New Ebola reservoir

  1. The Ebola virus as I understand it infects several mammals, including bats, monkeys and people of course. The reservoir of the virus is currently unknown I believe, though some of the hosts that people have contact with have been identified.

    With the current infections in major population areas in Africa, with both wild and domestic as well as feral animals (once pets) and bodies being dumped in the street, intimate contact between pets and humans there, (I am sure some of those people have monkeys as pets,) is there a risk that a new reservoir of ebola will come to exist and reside within and near these cities? Increasing the likeliehood of future outbreaks on a much larger scale?

    And if so, isn't it also just as important to detect, monitor, and prevent this from happening as well as quarantining the sick human patients?

    I have seen of course like everyone, a lot of attention by the media regarding ebola, but I have not seen anyone address this issue (if in fact it is one) and it seems to be an important thing that seems to be being overlooked.
     
  2. jcsd
  3. phinds

    phinds 9,155
    Gold Member

    Seems to me that a far more serious matter (or perhaps you could look at it as alternate source of what you are concerned about) is the fact that the people in several of the affected countries so distrust their corrupt governments that they do not believe the health instructions that have been disseminated and are hiding infected people, readily touching potentially infected sources (bloody sheets, bodies, etc) and generally oblivious to pertinent sanitation measures.
     
  4. And I would agree completely. But we are aware of that. My concern is that once the domestic animals and wild animals in close contact with the humans in these area are exposed (those that might catch and transmit the disease,) then in back alleys among strays and other wild animals in the area might then also get the disease (rats? mice? I don't know which animals CAN catch ebola though,) thereby disseminating the disease further and more extensively and making it much more difficult to contain or to isolate. Then what do you do? Or perhaps it is not even a remote possibility what I am suggesting, and if so, it would be nice to know.
     
  5. AlephZero

    AlephZero 7,298
    Science Advisor
    Homework Helper

    According to Wikpedia, the most likely reservoir of the disease is bats, which show no clinical symptoms of it.

    Other primates can be infected (possibly by eating fruit previously half-eaten by infected bats) but as with humans, the rapid fatality of the disease means they are unlikely to be a major cause of spreading the infection. Previous outbreaks have been traced to human contact with infected (and already dead) primates and with bats.

    Other species do not appear to be involved significantly. Of the 30,000 animals tested during previous outbreaks, there were very few positive results.

    Because of the short incubation time and severity of the disease, human outbreaks are unlikely to spread widely unless people have large-scale access to rapid transportation. As phinds said, basic health education is probably the most important strategy, given there is no proven cure.
     
  6. While this is stated in the Ebola virus Wikipedia article, it's contested in other literature. Ebola-Zaire has been claimed to be pathogenic in certain species of bats. Bats are considered likely reservoirs, but perhaps not as efficient as such as previously thought.

    http://web.stanford.edu/group/virus/filo/bats.html
     
    Last edited: Aug 27, 2014
  7. Well there is a lot of finger pointing at bats as being the permanent reservoir for Ebola, but this hasn't been proven so far as I am aware, it is just strongly suspected. But here is a list of OTHER animals that can contract Ebola and pass it on to humans. There are 9 (other than man) so far known:

    chimpanzees, gorillas, fruit bats, monkeys, antelopes, porcupines, rodents, dogs, and pigs

    I see 3 of those as likely vectors in a city or populated areas (as in Africa.) Rodents, dogs and pigs and as well some people likely have pet monkeys as well.

    So, with cases where the victims of Ebola, as has been reported, are dumped into the streets and lay there for days (stray dogs coming up and sniffing or licking the deceased, perhaps a stray cat as well or rodents too,) as well as possible contact with improperly disposed of hazardous waste in the city dump where there are likely to be many rodents as well as stray dogs and cats, and pigs used as pets and farmed for their meat.

    I feel that there is a very considerable risk that enough animals could become infected and pass it through the other animals in and around the cities and towns, to ultimately bring the source of Ebola out of the jungle and entrench it in the population centers, where it would be very hard to eradicate, especially if it was in the rodent populations.

    I am not trying to fear monger. But is it truly ONLY the human aspect that can get out of control and if one controls the humans passing on the disease to other humans that there is no chance that the disease will find a new environmental niche to reside and become a constant source of re-introduction of the disease?

    And how would one know or be able to tell? Persons getting the disease that did not travel anywhere and did not have contact with anyone who was infected? Would this be the indicator?

    Sorry for the hard questions, but I don't think it is too far fetched. It might be worth looking at a bit more closely by those who are monitoring and are attempting to contain the disease.

