10:24 a.m. November 21, 2012

Ebola Double Cheeseburger: The Baddest Bitch Of All Viruses Is Now In Pigs!

The last time we spoke of Ebola, in the midst of an outbreak in Uganda, I failed to mention one, giant, glaring detail: Ebola is zoonotic.

Zoonoses, to the uninitiated, are infectious diseases that can be transmitted from or are shared by animals to humans. Influenza, cholera, rabies, anthrax, HIV, dengue fever, and plague are all zoonotic diseases. And so - hurrah! - is Ebola.

We already know that Ebola is the undisputed king of hemorrhagic gore in primates. And yet, other animals can carry the virus with few to no ill effects. It is almost perverse that the seven protein menace of the RNA filovirus we so intensely fear is shrugged off by other animals -- but, hey, Nature wants to kill you and she needs a place to stash her doomsday weapons.

Like bats, for example. Ebola antibodies have been found in several species of fruit bat and it has been suggested that Ebola may infect dogs and other wild animals.

Which brings me to pigs. Specifically, Filipino pigs. The Philippines are lucky enough to have their very own species in the Ebolavirus genus: it's called the Reston virus, or RESTV. And lest we Americans get too smug -- it’s named for its first outbreak, which occured in Reston, Virginia.

So why haven’t you heard about Reston virus? Easy: RESTV is non-pathogenic to people. A change in just one of the proteins that makes up this seemingly menacing filovirus turned killer Ebola into a pussycat before it appeared in Virginia as RESTV.

The outbreak was thanks to a group of crab-eating macaques that had been imported into the US by way of the Philippines for research purposes and were being held at a research primate quarantine unit in Reston, Virginia. Given Reston’s close proximity to Washington, D.C., as well as the fact that they thought RESTV was an Ebola virus, well, you can imagine the catastrofuck of panic that swept through the public health workers assigned to the case. Thankfully, Ebola did not get loose in the D.C. suburbs and the public at large went generally unaware of how close they had come to death by nosebleed.

Reston went quiet in 1997, when the facility in the Phillipines associated with exporting the sick macaques shut down, only to surface again in 2008. In pigs. Pigs! Cue real panic.

Ebola had never before been seen in pigs. And sure enough, six of the pig caretakers tested positive for the virus. Pork exports from the Philippines were shut down, but further testing confirmed what we already knew: RESTV isn’t a problem for people, so the pig outbreak was not considered to be of significant public health importance, at least in the short term. However, RESTV in pigs did bring into question the potential for pigs to facilitate human exposure to the virus through contaminated meat.

And if pigs can get RESTV, can they also get Ebola?

Answer: Yes. Pigs can definitely get Ebola. The researchers that tackled this unholy question infected pigs with the incredibly deadly Zaire strain of Ebola, ZEBOV. That is, the slate-wiper. The 90% mortality strain. This is the apocalypse written in RNA, lurking in the tropics, just waiting for some ecotourist to bring it back to a metropolitan hub. This is the nightmare strain.

The study authors infected pigs with ZEBOV via intranasal, intraocular, and oral routes, and all of the infected animals developed fevers, respiratory disease, and some hemorrhaging. There was also evidence of airway replication by Ebola. Interestingly, the pigs did not seem to get the bloody Ebolas the way primates do - the pigs didn’t develop the severe, systemic disease we know and loathe, instead sticking to respiratory symptoms. (Side note: there are a lot of respiratory diseases that pigs can get, and the idea that Ebola Zaire could be masquerading as the pig sniffles is fucking terrifying).

In a separate experiment, the authors infected a few pigs, then let four non-inoculated pigs hang out with the soon-to-be sick pigs. And sure enough, by the study’s end, there was viral RNA in the mucosa of all animals. This establishes pig-to-pig transmission. What the study didn’t establish was how the virus was spread. Yes, there was airway replication, but it was unclear if direct contact was necessary to share Ebola Zaire among pig friends. In case you were wondering, Ebola in humans is generally transmitted via contact with bodily fluids. So, breathing near an Ebola Zaire patient is maybe safe; being within the splash zone of their blood geysers is definitely unsafe. But who knows what kind of infected pig contact is required for Ebola transmission.

