Ebola’s Predecessors: What These Five Epidemics Can Teach Us

Media portrayals of Ebola paint a stark picture: images of patients treated by doctors in hazmat suits, mass unmarked graves, news broadcasts listing staggering statistics about the most recent outbreak in West Africa. The media and political hype is for good measure—with no cure and a fatality rate of up to 90%, Ebola is one of the most deadly illnesses on the planet and, as this New York Times graphic starkly illustrates, the current outbreak is much more deadly than in the past.

One of the biggest problems with Ebola is misinformation. The most important first step is understanding the virus and its effects as well as examining what makes this disease and outbreak different from past outbreaks. In fact, despite the recent outbreak, Ebola is not very contagious but is very infectious. It’s less contagious than many other illnesses and is transmitted by body fluids (similar to HIV and hepatitis), but Ebola can take up to 21 days to show symptoms (known as the “latency period”) even though a person is not contagious until symptoms are shown. Once symptoms are shown, as Dr. Sanjay Gupta says, “it’s the stuff out of horror movies.”

While we’re still learning more about Ebola, it’s helpful to examine the epidemic’s predecessors—these five worldwide epidemics provide lessons for how society can respond to Ebola and future outbreaks.

1) Bubonic Plague or ‘Black Death’

The Bubonic Plague was one of the most notorious plagues and diseases in history—it was spread by insects and fleas from rats but was also airborne. Extremely deadly, it’s estimated to have killed 30-60% of Europe’s population.

Currently, the Ebola outbreak pales in comparison to the devastation of the Bubonic Plague. Especially as Ebola is not airborne, the established hospital system of the United States and Europe are well-equipped to contain the disease. The Bulletin of the World Health Organization confirmed those expectations in analyzing individuals exposed to Ebola patients (and in confined spaces), showing there was no spread of the illness. However, Ebola remains highly infectious, as the study showed a fivefold increase in individuals who provided nursing care of infected patients. This highlights the importance of proper hygiene and protection when providing care to infected individuals.

2) Typhoid

Typhoid fever is a deadly illness with many historical outbreaks and is spread by contaminated food or water. The disease is especially dangerous following disasters or in times of overcrowding. In 1903 and then 1924, typhoid epidemics killed hundreds and infected thousands in the US. The 1903 epidemic coincided with the infamous ‘Typhoid Mary’ who may have been responsible for up to 50 deaths. This Canadian Medical Association Journal article by Dr. Venita Jay describes the epidemiology in tracking down Mary; as Dr. Jay notes, Mary was in fact a carrier for the disease and one of the first success stories of identification, control, quarantine, and prevention from additional spread of a highly infectious illness.

Today, an existing typhoid vaccine is found to be successful 95% of the time and typhoid is easily detectible in contaminated water. There are only an average of five cases per million people in developing countries. Still, a study by Watson, Gayer, and Connolly in Emerging Infectious Diseases reports an increase in risk and a disproportionate effect in developing countries where a lack of infrastructure, resources, and preparedness (especially for population displacement) tend to exacerbate the spread and control of such diseases.

Typhoid provides a good comparison to Ebola in terms of risk. While infecting over 21 million people per year, there are only an average of 5700 cases per year in the US, according to the CDC. Most of these cases were reported in people who recently traveled to another country. According to a WHO report, the incidence is over 50 per 100,000 people in most of the developing and underdeveloped world, but far less than 1 per 100,000 people in the US and Western Europe.

3) Influenza (the common flu)

The flu has long been one of the most consistent epidemics worldwide. At its worst, the flu killed over 50 million people including over 600,000 in the United States between 1917-1918. Today, despite many variations, the flu is highly controlled and most deadly in the immuno-suppressed (those with AIDS, undergoing chemotherapy, or other immuno-deficient illnesses/situations), elderly, and children. Vaccines including the yearly flu shot exist, and last year only 170 pediatric cases of the flu were fatal in the United States.

The flu is also at the forefront of epidemiology. Recent studies such as “Twitter Catches the Flu: detecting influenza epidemics using Twitter” have shown the successful tracking of influenza in near real time via social media. The study’s authors note:

“More than a thousand messages include the word “influenza” each day (Nov. 2008 – Oct. 2009). Such a huge data volume dwarfs traditional surveillance resources. Real time: Twitter enables real-time and direct surveillance…extremely suitable for influenza epidemic detection because early stage detection is important for influenza warnings.”

The paper elaborates that while at times Twitter may provide inaccurate information, trigger words are still accurate and helpful in showing that influenza is nearby, providing profound benefits in terms of disease control and prevention.

4) Severe Acute Respiratory Syndrome (SARS)

Much like Ebola today, SARS took the world by storm in 2003, spreading globally to more than 24 countries on almost every continent before it was controlled—there have been no reported cases since 2004. A decade ago, the global response to SARS exemplified the effectiveness with which epidemics could be handled; those fearing Ebola should seek reassurance in the capability of international organizations to identify and control the spread of epidemics like SARS.

SARS remains a unique case: the disease is still a new phenomenon and recent studies even suggest poor air quality may contribute to the risk of infection. As cited in “Modeling Respiratory Illnesses with Change Point: A lesson from the SARS epidemic in Hong Kong,” government and public awareness are also factors, though studies continue to be performed and lack of information from some affected countries means many studies are still without conclusions.

5) Malaria

3.4 billion people, or half the world’s current population, are at risk for contracting malaria, according to the WHO. Malaria, while not a contagious disease due to its transmission by mosquito, has seen one of the greatest reductions in death rates. Still, malaria accounts for one of every six child deaths in Africa, killing one child every second, though this has been reduced by 25% from 2000 to 2010. Thanks to increased awareness and global assistance, malaria is becoming more controlled and is one example of how education, awareness, and aid can provide significant benefits in regards to disease control, identification, and prevention.

One recent study in Malaria Journal found that school-based education programs not only had a significant impact on children and in the school, but also on communities thanks to using children as health messengers. The study concluded that:

“School-based malaria intervention engaging school children as health messengers had a substantial impact not only on school children, but also on community adults in improving knowledge on cause and prevention and bed net impregnation practices. The improved knowledge and practices could be associated with the decrease in the malaria prevalence observed in school children…[Results]: After the intervention, the misperception that malaria has multiple causes was significantly improved, both among children and community adults. Moreover, the community adults who treated a bed net with insecticide in the past six months, increased from 21.5% to 50.0% (p < 0.001). Parasite prevalence in school children decreased from 30.9% to 10.3% (p = 0.003). These positive changes were observed only in the intervention group.”

The role of education is clearly applicable to the current Ebola outbreak, as highlighted in recent WHO community education outreach.

Ultimately, what do these epidemics teach us about Ebola? For starters, the current outbreak would be unlikely to have the same impact in the US, Western Europe, or other developed countries where education about the disease may be easier to institute thanks to funding initiatives both public and private. As evidence of this, on September 30, 2014 Bill Gates pledged $50M to emergency Ebola aid, echoing President Obama’s concern that the crisis “is a marathon, but you have to run it like a sprint.” Mutations of the virus are always a concern and stopping this particular strain from changing course is a critical piece of what will otherwise become an ever-urgent crisis.

Image credit: NIAID via flickr