In no time, SARS has infected a great part of news through all over the world. Statistics gathered by WHO(World Health Organization) disclosed 3,947 sufferers of SARS from 27 nations and 229 victims by April 22, since the first case from China's southern province Guangdong in last November. SARS, that is being recorded as the initial worldwide epidemic in the century of 21st! What gave birth to such a disastrous monster indeed?

Corona Virus - the principal offender of SARS

Scientists of University of Hong Kong discovered corona virus from tissues of SARS cases. WHO proclaimed a special alertness against SARS to the whole world on March 12, launching into researches to reveal the identity of SARS. After all, on April 16, WHO declared that the corona virus was confirmed to be the source of SARS. Corona virus, originally a pathogen of only a slight cold, was named as it is for the corona-like projections on its surface.

Corona virus can be found not only in the human body but also in the animal body as well. It is classified into three classes according to host ; the first class of dogs, cats, and pigs ; the second class of cows and rats ; the third class of birds. Corona virus brings about a cold normally in a human body, but in an animal body it can be fatal. However, this time it is carrying off human lives.

The incubation period of SARS is 2-7 days in general. The early stage of symptoms is accompanied with high fever over 38 , chill, headache, and stiffness. After the latent period, symptoms such as dry coughing, respiratory problems, and hollow respiration that can lead to hypoxemia show up. According to WHO, the fatality of SARS is 4%. However, experts say that the other 96% depend upon the treatments they receive. Moreover, an opinion which states that the actual fatality of SARS may be higher than the estimation has been brought forward. It is said that the correct way to draw a fatality is deviding the death toll by the sum of deaths and fully recovered cases. For example, when the estimated fatality is 4%, 4 cases are supposed to die and 96 cases recover. That is, if the uncertain cases which could either survive or pass away are also included in the sum as they are, the fatality of SARS would be underestimated. After all, the newly estimated SARS fatalities are 18.2% in Hong Kong and Canada, 13.8% in Singapore, 9.8% in Vietnam, and 5.4% in China inland.

Possibility of Viral Infection from Birds to Human

Scientists assume that the simple cold pathogen transformed into the threatening virus by the likely mutation through the process of its transference from an animal to a human being. The result of the base-sequence examination showed that the SARS virus is more analogous(57%) to the second class of corona virus such as those of rats or cows rather than the common human corona virus - relatively still more similar to the third class such as birds corona virus. The possibility of viral infection with birds corona virus was initially brought up.

The Presumptive Trace of SARS

Currently scientists presume that SARS originated from China's southern province Guangdong, China and through Hong Kong it spread to the world over. The first group of cases are the distributors and cooks used to deal with birds, and all over Guangdong province are concentrated with farmhouses which breed livestock such as ducks, chickens, and pigs. With these facts it is possible to presume that the animal corona virus infected human beings and under mutation it changed into the malignant pathogen of SARS.

Genom Analysis - a starting point of the identity examination

Generally, genom of corona virus is composed of the number of 29,000~31,000 bases. A SARS virus which CDC(Centers for Disease Control) research team analized consists of 29,027 bases. Through the analysis of the genom, they found out that the corona virus is akin to the hepatitis virus of rats and the bronchitis virus of turkeys. It shows that the corona virus has gone under mutation becoming the fatal SARS virus.

Most scientists agree to the transference of corona virus from animals to human beings, yet are unaware of the exact trace of infection. It is said that the genom analysis could help them get acquainted with the infection trace of corona virus.

In conclusion, we have a plausible hypothesis that human corona virus, the fatal pathogen of SARS, originated from animal corona virus. Yet, there are no valid evidence. Besides, we can not completely rule out the possibility that a benignant virus was transformed into a malignant virus in a human body recently to become the origin of SARS.

Getting at the root of SARS virus may not be so powerful over controlling proliferation of the corona virus for the present, and yet it will be helpful to avoid corona virus acting up in the future. The original animal could be used to develop remedies and to test the efficacy of treatments as well. Continuous researches such as genom analysis and experiments both in vitro and in vivo are thought to contribute to the comprehensive understanding of corona virus.