Which brings me to a study published November 15th in Scientific Reports on the transmission of Ebola virus from pigs to non-human primates. Their findings? Not only is the pig-primate transmission possible, it appears to be airborne.

Airborne Ebola.

Welcome to your absolute worst nightmare.

Using the dreaded Ebola Zaire strain, the study demonstrated ZEBOV transmission from infected pigs to non-inoculated macaques without direct contact. The study involved inoculating piglets with ZEBOV and then allowing them to share room with healthy macaques in an open, inaccessible cage system. And waiting. And sure enough, all of the macaques sharing a room with the infected piglets became infected with ZEBOV: infectious virus was detected in the oronasal swabs of the pigs, as well as the blood, swabs, and tissue of the macaques. Furthermore, transmission between macaques in similar housing conditions to the pig-macaque setup did not occur. Which means that the pigs are apparently making Ebola airborne.

Given the results of the 2009 RESTV study, which found high concentration of viral particles in the lungs and airways of the pigs, it seems plausible that pigs are well-suited to spread Ebola through air. And not only are they well-suited for airborne transmission, but pigs aren’t as violently affected by the virus as primates are. During the study, the infected piglets had mild fevers and increased respiratory rates, but all apparently recovered from ZEBOV by nine days post-inoculation. The monkeys, however, did not fare as well. All macaques developed the tell-tale bloody spots (petechial hemorrhages) on their chests and the internal surfaces of their limbs, and showed significant signs of lung damage. (The monkeys were euthanized when signs of Ebola infection first became apparent, for clear humane reasons).

Additionally, not only did this study establish clear evidence of airborne Ebola transmission, but it also marks the first report of experimental interspecies viral transmission.

What does this mean? Well, for starters, keep in mind that this study does not establish Ebola as a straightup airborne virus like tuberculosis or the flu. It does appear that pigs can transmit Ebola without direct contact, but that doesn’t mean the monkeys that get it from the pigs can do the same. And remember that the transmission occurred under experimental conditions, which aren’t exactly the same as pigs frolicking out and about in the mud. Plus, pigs don’t have a huge presence in Africa, where Ebola lurks. So, naturally, the next step is to launch a comprehensive investigation into whether pigs in Africa are potentially playing a role in the disease ecology of Ebola.


Pigs are amazing disease vectors. We keep them in very close quarters, both with other pigs and with humans. We eat them. A lot of them. And when there is such an intimate relationship between humans and other species, zoonoses are bound to rear their unwelcome little heads. (Case in point: rats, rat fleas, and the Black Death.)

We are certainly intimate with pigs. They are part of the bats-pigs-humans Nipah triangle. They might spread Hendra. They have an influenza named after them. And now … Ebola. The simple fact that pigs are now known to be able to acquire and spread Ebola is cause for significant worry, and their apparent capacity to spread it through the air is the zoonotic equivalent of shit pie with turd ice cream. It’s bad news.

So, when you’re cruising the grocery store and see that package of bacon, try not to think about the way blood looks as it pools under skin in a blooming, crimson rash. Pork chops? Never mind what it would be like to watch pureed death from inside your own body stream down your face and out your asshole, bursting forth in a soupy surge from turgid, dead genitals with a ripping wet sound like tearing canvas. How long until Boston butt begins to look like a howling purple maw, all vermillion eyes and mottled skin, leaking the hot, red stew of destroyed blood. One day, you see pork sausage and recall that Ebola starts out feeling just like the flu. Pork loin reminds you that many Ebola patients show marked clinical improvement in the days before the hemorrhaging starts. Christmas ham? Did you know that hiccups are an actual symptom of Ebola?

That’ll do pig. That’ll do.

Back channel chatter

There is a scribble about this dispatch in the backroom, with two contributors.