7.2: Communicable Diseases
It happens pretty regularly right around midterms and finals: you find yourself feeling a little tired and rundown, and then in a few days you have a full-blown head cold. Infectious or communicable diseases include familiar, yearly bugs like colds and the flu, and also much more serious illnesses like cholera or meningitis. Communicable diseases are called such because they can be “communicated” or transferred from one living being to another. They all have an infectious agent that causes the disease, which could be a virus, bacteria, fungus, or other pathogen. Typically infectious diseases cause acute illness - perhaps within a few hours to a few weeks from being exposed to the pathogen, a person will develop symptoms. However, some infectious diseases also have latent effects which cause damage to organ systems months or years later, or some may lie dormant in the human body and then cause a flare-up of symptoms when the immune system is weakened. In this section we will discuss how infectious diseases are transmitted, some classic and emerging infectious disease examples, and public health responses. It would be impossible to cover all pathogens and the diseases they cause in this chapter, so further reading is recommended on specific communicable diseases.