1980 marked a milestone in infectious disease epidemiology: the World Health Organization declared the smallpox virus eradicated in the wild. However, while smallpox currently exists only in frozen stocks, poxviruses as a class certainly haven’t disappeared. A related virus, monkeypox, regularly causes illness in Africa, and even spread half a world away in the American midwest.

Additionally, Africa isn’t the only area with endemic poxvirus infections. Brazil has been dealing with their own poxvirus outbreak, and poxviruses have popped up in Europe as well. More on both of those after the jump…

I mentioned yesterday that we need to move beyond just responding to outbreaks, but instead, anticipating them. Emergent poxviruses are a good example of this philosophy. Since 1999, in several different regions in Brazil, the poxvirus they’ve been dealing with is vaccinia virus. The history of the virus in this country is detailed in this 2007 publication. Briefly, vaccinia virus was initially brought in on the arms of slaves returning to the country from Portugal, and was propagated arm-to-arm for the better part of a century. By mid-century, the virus was found to be present in mice and cattle on dairy farms, and has recently caused several outbreaks in the country.

Human patients identified thus far have largely been young (75% under the age of 25) and unvaccinated, with a seasonal peak from July through September (winter in Brazil, and the dry season). Cows are highly affected, with attack rates ranging from 80-100%. This has a huge economic impact: infected cows experience a 30-50% drop in milk production. Most of the human cases have worked on dairy farms, and specifically, have manually milked the cows there.

Is this a case of a vaccine strain gone “feral”–that is, moving from a vaccinated human into an animal reservoir, where it’s continued to evolve and be transmitted back to other animals (including humans?) Molecular analyses suggest this isn’t the case, but a reservoir hasn’t yet been identified.

In Europe, the related cowpox virus is somewhat better understood, with a rodent reservoir and occasional infections of cattle, humans, and other species. A 2006 paper documents transmission of cowpox virus between rats and monkeys at an animal sanctuary in the Netherlands. In the April 2008 Emerging Infectious Diseases, an even more complicated outbreak is described, with the virus moving from rat to elephant to the elephant’s keeper in Germany. Zoo and circus animals seem to be particularly susceptible to the virus, and while rats have been identified as a reservoir species, the prevalence of the virus in the rodent population in Europe isn’t known.

Will human poxvirus infections increase in the coming years? It seems likely. Any residual immunity to vaccinia that’s come via vaccination is not only waning in those who were vaccinated, but that proportion of the population that received the smallpox vaccine is decreasing every day, leaving us unprotected in the face of an emergent poxvirus.

References

Trindade, G.S. (2007). Brazilian Vaccinia Viruses and Their Origins. Emerging Infectious Diseases, 13(7), 965-972.

Martina, B. (2006). Cowpox Virus Transmission from Rats to Monkeys, the Netherlands. Emerging Infectious Diseases, 12(6), 1005-1007.

Comments

  1. #1 Poodle Stomper
    March 26, 2008

    Tara,
    Do you know how many of the other known poxviruses are as dangerous as smallpox or was smallpox the worst so far?

  2. #2 Tara C. Smith
    March 26, 2008

    Smallpox is the worst we’ve seen, by far. Monkeypox, cowpox, and vaccinia can be nasty, especially when the patient is immunocompromised or has a pre-existing skin condition, but we still don’t see anything approaching mortality rates of variola major.

  3. #3 Poodle Stomper
    March 26, 2008

    “smallpox currently exists only in frozen stocks”

    I don’t remember if it was smallpox or polio but I remember an article by a lab that used the genebank sequence for one of these two and pieced together a working viral genome de novo…I’m tempted to say it was for smallpox but I could be wrong. Either way…creepy!

  4. #4 jspreen
    March 26, 2008

    Will human poxvirus infections increase in the coming years?

    You bet it will. World Hype Org will see to that. We had about one new threat per year over the last decade so this might be the new emerging catastrophe rumor replacing the avian flu nonsense.

    I’m amazed Tara&Co never get tired preaching doom where the first retard easily recognizes it’s all nonsense.

