7+ takeaways from this lesson:
An epidemic is “the rapid spread of infectious disease to a large number of people in a given population within a short period of time, usually two weeks or less.” A pandemic “is an epidemic of disease that has spread across a large region; for instance multiple continents, or even worldwide.”
In the aftermath of the 2010 earthquake in Haiti, the water source in the overcrowded refugee camps housing survivors who lost everything became a breeding ground for cholera, infecting the refugee camp residents.
Antigenic shift is “the process by which two or more different strains of virus or viruses combine to form a new subtype.” The greatest example to date would be the great flu pandemic of 1918-19, in which over 50 million people died worldwide. Another example would be in 2017 in Maryland the H3N2 swine flu made the jump from pigs to humans. At least 40 people who had either pet the pigs or merely been in close proximity to the pigs were infected.
Although it’s rare for ‘viral host jumps’ from sick animals to humans, when it does happen the consequences can be catastrophic. Commonly known examples include:
- The ‘common’ flu (influenza) affects over 3 million people and kills over 650,000 people every year worldwide.
- Tuberculosis affects nearly 25% of the population and has killed over 1.6 million
- The “black death” plague killed over 34 million Europeans
- Cholera affects an estimated 3–5 million people worldwide and causes 28,800–130,000 deaths a year.
- The new coronavirus has so far (as of 9 February 2020) infected over 25,000 and killed over 800 people. John Hopkins University has created a application that allows you to track the new coronavirus impact in real time.
- Severe Acute Respiratory Syndrome (SARS) infected 20 countries and killed roughly 1,000 people.
- Human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV/AIDS) has so far infected over 38 million people with over 770,000 deaths.
Viruses spread through a 3-step process:
- Contact with a susceptible host. Once the virus enters your body it’s survival depends on establishing a base before your immune system identifies and attacks. To delay detection while spreading, viruses enter cells by mimicking the cell’s protein-based interface, and then hijack the cell’s reproductive process, moving on to phase 2.
- Replication and infection. If the infected cells can successfully evade it’s host’s immune system and gain an advantage. To evade, viruses have learned how to mutate and evolve, making it hard to identify and treat medically. At this point the virus moves on to phase 3.
- Transmission to other susceptible hosts. Viruses are then indiscriminately transmitted directly to other hosts, or indirectly via shared surfaces (desks, door handles, coffee lids at your local coffee shop…). A single sneeze, for example, can:
- Project droplets of harmful pathogens +70 mph (+112 mph),
- Cover distances of over 26 feet (8 meters),
- Float in the air for up to 10 minutes, and
- Live outside of a host for up to 24 hours
[EDITOR’S NOTE: For related information on the psychological side of infectious diseases and when news media outlets and bloggers create hysteria, check out lessons: