PandemicA global disease outbreak
Definitions:
A disease prevalent over a whole country or the world
InfluenzaA common viral disease
Definitions:
A viral infection that attacks your respiratory system
EpidemiologyStudy of disease patterns
Definitions:
The branch of medicine which deals with the incidence, distribution, and possible control of diseases
VirulentExtremely harmful
Definitions:
(of a disease or poison) extremely severe or harmful in its effects
OutbreakSudden increase in an undesirable event
Definitions:
A sudden occurrence of something unwelcome, such as war or disease