Epidemiology of Infectious Diseases: Host Susceptibility (Page 1 of 2) Host susceptibility is dependent upon genetic factors, general factors of resistance, and specific immunity. General factors of resistance may include skin, cilia in respiratory tract, cough reflex, gastric acidity, and specific acquired immunity (through natural and artificial means). Factors increasing susceptibility are malnutrition, preexisting poor health, and depressed immune system.