Spoilers! Ebola worries are non-existent for us in South Central Pennsylvania. However, according to an email I received this week might lead one to believe that the risk is far, far worse. A notice to staff, faculty, and students at York College requires that anyone planning on traveling anywhere outside of the United States through the beginning of March 2015 self identify themselves to the Health Center, and monitor their temperature for the 3 week Ebola Hemorrhagic Fever incubation contagious period. The notice also contains several editorialized Ebola facts, which unfortunately convey a sense about the risks of contracting Ebola virus that are perhaps a bit exaggerated.
A posting in the Atlantic Monthly gives a concise summary of our current understanding. There is no indication today, and there never has been, any evidence to support the hypothesis that Ebola viruses can be transmitted between humans via any indirect means. Ebola virus is what is known as an enveloped virus, and contains a genome made of RNA; consequently, intact virus particles with these characteristics are unable to survive in an infectious state outside of a mammalian host. As a result, in contrast to many bacterial pathogens, inanimate objects (fomites) in the environment are very poor reservoirs for these types of viral pathogens, although virus shed via sneezing does pose a temporary risk.
Distinction between droplet and airborne transmission, via the Virology Down Under blog
The one study that examined the possibility of airborne transmission found that transmission between infected pigs and non-human primates can occur in specialized situations. This study has a big caveat (and indeed was followed up with an additional study to address this), in that in pigs Ebola virus has a hugely significant lung involvement, resulting in massive amounts of the virus in respiratory secretions. This doesn’t happen in primates, which show mainly hemorrhagic disease. The followup study looking at primate to primate aerosol transmission found no infection between test animals. Because of the very nature of Ebola virus in comparison to many respiratory viruses, we are not likely to see a change in these properties.
What about the risk to York College community members who are planning on traveling overseas in the near future? The Centers for Disease Control and Prevention and the Pennsylvania Department of Health remain the best sources of information to assess the risks of this scary disease to the general public. The CDC in fact has a page devoted to precautions that are recommended for college students planning travel abroad. All of these precautions are directed towards travel to those countries where the Ebola outbreak is occurring (Guinea, Liberia, Sierra Leone). The CDC also has a page which clearly indicates epidemiological risks for contracting Ebola virus for use in evaluating whether an individual has potentially been exposed. Class 4–No Identifiable Risk is indicated for persons traveling to a country without widespread Ebola virus transmission–this includes travel anywhere besides Guinea, Liberia, and Sierra Leone. Persons traveling to the Democratic Republic of the Congo should practice enhanced precautions, however the CDC risk assessment is very low for travel there. The Pennsylvania Department of Health echoes all of the CDC guidelines, and as of 27 October 2014, is monitoring a total of 105 residents of the Commonwealth who are considered “at some risk” for exposure to Ebola virus, due to recent travel to one of the afflicted countries. These individuals are being monitored for potential exposure to Ebola by local and state health officials. As indicated on the PA Department of Health page, travel into Pennsylvania from any other international origin is NOT considered a risk factor for Ebola exposure.
There is an awful lot of poorly cited information circulating and straight out disinformation about this epidemic at present. Advocating unwarranted steps in screening for potential exposure when the risk is non-existent creates an atmosphere of uncertainty, and this can be damaging in the long run. I urge all BIO230 students to follow the links they see on the Internet, and check to see whether they represent experimentally-supported science, or merely reflect someone’s opinion.
