Spanish Flu - Viral Pandemic

I’ve just finished reading “The Great Influenza,” a book which can make anyone seriously paranoid. It’s a comprehensive history of the Spanish Flu Pandemic of 1918. You can’t help but wonder about the possibility of another worldwide viral pandemic.

Just to be clear, I don’t count myself as a “Doomsday Prepper.” Even so, after reading this book, you start to think that making a few preparations might not be such a bad idea.

Current estimates and models suggest that the influenza killed between 50 and 100 million people. Many of the fatalities were not the direct result of the virus, but of pneumonia, which attacked the weakened immune systems of recently infected people.

It also killed a remarkably high percentage of young and healthy adults. Those deaths were the result of a cytokine storm, a rapid and violent overreaction of the immune system. There were many well documented cases where a person would feel fine in the morning, sick before lunch, and dead by supper.

It’s very difficult to accurately define the mortality rate, since if varied widely. The best estimates suggest it killed between 10% to 20% of those infected. Perhaps as much as 5% of the world population.

Those estimates are drawn from specific incidents where there are accurate records. The author, John Barry, tells the story of a troop train which left Camp Grant, located near Rockford, Illinois with 3108 soldiers, all young and healthy. An unknown number were infected, but not yet symptomatic. A few days later, when the train arrived at Camp Hancock, outside Augusta, Georgia, more than 700 soldiers were sick, many were taken off the train on stretchers. Over the next few days 2000 were hospitalized. It’s believed that more than 300 died, more than 10% of fit, young, healthy adult males. It was World War 1, and soldiers were packed in close quarters in several countries. While it’s impossible to determine how much that affected the spread of the disease, it would not have been helpful.

In the worst hit areas of the northeast, all available coffins were used up within a few weeks, funeral homes refused to accept new bodies. Steam shovels were used to dig mass graves at the edge of town. In the early stages of the pandemic, many people volunteered to help, but as the death toll continued to rise, good Samaritans became increasingly hard to find. Stores would demand customers stand in the street and shout their orders, which would then be thrown into the street.

Fortunately it wasn’t that bad everywhere. The virus came in three waves, of which the second was by far the most deadly. The first wave, in late 1917 and early 1918 was relatively mild. One of the features of avian influenza is that it can change rapidly. Barry speculates that the mild flu mutated, and became the far more contagious and lethal second wave. That conclusion is not supported by modern science. However, it’s clear that there were three waves of infection, with varying levels of virulence. There is only a single genome, which was reconstructed in 2005 from preserved specimens. Nothing is known of possible other strains.

Some small towns, quarantined themselves, allowing no travelers into town. Those that adopted that strategy early suffered zero infections. The third wave in late 1918 through 1919 had a much lower fatality rate.

There are important lessons to be learned from the 1918 Pandemic and other outbreaks over the last 120 years.

All influenza is Avian. The natural hosts are birds. When the bird flu jumps to the human population, it often starts in a place where large numbers of birds are being raised for food, and where the human population density is high. In some cases the disease first jumps into swine, and then from swine into humans. This is because the receptor cells in the lungs share common shapes. Humans can also transmit the disease back into both swine and birds. With each jump, the disease can mutate slightly as it adapts to a new host species. The disease can be relatively benign in birds or pigs, and lethal in humans, or vice versa. Just because the receptor cells are similar does not mean the immune systems will react in the same way.

The key number that determines the spread of a disease is called the Basic Reproduction Ratio, often referred to as R0, or R-naught. It’s defined as the number of new cases generated by a single individual over that person’s infectious period, in an otherwise uninfected population.

Disease

Transmission

R0

Measles

Airborne

12-18

HIV / AIDS

Sexual Contact

2 – 5

Diptheria

Saliva

6 – 7

Polio

Fecal-Oral

5 – 7

Rubella

Airborne Droplet

5 – 7

Smallpox

Airborne Droplet

5 – 7

Mumps

Airborne Droplet

4 – 7

SARS

Airborne Droplet

2 – 5

Influenza – 1918

Airborne Droplet

2 – 3

Ebola – 2014

Bodily Fluids

1.5 – 2.5

The 1918 influenza traveled around the world in nine months at a time when there was no commercial aviation at all. It infected tiny villages in Alaska and remote islands. In some cases, those populations had little or no immunity and mortality rates were 70% or higher. That strongly suggests that the 1918 Pandemic was not a worst case event. Far from it. That first, relatively mild wave of infections, might have saved millions of lives as it likely provided some level of immunity. That’s not a proven fact, but a possibility. It still raises the question, “How fast would it spread today.”

