Pathogens and infections

Disease

• Microorganisms that cause disease are called pathogens.
• Bacteria can reproduce rapidly inside the body They may produce toxins (poisons) that make us feel ill.
• Viruses reproduce inside a body cell then destroy it when they burst out. The viruses then invade other cells.
• An epidemic occurs when a wide spread of people have a disease. A pandemic is when the disease affects a whole country or goes worldwide.
• In the 1840's, a doctor called Semmelweis used evidence from the death rates of women to work out that they were dying because doctors were transferring something to them from dead bodies. He made all the doctors wash their hands in chlorine water and, within a very shot time, the death rate plummeted. We now know the infection that killed the women was caused by bacteria.