epidemic

• • Occur when there is a sudden increase in the occurrence of a particular disease among a popualtion within a community in a given area
• • Epidemics are result of a change in one or more of the following factors: virulence of the pathogen (degree of causing a disease)
• • Mutations can occur that increase pathogen virulence meaning new staring can emerge in a population where the hosts had largely built up immunity
• • Pathogen migration: rapid movement of movement hosts due to transport such as planes, meaning a pathogen can be introduced into a new host population before symptoms show in the migrating population
• • Host exposure and susceptibility
  • Exposure to pathogens can be increased by poor sanitation or hygiene and high density opopualtions
  • Lack of timely and effective interventions to limit a pathogens spread
  • Loss of genetic variation or selection pressure can cause a population to lose genetic resistance and become more susceptible to a certain pathogens