The collapse of the normal blood pressure caused by blood stream invasion of microorganisms (sepsis). Frequently, the lungs, kidneys, and other organs fail as a result. This collapse can be caused by fungi and viruses, but the most frequent cause is bacteria. In the US alone, fifteen to twenty thousand people die each year from septic shock. Those who have had their spleens removed are the most susceptible to a sudden onslaught of infectious microbes. Diabetics can go septic when their kidneys or feet become infected, as can those with heart or lung diseases that quickly produce pneumonia. Septic shock can strike those following surgical procedures on germ-filled intestines. Some of the most dangerous blood infections happen to those going through chemotherapy because it leaves the immune system vulnerable to attack. During very serious illnesses when the immune system is struggling to regain strength, the bone marrow can push out immature white cells or band forms which are not ready to perform their duties.