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Chronology of Ebola Virus Disease outbreaks, 1976-2014

on Tue, 06/10/2014 - 04:01

The previous blog post Ebola virus disease outbreak, West Africa, 2014 presented the current situation of the outbreak of Ebola virus disease (EVD) that is currently taking place in Guinea, Sierra Leone Liberia and Nigeria. Some readers requested additional information about the number of outbreaks of EVD in history and affected countries, so I decided to visualized the chronology of Ebola outbreaks.

The data used in the visualization bellow comes from the Fact sheet N. 103, Ebola virus disease and the Ebola virus disease outbreak 2014 updates and Situation Report: Ebola response roadmap published by The World Health Organization (WHO). The map shows all countries affected by outbreaks and label displaying the number of outbreaks occurred in each country. To the right-side of the map, the complete list of Ebola outbreaks (a total of 26) sorted in ascending order by year of occurrence is presented. Hover the mouse over the affected countries in the map to get additional information. Click on any affected country on the map to select and filter outbreaks on the list. Click on any row of the list to highlight the affected country in the map.  

The first outbreak of Ebola virus disease was reported in Democratic Republic of Congo in 1976, in a community near to Ebola River, that is the reason of its name.That was a devastating outbreak with 318 cases and 218 deaths for a case fatality ratio of 88%, one of the most deadly outbreak in history.

Since 1976, 26 outbreaks of Ebola virus has occurred in ten countries of Africa, including Democratic Republic of Congo, Sudan, Gabon, Cote d'Ivoire,  South Africa, Uganda. Congo, Guinea, Sierra Leone and Liberia; one of America, United States of America and one of Europe, Spain.

Democratic Republic of Congo is the country with the highest number of outbreaks (7) followed by Uganda which has been affected by five outbreaks.All these outbreaks have presented a high level of severity with case fatality rate in the range of 25% (Uganda, 2007) to 90% (Congo, 2003), excluding those outbreaks with cero deaths (0% fatality) and those with only one case that died (100% fatality). as considered extreme situations.

The current outbreak initiated and reported in Guinea on March 2014 that is also affecting Sierra Leone, Liberia, Nigeria, Senegal, Mali, United States of America and Spain is the most severe and deadly outbreak so far taking into account the cumulative number of cases and deaths. As illustrated by a tool to track the Ebola virus disease outbreak in West Africa, as of December 7th 2014 the World Health Organization (WHO) has reported 17,942 confirmed, probable and suspected cases including 6,388 deaths for a case fatality rate of 36%. Senegal and Nigeria have been declared free of EVD transmission. A forecast of the cumulative number of Ebola cases in countries with widespread and intense transmission (Guinea, Liberia and Sierra Leone) helps to see the expected number of cases in the next weeks assuming the conditions remain similar to the past weeks. 

On August 27th, 2014, WHO informed about a Ebola virus outbreak in Democratic Republic of Congo with 24 cases and 13 deaths and on September 2nd 2014, a virological analysis confirmed that this is separated and independent event from the current Ebola outbreak in West Africa, having the Zaire virus strain, in a lineage most closely related to a virus from the 1995 Ebola outbreak in Kikwit, Democratic Republic of Congo. As of November 9th, this outbreak has a total of 66 cases (38 confirmed and 28 probable) including eight cases among health-care workers (HCW). In total, 49 deaths have been reported, including eight among HCW. 

References:

1.- WHO. Ebola viurs disease. Fact sheet No 103. Updated September 2014.World Health Organization (WHO). [Available online]
2.- CDC. Outbreaks Chronology: Ebola Virus Disease. Centers for Disease Control and Prevention (CDC), Atlanta, USA. [Available online]

Related content

P.S. The visualization of this article was selected by Tableau Public as Visualization of the Day on June 10th, 2014.

Tableau Public Visualization of the Day, June 10th, 2014

Comments

Anthony Borelli's picture

Um.. Where's the United States?

martiner's picture

Anthony,

Thanks for your question.

As informed on Septerber 30 2014 by the Center for Disease Prevention and Control (CDC) and Texas Health Department, the Pan American Health Organization (PAHO) and then on October 1srt 2014 by the World Health Organization (WHO), the Ebola case diagnosed and reported in the United States of Americas is a confirmed imported case. 

The Centers for Disease Control and Prevention (CDC) confirmed today, through laboratory tests, the first case of Ebola to be diagnosed in the United States in a person who had traveled to Dallas, Texas from Liberia. The patient did not have symptoms when leaving West Africa, but developed symptoms approximately four days after arriving in the U.S. on Sept. 20.

The person fell ill on Sept. 24 and sought medical care at Texas Health Presbyterian Hospital of Dallas on Sept. 26. After developing symptoms consistent with Ebola, he was admitted to hospital on Sept. 28. Based on the person’s travel history and symptoms, CDC recommended testing for Ebola. The medical facility isolated the patient and sent specimens for testing at CDC and at a Texas lab participating in the CDC’s Laboratory Response Network. CDC and the Texas Health Department reported the laboratory test results to the medical center to inform the patient. A CDC team is being dispatched to Dallas to assist with the investigation.

This situation does not mean there is a current or active outbreak of Ebola virus disease in the United States of America. For this reason, United States of America is not included as a country with Ebola virus disease outbreak in this post. 

Jessica's picture

It might be prudent to update this post (specifically the visualization), as there are people currently using it to support a misleading claim that "ebola has only killed 4000 people in the last 40 years"... not only are they basing it on outdated data, but they are ignoring the fact that almost all of them have occurred in the last 7 months. Obviously that's your call, but I thought you should know.