    And will that rat infected with Ebola that jumps aboard a ship carrying produce to New York City survive that trip? Then what?

    Here is a quote from a recent article:
    "Blaming humans, bats, chimps or birds for the illness does not then take into account its full possible scope within the ecosystem. That, the present unprecedented epidemic, the potential for bioterrorism, and the fact that no vaccine is available for clinical use have scientists around the world paying greater attention to Ebola and to the animals it can infect.

    Sanders and his colleagues continue to study birds and their possible role in Ebola's evolution and transmission. They are also attempting to determine what other animals might be added to the already long list of species that the virus and related viruses could impact."
     
    Last edited: Aug 27, 2014
  8. Do you have a reference for the affected animals?

    Bats are infected by types of Filovirus, specifically Lloviu virus found in dead bats in caves of Spain, France, Portugal, and suggested that the Marburg virus resides in bats.
    By deduction it is thus suggested that Ebola, another Filovirus, is carried by bats in the wild, although the transmission to humans is not completely known.


    Do you know the level of survival with the animals mentioned if they develop the desease? If dogs aquire the disease one would expect their population to decline.
    http://wwwnc.cdc.gov/eid/article/11/3/pdfs/04-0981.pdf is a discussion of a study regarding dogs in previous ebola outbreaks.


    Do rats aquire the disease? Source?
     
  9. List of some animals that get ebola mentioned in article:

    http://news.discovery.com/animals/ebolas-deadly-jump-from-animal-to-animal-140730.htm

    About dog infection, same article, and a quote from it:

    http://wwwnc.cdc.gov/eid/article/11/3/pdfs/04-0981.pdf

    " Although dogs can be asymptomatically infected, they may excrete
    infectious viral particles in urine, feces, and saliva for a
    short period before virus clearance, as observed experi-
    mentally in other animals. Given the frequency of contact
    between humans and domestic dogs, canine Ebola infec-
    tion must be considered as a potential risk factor for human
    infection and virus spread. Human infection could occur
    through licking, biting, or grooming. Asymptomatically
    infected dogs could be a potential source of human Ebola
    outbreaks and of virus spread during human outbreaks,
    which could explain some epidemiologically unrelated
    human cases. Dogs might also be a source of human Ebola
    outbreaks, such as the 1976 Yambuku outbreaks in
    Democratic Republic of Congo (19), the 1995 Kikwit out-
    break, some outbreaks that occurred in 1996 and 2004 in
    Gabon and Republic of Congo (5), and the 1976 (6), 1979
    (20), and 2004 (21) outbreaks in Sudan, the sources of
    which are still unknown. Together, these findings strongly
    suggest that dogs should be taken into consideration dur-
    ing the management of human Ebola outbreaks."

    And don't forget the natural mutation of the disease. With dogs in some cases running 30% infection in the report in areas that had human infections, in these areas, the more animals with the infection and exposure to humans, the better the chance of a new strain that resides in dogs asymptomatically and infects humans more effectively can evolve.

    In this same article it mentions other animals such as horses and guinea pigs. I guess you didn't read it.
     
    Last edited: Aug 28, 2014
  10. So I guess that kind of answers my original question, as it appears that someone has taken a look at the potential for this to occur and has found it significant enough to be "...taken into consideration during the management of human Ebola outbreaks."

    Sounds to me that in Africa right now they should be running a con-current program of rounding up stray dogs, cats and work toward eliminating indigenous rodents in the communities as a precaution. Besides, getting rid of the rats and mice might also have the benefit of creating a more healthy environment for them and helping to prevent other diseases transmitted by rodents.

    Any disease management plan put in place in any other countries that the disease may become epidemic in (perhaps other neighboring African countries) should put that in their contingency plans too. Hindsight is 20/20.
     
  11. I was looking and did not find any actual impact upon these animals except for the dogs.

    The PDF mentions that ( red bold )
    which is why the other animals were not mentioned by me in that they have not been observed in the wild to be infected.

    Mice have been experimentally infected also in a laboratory setting, but not with the strains of Ebola found in the wild.

    From what I have read, they do not know for certainty the actual incubator of the virus. Arthropods, which includes insects and all those other buggy looking creatures, have come to mind to researchers.


    From Wiki, in support of your conjecture
    http://en.wikipedia.org/wiki/Filoviridae
     
  12. The article stated that this was the list of animals able to be infected by Ebola, but also goes on to say that there may be other animals that can contract the disease, they just don't know.

    You're talking about the statistical possibilities of it mutating. Problem with statistics is that even though the odds of rolling 5 dice at the same time all coming up the same number are very small, it does happen, and can happen on the first roll of the dice, though the odds are against it. With increased exposure between animals and humans infected, it greatly accelerates that mutation process. If all animals and all humans on earth were infected with Ebola, I would venture a guess that the mutation of the virus would happen every few years!

