Impairment of natural defenses- II: Endogenous causes: diseases, malignancies, malnutrition, organ transplants.

This article provides evidence that opportunistic infection can be expected in chronically 
debilitated, immunosuppressed persons. The onset of an infectious disease in these 
patients can be sudden or insidious with few prodromal signs. Anorexia, 
malaise, fever, and vomiting are nonspecific symptoms that these children may 
manifest because of their primary illness or its treatment. Any insult 
to natural defense barriers may cause serious infections in the compromised 
host. An infected wound from an insect bite, easily controlled by 
local measures in a healthy person, may become a focus for 
septicemia in a child with leukemia. Despite the diagnosis and appropriate 
treatment of the specific infection, the immunosuppressed person is still subject 
to overwhelming infection by resistant opportunistic organisms until the natural defense 
mechanisms are restored. An awareness of the vulnerability of the compromised 
host is the key to effective diagnosis and management of the 
various complications of infectious disease. 