# Disease Fighters Need Math

In films like *Contagion* the heroes are the men and women in lab coats*,* desperately searching for a cure to epidemics that threaten humanity. In real life*, *it’s not just scientists*,* but men and women in front of screens and calculators that battle and prevent the spread of dangerous diseases.

So if this is a field your child is interested in, please tell them that they definitely need math, and a lot of it, to do a good job!

Recently, the Zika epidemic threatened to infect masses, and public health workers and policy makers need to know the following to start putting together a plan of attack:

- How rapidly is the disease likely to spread?
- How many people does it threaten to infect?
- What areas are most at risk?
- When is the worst risk?
- Which interventions need to be placed to stop the outbreak?

So what do researchers do? They use statistical and mathematical models to simulate and test all the potential outcomes of the epidemic and to test various intervention strategies.

**Statistical Models**

These are based on the number and the location of the infections and useful for making speedy forecasts and putting together risk maps.

**Mathematical/Mechanistic Models**

These are good for “what-if” scenarios. In the case of the Zika virus, these were used to test how decreasing bites or eliminating the mosquito population would stop the spread of the disease.

Most mathematical models of disease are based on the basic premise that the population can be divided into three groups:

- People who are susceptible
- People who are infectious
- People who have recovered

As Plus Magazine explains, this is called the SIR model:

“Individuals are born into the susceptible class. Susceptible individuals have never come into contact with the disease and can catch the disease, after which they move into the infectious class. Infectious individuals spread the disease to susceptibles and remain in the infectious class for a given period (the infectious period) before proceeding into the recovered class. Finally, individuals in the recovered class are assumed to be immune for life.”

Diseases models aside, the cost of the strategy is also necessary. If researchers are looking at something like the Zika virus they have to note that spraying mosquitoes is very expensive and using mosquito repellent could potentially be cheaper, so applied mathematicians need to see what the best use of resources could be.

So there you go, tell your child that in the case of saving the world from the plague, math is crucial in saving both lives and money.

Sources: +Plus Magazine; Wall Street Journal

*Marina Gomer is a journalist and mother of two. She lives with her family in Sydney, Australia.*

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