There have been models of what would happen if the 1918 virus was reintroduced today. These models suggest that a viral pandemic would be avoided. Modern medicine would reduce fatalities by as much as 90%. They take into account that secondary infections of pneumonia would be better managed, and we have anti-viral drugs now, which should be effective against an H1N1, or other viral outbreak.

I don’t believe these numbers for a minute. They are based on the assumption that there would be more than a enough drugs to treat a billion people, and that logistics would continue to function normally.

In the US many people without insurance will stay home until they are seriously ill. They will infect their family. Then they will go to emergency rooms where they will infect other people. A highly contagious disease can overwhelm the number of beds and the available supply of drugs within a few weeks.

The Spanish flu infected 30% of the world population in 9 months. Now imagine a similar disease, with modern transportation. The result might easily be 30% of the world population infected and sick within 9 weeks.

In the case of the 2014 West African Ebola outbreak, with millions of dollars spent, and some of the best medical minds working on the problem, it took more than a year to develop a vaccine.

With no vaccine, it’s easy to say that we’ll ramp up the production of drugs. By the time that decision is made, 20% of the workers needed to manufacture the drug might be infected. And how many people in the supply chain will stay home?

The 2014 cases of Ebola in the US also tell us something about human nature. In spite of it being on the news every day, a hospital worker who had been exposed was sent home to voluntary quarantine. She then got on an airplane to visit her family, because she didn’t feel sick. Keep in mind this was an educated person who worked in a major hospital, and had been specifically advised about the danger of spreading the disease before being sent home. It’s human nature, when in danger, people want to be with family.

Viral Pandemic Headlines

With influenza, there is an incubation period of 72 hours, people who have been infected are contagious during the 24 hours before symptoms are evident.

So imagine that same situation with a highly virulent and lethal virus. Every person the carrier was close to would have to be tracked down and quarantined within 48 hours. Every surface that person touched would have to be tested, since the virus can live for 48 hours on anything not exposed to UV light or cleaned with bleach. That would be every door knob, the interior of any vehicle an infected person used. In the real world, a highly contagious disease has to be contained early. If that first chance is missed, the odds of a pandemic go ballistic.

In 2003 the public health system was tested by the SARS coronavirus. In this case, the system worked perfectly. The SARS virus had a similar R0 value and mortality rate (9%) to the 1918 Influenza. The opportunity for a major epidemic was there, but it was contained early. It was close to the best of all possible outcomes.

There is even more good news in all of this. A highly lethal virus makes itself extinct fairly quickly. It’s not like zombies in the movies. People in the terminal stages of disease are not walking around trying to bite people.

In 1918 the virus moved into an area, infected everyone that was available and then vanished within 8 – 10 weeks. You could go into an area 12 weeks after the index case was diagnosed with minimal risk of getting sick. The virus was dead and many of the survivors were immune.

I draw two conclusions from this. First, it is absolutely critical to identify and contain any infectious disease early. We have the positive case of SARS, a mildly contagious disease that was caught and contained early. And we have the 1918 Pandemic, with a similar R0, which was allowed to spread. There is also the case of HIV, which was not contained early. Even though HIV is difficult to transmit, and we know how to treat it, the death toll is more than a million people every year, 35 million in total.

The second conclusion is that if an epidemic starts, it’s a good idea to have 12 weeks of provisions, ammo, and plenty of good books and movies at hand. And don’t forget several gallons of bleach.

For a more visual look at how a modern day viral pandemic would play out, try watching the 2011 thriller Contagion, by director Steven Soderbergh. It’s a rare movie with really solid science behind it, as well as great performances by Matt Damon, Gwyeneth Paltrow, Kate Winslet and many others.

Links

The 1918 Spanish Flu

Problems with John Barry’s The Great Influenza

The 2003 SARS coronavirus

How a Cytokine Storm Kills

IMDB on Steven Soderbergh’s Contagion

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