    I mentioned yesterday that we need to move beyond just responding to outbreaks

    I suggest you start with trying to go beyond your silly hype responses and fear mongering. Look over there, see the moutains of tamiflu stock? The materialisation of the bull shit pushed last year.

  5. #5 boomer0127
    March 26, 2008

    Poodle Stomper – I believe it was Poliovirus that was made in the lab from synthetic nucleic acid. It was done at SUNY Stony Brook, if I recall. Google University is not helping though, so perhaps I am wrong…

  6. #6 Poodle Stomper
    March 26, 2008

    boomer0127,
    Yup, I just found it and you are correct; it was polio. Good times with synthetic viral genomes…

  7. #7 Poodle Stomper
    March 26, 2008

    And here was the link I found to the story in case anyone is interested:
    http://news.bbc.co.uk/2/hi/science/nature/2122619.stm

  8. #8 Dave Briggs
    March 27, 2008

    It seems we are in a never ending game of catch up here! Maybe one day we can just genetically engineer a male and female prototype that is impervious to every virus and bacteria and use them to perpetuate the species, illness free, for all of us! LOL!
    Dave Briggs :~)

  9. #9 Dave Briggs
    March 27, 2008

    It seems we are in a never ending game of catch up here! Maybe one day we can just genetically engineer a male and female prototype that are impervious to every virus and bacteria and use them to perpetuate the species, illness free, for all of us! LOL!
    Dave Briggs :~)

  10. #10 mary
    March 28, 2008

    Wonder if jspleen has one of those nice round vaccination scars on his left shoulder? Really appreciate your information, Tara, you have a very informative, easy to read blog.

  11. #11 jspreen
    March 28, 2008

    Wonder if jspleen has one of those nice round vaccination scars on his left shoulder?

    Yes, I have. Nobody asks a baby’s opinion. And of course, back then neither I nor my parents knew what we know today, some 50 years later. Vaccination? Bull shit. And very unhealthy by that

    Really appreciate your information, Tara, you have a very informative, easy to read blog.

    Right you are. Easy to read, readily fits into everything everybody takes for granted today. A blog for no brainers, that’s what it is.

  12. #12 boomer0127
    March 28, 2008

    jspreeen, It must be a wonderful world if we can mock the smallpox vaccine. You obviously have no clue whatsoever about how horrible smallpox was.

    Do you really think it is bullshit? Do you really think that after centuries of this scourge, it just decided on its own to go away and the efforts of the world to eradicate it were just a big worthless joke?

    You, sir/madam, are the joke. It would be unfortunate irony if Tara is correct about poxvirus re-emergence and you are one of the lucky survivors who never had a choice of being vaccinated or not.

  13. #13 boomer0127
    March 28, 2008

    After reading my previous post, I believe I was a tad harsh on jspreen. No, you are not a joke, and it would not be unfortunate if you survived a poxvirus outbreak due to your vaccination status.

    I’ll have another drink to the human race, to hopefully changing the minds of the naysayers, and to critical evaluation of scientific endeavor.

    Cheers!

  14. #14 Mountain Man
    March 30, 2008

    According to Wikipedia:

    “By 1897, smallpox had largely been eliminated from the United States”

    So, tell me, genius morons, who tremble at the fear of unseeable microbes — how effective was a small pox vaccine 110 FRICKING YEARS ago, before: (a) anyone had ever seen a virus, (b) the development of the electron microscope, (c) the development of PCR?

    This was purely natural immunity at work. No credit to your bogus vaccines.

    Moreover, if such a clumsy, old vaccination methods could work (injecting blood of pox victims into healthy patients), why the need for all the technological advances?

    The last documented case of small pox in the US is 1949, fools.

