communicable disease
a disease that is spread from one living thing to another or through the environment
infection
a condition that occurs when pathogens enter the body, multiply, and damage body cells
virus
piece of genetic material surrounded by a protein coat
bacteria
single-celled microorganisms
toxins
a substance that kills cells or interferes with their functions
vector
an organism, usually an arthropod, such as a tick, that carries and transmits pathogens to humans or other animals
contact
union or touching of surfaces
respiratory tract
the passageway that makes breathing possible
mucous membrane
the lining of various body cavities, including the nose, ears, and mouth
pneumonia
an infection of the lungs in which the air sacs fill with pus and other liquid
jaundice
a yellowing of the skin and eyes
cirrhosis
scarring of the liver
immune system
network of cells, tissues, organs and chemicals that fights off pathogens
inflammatory response
a reaction to tissue damage caused by injury or infection
phagocytes
white blood cells that attack invading pathogens
antigens
a substance that is capable of triggering an immune response
immunity
the state of being protected against a particular disease
lymphocyte
a specialized white blood cell that coordinates and performs many of the functions of specific immunity
antibody
a protein that acts against a specific antigen
vaccine
a preparation of dead or weakened pathogens that are introduced into the body to stimulate an immune response
emerging infections
communicable diseases whose occurrence in humans has increased within the past two decades or threatens to increase in the near future
giardia
a microorganism that infects the digestive system
epidemic
a disease outbreak that affects many people in the same place and at the same time
pandemic
a global outbreak of an infectious disease