1. Severe Acute Respiratory Syndrome (SARS) SARS, an atypical pneumonia of unknown aetiology, was recognized at the end of February 2003. WHO is co-ordinating the international investigation with the assistance of the Global Outbreak Alert and Response Network and is working closely with health authorities in the affected countries to provide epidemiological, clinical and logistical support as required. http://www.who.int/csr/sars/en/[New Window]