Great blog, by the way. Kudos.

- Jess

martiner's picture

Jessica,

Thanks for your comment and suggestion.

As the title suggest, this data visualization has the purpose to show the chronology of Ebola virus outbreaks irecorded n history. As you realized the title reflects the period -from 1976 where the first outbreak was reported in Democratic Republic of Congo to the current outbreak in West Africa. Details about avery ourbreak is given geographically -in the map- and in a table informing metrics such as total number of cases and desths, virus circulating and the case fatality rate.

Since this blog post and data visualization was published, I have periodically updated the data of the current/active outbreaks based on official reports from the World Health Organization (WHO). As you may see the data visualization present the exact cumulative number of cases and deaths reported by the Situation Report on Ebola virus disease dated October 1st, 2014. Writing this answer, I've just noted that WHO has published today (Otober 4th, 2014) the latest Situation Report on Ebola virus disease dated October 3rd, 2014, so now it is time to update the dataset of this visualization.

I'm sad to know from you that there are people using this data visualization claiming that Ebola virus diseases "has only killed 4000 people in the last 40 years" but as you may realized it hard to manage how others interpret and misuse the information.

In order to have a more complete information about the current and active Ebola virus disease outbreak, I suggest also reading two addictional blog posts from Health Intelligence:

1.- "Tracking the Ebola virus disease outbreak,West Africa 2014" and

2.- "Predicting the Number of Cases from the Ebola Virus Disease Outbreak in Countries with Widespread and Intense Transmission

Jessica's picture

it would appear the visualization was in the process of being updated as i commented last, my apologies. it now reflects more current data and no longer says it's from june of 2014---it now simply says 2014.

sabrina's picture

A lot of articles and friends of mine have been saying that this virus will soon be or is airborne but I don't think is or nor it ever be since this virus was around in 1976 i t would already have been airborne. Do you think that this virus will soon become airborne?

martiner's picture

Dear Sabrina,

Probably I'm not the right person to answer your question because I'm a public health professional and not a virologist. 

I would answer your question by refering to information provided by WHO in the document "What we know about transmission of the Ebola virus among humans" published October 6, 2014. I'm going to quote a couple of paragraphs that give the answer:

Speculation that Ebola virus disease might mutate into a form that could easily spread among humans through the air is just that: speculation, unsubstantiated by any evidence.

This kind of speculation is unfounded but understandable as health officials race to catch up with this fast-moving and rapidly evolving outbreak.

Best

Ramon

Ian Mackay's picture

Nothing is 100% (apart from death) but vanishingly small chance of this possibility.

I recommend the following reading for why...

1. http://www.who.int/mediacentre/news/ebola/06-october-2014/en/
2. http://virologydownunder.blogspot.com.au/2014/09/the-wind-beneath-my-ebo...
3. http://virologydownunder.blogspot.com.au/2014/08/ebola-virus-may-be-spre... (and its linked companion post)

Best,
Ian

martiner's picture

Hi Ian,

Thank you so much for providing valuable information to help answering the question posted by Sabrina.

Best
Ramon

Eustace Eater's picture

I find the statistics of Ebola interesting. Why are the Western governments and their controlled media hyping it? What's up with the US military going into resource-rich Africa to "fight Ebola"? See the statistics below.

DAKAR, Sept 26 (Reuters) - The death toll from an outbreak of Ebola in West Africa has risen to at least 3,091 out of 6,574 probable, suspected and confirmed cases, the World Health Organization said on Friday. - Reuters in Huff Post - October 6, 2014.

Total number of deaths from Ebola virus from 1976 through 2013 was 1,430 out of 2,216 cases. - CDC http://www.cdc.gov/vhf/ebola/outbreaks/history/chronology.html

(The above data from the CDC includes 16 cases of Ebola-Reston virus in humans. Ebola-Reston virus has come from monkeys in the Philippines sent to the USA for research purposes.)

Reston virus (abbreviated RESTV) was first described in 1990 as a new "strain" of Ebola virus (EBOV), a result of mutation from Ebola virus. It is the single member of the species Reston ebolavirus, which is included into the genus Ebolavirus, familyFiloviridae, order Mononegavirales. Reston virus is named after Reston, Virginia, US, where the virus was first discovered. - Wikipedia

Jun 27, 2012 (CIDRAP News) – Working with admittedly sparse data, a research team led by the US Centers for Disease Control and Prevention (CDC) has estimated the global death toll from the 2009 H1N1 influenza pandemic at more than 284,000, about 15 times the number of laboratory-confirmed cases. - CIDRAP, University of Minnesota.
http://www.cidrap.umn.edu/news-perspective/2012/06/cdc-estimate-global-h...

There were an estimated 207 million cases of malaria in 2012 (uncertainty range: 135 – 287 million) and an estimated 627 000 deaths (uncertainty range: 473 000 – 789 000). 90% of all malaria deaths occur in sub-Saharan Africa. - WHO, 2013. http://www.who.int/malaria/media/world_malaria_report_2013/en/

Chris's picture

Hi, just would like to ask why there is a 15 year gap in outbreaks between 1979 and 1994?
Many Thanks

martiner's picture

Hi Chris,

I don't have an answer to "why" there is not outbreaks between 1979 and 1994, but what I can say is that based on documented evidence any Ebola outbreak has been recorded or publicly documented between Sudan 1979 and Gabon 1994.

I suggest to review the References of the blog post for a more complete information about the Ebola outbreaks with human-to-human transmission.

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