    With the estimates now that probably around 20,000 people will become infected by the virus before it is under control, I will venture a guess that that is more cases than has existed in the last 1000 years before. That would probably guarantee a new mutation in my opinion.

    The reason this virus doesn't mutate often is that it resides in very remote areas with little contact between the animals infected and a very small human population, until now.

    And if you check my original post, my question was whether or not there should be concern, monitoring and control of the animal populations in the affected cities as well as taking care of the sick humans, to prevent a possible entrenched source in the cities and towns. I don't know where having 30% of the stray dogs running around in the street carrying the Ebola virus is a comforting thought.

    So your advice would be then ... ??? ... just forget about the animals they are of no concern??
     
    Last edited: Aug 29, 2014
  13. Here is a quote from another post in another thread regarding it's mutability:

     
  14. I thought they had re-visited, and concluded the recent outbreak was Zaire-Ebola.
     
  15. Astronuc

    Staff: Mentor

    The Stanford article is dated 1999, and so is already 15 years old.

    From WHO site - Fruit bats of the Pteropodidae family are considered to be the natural host of the Ebola virus.
    http://www.who.int/mediacentre/factsheets/fs103/en/

    Also from the WHO site:
    As one can see, there is already research into hosts and transmission vectors.
     
  16. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4014719/

    This review, published this year, appears to sum up the current knowledge regarding bats as Ebolavirus reservoirs. At the top of page 10, the authors seem to use the term Ebolavirus to include Lloviu virus. Lloviu is a recently discovered filovirus associated with a bat die-off in Europe in 2002. I'm wondering if the 1999 Stanford article was referring to an earlier bat die-off in Africa that may have been associated with the then unknown Lloviu virus. Lloviu is not known to infect humans.
     
    Last edited: Aug 31, 2014
  17. Ygggdrasil

    Ygggdrasil 1,694
    Science Advisor

    Researchers have classified ebolaviruses into five major subtypes and the current outbreak is indeed the Ebola Zaire subtype. However, this does not mean that the current outbreak is the same virus that caused previous Ebola-Zaire outbreaks. A new study published earlier this week in Science, has sequenced virus samples collected from patients in Sierra Leone in order to better understand the origins of the virus and the mutations it is undergoing. The data suggests that the recent outbreak resulted from an independent zoonotic event from the same natural reservoir of viruses that produced the 2002 outbreak in Gabon and the 2007-2008 outbreak in the DRC. The sequencing data also indicates that the current outbreak has resulted from human-to-human transmission and additional zoonotic events are not contributing to the spread of the outbreak.

    Thus, dealing with the natural reservoir will likely be important for preventing outbreaks in the future, but it will not help with the current outbreak.
     
  18. I wasn't thinking about the short term control of the outbreak. My whole concern was a long term entrenchment of Ebola in the indigenous animal populations in these cities, becoming a local source for future infection of the residents there. Yay or nay? Can or can't happen? Should be monitored and prevented, or don't waste time or money on it? That's what I want to know personally.
     
  19. Ygggdrasil

    Ygggdrasil 1,694
    Science Advisor

    I would agree that for preventing future outbreaks of the disease, it is important to understand which species harbor the natural reservoir of Ebola virus. Monitoring is certainly warranted, especially if we develop vaccines against Ebola, since we would want to track how the virus evolves in its wild populations in order to update Ebola vaccines. In terms of prevention, probably making the population aware of which species harbor the disease and promoting practices to minimize the risk of zoonotic infection would be important.

    I'm not sure it would be wise, however, to dedicate too many resources to trying to control ebola in animal populations, however. Despite the media attention the disease has drawn, orders of magnitudes more people have died from more common diseases like malaria and tuberculosis during the current outbreak. Given limited resources, it would seem to make sense to address these diseases (for which we have effective ways of preventing and treating them), that to focus too much on a relatively rare disease that is fairly limited in its ability to spread between individuals.
     
  20. Drug show promise.
    http://www.nature.com/news/drug-saves-monkeys-from-close-relative-of-ebola-1.15745

    The results from this study were posted in Nature Friday Aug 22, 2014

     
  21. Ebola virus stays virulent only a few days outside a human host. In a densely packed area such as the slums in Sierra Leone that are now quarantined, is it possible for biting insects and flies to transmit the disease from human to human? I know they say it is not a mosquito borne illness like malaria, but then most of the places that the disease was before was in areas of low population density. What about now that it's in a high population density city?
     
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