Medical microbiology is a branch within the field of microbiology which focuses on microorganisms of medical interest. how they cause infections in humans, how they spread, what they do to the human body, and how they can be eradicated. People in this field may work in research labs studying microorganisms, or they may work in diagnostic labs, performing tests to identify disease-causing organisms in patients and making treatment recommendations. This branch of microbiology is amongst the most widely studied and followed branches due to its great importance to medicine. Along with providing a deep knowledge and understanding of the nature of pathogens this line of study has also been applied in several immunological innovations in the field of medical science. Through the development of vaccines against invading organisms, deadly and debilitating diseases such as small pox, polio, and tuberculosis have been either eradicated or are more treatable because of the efforts of scientists and researchers in the field of medical microbiology. Bacteria, fungi, protozoans, and viruses can all cause disease in humans.