Most patients develop lower respiratory features early during the illness. Dyspnea usually develops after a median of 5 days of initial symptoms [15] . Respiratory distress, tachypnea and inspiratory crackles are commonly seen. Most patients have clinical and radiological features of pneumonia which is seen to rapidly progress to respiratory failure with manifestations of adult respiratory distress syndrome (ARDS). In a report from Thailand, the median time for progression to ARDS was 6 days (range 4 to 13 days) [15] .