CSS is diagnosed based on clinical symptoms: fever, fatigue, loss of appetite, headache, vomiting and nausea, tachycardia, hypotension... and laboratory workups including leukocytosis (especially lymphocytes <800), reduced CD4, CD8; decreased Th17 and platelets and increased anti-inflammatory cytokines TNF-α, IL-1β, IL-6, IFNs, GCSF, IP-10, CP-1, Ferritin, CRP, LDH. Respiratory failure progresses with decreased PaO2, normal or decreased PaCO2, severe acidosis, increased DA-a with intrapulmonary shunt and pulmonary hypertension.