3 Viruses Go "Viral"

Reading 1

Introduction to Viruses go "Viral"

Have students read the introduction to the module. The purpose of this reading is to introduce students to the idea that the characteristics of viruses can determine whether an outbreak will emerge and escalate into an epidemic and to inform them of what they will be exploring in the module.

The purpose of this reading is to introduce you to the idea that the characteristics of viruses can determine whether an outbreak will emerge and escalate into an epidemic and to inform them of what they will be exploring in the module.

Investigating Epidemics
  • What causes a localized outbreak of an infectious disease to escalate into an epidemic or even a worldwide pandemic?
  • Are all viruses equal in their ability to cause an epidemic?
  • What factors are involved in determining whether an outbreak of a disease will develop into an epidemic?

When an outbreak of a disease occurs anywhere in the world, it is critical to identify the first case of an outbreak or epidemic (Patient Zero or index case), determine the causative agent, and track how the disease spreads — all important information in figuring out how to halt an epidemic.

Human Behavior

Human behavior is an important factor in the spread of infectious diseases.

  • Disease-causing bacteria can contaminate food during its preparation as in Salmonella infections.
  • Failure to keep water for human consumption separate from human waste has resulted in cholera epidemics.
  • Traditional burial rites contributed to the tragic Ebola epidemic in 2015. Trash that accumulates around places where people live provides breeding grounds for insects carrying viruses (vectors).
Biology and Ecology

Another major determinant in whether outbreaks of disease escalate into epidemics or pandemics is the biology and ecology of the infectious agent. Questions that can be asked about whether an infectious agent will go "viral" include:

  • How is the infectious agent transmitted?
  • Does transmission occur from contaminated food or water or by breathing in infected droplets from a cough or sneeze?
  • Does it require direct contact with an infected person or does an insect vector carry it?
  • Has the agent changed its host specificity?
  • Is it highly contagious or difficult to catch?

In this module, you explore the biology and ecology of different viruses that may determine whether an outbreak will remain confined to a local area or result in an epidemic or pandemic and whether the diseases they cause could ever be eradicated.