SARS!

Severe Acute Respiratory Syndrome (SARS)
Severe acute respiratory syndrome (SARS) is a respiratory illness caused by SARS coronavirus (SARS-CoV), which are positively stranded RNA enveloped viruses, with 8,096 known infected cases and 774 deaths (a case-fatality rate of 9.6%) worldwide between November 2002 and July 2003, listed in World Health Organisation(WHO) report in April 2004, originating from Guangdong China, where a farmer contracted symptoms and died soon after, without a definite diagnosis on his death. The disease soon spreads to other provinces of China like Shanxi and Tianjin. Several countries like Hong Kong, Toronto, San Fransisco, Taiwan and Singapore have local transmissions. Mortality by age group as of 8 May 2003 is below 1 percent for people aged 24 or younger, 6 percent for those 25 to 44, 15 percent in those 45 to 64 and more than 50 percent for those over 65. For comparison, the case fatality rate for influenza is usually around 0.6 percent (primarily among the elderly) but can rise as high as 33 percent in locally severe epidemics of new strains. The mortality rate of the primary viral pneumonia form is about 70 percent.
What is main source of virus? It was found by Chinese researchers from animals like palm civets (cat-like animal), that SARS coronavirus can spresd from the civets to humans. Other animals like raccoon dogs, ferret badgers, cats and Chinese Bats are also likely to have isolated the viruses, in which bats are aymptomatic to virus, but are possibly reservoirs for transmission of SARS-like coronavirus.

Viral replication
Replication takes place in cytoplasm in membrane-protected microenvironment and starts with the translation of the genome to produce the viral replicase. CoV transcription involves a discontinuous RNA synthesis (template switch) during the extension of a negative copy of the subgenomic mRNAs. The requirement for base pairing during transcription has been formally demonstrated in arteriviruses and CoVs. The CoV N protein is required for coronavirus RNA synthesis and has RNA chaperon activity that may be involved in template switch. Both viral and cellular proteins are required for replication and transcription. CoVs initiate translation by cap-dependent and cap-independent mechanisms. Cell macromolecular synthesis may be controlled after CoV infection by locating some virus proteins in the host cell nucleus. Infection by different coronaviruses cause in the host alteration in the transcription and translation patterns, in the cell cycle, the cytoskeleton, apoptosis and coagulation pathways, inflammation and immune and stress responses. The balance between genes up- and down-regulated could explain the pathogenesis caused by these viruses. Coronavirus expression systems based on single genome constructed by targeted recombination, or by using infectious cDNAs, have been developed. The possibility of expressing different genes under the control of transcription regulating sequences (TRSs) with programmable strength and engineering tissue and species tropism indicates that CoV vectors are flexible. CoV based vectors have emerged with high potential vaccine development and possibly for gene therapy.[19]

Symptoms of SARS are similar to influenza together with fever, muscle pain, lethargy, gastrointestinal symptoms, cough, sore throat, shortness of breath and other non-specific ones, in which the most common symptom is fever above 38 °C (100.4 °F). They usually appear between 2 days to at most 13 days following infection, usually within 2–3 days. About 10–20% of cases require mechanical ventilation.
Phlegm present in lungs can be an indication of SARS. This can be examined from Chest X-Ray.
There are also high white blood cell and platelet counts, some likely reasons are: tendency to relative neutrophilia and a relative lymphopenia, raised lactate dehydrogenase and creatine kinase and C-Reactive protein levels.
Some approved tests to identify SARS are: ELISA (Enzyme-Linked Immunosorbent Assay), Immunosorbent Assay and Polymerase Chain Reaction (PCR). However, there are some pros and cons to each test. For example, ELISA is reliable only 21 days after symptoms occur in patient, while immunosorbent assay takes only 10 days, but requires sophisticated equipment, like immunoflourescence microscope and PCR may not be sensitive, which means that patient may still suspect of infected from SARS even though tested negative.
The process of finding cause of virus was initially hypothesized that SARS was caused by paramyxovirus-like particles, from Hong Kong and German researchers, while Chinese researchers reported Chlamydia-like disease a likely cause. French and Hong Kong scientists soon found out that a newly discovered subtype of coronavirus was a likely cause of SARS, after cultivating virus in vitro and invent a test to identify virus. This was confirmed by Dutch scientists in 2003, by demonstrating that SARS coronavirus fulfilled Koch's postulates, using macaques as hosts, which developed same symptoms as SARS patients.
So far, antipyretic drugs with oxygen supplemental and ventilator support can treat SARS. Antiviral drugs like ribavirin and corticosteroids are the most common drugs to treat disease. Iminocyclitol 7 has also been found to have inhibited SARS-CoV by disrupting envelope assembly and inhibits production of human fucosidase. In vitro trials yielded promising results in treatment of SARS, but lacking of fucosidase can lead to fucosidosis which is a decrease in neurological function.
Acknowledgement
http://en.wikipedia.org/wiki/SARS

Here are links to World Health Organisation to guides of SARS surveillances and recommendations, plus risk assessment and preparedness framework to prevent a SARS pandemic:
http://www.who.int/csr/resources/publications/SARSNEWGUIDANCE/en/index.html
It may be dated to 2004, but is still quite useful to learn more about SARS.
Wilson reported.