or touch these particles. The SARS virus may live on hands, tissues, and other surfaces for up to 6 hours in these droplets and up to 3 hours after the droplets have dried.

While droplet transmission through close contact was responsible for most of the early cases of SARS, evidence began to mount that SARS might also spread by hands and other objects the droplets had touched. Airborne transmission was a real possibility in some cases. Live virus had even been found in the stool of people with SARS, where it has been shown to live for up to four days. And the virus may be able to live for months or years when the temperature is below freezing.

With other coronaviruses, re-infection (becoming infected and falling ill again) is common. Preliminary reports suggest that this may also be the case with SARS.

Symptoms usually occur about 2 to 10 days after coming in contact with the virus, although there have been some cases where the illness started considerably sooner or later. Those with active symptoms of illness are clearly contagious, but it is not known how long a person may be contagious before or after symptoms are present.

Symptoms

The hallmark symptoms are fever greater than 100.4 degrees F (38.0 degrees C) and cough, difficulty breathing, or other respiratory symptoms. Symptoms in the order of how commonly they appeared have included:

• Fever
• Chills and shaking
• Muscle aches
• Cough
• Headache

Less common symptoms include (also in order):

• Dizziness
• Productive cough (sputum)
• Sore throat
• Runny nose
• Nausea and vomiting
• Diarrhea

Signs and tests

Your health care provider may hear abnormal lung sounds while listening to the chest with a stethoscope. In most persons with SARS, worsening chest x-ray or chest CT changes show the presence of pneumonia or respiratory distress syndrome.

Tests tests used to diagnose SARS might include:

• Blood clotting tests
• Blood chemistries
  • ALT and CPK are sometimes elevated.
  • LDH levels are often elevated.
  • Sodium and potassium are sometimes low.
• Chest x-ray or chest CT scan
• Complete blood count (CBC)
  • White blood cell (WBC) count may be low.
  • Lymphocyte count may be low.
  • Platelet countmay be low.

Much attention was given early in the outbreak to developing a quick, sensitive test for SARS. Specific tests include the PCR test for SARS virus, antibody tests for SARS, and direct SARS virus isolation. All current tests have some limitations.

Treatment

Persons suspected of having SARS should be evaluated immediately by a health care provider, and hospitalized under isolation if they meet the definition of a suspected or probable case.

Treatment may include:

• Antibiotics to treat bacterial causes of atypical pneumonia
• Antiviral medications
• High doses of steroids to reduce lung inflammation
• Oxygen, breathing support (mechanical ventilation), or chest physiotherapy

In some serious cases, blood serum from people who have already recovered from SARS has been given. There is no strong evidence that these treatments work well.

Expectations (prognosis)

As the first wave of SARS began to subside, the Death Rate proved to have been about 14 or 15 percent of those diagnosed. In people over age 65, the death rate was higher than 50 percent. Many more were sick enough to require mechanical ventilation. And more still were sick enough to require hospitalization in intensive care units.

Intensive public health policies are proving to be effective in controlling outbreaks. Many nations have stopped the epidemic within their own countries. All nations must be vigilant, however, to keep this disease under control. Viruses in the coronavirus family are known for their ability to change (mutate) in order to better spread among humans.

Complications

• Respiratory failure
• Liver failure
• Heart failure

Calling your health care provider

Call your health care provider if you suspect you or someone you have had close contact with has SARS.

Prevention

Reducing your contact with someone with SARS lowers the risk for the disease. Ways to do this may include limiting travel to locations where there is an uncontrolled outbreak. When possible, avoid direct contact with persons who have SARS for at least 10 days after their fever and other symptoms are gone.

The U.S. Centers for Disease Control and Prevention (CDC) says hand hygiene is the most important part of SARS prevention. This might include hand washing or cleaning hands with an alcohol-based instant hand sanitizer.

Persons should be taught to cover the mouth and nose when sneezing or coughing. Respiratory secretions should be considered infectious, which means no sharing of food, drink, or utensils. Commonly touched surfaces can be cleaned with an EPA approved disinfectant.

In some situations, appropriate masks and goggles may be useful for preventing spread of the disease. Gloves might be used in handling potentially infectious secretions.

References

Vijayanand P, Wilkins E, Woodhead M. Severe acute respiratory syndrome (SARS): a review. Clin Med. 2004 Mar-Apr;4(2):152-60.

Ng EK, Lo YM. Molecular diagnosis of severe acute respiratory syndrome. Methods Mol Biol. 2006;336:163-75.

Answer 2

Alternative Names

SARS

Definition

Severe acute respiratory syndrome (SARS) is a serious form of pneumonia. It is caused by a virus that was first identified in 2003. Infection with the SARS virus causes acute respiratory distress (severe breathing difficulty) and sometimes death.

SARS is a dramatic example of how quickly world travel can spread a disease. It is also an example of how quickly a connected health system can respond to a new health threat.

Background Information:

World Health Organization (WHO) physician Dr. Carlo Urbani identified SARS as a new disease in 2003. He diagnosed it in a 48-year-old businessman who had traveled from the Guangdong province of China, through Hong Kong, to Hanoi, Vietnam. The businessman and the Doctor Who first diagnosed SARS both died from the illness.

