On the Origin of (a Virus) Species

I wrote a piece on the MERS coronavirus a while ago for the Cambridge University BlueSci magazine. The story has moved on since (with an increased number of cases in the Middle East, and the first infections recorded in the US, including human-to-human transmission), but it’s still a useful round-up of the beginning of the MERS story.

The full piece can be found at the BlueSci website (and in print), but here’s an excerpt I particularly enjoyed writing, even if it does stretch the term ‘animal reservoir’ to near breaking point:

When using the phrase ‘animal reservoir’, most imagine the animal kingdom spreading parasites and viruses via malarial mosquitoes, rabies-infected dogs, and Dustin Hoffman chasing a screeching ebolavirus- riddled capuchin monkey in the 1995 film, Outbreak. Not camels.

 

Associated Press Blog: Survivors of ebola face second ‘disease’: stigma

I aim to give Ebola virus and the current West African outbreak a proper write-up in the near future, but here’s a quick link to the Associated Press blog. The blog has an interesting piece about the stigma suffered by the virus survivors in Guinea.

It is perfectly understandable that the population is terrified of the disease, and to many, contact with the survivors of the virus is deemed too much of a personal risk. One of the most interesting parts of the piece is the way that health officials are trying to fight this public perception:

The most powerful tool to combat stigma is the way health care workers treat a discharged patient, said Corinne Benazech, the representative in Guinea for Doctors Without Borders in Guinea.

“The patient never leaves alone,” she said of when Ebola survivors leave their isolation wards, and health care workers individually shake hands with the survivor.

Discharged patients receive a certificate from the minister of health that states they are no longer contagious, said Tom Fletcher, an infectious disease physician with the World Health Organization who is working in Guinea.

There is a fascinating clinical addendum to surviving ebola: the virus can linger in surviving individuals. Immunologically protected sites within the body (parts of the body where the immune system cannot fully function) appear to clear the virus more slowly. Ebola virus has been found in such regions, including the testes, the anterior chamber of the eye (the fluid behind the cornea) and potentially the mammary glands (the discussion of this paper [open access] is useful here). Whilst the virus can persist in these sites, it is eventually destroyed. Condom usage and breast milk alternatives are used to prevent spread to partners and mother to child transmission.

Importantly, from the same paper cited above:

“The absence of EBOV [Ebola virus] in the urine, low prevalence on the skin, and rapid clearance from the saliva in surviving patients provides some reassurance that the risk of secondary transmission from casual contacts, fomites, or the sharing of toilet facilities in the home after discharge from the hospital is minimal.”

Bottom line: casual contact with surviving ebola patients is not risky.

Tom Fletcher from the WHO:

“These people should be celebrated, really, as opposed to stigmatized.”

 

Cited articles:

Associated Press Blog: Survivors of ebola face second ‘disease’: stigma – Apr. 27, 2014. Diallo B. and DiLorenzo S. http://bigstory.ap.org/article/survivors-ebola-face-second-disease-stigma

Primary literature: Assessment of the Risk of Ebola Virus Transmission from Bodily Fluids and Fomites. Bausch D, et al., 2007. J Infect Dis. 196 (Supplement 2): S142-S147. doi: 10.1086/520545

 

An additional foe in the Guinea Ebola outbreak: geography

From the Guardian today:

“We are facing an epidemic of a magnitude never before seen in terms of the distribution of cases in the country,” said Mariano Lugli, the co-ordinator of Médecins sans Frontières’ project in Conakry, the capital of Guinea.

The organisation said on Monday it had been involved in dealing with nearly all other recent Ebola outbreaks, mostly in remote parts of central African nations, but Guinea is fighting to contain the disease in numerous locations, some of which are hundreds of miles apart.

You don’t need an overwhelming number of sick individuals to hinder virus containment. If the sick are dispersed across the country a concentrated relief effort is going to be less effective. Neighbouring countries are trying to prevent the virus entering in the first place, with Senegal closing its Southern border into Guinea. However, note the following from ProMED-mail’s Jack Woodall:

“Senegal has closed its southern border with Guinea.” Anyone who has lived in Africa knows this is impossible. Extended families live on both sides of the frontiers and people travel across unhindered on local footpaths.

