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Much Is Still Unknown About New Asian Virus
Scientists are reporting success in identifying the virus behind a lethal respiratory illness, dubbed severe acute respiratory syndrome, or SARS.
Most evidence points to a new strain of a common cold virus, coronavirus, as the cause; indeed, some scientists -- saying they are sure of their findings -- want to rename the disease coronavirus pneumonia, or CVP.
Here are some frequently asked questions about the disease, how it spreads, what can be done to contain it, and how global health authorities are involved:
What causes this disease?
The pathogen is believed to be a new strain of coronavirus, a family of highly contagious viruses that causes a range of illnesses including the common cold and other upper-respiratory tract infections. It isn't clear where the new strain came from, but it may have mutated from a strain known to infect animals. Researchers in some areas also have identified a different virus family, the paramyxovirus, among patients with the disease. But scientists now suspect it may play a secondary, perhaps opportunistic role.
Where and when was the first case of this disease reported?
A majority of cases outside mainland China originated with a doctor from China's Guangdong province, who caught the disease there and then transmitted it to seven people who visited the ninth floor of the Metropole Hotel in Hong Kong, where he stayed in late February.
Those people in turn carried the disease to Vietnam, Canada and Singapore, and to other people in Hong Kong. The mainland China outbreak began in November, according to the Chinese government, and constitutes the earliest known cases. The origin of the disease is unclear.
How many cases have been confirmed to date?
There are 1,408 cases, with 54 deaths in 13 countries. Those include 51 suspected cases in the U.S. No deaths from the disease have been reported in the U.S.
Where are the most cases, and how quickly have they been spreading?
Mainland China has reported the most cases in total, but the disease appears to be spreading fastest in Hong Kong, which reported 370 cases on Thursday, up 51 from the previous day.
With 36,000 people dying from influenza each year in the U.S., why is this setting off alarm bells?
It is a threat because it is an entirely new strain of virus. The only people who have antibodies to fight it are those who have already been sick and recovered, and there is no known treatment. With the rest of the population exposed, a new virus strain can quickly erupt into an epidemic.
What are the chances of a large-scale outbreak in the U.S.?
While the numbers are growing every day in the U.S., most of the people who are sick appear to have contracted the disease during recent travel to Asia. Only seven out of 51 sick people in the U.S. came down with the disease by caring for or otherwise being in close contact with those who picked it up in Asia. The U.S. Centers for Disease Control and Prevention has officials meet as many as 65 flights a day from Asia, hands out notices describing the symptoms, and also gets passengers who are already sick to a hospital and isolates them.
How is it transmitted?
The World Health Organization believes close contact with an infected person is needed for the infective agent to spread from one person to another. Contact with exhaled droplets -- such as a cough or sneeze -- and bodily secretions from an infected person appear to be important. To date, the majority of cases have occurred among hospital workers and close family members who have cared for infected people. Scientists say the virus can last outside the human body only for a few hours. However, they also warn that it can be spread by touch, such as contact with elevator buttons or handrails.
What are the symptoms?
The illness begins generally with a fever greater than 100.4 degrees Fahrenheit, according to the CDC. The fever is sometimes associated with chills, headache, malaise, and body aches. Some also experience mild respiratory symptoms at the outset. After three to seven days, the person 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% to 20% of cases, patients will require mechanical ventilation.
How long is the incubation period?
The CDC reports that the incubation period is typically two to seven days. However, isolated reports have suggested an incubation period as long as 10 days. Infected people aren't thought to be contagious until symptoms appear.
What is the rate of contagion compared with other illnesses?
Less than mumps and measles and influenza, according to the WHO. However, the speed of international travel creates a risk that cases can rapidly spread around the world. There is also as yet no evidence that the disease can be transmitted through building or airplane ventilation systems.
What is the treatment?
Doctors are trying to figure out what works best. The CDC recommends that patients be treated as if they had "community-acquired pneumonia of unclear etiology." They are isolated in rooms with negative air pressure, given antibiotics and other care. About 90% of patients recover by day six. Half of the remaining 10% need ventilators.
When does the disease become lethal? Are older adults or children more at risk?
In Hong Kong, most patients who have died had other serious illnesses at the time they were infected. While people of all ages have been seriously affected, clinicians report that young, fit adults have generally fared better and recovered faster.
What are the prospects for developing a vaccine?
A vaccine is still years off.
Should I limit my travel?
CDC advises postponing elective or nonessential travel to Hong Kong and Guangdong Province until further notice. The U.S. State Department also advises deferring nonemergency travel to Vietnam.
Updated March 28, 2003
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