A profoundly threatening new epidemic, easily transmissible and capable of killing up to 6 percent of the people who contract it, emerged out of nowhere  in November 2002, spreads through populous China, and then speeds around the world at lightening speed.

Each year, we experience various new strains of viruses that cause the common cold. What is so special about the SARS virus is that it is much more deadly.

SARS is caused by a coronavirus.  Coronaviruses are a group of viruses that have a halo or crown-like (corona) appearance when viewed under a microscope. These viruses are a common cause of up to 1/3 of mild to moderate upper-respiratory illness in humans and are associated with respiratory, gastrointestinal, liver and neurological disease in animals. Coronaviruses generally do not cause severe debilitative diseases, although they have occasionally been linked to pneumonia in humans, especially people with weakened immune systems.

The viruses also can cause severe disease in animals, including cats, dogs, pigs, mice, and birds. The SARS coronavirus is likely to have originated in animals that subsequently passed it to humans. Therefore, we do not have the built up immune system and antibodies to combat it.

Symptoms

The illness usually begins with a fever (measured temperature greater than 100.4°F [>38.0°C]). The fever is sometimes associated with chills or other symptoms, including general feelings of discomfort, headache, and body aches. Some people also experience mild respiratory symptoms at the outset.

After 2 to 7 days, SARS patients may develop a dry, nonproductive cough that might be accompanied by or progress to the point where insufficient oxygen is getting to the blood. In 10 percent to 20 percent of cases, patients will require mechanical ventilation.


Incubation Period

The incubation period for SARS is typically 2 to 7 days. There have been reports, however, of incubation periods as long as 10 days.

Transmission

The primary way that SARS appears to spread is by close person-to-person contact.  Most reported cases of SARS have involved people who cared for, lived with someone with SARS, or had direct contact with infectious material (for example: respiratory secretions from a person who has SARS).  Common ways in which SARS can be spread include touching the skin of other people or transmission through infectious droplets and then touching the eye(s), nose, or mouth. This can happen when someone who is sick with SARS coughs or sneezes droplets onto themselves, other people, or nearby surfaces.

In general, enveloped viruses such as coronaviruses do not last a long time in the open air and die quickly, in a matter of a few hours.  The SARS coronavirus may be different and may be able to survive as long as 24 hours in the open environment.  It is not uncommon for respiratory viruses to be found in feces for a period of time. Some laboratories in the WHO network have reported finding the new coronavirus in stool specimens.


Is there a test for SARS?

No "test" is available yet for SARS at this time.

What should I do if I think I have SARS?

If you are sick with a fever greater than 100.4°F (>38.0°C) that is accompanied by a cough or difficulty breathing, you should (together with your travel or exposure history if any to SARS inflicted people) consult a health-care provider.

It is important to remember that the vast majority of infected people do not die from this virus.  The key determinant is the immune status of the individual.  A body with a strong immune system is able to fight the SARS virus.  The infected person may have some symptoms, but complete recovery can be expected with supportive therapy.  On the other hand, if the immune system is sub-optimal, the body will easily succumb to the SARS virus, potentially resulting in death.

The key to prevention or overcoming SARS lies in having a strong immune system.  Let us look now at how the immune system works.

IMMUNE SYSTEM 101

In our immune system there are two important elements called T- and B-lymphocytes.

B-lymphocytes make and distribute antibodies in our bodies.  There are many different forms of antibodies.  They are classified into five major classes: IgA (immunoglobulin A), IgD, IgG, IgM, and IgE.  Each class has its own function. They work together to ensure that all foreign bodies are destroyed.

T-lymphocytes are in charge of the cell's immunity.  They act as a command post from which most orders for the immune system flow, as well as stimulating macrophages and B-lymphocytes. T-lymphocytes are the pillars for protecting the body from diseases such as bacterial infections, strong viruses, fungi, cancer, and parasitic infections.

These T-lymphocytes are assisted by a group of T-helper cells.  They help to control various white blood cells by issuing chemical codes known as cytokines. Some examples are interleukins and interferons.  T-helper cells coordinate the efforts of white blood cells and destroy unwanted substances.

Our bodies also manufacture T-suppressor cells to slow down the destructive activities of cytokines from other white blood cells.  This is an important function, as it serves to protect the host.  The correct ratio of T-helper to T-suppressor cells is crucial.  It maintains a balance between the aggressive actions to destroy bad cells while protecting the good cells.

Today, biology's greatest achievements have brought about much research into some of the immunity boosting agents derived from natural sources.