Severe acute respiratory syndrome (SARS)

SARS is a severe acute respiratory infection of viral origin. The virus that causes the disease was identified in record time (just a few weeks), which made it possible to develop a diagnostic test. This new virus belongs to the genus Coronavirus (Coronaviridae family), which are known for their frequent mutations. The incubation period lasts three to ten days (six days on average). SARS mainly affects adults; it is rarely seen in children under 15 and only exceptionally in infants under 12 months. The virus spreads from person to person in saliva droplets (by sneezing, coughing). Those who are in close contact with patients run a greater risk of contracting the disease. To date, 30 to 50% of those infected have been healthcare workers.

Impact on public health

SARS is the first serious and highly contagious disease to emerge in the 21st century. The first case, officially registered in Hanoi in February 2003, actually came after cases occurring in China which date back to November 2002. Up to now, the virus has been found in particular in certain wild animals (civet cats, badgers, etc..), which are part of the traditional diet in Southern China. The scope of the spread of the disease qualifies it as the first major pandemic of the 21st century: in the space of a few months, around 8,000 people were affected in about 30 countries and several hundred people died. Mortality due to SARS increases with the age of the patient; from 1% in persons under age 24 to more than 50% in those over 65.

Diagnosis

There is no specific sign that indicates the presence of SARS ; all its symptoms can be observed in other respiratory infections of viral origin.
- Clinical signs: the initial clinical signs include fever or hypothermia, headache, faintness, and muscle pain. After 24 to 36 hours, patients develop a dry cough and have difficulty breathing. Other signs may include shivering, diarrhea, nausea, vomiting, loss of appetite, pharyngitis, joint, chest, and abdominal pain, expectoration, and runny nose. The disease evolves toward a syndrome of acute respiratory distress requiring respiratory assistance.
- Additional examinations: Usually an x-ray of the lungs reveals anomalies that are essentially similar to those observed in certain cases of bacterial pneumonia (atypical), yet certain nonetheless suggest a diagnosis of SARS. The lung x-ray may initially be normal in 20% of patients; in this case, a chest scan is used to determine whether the lungs are affected.
- Biological analyses: Biological anomalies are not specific but they resemble those seen in respiratory infections of viral origin. Microbiological examinations screen for the coronavirus that causes SARS as well as other pathogens that are associated with or responsible for this non-specific respiratory infection. The first molecular biology tests were developed very quickly following the discovery of the virus that causes SARS.