SARS

Severe acute respiratory syndrome, or SARS, is a serious respiratory disease. It was caused by the SARS-CoV-1 virus. This virus was the first identified strain of the SARS-related coronaviruses. This disease matters because it showed how quickly a new virus can spread across the world. It caused a major global outbreak between 2002 and 2004. While the SARS-CoV-1 strain has not been reported since 2004, a second strain called SARS-CoV-2 appeared in 2019. This newer strain is the cause of the COVID-19 pandemic.

The virus spreads primarily through contact with respiratory droplets. These are tiny drops released when people breathe, talk, or sing. The virus can also be carried by aerosols, which are even smaller particles in the air. Another way it spreads is through fomites, which are objects that have the virus on them. People can also catch it through the fecal-oral route. This occurs when the virus moves from waste to the mouth. The virus is most infectious during the second week of illness. This delay in infectiousness made quarantine very effective. If people were isolated before their fifth day of illness, they rarely spread the disease.

SARS produces symptoms that feel like the flu. These include fever, muscle pain, lethargy, cough, and a sore throat. Many patients also experience shortness of breath and pneumonia. Pneumonia can be caused directly by the virus or by a secondary bacterial infection. A chest X-ray might show patchy infiltrates, which are areas of abnormality in the lungs. The average incubation period, or the time between catching the virus and feeling sick, is four to six days. However, it can be as short as one day or as long as 14 days.

Scientists have traced the origin of the virus through a chain of animals. It started in cave-dwelling horseshoe bats in Xiyang Yi Ethnic Township, Yunnan. The virus moved from these bats to Asian palm civets. From the civets, it eventually reached humans. The first known cases were reported in Foshan, China, on November 16, 2002. In early 2003, the virus spread to other regions like Vietnam, Singapore, and Taiwan. Dr. Carlo Urbani, a physician with the WHO, helped identify the threat in Vietnam. He later died from the virus himself.

The outbreak had a significant impact on global health. By the end of the epidemic in June 2003, there were 8,422 reported cases. The case fatality rate, or the percentage of sick people who die, was 11%. This rate varied greatly depending on a person's age. For people under 24, the death rate was less than 1%. For people aged 65 or older, the death rate was over 55%. Males died at significantly higher rates than females. Control measures introduced in April 2003 successfully reduced the basic reproduction number, or R0, from a range of 2 to 4 down to 0.4.

Treating SARS is difficult because there is no proven antiviral therapy. Doctors often use supportive care instead. This includes using antipyretics to reduce fever and supplemental oxygen to help breathing. In severe cases, mechanical ventilation may be necessary. Some medicines like ribavirin have been used, but they show little to no effect on the disease. Doctors may also use corticosteroids for patients with very low oxygen levels. Because the virus is so contagious, patients are often kept in negative-pressure rooms. This helps prevent the virus from escaping into other parts of the hospital.

Even after recovering, some people face long-term health challenges. These are called sequelae. Some patients developed pulmonary fibrosis, which affects the lungs. Others experienced osteoporosis or femoral necrosis. The stress of the outbreak and quarantine also led to mental health issues. Some patients were diagnosed with post-traumatic stress disorder (PTSD) or major depressive disorder. This shows that a virus can affect a person's body and mind long after the infection is gone.