Post by Lex Hurley on Oct 31, 2016 19:15:17 GMT
In 2014 (the most recent date that I could find), the United Nations approximated that 54% of the world's population lives in condensed urban environments, amounting to 3.9 billion people; further, there are 28 "megacities" in the world that are home to >453 million people each, or 12% of the rural population.1 These densely packed environments are obviously rife with interpersonal contact and opportunities to spread disease, and as each of them doubtlessly have airplane transportation between each other, one can assume that each of them can be quickly connected to one another if a contagious pathogen were to arrive first unnoticed. Now the Ebola virus has received loads of media attention following the recent outbreak in West Africa, however I'll use it as low-hanging fruit for this example as most people are familiar with the symptoms (fever, vomiting, diarrhea, and bleeding from orifices) and because it has an average case fatality ratio (CFR) of ~50% (ranging from 20%-90% in past outbreaks).2
Ebola can spread from interpersonal contact if a person a) directly touches an infected person's broken skin, mucous membranes, or any of their fluids or b) touches places where fluids have been (clothes, walls, furniture, etc.) if they haven't been completely and entirely disinfected or destroyed -- actually, the virus can remain active and contagious on a surface for over 2 months. Post infection, the virus typically has an incubation period of 2-21 days where the person is not contagious, then it violently manifests and can kill the host in no time.2 This is Ebola's main weakness -- it burns out too quickly. It can devastate a given population in a month if gone unchecked, everyone stays away, and then there are no more hosts left to transmit it so it fades away.
Now imagine if Ebola got smarter, or perhaps more patient. Imagine its incubation period lasted a flat 10 days where it would then transition to a contagious phase of another 10-15 days which would only cause mild symptoms such as a slight fever, headache, and fatigue but still be fully transmissable by all current modes before erupting into the same CFR. A person from an urban area could get the disease, go back home, and inadvertently and exponentially spread the virus to people and surfaces throughout the city, which would reach airports, and therefore many other urban areas. The symptoms would be vague enough that even if people went to the doctor, they might just get a round of antibiotics and NyQuil, and I sincerely doubt that a tropical disease such as Ebola would even be screened for in preliminary tests. Then the infection erupts.
People come to hospitals with Ebola's symptoms and are immediately quarantined, the hospitals and public health agencies warn of the outbreak and encourage testing, which floods hospitals and clinics; bogging them down and providing fertile mixtures of infected and non-infected individuals for further spread. There would soon be no room or too few staff to safely care for patients and provide them with treatment and cities would go into lockdown while the infection finishes its work on those told to stay in their homes. Assuming the average CFR, that's about a quarter of the population gone, but wait -- these cities will still be completely contagious environments for at least the next two months, prompting a mass exodus and the opportunity for further spreading to the areas of refuge.
With that thought, I'm very glad that Ebola is impatient.
1) n.a. (2014). World's population increasingly urban with more than half living in urban areas. Accessed online on October 31, 2016 from www.un.org/en/development/desa/news/population/world-urbanization-prospects-2014.html.
2) n.a. (2016). Ebola Virus Disease. World Health Organization. Accessed online on October 31, 2016 from www.who.int/mediacentre/factsheets/fs103/en/.
Ebola can spread from interpersonal contact if a person a) directly touches an infected person's broken skin, mucous membranes, or any of their fluids or b) touches places where fluids have been (clothes, walls, furniture, etc.) if they haven't been completely and entirely disinfected or destroyed -- actually, the virus can remain active and contagious on a surface for over 2 months. Post infection, the virus typically has an incubation period of 2-21 days where the person is not contagious, then it violently manifests and can kill the host in no time.2 This is Ebola's main weakness -- it burns out too quickly. It can devastate a given population in a month if gone unchecked, everyone stays away, and then there are no more hosts left to transmit it so it fades away.
Now imagine if Ebola got smarter, or perhaps more patient. Imagine its incubation period lasted a flat 10 days where it would then transition to a contagious phase of another 10-15 days which would only cause mild symptoms such as a slight fever, headache, and fatigue but still be fully transmissable by all current modes before erupting into the same CFR. A person from an urban area could get the disease, go back home, and inadvertently and exponentially spread the virus to people and surfaces throughout the city, which would reach airports, and therefore many other urban areas. The symptoms would be vague enough that even if people went to the doctor, they might just get a round of antibiotics and NyQuil, and I sincerely doubt that a tropical disease such as Ebola would even be screened for in preliminary tests. Then the infection erupts.
People come to hospitals with Ebola's symptoms and are immediately quarantined, the hospitals and public health agencies warn of the outbreak and encourage testing, which floods hospitals and clinics; bogging them down and providing fertile mixtures of infected and non-infected individuals for further spread. There would soon be no room or too few staff to safely care for patients and provide them with treatment and cities would go into lockdown while the infection finishes its work on those told to stay in their homes. Assuming the average CFR, that's about a quarter of the population gone, but wait -- these cities will still be completely contagious environments for at least the next two months, prompting a mass exodus and the opportunity for further spreading to the areas of refuge.
With that thought, I'm very glad that Ebola is impatient.
1) n.a. (2014). World's population increasingly urban with more than half living in urban areas. Accessed online on October 31, 2016 from www.un.org/en/development/desa/news/population/world-urbanization-prospects-2014.html.
2) n.a. (2016). Ebola Virus Disease. World Health Organization. Accessed online on October 31, 2016 from www.who.int/mediacentre/factsheets/fs103/en/.
