View Mobile Site

Ebola, math and next steps

Posted: October 20, 2014 2:39 p.m.
Updated: October 20, 2014 2:36 p.m.
Phong Pham, ©istockphoto.com/Bumbasor

The world may be facing the worst Ebola outbreak ever recorded. According to the Centers for Disease Control and Prevention, as of Oct. 15, there have been 8,376 cases and 4,024 people have died. These figures are both probably low because some people contract the disease and die of it without being diagnosed.

Ebola has been in the news. But much of the news has not offered background information about the disease.
The world may be facing the worst Ebola outbreak ever recorded. According to the Centers for Disease Control and Prevention, as of Oct. 15, there have been 8,376 cases and 4,024 people have died. These figures are both probably low because some people contract the disease and die of it without being diagnosed.

After sequencing this Ebola strain, scientists found 98 percent similarity with the Ebola-Zaire strain, which in past outbreaks killed around 70 percent of those infected. In the current outbreak, its mortality rate is close to 50 percent.

Scientists discovered Ebola during 1976, yet it is believed that it has existed for thousands of years. Consequently, we are not certain that the current outbreak is the worst in history.

According to The Telegraph, the 2014 outbreak started when the virus infected a child in December 2013. The child soon died, but people who were in close contact or attended the funeral got infected. Not all people that attended the funeral belonged to the village of the child, so when they went back to their villages, they infected more people. This cycle repeated itself until Ebola reached big cities such as Freetown and Monrovia.

Some factors that help the virus spread rapidly in this part of Africa are, first, that people can move freely through Guinea, Sierra Leone and Liberia. Second, according to Dr. Chowell-Puente from Cornell University, for every two weeks that the outbreak went untreated, there could have been an approximate doubling of the final epidemic size. During 2014, the outbreak wasn’t diagnosed as a pandemic until 14 weeks after the first death.

Let’s use this math and take a look at the Ebola outbreaks in Congo (1995) and Uganda (2000). The time from onset to first diagnosis in both outbreaks was 150 days. Containment measures in Congo started after almost the same number of days as in Uganda. In both these cases, the containment measures started at the time the epidemics hit their strongest points. In each of these countries, the officials managed to contain the epidemics.

Health organizations are trying quickly to create mathematical models that help us understand how Ebola spreads. Mathematicians forecast that if containment measures continue as they are, there may be up to 20,000 cases by the end of the year. We actually made our own estimations and calculated as many as 26,000 cases, almost all in Africa.

A very important epidemiological indicator is the reproduction number, it measures the average number of people that an initial patient may infect. A health care intervention aimed at disrupting an outbreak’s spread is considered successful if the reproduction number drops to less than one. According to Richard Althus from the University of Bern, by the end of August, the reproduction number ranged from 1.5 to 2.5, meaning that the epidemic was going to grow, as actually happened.

Other scientists tried to estimate the likelihood of the virus jumping outside Africa by studying international commercial airline flights. They found, several weeks ago, that the probability of Ebola spreading outside Africa was small, less than 5 percent, except for the U.S., U.K., Belgium and France. They were right about the U.S.

This Ebola epidemic, like the others, has been a disaster for a number of African societies. According to the World Bank, it has already cost about $359 million for Sierra Leone, Liberia and Guinea. The figures could range from between 2 and 12 percent of gross national product for these countries. Likewise, the World Bank has estimated the total loss to West Africa could climb to as much as $32 billion by the end of 2015, in the worst-case scenario.

Perhaps soon it will be time for some Western business people, once the plague has subsided and a semblance of health has been restored, to make investments in the three most influenced countries to help bring their economies into a stronger position and create some jobs. Of course, the main roles will be played by NGOs and governments as health care needs are addressed. But others will also have a responsibility soon, as well.

(John Hoffmire is director of the Impact Bond Fund at Saïd Business School at Oxford University and directs the Center on Business and Poverty at the Wisconsin School of Business at UW-Madison. He runs Progress Through Business, a nonprofit group promoting economic development. Mario Mercado, Hoffmire’s colleague at Progress Through Business, did the research for this article.)

Comments

Commenting not available.
Commenting is not available.


Contents of this site are © Copyright 2017 Chronicle Independent All rights reserved. Privacy policy and Terms of service

Powered by
Morris Technology
Please wait ...