Friday, October 17, 2014

Ebola, the latest pandemic

According to the World Health Organization there are currently 1,000 new Ebola cases per week, but the WHO now estimates that this will rise to 10,000 new case per week by the end of the year.

The WHO has also warned that the death rate in the current outbreak has risen to 70%. Previously it had estimated the Ebola mortality rate at around 50%. In contrast, in the past flu pandemics the death rate was approximately 2%. Some estimates of the death rate for Ebola place it as high as 90%.

Ebola virus disease, which was formerly known as Ebola hemorrhagic fever, is a severe, often fatal illness. It is one of the world’s most virulent diseases. The infection is transmitted by direct contact with the blood, body fluids and tissues of infected animals or people.

Severely ill Ebola patients require intensive supportive care. During an outbreak, those at higher risk of infection are health workers, family members and others in close contact with sick people and deceased patients.

Unfortunately, the West African countries that have experienced the most cases (about 8,000 by now) and the most deaths (approaching 5,000 currently) have been unable to control the outbreak in their countries. They lack the resources to control the spread of the disease and have difficulty controlling their own citizens.

The number of Ebola cases and deaths, as of October 15, 2014

A pandemic has been defined as a global epidemic -- an epidemic that spreads to more than one continent. By this definition, Ebola may already be a pandemic since it already found on more than one continent, even though it not yet epidemic except in Africa.

A pandemic is determined by how the disease spreads, not how many deaths it causes. In order to be a pandemic a disease must also be infectious. Ebola is highly infectious, It is spread by direct contact with infected animals and people. Some have suggested that it may be spread in other ways as well, although there is as yet no evidence for this.

In West Africa the number of deaths caused by Ebola is predicted to grow exponentially if no way is found to stop the spread of the disease. The international community is now very much involved in that region in order to help stop spread of Ebola, but these efforts have thus far been unable to do so.

The WHO has a six-stage classification that describes the process by which a new virus moves from the first few infections in humans through to a pandemic. The process ends with a pandemic when infections from the virus have spread worldwide and it might then be out of control until it is eventually stopped.

Bubonic plague

There have been a number of significant pandemics recorded in human history. Perhaps the most well known one is the Black Death which started in Asia and was responsible for an estimated 75 to 200 million deaths worldwide over several decades during the 14th and 15th centuries. Since then it has recurred in Europe and elsewhere, most recently in China in the 19th century.

Today it is commonly assumes that Black Death was a bacterial bubonic plague pandemic caused by flea bites and spread by rats. But there is evidence to the contrary that the Black Death also killed a high proportion of Scandinavians who lived in a region that was too cold for fleas to survive.

The Biology of Plagues (Cambridge University Press, 2005) helps to explain this mystery. It analyzed 2,500 years of plagues and concludes that the Black Death was caused by a viral hemorrhagic fever pandemic similar to Ebola. If this view is correct, the future medical and economic impacts from Ebola have been vastly underestimated.

The authors, Dr. Susan Scott, a demographer, and Dr. Christopher J. Duncan, a zoologist, contend that the threat of plagues such as AIDS and Ebola is constantly with us. They point out that the Bible used the term "plague" to describe a catchall of afflictions resulting from divine displeasure.

The researchers discern “Four Ages of Plague”, including the "Plague of Athens" from 430 to 427 BC that killed about a third of the city; the "Plague of Justinian" from 542 to 592 AD that killed 10,000 a day in Constantinople; the Black Plague from 1337 to 1340 AD that killed a third of Eurasia; and a series of plague outbreaks in Europe from 1350 to 1670 that killed about half of the populations of a number of cities.

The book combines modern concepts of epidemiology and molecular biology with computer-modelling. By applying these to the analysis of historical epidemics, the authors show that these plagues were not outbreaks of bubonic plague but a viral pandemic similar to Ebola.

The Athenian plague, for example, was similar to the Black Death and the current Ebola pandemic. Like Ebola, this plague is believed to have originated in Africa and then traveled northward. 

The bubonic plague, which was first recorded in China about 37 AD and still is a worldwide public health problem, with thousands of cases each year, is a very different disease and should not be confused with the viral plagues that Biology of Plagues deals with.

An inguinal bubo on the upper thigh of a person infected with bubonic plague.

The first symptom of bubonic plague is a mild and non-alarming fever. Bubonic swellings follow within a few days. Sufferers either go into a deep coma or become violently delirious, paranoid and suicidal. Most victims die within a few days. Before antibiotics, the appearance of black blisters was considered a sign of imminent death.

Bubonic plague is very seldom spread from person to person. The disease needs a rodent population, usually rats, to carry fleas to spread the infection to humans. However, once the local rats die out from the infection, human infections tend to tail off.

In the 2011 book The Black Death in London, Barney Sloane, an archaeologist who has worked on medieval sites for the Museum of London, documents the 1348-49 epidemic that killed two thirds of the city and argues that this could not have been bubonic plague. He writes:
The evidence just isn't there to support it. We ought to be finding great heaps of dead rats in all the waterfront sites but they just aren't there. And all the evidence I've looked at suggests the plague spread too fast for the traditional explanation of transmission by rats and fleas. It has to be person to person – there just isn't time for the rats to be spreading it.
Bubonic plague is a bacterial disease that is spread by animals, while Ebola and its kindred diseases is viral and spread especially through person-to-person contact. These diseases should not be confused.

Today scholars remain divided about the nature of the Black Death. Many would still argue that it was bubonic plague. Whether that was the case or not does not detract from the argument that a viral hemorrhagic disease similar to Ebola may have been responsible for many plagues in the past.

This argument offers a reason for hope. It means that Ebola can be stopped. It has stopped in the past and it can be stopped again today if the necessary measures are taken.

Many people today are so frightened of Ebola that they want to quarantine parts of Africa by cutting off air travel with the countries that are currently infected. But, as the head of the Center for Disease Control in the US has argued, this would be ineffective since people would find other ways to travel to the rest of the world and this might make it even more difficult to track possible infected people.

Rather, I suggest that Western countries, because of the relative wealth, should fund the efforts to stop Ebola in West Africa. UN Secretary-General,Ban Ki-moon has issued another urgent appeal for funds to help fight Ebola. He said a $1bn trust fund he launched in September has received just $100,000 so far (from Columbia).

Ban joins a growing chorus of world leaders who have criticized the global effort to tackle the Ebola outbreak. Donors have given almost $400m to other UN agencies and aid organisations directly, but these funds are still inadequate. Much more money and other aid is needed immediately.

Ebola is the latest pandemic, but the world must not panic in fear. Ebola can be stopped, but that will require the best efforts from many countries to fund these efforts and provide the necessary manpower. 

Sierra Leone, Guinea and Liberia are unable to do so on their own. They need help urgently. If that help is not provided soon, Ebola threatens to become one of the worst pandemics of all time. The medical and financial consequences of the latest pandemic may exceed that of the Black Death.

Let us pray earnestly that that does not happen.

1 comment:

  1. The best historical fiction book I have read on dealing with a plague is "Year of Wonders by Geraldine Brooks. (based on a true story). Written from the perspective of an 18 year old woman in the town of Eyam, England which decided to shut its borders in order to contain the plague in their town. It shows the variety of ways people deal with large numbers of people sick and dying in a community. While this is sounds like a depressing book, it is actually very hopeful.