SARS (সার্চ ভাইরাস)

In April 16, 2003 SARS (Severe Acute Respiratory Syndrome) is the disease caused by SARS corona virus. It causes an often severe illness marked initially by systemic symptoms of muscle pain, headache, and fever, followed in 2–10 days by the onset of respiratory symptoms, mainly cough, dyspnea, and pneumonia. Another common finding in SARS patients is a decrease in the number of lymphocytes circulating in the blood.

In the SARS outbreak of 2003, about 9% of patients with confirmed SARS infection died. The mortality rate was much higher for those over 50 years old, with mortality rates approaching 50% for this subset of patients.

The SARS corona virus, sometimes shortened to SARS-CoV, is the virus that causes severe acute respiratory syndrome (SARS). The outbreak of SARS in Asia and secondary cases elsewhere in the world, the World Health Organization (WHO) issued a press release stating that the corona virus identified by a number of laboratories was the official cause of SARS. Samples of the virus are being held in laboratories in New York, San Francisco, Manila, Hong Kong, and Toronto.

Transmission:
Bat corona viruses have been coevolved with their hosts for a long time then jumped species from bats to humans.

Symptoms:

Once a person has contracted SARS, the first symptom that they present with is a fever of at least 38 °C (100.4 °F) or higher. The early symptoms last about 2–7 days and include non-specific flu-like symptoms, including
1. Chills/rigor
2. Muscle aches
3. Headaches
4. Diarrhea
5. Sore throat
6. Runny nose
7. Malaise and myalgia (muscle pain)

Next, they develop
1. A dry cough
2. Shortness of breath
3. And an upper respiratory tract infection

At that time, a chest x-ray is ordered to confirm pneumonia. If the chest appears clear and SARS is still suspected, a HRCT scan will be ordered, because it is visible earlier on this scan. In severe cases, it develops into respiratory failure and acute respiratory distress syndrome (ARDS), and in 70-90% of the cases, they develop lymphopenia (low count of lymphocyte white blood cells).
The incubation period for SARS-CoV is from 2–10 days, sometimes lasting up to 13 days, with a mean of 5 days. So symptoms usually develop between 2–10 days following infection by the virus. As part of the immune response, IgM antibody to the SARS-CoV is produced. This peaks during the acute or early convalescent phase (week 3) and declines by week 12. IgG antibody is produced later and peaks at week 12.

References: Sars-Cov Wikipedia