Sepsis is a dysregulated host response to infection that leads to life-threatening organ dysfunction. Infectious damage triggers an immune response that variably activates and suppresses multiple body functions. Susceptibility to developing or succumbing to sepsis is influenced by pathogen load and virulence. Other factors are site of infection, host characteristics such as genetics, biological variability, comorbidities, immunosuppression, and extreme ages. Sepsis is also caused by external influences, including social deprivation and the local environment.