  15. #15 Poodle Stomper
    March 30, 2008

    Mountain,
    In case you hadn’t thought of this, it would seem fairly obvious to most rational people that while the low tech vaccines worked, it also offered the possibility of contaminations and infections from other blood born diseases carried by pox infected people. The use of recombinant vaccines is to minimize the possibilities of contaminants entering the population through treatments. Also, Jenner’s vaccine was not made through “natural immunity” against smallpox but rather through vaccination by exposure to the less dangerous Cowpox which, due to its close relationship to smallpox, shared common epitopes. Jenner came about the vaccine when he realized that people who had been infected with cowpox did not develop smallpox despite repeated exposure. This is science at work.

  16. #16 Poodle Stomper
    March 30, 2008

    Also, if you are going to quote Wikipedia as a credible source , don’t say things like:
    “The last documented case of small pox in the US is 1949, fools.”

    When Wiki (your own source) says:
    “The last major European outbreak of smallpox was in 1972 in Yugoslavia”

    and

    “The last naturally occurring case of the more deadly Variola major had been detected in October 1975 in a two-year-old Bangladeshi girl, Rahima Banu”

  17. #17 Poodle Stomper
    March 30, 2008

    The lack of cases in the US would still not justify lack of vaccinations elsewhere. The problems in Eurpoe was due to an infected immigrant and such events could easily have occured again in the US. Vaccinations were a logical precaution.

  18. #18 jspreen
    March 30, 2008

    The problems in Eurpoe was due to an infected immigrant

    What kind of underdeveloped brain must one have to take such a hypothesis seriously? Problems in Europe due to AN infected immigrant? Wow, they checked EVERY immigrant and one of them, yes, that guy over there with the pale looks, that’s the one. He’s got these viruses nobody ever saw crawling all over his body. Pretty damn sure he caused the epidemic.

    HAHA HAHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHA

  19. #19 Poodle Stomper
    March 30, 2008

    JSpreen,
    I’m just quoting his own source. Also, simply because you are unable to understand the process of narrowing down who the most likely patient 0 is doesn’t mean it isn’t correct; just that you don’t currently have the capacity to understand. Maybe you could take a few high school or college biology classes. It could help.

  20. #20 boomer0127
    March 31, 2008

    Not to stoke the flames too much, but what does everyone think of the CERN supercollider thingie? It is going to send the earth into a parallel universe? Turn the earth into a black hole? Just a big waste of money?

    Or do the naysayers here even believe in subatomic particles?

    I’d love to hear the poliovirus-vaccine-denier’s take on this one…

  21. #21 Mustafa Mond, FCD
    March 31, 2008
  22. #22 Calli Arcale
    April 2, 2008

    Not sure what the Large Hadron Collider has to do with poxviruses, but no, it is not going to send the Earth into a parallel universe or turn the Earth into a black hole. LHC may create microscopic black holes. But these are not dangerous. Indeed, such black holes would be the size of subatomic particles, would rapidly evaporate due to Hawking radiation, and could actually pass straight through the Earth, just like a neutrino. Basically, black holes do not have magically powerful gravitational fields. It’s just that the fields are incredibly concentrated. The normal laws of physics still apply, at least while the observer is not about to cross the event horizon. In particular, the gravitational force exerted is exactly the same. If you stand a foot away from such a black hole, you feel nothing. Its event horizon is narrower than the space between electrons in the molecules that make up your body, so it could pass *through* you and you would still feel nothing.

    Cool factoid: in order to make the Earth into a black hole, you would have to compress it to the size of a pea. If you could somehow do this without disturbing the Moon, the Moon’s orbit would stay more or less the same.

    Whether or not LHC will be a waste of money is a rather more complicated question to answer, because it depends on what you think money ought to be spent on. It’s intended for pure research — science with no immediate application. Some do consider that wasteful, because it’s nearly impossible to predict which discoveries will later turn out to have a really good practical application. Others say that pure research is vital for precisely the same reason. ;-)

    (I know you were addressing that to vaccine deniers, but I can’t resist answering questions like that!)

  23. #23 tarsus
    April 24, 2008

    Cool factoid: in order to make the Earth into a black hole, you would have to compress it to the size of a pea. If you could somehow do this without disturbing the Moon, the Moon’s orbit would stay more or less the same.