Terms and Facts

Infectious Diseases are illnesses caused by microorganisms (either a virus or a bacteria), and are transmitted from an infected person or animal to another person or animal. Can also be called Communicable Diseases or Contagious Diseases. Bacterial Disease: A bacteria is a one-celled organism visible only with a microscope. Less than one percent of bacteria are harmful, but when infectious bacteria enter your body, they rapidly reproduce, and many produce toxins. A bacterial disease can be effectively treated with antibiotics once the type of infectious bacteria is correctly identified.

Viral Disease: A virus is a capsule that contains genetic material, whose single mission is to reproduce. When virus invades your body, it enters some of the cells and takes over, instructing these host cells to manufacture what the virus needs for reproduction. Host cells are eventually destroyed during this process. A viral disease cannot be treated with antibiotics.

Epidemic: The occurrence of cases of an illness in a community or region which is in excess of the number of cases normally expected for that disease in that area at that time. Can refer to communicable diseases or chronic diseases.

Pandemic: A global disease outbreak, or an epidemic that has moved from country to country.

Vector: A vector-borne disease is one in which the infection-causing microorganism is transmitted from an infected individual to another individual by an arthropod (insect) or other agent, sometimes with other animals serving as intermediary hosts. Malaria is a vector-borne disease transmitted to humans from mosquitoes (vector).

Epidemiology: The branch of medicine that deals with the study of the causes, distribution, and control of disease in populations. Epidemiology is the scientific study of factors affecting the health and illness of individuals and populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine.

Seasonal (or common) flu is a respiratory illness that can be transmitted person to person. Most people have some immunity, and a vaccine is available.

H1N1 (referred to as "swine flu" early on) virus was first detected in people in the United States in April 2009 and is spreading from person-to-person worldwide, probably in much the same way that regular seasonal influenza viruses spread. On June 11, 2009, the World Health Organization (WHO) signaled that a pandemic of novel H1N1 flu was underway. More information about the H1N1 Flu is available on the Center for Disease Control's website.

Avian (or bird) flu is caused by influenza viruses that occur naturally among wild birds. The H5N1 variant is deadly to domestic fowl and can be transmitted from birds to humans. There is no human immunity to high path H5N1 and no vaccine is available. Currently, H5N1 cannot be transmitted from person to person, but if the virus mutates to be able to do so, a pandemic could occur.

Pandemic flu is virulent human flu that causes a global outbreak, or pandemic, of serious illness. Because there is little natural immunity, the disease can spread easily from person to person. Currently, there is no pandemic flu.

CDC: The Centers for Disease Control and Prevention, headquartered in Atlanta, GA, with worldwide offices and employees. The CDC, one of the 13 major operating components of the Department of Health and Human Services, was founded in 1946 to help control malaria. It has grown into one of the most respected public health institutions in the world, and has remained at the forefront of public health efforts to prevent and control infectious and chronic diseases, injuries, workplace hazards, disabilities, and environmental health threats. www.cdc.gov

WHO: The World Health Organization is the United Nations specialized agency for health. Established in 1948, WHO's objective, as set out in its Constitution, is the attainment by all peoples of the highest possible level of health. WHO is governed by 192 Member States through the World Health Assembly. The Health Assembly is composed of representatives from WHO's Member States.