| Sars
ust some facts to enhance our knowledge about the dreaded disease SARS.
SARS
Overview
Severe acute respiratory syndrome (SARS) — a contagious and sometimes fatal respiratory illness — first appeared in China in November 2002. It became the first newly emerged, serious and contagious illness of the 21st century.
The rapid and unexpected spread of SARS alarmed both health officials and the public. The emergence of SARS illustrates just how quickly infection can proliferate in a highly mobile and interconnected world.
SARS is particularly troubling because health experts know so little about it. Scientists do know that the cause is a new type of coronavirus — one of a family of viruses that in humans usually causes mild upper respiratory infections, including common colds. How the new coronavirus evolved or why it turned deadly isn't known, though this family of viruses is known for its ability to evolve. Nor is it clear why some people succumb to the disease and others recover. Although many who died were older adults with other health problems, SARS has also proved fatal in healthy, young adults. Adding to the uncertainty is that the signs and symptoms are similar to those of other respiratory illnesses.
Although SARS was contained in the months after its emergence, additional cases later emerged. The sense of concern surrounding SARS remains because as yet there's no known treatment.
Signs and symptoms
SARS often resembles pneumonia or influenza with signs and symptoms that include:
Fever — a measured temperature of 100.4 F (38.0 C) or higher that may be accompanied by chills
Headache
General feeling of discomfort (malaise)
Body aches
Dry, nonproductive cough
Signs and symptoms that usually occur with colds, such as sneezing and a runny nose, often don't occur in people with SARS.
SARS begins with a fever that usually occurs two to seven days after you've been infected, although signs and symptoms sometimes may not appear for up to 10 days. Chills, headache, muscle soreness and a general feeling of discomfort also are common. Two to seven days later, you're likely to develop a dry cough. SARS may progress to severe pneumonia, leading to an insufficient amount of oxygen in your blood (hypoxemia).
You're probably most contagious while you have active signs and symptoms. It's unclear whether you can transmit the disease to others before your signs and symptoms begin or after they've disappeared. As a precaution, the Centers for Disease Control and Prevention (CDC) recommends that people who have recovered from SARS refrain from going out in public for 10 days after symptoms go away.
Pneumonia
Influenza (Flu)
Fever
Causes
As soon as the first case of SARS was identified in mid-February 2003, scientists began searching for the cause. Early findings suggested a type of coronavirus, viruses that normally cause mild respiratory problems, including the common cold.
This theory was borne out in April 2003 when researchers discovered an entirely new strain of coronavirus in people diagnosed with SARS. Coronaviruses are a group of viruses that have distinctive crown-like spikes when viewed with an electron microscope. Until now, these viruses have never been particularly virulent in humans, although they've been linked to pneumonia in people with weakened immune systems. And they can cause severe illnesses in animals. For that reason, scientists speculated that the SARS virus might have crossed from animals to humans, but it now seems likely that it evolved from one or more animal viruses into a completely new strain.
This theory got a boost when Canadian and CDC scientists sequenced the entire genome of the suspected SARS virus. Both teams reported that the genome is unique and unrelated to any known human or animal viruses.
How SARS spreads
Most respiratory illnesses, such as colds and influenza, spread through droplets that enter the air when someone with the disease coughs or sneezes. This type of transmission can occur in two ways:
a. Droplets. In droplet transmission, the infected particles are large and can travel only about three feet. To inhale them, you literally must be face to face with someone who's sick.
b. Airborne particles. Because airborne particles are much smaller than droplets, they travel farther and linger longer in the air. As a result, you can become infected even after the person who coughed or sneezed has left the room.
Most experts think SARS spreads mainly through face-to-face contact, but unusual patterns of transmission have caused them to look for additional explanations. It now seems likely that the virus can also spread through contact with contaminated objects, including doorknobs, telephones and elevator buttons, and because some people seem to have acquired the infection on airplanes, health officials think airborne transmission may be a possibility.
As the illness progressed, health officials in China suspected numerous causes of the disease, including cockroaches, flies, mosquitoes or rats. What's more likely is that the SARS virus, which has been found in the stool of some patients, can spread in contaminated sewage. In fact, the World Health Organization (WHO) issued a press release in September 2003 that said inadequate plumbing may have played a role in the Hong Kong SARS outbreak.
Disease specialists are also debating whether some people with SARS, dubbed "superspreaders," might be more contagious than most people. Health experts suspect superspreaders of transmitting the illness to unusually large numbers of people.
Common cold
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Risk factors
In general, you're at greatest risk of SARS if you've had direct, close contact with someone who's infected, such as a roommate or family member.
Doctors and hospital workers who treated SARS patients before the disease was identified were some of the first SARS casualties. But stringent guidelines — including the use of gowns, gloves, goggles and special masks, which block nonoily, solid and liquid particles — are now in place to help protect health care professionals from infection.
Researchers also have identified a variation in an immune system gene that may make people with the variation much more vulnerable to the SARS virus. The genetic variation is common among people of Southeastern Asian descent but is rare in other populations, which may help explain why most SARS cases have occurred in China and Southeast Asia.
