This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 12th (it came out in 2015), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

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Monday, October 20, 2014

How Scary is Ebola?

None of us really knows how afraid we should be of Ebola (or of any other emerging infectious disease). But two stories came across my radar screen today that warrant consideration. First, Dr. Rumbaut pointed me to a story in the New Republic, by a Distinguished Professor of Medicine at the University of Michigan, detailing the similarities between Ebola and the outbreak of cholera in 1892.
It’s been more than a hundred years, so a lot has changed. Medical science is much more advanced. The world is a more interconnected place. But there are some important parallels between now and then. In some respects—the fear of travelers carrying the disease, the intense criticism of public health authorities—things haven’t changed much at all.
Asiatic cholera was spread by body fluids—especially the copious diarrhea it produced to the point of dehydrating a grown man in a matter of hours. Indeed, to the nineteenth-century American, cholera was every bit as scary, deadly, and disgusting as Ebola fever is today. The cholera of 1892 had already decimated much of India, the Middle East, Asia, and Eastern Europe and shut down the port of Hamburg, the largest in the world. By August 30, New York City, the world’s second largest port, began to receive its first cholera victims, mostly impoverished Russian Jewish immigrants.
It’s probably true, for example, that in 1892 the 20-day quarantine helped by reducing the flow of immigrants and the overwhelming workload of medical inspection. But the quarantine also caused collateral damage—starting with the scapegoating of all Eastern European immigrants. Meanwhile, those of us who have studied the outbreak have concluded that it was not the quarantine that deserves most of the credit for containing the disease. It should go instead to public health officials in New York City and to the federal government. They worked aggressively to ensure that the water supply was not tainted with the cholera microbe—and used case tracing and isolation of the ill to keep the disease from spreading.
And then thanks to Dr. Pollock who linked us to a story in the Washington Post enumerating what we do and, more importantly, don't know about Ebola. One concern is whether or not a person could carry the Ebola virus without showing symptoms, and thus be a carrier of the disease like Typhoid Mary back in NYC in the 19th century. Fortunately, the answer seems to be no, although of course we don't know for sure. The evidence suggests that if you have the disease your viral load is very low until you start to show symptoms. The implication is that if you have the virus but have no symptoms, your are unlikely to spread the disease. Of course, that doesn't mean it can't happen, and that uncertainty is what feeds fear...

3 comments:

  1. So ... a couple of thoughts. I does appear that all of the ebola-infected people who traveled to the West - did NOT spread their infection while on airplanes. Some of them did spread it the virus to care givers in Western hospitals. But the fact that the ebola did not spread while the travelers were in casual contact with other people in airports (or on airplanes) ... is encouraging!! This particular strain of ebola does not seem to be highly transmissible, at least with casual contact. That is GOOD news.

    Now, the slightly bad news. Which by the way, goes back to demographics :-) We have seen a lot of news stories about this crisis from Liberia and Sierra Leone. Two West African countries that are very poor, have been ravaged by conflict, and have terrible infrasructures. So of course a disease like Ebola can spread quickly there. But what about their neighbors? Those countries would be the Ivory Coast and Ghana. The combined population for the next two is about 50 million people. So let's do the math. Let us suppose that just 1% of the population becomes infected with Ebola (in the Ivory Coast and Ghana). That gives 500,000 people. That would be a huge leap in the number of ebola infections.

    So it suddenly becomes extremely clear why the Director of the CDC wants to "stop Ebola at its source". And also why the USA has deployed 4,000 troops to the area to help curb this outbreak.

    The challenge is a little more severe than the numbers tell. By the time that 500,000 people would be infected with Ebola (hypothetically), there exists some finite chance that the virus could mutate. And the next version of Ebola, could (in principle) be more contagious. There is no proof of this possibility, because mutation is always a random process. But if I sit down and crunch the numbers for typical mutations for Ebola, the risks grow considerably when hundreds of thousands of people (or millions) are infected. So this thought crystallizes the problem. It is rather important that the disease be stopped now ... not later.

    Pete Pollock, Redondo Beach, CA

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    1. To be sure, your calculations generally make sense and are scary, which is why, as you say, it needs to be contained at its source. Will Liberians go to Ghana? I checked the 2010 census and the number of Liberians/Sierra Leonians/Guineans living in Ghana is very small. People are more likely to want to go to the bigger economy of Nigeria, and they have, in fact, closed the doors for the moment, as has Senegal.

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  2. You know what - I just saw a news article that said Liberians have indeed goen to Ghana. In fact, I cant blame them. I would do exactly the same thing if I was in their shoes. The problem however, is that thay are now "trapped" in Ghana. Many airplane flights have been cancelled. And a lot of roads are restricted. So they cannot get back to Liberia.

    As far as infected people going to the Ivory Coast or Ghana ... good question. Probably many would not for tribal reasons - they have no support base. But if the virus spreads to the border area, then that may be a different story. It is a little furstrating that there is an information "blackout" operating, and maps of the infected zone (in Africa) are not easily available. I dont know if this is a deliberate policy, or just the standard "fog of information" that always affects Africa :-)

    Pete

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