Mitigating Shortcuts to Prevent New Disease Fronts

As depicted in fictional movies like Contagion (2011) and Outbreak (1995), new deadly viruses are cropping up via accidental interactions with nature and via purposeful scientific research. Compounded with modern modes of transportation, these deadly diseases have the lethal potential to spread worldwide overnight and become widespread pandemics that wipe out mankind.

Beginning in the last few hundred years, diseases no longer spread via predictable two-dimensional directions. The boundary of where a disease encounters and infects new victims – called the disease front – is now incredibly difficult to map as planes, trains, and automobiles can create new fronts thousands of miles away from an initial outbreak.

Before the 1700s, the size of an infected population did not really matter since the size of any disease front – like a ripple emanating from a single point – was predictable and relatively fixed in size. Because of their slow two-dimensional spread, only the most infectious diseases developed into true epidemics (even the black plague of the 14th century is considered weak as it had a slow three-year spread from southern Italy throughout Europe). Thus if a two-dimensional epidemic happened today, it would be slow and creeping, and public health officials would be able to respond to the well-defined disease front quickly.

Of course, however, modern society no longer allows for simple two-dimensional spreads. The ease and speed of transportation creates shortcuts in which viruses can break into fresh territory and create new disease fronts. Instead of fighting an outbreak in a localized area, viruses can now travel across countries and continents, creating new outbreaks, new victims, and new disease fronts.

For instance, the foot-and-mouth disease outbreak that crippled English cattle farms in 2001 did not have two-dimensional spread although that is what was expected based off how the virus usually spreads: the virus spreads between animals through direct contact, by wind-blown droplets of excrement, or by soil. A two-dimensional spread would have been expected, yet foot-and-mouth disease struck simultaneously on 43 non-neighboring farms. Modern transportation, modern livestock markets, and soil from people’s boots were all shortcuts that allowed the disease to be introduced to new victims, and suddenly animals could be infected anywhere in the nation overnight.

Shortcuts in modern transportation are in essence random, and government officials must create policies that mitigate them in order to effectively stop the spread of an epidemic in its earliest stages. English officials minimized shortcuts by eliminating livestock interaction, preemptively slaughtering nearby cattle farms, and banning travel on countryside roads. Ultimately, the discovery of lethal diseases is inevitable, so we must conduct research to better understand transportation networks and to eliminate shortcuts that will transplant diseases in fresh territory. — Delaney