Organ Systems and Disease

This chapter provides an overview of organ systems and diseases caused by the infections of these organ systems. The respiratory system is a portal of entry for micro-organisms. Viruses are responsible for the majority of upper respiratory tract infections, while bacteria are responsible for the majority of the lower respiratory tract infections. The urinary tract is a sterile system. Infection of the urinary tract can be exogenous or endogenous. Urinary tract infection is expressed as bladder infection — frequency, urgency, and burning. The cardio-vascular system represents one of the normally sterile anatomical areas. Invasion of the blood stream by bacteria may occur from breaches in the skin or mucous membranes. Infection of any organ system may be associated with a bacteraemia, for example, pneumococcal pneumonia can often be diagnosed by the presence of lung pathology and a positive blood culture. Certain diseases are typically characterized by the blood spread of organisms during particular phases of the illness, such as, typhoid, and measles.