Severe Acute Respiratory Syndrome, or SARS, has infected 3,947 people and claimed 229 lives since Nov. 1, 2002, when the first case was discovered. The effects of the disease are hitting close to home for many international students studying at Iowa State.

Olivia Chan, graduate student in geological and atmospheric sciences from Hong Kong, said she was planning to return home for the summer. After reading news about the SARS outbreak and speaking with her mother, Chan said she decided it was not wise to travel to Hong Kong. She also said she feared not being allowed back into the United States after her visit.

Although there are no travel restrictions related to SARS, the Centers for Disease Control and Prevention recommends avoiding nonessential or elective travel to the People’s Republic of China; Hanoi, Vietnam; or Singapore. Officials are also carefully monitoring the spread of SARS in Canada, considering the possibility of a travel advisory.

SARS has become a daily conversation topic between Chan, her friends and family who are still in Hong Kong.”I know there is no cure or vaccine,” she said. “It makes me more scared for my family and friends.”

SARS begins with a fever greater than 100.4 degrees Fahrenheit, accompanied by a headache and body aches. After two to seven days some patients may develop a dry cough and have trouble breathing. In 10 to 20 percent of cases, patients require mechanical ventilation.

The illness is spread through close contact with an infected person. It may take between two to seven days following exposure for symptoms to appear. Close contact is normal for a contagious respiratory or flu-like illness.

There is no known treatment for SARS.

Medical experts hypothesize a previously unnoticed coronavirus — a type of virus that has a crown-like appearance when viewed under a microscope — is the cause of SARS. This group is commonly the cause of mild upper-respiratory illnesses and has been linked to pneumonia. Coronaviruses can survive alone in the environment up to three hours.

ISU student Anson Tsang’s family operates a clothing store in Hong Kong, which has been economically affected by the SARS outbreak, he said.

Tsang, junior in finance, said people don’t leave their homes for fear they will catch SARS. They have no idea how they can protect themselves from the disease, he said.

Tsang said he is not worried about catching SARS, and he is planning to return to Hong Kong next month. “Although it is a very quick spreading virus, it’s still a very small portion of Hong Kong [that is affected by SARS],” he said.

LuLu Chan, sophomore in pre-advertising from Hong Kong, said the news from her home country makes the disease sound serious and it worries her.

“My mom told me it’s not as bad as I think it is,” she said. “But maybe she’s trying to make me feel better.”

She said she purchased surgeon’s masks to send to her parents. When the people go out of their homes, they wash their hands often, wear surgeon’s masks and eat oranges for Vitamin C, she said.

She said the Chinese government didn’t let the public know about SARS when it first appeared in November. In response, the mayor of Beijing and other officials have been fired.

“People should have known earlier than now,” she said.

— The World Health Organization and Centers for Disease Control and Prevention contributed to this article.