In the meantime, SARS was spreading. Quickly it infected thousands of people around the world, including people in Asia, Australia, Europe, Africa, and North and South America. Schools closed throughout Hong Kong and Singapore. National economies were affected.

The WHO identified SARS as a global health threat, and issued a travel advisory. WHO updates closely tracked the spread of SARS. It wasn't clear whether SARS would become a global pandemic.

The fast global public health response helped to stem the spread of the virus. By June 2003, the number of new cases was down enough that on June 7, the WHO stopped its daily reports. But even though the number of new cases dwindled and travel advisories began to be lifted, every new case had the potential to spark another outbreak.

SARS appears to be here to stay. It has changed the way that the world responds to infectious diseases during a time of widespread international travel. The 2003 outbreak had an estimated 8,000 cases and 750 deaths.

Causes, incidence, and risk factors

SARS is caused by a member of the coronavirus family of viruses (the same family that can cause the common cold). It is believed the 2003 epidemic started when the virus spread from small mammals in China.

When someone with SARS coughs or sneezes, infected droplets spray into the air. You can catch the SARS virus if you breathe in or touch these particles. The SARS virus may live on hands, tissues, and other surfaces for up to 6 hours in these droplets and up to 3 hours after the droplets have dried.

While the spread of droplets through close contact caused most of the early SARS cases, SARS might also spread by hands and other objects the droplets has touched. Airborne transmission is a real possibility in some cases. Live virus has even been found in the stool of people with SARS, where it has been shown to live for up to 4 days. The virus may be able to live for months or years when the temperature is below freezing.

With other coronaviruses, becoming infected and then getting sick again (re-infection) is common. This may also be the case with SARS.

Symptoms usually occur about 2 to 10 days after coming in contact with the virus. There have been some cases where the illness started sooner or later after first contact. People with active symptoms of illness are contagious, but it is not known for how long a person may be contagious before or after symptoms appear.

Symptoms

The hallmark symptoms are:

• Cough
• Difficulty breathing
• Fever greater than 100.4 degrees F (38.0 degrees C)
• Other breathing symptoms

The most common symptoms are:

• Chills and shaking
• Cough -- usually starts 2-3 days after other symptoms
• Fever
• Headache
• Muscle aches

Less common symptoms include:

• Cough that produces phlegm (sputum)
• Diarrhea
• Dizziness
• Nausea and vomiting
• Runny nose
• Sore throat

In some people, the lung symptoms get worse during the second week of illness, even after the fever has stopped.

Signs and tests

Your health care provider may hear abnormal lung sounds while listening to your chest with a stethoscope. In most people with SARS, changes on a chest x-ray or chest CT show pneumonia, which is typical with SARS.

Tests used to diagnose SARS might include:

• Blood clotting tests
• Blood chemistry tests
• Chest x-ray or chest CT scan
• Complete blood count (CBC)

Tests used to quickly identify the virus that causes SARS include:

• Antibody tests for SARS
• Direct isolation of the SARS virus
• Rapid polymerase chain reaction (PCR) test for SARS virus

All current tests have some limitations. They may not be able to easily identify a SARS case during the first week of the illness, when it is most important.

Treatment

People who are thought to have SARS should be checked right away by a health care provider. If they are suspected of having SARS, they should be kept isolated in the hospital.

Treatment may include:

• Antibiotics to treat bacteria that cause pneumonia
• Antiviral medications
• High doses of steroids to reduce swelling in the lungs
• Oxygen, breathing support (mechanical ventilation), or chest therapy

In some serious cases, the liquid part of blood from people who have already recovered from SARS has been given as a treatment.

There is no strong evidence that these treatments work well. There is evidence that the antiviral medication, ribavirin, does not work.

Expectations (prognosis)

The death rate from SARS was 9 to 12% of those diagnosed. In people over age 65, the death rate was higher than 50%. The illness was milder in younger patients.

Many more people became sick enough to need breathing assistance. And even more people had to go to hospital intensive care units.

Public health policies have been effective at controlling outbreaks. Many nations have stopped the epidemic in their own countries. All countries must continue to be careful to keep this disease under control. Viruses in the coronavirus family are known for their ability to change (mutate) in order to spread among humans.

Complications

• Respiratory failure
• Liver failure
• Heart failure

Calling your health care provider

Call your health care provider if you or someone you have been in close contact with has SARS.

Prevention

Reducing your contact with people who have SARS lowers your risk for the disease. Avoid travel to places where there is an uncontrolled SARS outbreak. When possible, avoid direct contact with persons who have SARS until at least 10 days after their fever and other symptoms are gone.

• Hand hygiene is the most important part of SARS prevention. Wash your hands or clean them with an alcohol-based instant hand sanitizer.
• Cover your mouth and nose when you sneeze or cough. Droplets that are released when a person sneezes or coughs are infectious.
• Do not share food, drink, or utensils.
• Clean commonly touched surfaces with an EPA-approved disinfectant.

In some situations, masks and goggles may be useful for preventing the spread of the disease. You may use gloves when handling any items that may have touched infected droplets.

References

Anderson LJ. Coronaviruses. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 389.

McIntosh K, Perlman S. Coronaviruses including severe acute respiratory distress syndrome (SARS)-associated coronavirus. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Disease. 7th ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 155.

Reviewed By

Review Date: 02/19/2011

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.