Ebola Diaries: The First Cases of Ebola Originally Thought to be Caused by Lassa Virus

Mobile laboratory in Guekedou, where laboratory personnel inactivates Ebola virus to analyze the samples. Photo courtesy of the World Health Organization/Stéphane Saporito 

 
The World Health Organization (WHO) is publishing a series, "Ebola Diaries," with first-person accounts of WHO staff and others deployed to the field for Ebola response since the first cases were reported in West Africa on 23 March 2014. This first diary, by Dr. Pierre Formenty, recounts how he received word of a cluster of cases in Guinea thought to be caused by Lassa virus but with features that made him very concerned that this was not Lassa fever but possibly Ebola virus disease, and how urgent testing revealed it was in fact the first-ever outbreak of Ebola Zaire in West Africa.

Dr. Pierre Formenty has spent the past 20 years investigating communicable disease outbreaks, including many Ebola outbreaks. In mid-March 2014, while in Kinshasa, training healthcare workers to safely take and dispatch blood samples that may contain ‘dangerous pathogens’ such as Ebola virus, he began receiving emails that got him worried.

They described a cluster of cases in Guinea thought to be caused by Lassa virus. But features of the cases and how they occurred made him very concerned that this was not, in fact Lassa fever but possibly Ebola virus disease. Here, Formenty describes what it was like to realize that Ebola Zaire had arrived for the first time in the heart of West Africa.

“We received the first emails on the Guinea event on March 14. During the weekend, I was traveling in the DRC [Democratic Republic of Congo] for a training course on how to take blood samples in Ebola. It was a three-day training course.

"The first emails received from Guinea were mentioning suspected cases of Lassa fever. The first emails just gave numbers (nine cases including eight fatalities) but on 18 March we had a more detailed description. I was a little irritated because in the description they were talking about transmission following funerals and among health care workers which is something that you have for Ebola but is rare for Lassa fever.

"So I was thinking what is happening there? This is maybe not Lassa fever this is maybe something else. We have to be prudent; we have to follow this one. I returned to Geneva but continued to follow this carefully.

"It was MSF who sent the samples taken by WHO and the MOH (Guinea Ministry of Health) to France for diagnostic investigation. So I called Paris and said look, test for Lassa fever but please also test for Marburg and Ebola because of this story about people being infected after funerals and also doctors and nurses being infected. Lassa in the classical setting does not spread like fire. The transmission is less than you would see with Marburg or Ebola.

"On the early morning of March 21, I got the answer: it’s positive for filovirus. So it’s maybe Marburg or maybe Ebola. Marburg was not my first choice because we have the Ebola Cote d’Ivoire (the Tai forest strain had caused one case in Cote d’Ivoire in 1994) and for Marburg you need a lot of specific circumstances - you need large Roussettus bat colonies that live in caves - and the open-cut style of mining used in Guinea would not support these types of large bat colonies. So I was thinking more about Ebola right from the start.

"I think it was on March 21 around 7 p.m. that it was identified as Ebola but it was not until Saturday late evening I got the text that confirmed it was Ebola Zaire. I was sitting in a restaurant and I remember thinking this was the worst case scenario for the country. No-one wants this to be Ebola - and if it is Ebola they want it to be the Cote d’Ivoire strain, because the only case of that survived. There is a lot of stigma around Ebola Zaire.

"Although it was the worst case scenario for the country, the good news was that we have in principal good control measures that have been effective in many countries.

WHO staff at a partners meeting on the Ebola outbreak, Guinea. Photo courtesy of WHO/Marie-Agnès Heine

"During Sunday we swung into action. Because of this meeting in the DRC we had developed many documents, training packages and lists of equipment related to Ebola outbreak investigations; we shared them with the country together with updated SOPs (standard operating procedures) for Ebola outbreak control.

"On March 21, when we knew it was filovirus, we had made arrangements to send the PPE (personal protective equipment). On the Monday we organized who was traveling to help investigate and control the outbreak and two international laboratory teams arrived in the country that week: one from Institut Pasteur Dakar was based in Conakry and one from the EU Mobile Lab consortium was deployed in Guéckédou. On March 27, the first cases were detected in Conakry.

"We knew since day one that we needed to protect Sierra Leone and Liberia. Both countries were informed in real time about the event and the laboratory findings, participating in all teleconferences with Guinea.

"This outbreak always looked a little strange to me. I didn’t see the same thing when I looked at the numbers. The way the outbreak was sustained and not decreasing quickly. There was something wrong there. And the number of cases: in a few weeks it was increasing in Conakry -- more than 50 cases -- this was too much for a capital city. And 30 percent of the cases were healthcare workers. There was something that was different there."

Source: WHO