Ebolavirus spreads to Liberia

The Ebola Zaire outbreak in Western Africa as of 27/03/14
The Ebola Zaire outbreak in Western Africa as of 27/03/14 – ProMED Mail / Google

The New Dawn Liberia reports that six people have been taken ill with ebolavirus in Liberia, of which five have since died. It appears that the cases originate from Guinea, but came to Liberia for hospital treatment.

A note to add to my previous post regarding contagion and spread: it’s not just the countries in which the outbreak originated that need to be watchful.

Threatwatch – 26 March 2014 – New Scientist

A nice roundup of the current ebolavirus outbreak in Western Africa in New Scientist.

Debora MacKenzie also raises an interesting question about whether an ebolavirus outbreak in an urban environment would give the virus a chance to mutate and become more contagious. Whilst an increased number of susceptible people would provide the virus with the ‘resources’ to mutate (i.e. more infections > more mutations > evolutionary selection for advantageous mutations), the comparison with avian influenza is a stretch. Avian Flu is a strain of a readily contagious, airbourne virus. Ebola transmission occurs through contact with infected body fluids; close physical contact is a requirement.

HIV, which is also mentioned in the article, provides a nice counter-point: it also spreads through contact with infected body fluids, but is of course now endemic in a number of countries. The difference to Ebola? Initial HIV symptoms are far more insidious and Flu-like. People spread the virus because they don’t know they have it. Ebola is a different story altogether. Haemorrhagic fevers are overtly scary diseases that hit around a week after infection. The ability for health enforcement to intervene in such an outbreak is very high because you can readily find out who is infected and separate them from susceptible, uninfected people.

So yes, the virus could evolve to more contagious in an urban environment, but the inefficient route of transmission the virus relies upon means that this would likely be a very slow process.

BBC News – Virus in Guinea capital Conakry not Ebola

BBC News – Virus in Guinea capital Conakry not Ebola.

Curiouser and curiouser. When most people think ‘killer viruses’ they think Ebola. The current haemorrhagic fever outbreak in Guinea started in February 2014 and has so far claimed 59 lives. A crucial aspect of ebolavirus outbreaks is determining what strain of virus is responsible. Unfortunately, signs currently point to this outbreak being caused by Ebola Zaire (ProMED), the strain with the highest case fatality rate (up to 90%).

The ebolavirus is spread between people by close contact with infected bodily secretions. Disease surveillance is key for interrupting its transmission, such as by isolating infected individuals and protecting healthcare workers, who are often the next victims of the virus. So when signs of the disease hit the Guinea capital of Conakry, a coastal city home to just under 2 million people, health officials have been quick to act.

Tests have now shown that two fatalities suffering with Ebola-like symptoms at the time of death in Conakry were not infected with the virus. Whilst this may suggest that the outbreak has not reached the capital, it is nevertheless worrying that an unknown haemorrhagic fever may be lurking.

Of note, it now also appears that ebolavirus has spread into neighbouring Sierra Leone (ProMED), though we shall have to wait for tests to positively identify this disease.

Ancient “Giant Virus” Revived From Siberian Permafrost (Nat Geo)

National Geographic is running a story about a team from Aix-Marseille University that has discovered a previously unknown giant virus similar to Pandoravirus, buried for over 30,000 years in Siberian permafrost. If that wasn’t cool enough (pun… intended), they could get the virus to infect amoeba back in the lab.

Whilst it makes me slightly sad that the article descends into “BUT WHAT ABOUT THIS RISK TO HUMANS?”, I understand. The idea of a rare virus that destroys all humanity isn’t exactly hard to find in our culture. And whilst I do agree with the researchers (who made sure to test that the virus didn’t infect animal or human cells) that you have to be open to the possibility of finding a virus that is dangerous, it seems a shame to focus on that as the main story.

Quote from the article:

“The idea would make a great movie but is extremely unlikely unless the virus came from a frozen human being who possibly died from a virus that is no longer in circulation. A very small proportion [of the viruses on Earth] represent viruses that can infect mammals and an even smaller proportion pose any risk to humans.” – Edward Mocarski of Emory University.

Viruses are absolutely everywhere. We should be careful when we go looking for them, but we shouldn’t only be interested in them if they can infect us.