An emerging infectious disease (EID) is an infectious disease whose incidence has increased in the past 20 years and could increase in the near future. Emerging infections account for at least 12% of all human pathogens. EIDs are caused by newly identified species or strains (e.g. SARS, AIDS) that may have evolved from a known infection (e.g. influenza) or spread to a new population (e.g. West Nile virus) or area undergoing ecologic transformation (e.g. Lyme disease), or be reemerging infections, like drug resistant tuberculosis. Some infectious diseases can be passed from person to person. Some are transmitted by bites from insects or animals. And others are acquired by ingesting contaminated food or water or being exposed to organisms in the environment.
Each infectious disease has its own specific signs and symptoms. General signs and symptoms common to a number of infectious diseases include: Fever, diarrhea, fatigue, muscle aches etc.
Treatment depends on the type of germ causing the illness. Antibiotics are reserved for bacterial infections, because these types of drugs have no effect on illnesses caused by viruses. Drugs have been developed to treat some, but not all, viruses. Examples include the viruses that cause: AIDS, herpes, hepatitis B, hepatitis C, influenza etc.