Tuesday, May 30, 2017

Ebola 2017

Photo 1: Ebola Poster. Source
Ebola epidemic has been the point of discussion in many of my past blog posts. Considering that the previous lethargic early response was met with a devastating outbreak, the global health community is currently monitoring a possible resurgence of the Ebola virus in the Democratic Republic of Congo (DRC). As of on May 26, 2017, I gather from reports that there have been at least 43 cases of suspected Ebola. Of these only two cases have been positively confirmed in a laboratory. There are 4 probable and 16 suspected cases and a number of approximately 400 contacts. The reported cases currently remain confined to Likasi. Regions of hot interest are currently Nambwa, Muma, Ngayi, Azande, Ngabatala, Mobenge and Mabongo. This is the 7th documented outbreak of Ebola in the DRC since the discovery of the virus in 1976.

Fig 1: Likasi, Democratic Republic of Congo.
Source 
The first case (Most probably the index case), was a 45-year-old hunter male seen on 22 April 2017 from Bas Uele Province in the north of the Democratic Republic of the Congo (DRC), bordering the Central African Republic. Currently, nothing much is known about the genetics of the strain and the outbreak appears to be very limited by geography. Based on an RT-PCR from one of the isolate, it appears that the virus is related to Zaire subtype.

A very interesting perspective is that the Ebola this time has the possibility of involvement of Pig. Though such a link is not yet established, here is the argument. A smoking gun is that 84 pigs have recently died in the epicentre of the current outbreak. There is also some possible evidence that Ebola- Zaire strain can infect and manifest in pigs and can be transmitted between them. They can further transmit it to primates. A counter thought is that considering huge deaths of pigs, experts suggest that there should have been more human cases. As epidemiologist Fabian Leendertz comments, “I’m doubtful that the pigs actually carry Ebola, but we have to test them".

Photo 2: Merck Ebola Vaccine
Recombinant vesicular stomatitis virus–Zaire Ebola virus (rVSV-ZEBOV) is a product of Merck, which was successfully tested earlier in 2015- 2016. The vaccine consists of vesicular stomatitis virus (VSV), which has been genetically engineered to express a glycoprotein from the Zaire Ebolavirus leading to a neutralising antibody immune response

The earlier clinical trial showed that of the 5837 people who received the vaccine, no Ebola cases were recorded 10 days or more after vaccination. In comparison, there were 23 cases 10 days or more after vaccination among those who did not receive the vaccine. That's a 100% coverage. However, questions were raised since the trial was conducted during the dying phase of the epidemic. It is also not know how long does the immune memory stays. The vaccine is unlicensed and ethics committee at the DRC has approved a clinical study of rVSV-ZEBOV Ebola vaccine, in the hope that it would arrest the outbreak.

References:

Ebola Virus Disease - Democratic Republic of the Congo: External Situation Report 14 (28 May 2017). Published on 28 May 2017. Link

Kai Kupferschmidt, Jon Cohen. Could pigs be involved in Congo's new Ebola outbreak? Link

Henao-Restrepo A, Camacho A, Longini I, Watson C, Edmunds W, Egger M et al. Efficacy and effectiveness of an rVSV-vectored vaccine in preventing Ebola virus disease: final results from the Guinea ring vaccination, open-label, cluster-randomised trial (Ebola Ça Suffit!). The Lancet. 2017;389(10068):505-518.

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