Explanation Scientists suspect that SARS originated in China's Guangdong province and many believe that the outbreak of atypical pneumonia that began there is probably linked to other cases of SARS worldwide. The widely reported case of the American businessman, who had traveled to China and Vietnam and had died due to SARS on March 16, 2003 created fear and panic worldwide. The World Health Organization (WHO) issued a global alert about SARS in March 2003. The disease spread to more than two dozen countries in America, Europe and Asia in the next few months. However by late July 2003, the disease is believed to have been contained. During this worldwide outbreak of the disease, 8098 individuals contracted the illness and of them 774 died according to WHO. SARS is caused by coronavirus. This virus belongs to a group characterized by crown-like halos or coronas and is commonly associated with common cold. The incubation period for the disease, that is, the length of time between infection and expression of symptoms, is two to seven days. The symptoms of SARS are: Fever above 100.4 oF or above 38 oC Headache General feeling of discomfort Body pain Mild respiratory distress Diarrhea (seen in 10% to 20[]f the patients) After 2-7 days, a dry cough may develop which may lead to hypoxia- a condition in which insufficient oxygen reaches the blood. The virus replicates in the respiratory tract and moves to the lungs creating severe respiratory distress. Most of the patients develop pneumonia The virus spreads mainly through close contact with individuals with SARS. The virus is transmitted by respiratory droplets produced when a SARS patient coughs or sneezes. The droplets can travel through a short distance of about three feet through the air and be deposited on the mucous membranes of the nose, eyes and mouth of individuals who are nearby. The virus may also spread when an individual touches a surface contaminated with infectious droplets and then touches his eyes, mouth and nose. In April 2003, when SARS spread rapidly among the residents of Amoy Garden Apartment, Hongkong, it left health experts puzzled about the mode of transmission of the virus. Health officials now believe that SARS may also spread through air borne transmission, that is, by small respiratory aerosol particles that are able to travel over a great distance and can be inhaled by people or by any other means that is currently unknown. According to the Center for Disease Control and Prevention (CDC), USA, the cases of SARS may be classified as Suspect or Probable, based on the following criteria: Suspect case An individual is considered a 'suspect case,' if he has high fever, greater than 100.4 oF, cough, shortness of breath, breathing difficulties within 10 days of close contact with persons with SARS or if he has traveled or lived in an affected area. Probable case A 'suspect case' is considered to be a 'probable case' if the X-ray of the chest shows pneumonia or respiratory distress syndrome. Some experts suggest that though the outbreak has subsided, the virus could emerge again with no warning or it might follow a seasonal pattern like flu.