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When to seek medical advice
If you've had close contact with someone who has SARS or who may be at risk of having SARS, the CDC suggests you monitor your health for at least 10 days. See your doctor if you develop a cough and fever during that time interval.
Screening and diagnosis
When SARS first surfaced, no specific tests were available to help doctors diagnose the disease. Now, however, several laboratory tests can help detect the virus. These include:
Reverse transcription polymerase chain reaction test. This has become an indispensable tool for detecting the cause of many infectious diseases. Using secretions from your nose or a blood or stool sample, scientists look for the DNA of a suspected pathogen. One study has also suggested that the virus may be present in tears, and detectable through reverse transcription polymerase chain reaction.
Serologic test. This checks a sample of your blood for the presence of antibodies to SARS-associated coronavirus. Antibodies are substances that your immune system produces to fight a specific infection.
Viral culture. In this test, a small sample of tissue or fluid is placed on a special medium (culture) that's incubated for a period of time and then checked for the presence of the SARS virus.
Complications
Between 10 percent and 20 percent of people with SARS become progressively worse and develop such severe breathing problems that they need the help of a mechanical respirator. SARS is fatal in some cases, often due to respiratory failure. Other possible complications include heart and liver failure.
Treatment
In spite of a concerted global effort, scientists have yet to find an effective treatment for SARS. Initially, people with SARS were treated with antibiotics. Once it became clear that SARS was a viral infection, doctors switched to antiviral medications such as ribavirin and oseltamivir, sometimes in combination with steroids — a treatment that wasn't always helpful.
But another combination of antiviral drugs commonly used to treat AIDS — lopinavir-ritonavir along with ribavirin — has been shown in clinical studies to prevent serious complications and deaths from SARS. Further testing is needed before these drugs are recommended for use in people with SARS.
Prevention
Even as researchers refine diagnostic tests for SARS and search for effective treatments, the main emphasis remains on preventing new cases from developing. The National Institute of Allergy and Infectious Disease reported that researchers are working on several types of vaccines for SARS. However, until an effective vaccine is developed — if ever — the WHO and the CDC have established a number of guidelines aimed at stopping transmission of the disease.
Protecting yourself
If you're caring for someone at home with SARS, these measures can help you stay healthy:
1. Wash your hands frequently with soap and hot water or use an alcohol-based hand rub.
2. Instead of touching your face with your hands, use a disposable tissue to rub your eyes or nose.
3. Wear disposable gloves if you have contact with the patient's body fluids or feces. Throw the gloves away immediately after use and wash your hands thoroughly.
4. Wear a surgical mask when you're in the same room as a person with SARS. Wearing glasses also may offer some protection.
5.Use soap and hot water to wash the silverware, towels, bedding and clothing of someone with SARS, and don't use these items yourself until they're clean.
6. Use a household disinfectant to clean any surfaces that may have been contaminated with sweat, saliva or mucus, or even vomit, stool or urine. Wear disposable gloves while you clean and throw the gloves away when you're done.
7. Follow all precautions for at least 10 days after the person's signs and symptoms have disappeared.
8. Keep children home from school if they develop a fever or respiratory symptoms within 10 days of being exposed to someone with SARS. They can return to school if symptoms abate after three days. Children who have been exposed but don't have symptoms can attend school, but watch their health closely.
9. Call your doctor immediately if you develop a fever or respiratory symptoms. Be sure to let him or her know that you've had close contact with someone with SARS.
Protecting others
If you've been diagnosed with SARS, the following measures can help prevent you from infecting others:
1.Wash your hands carefully and frequently with soap and hot water or an alcohol-based hand rub.
2. Cover your mouth and nose with a tissue when you cough or sneeze, and if possible, wear a surgical mask when you're in close contact with other people.
3. Don't share your silverware, towels or bedding with anyone in your home until these items have been thoroughly washed with soap and hot water.
4. Avoid going to school, work or other public places for 10 days after your signs and symptoms disappear.
Traveling safely
Although there are no longer any SARS-related travel restrictions, it's always wise to take certain precautions when you travel. The following measures can help ensure you have a safe trip:
Before you leave
1. Buy or assemble a basic first-aid kit. Make sure the kit includes an alcohol-based hand cleanser.
2. Inform yourself. Learn as much as you can about the SARS status of the countries you'll visit. You can find the latest information about SARS on the CDC's or WHO's Web site.
3. Make sure you're current on all of your immunizations. It's best to have any needed shots four to six weeks before your departure.
4. Check your travel insurance. You may want to purchase coverage for medical evacuation if you're traveling to a country that's having a SARS or other infectious disease outbreak.
5. Know where medical care will be available in the areas you visit. Take with you a list of the names, addresses and phone numbers of recommended English-speaking doctors and hospitals at your destinations. Your doctor or local or state medical society, the International Association for Medical Assistance to Travellers or the State Department's Overseas Citizens Services can help you develop your list.
6. In China, avoid visiting live food markets and avoid wildlife, especially civet cats, sold in these markets. Some civets have been found to carry viruses similar to the SARS virus.
In transit
Take care on airplanes. Some experts believe that infections spread on airplanes through the air valves located directly above your seat. It's best to turn these valves off and to carry disposable towelettes so that you can clean your hands frequently during a flight.
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