Public is being mislead by misinformation about Ebola

By Wendy A. Epstein, M.D., F.A.A.D, Adjunct Assistant Professor, NYU School of Medicine, Health Commissioner, Village of Grand View-on-Hudson, NY

Statements and guidelines have been made so often about Ebola that we come to accept them as fact based.  We have been told that all people infected with Ebola are symptomatic. We have been told that if, after 21 days of isolation, a person remains asymptomatic they can no longer come down with or infect others with Ebola.  We are told that the Ebola virus cannot be transmitted through the air, but only by direct contact with infected bodily fluids. We have been told that temperatures taken once in airports to screen for potential sick travelers from West Africa are an effective way to screen. Before we accept any statement about a disease that most of us have had no experience with, let us look at the evidence and change our protocols accordingly.

The designation of a 21 day period of isolation of people exposed to the Ebola virus is based upon a 95% chance that someone, exposed to Ebola, won’t have Ebola after 21 days. That means that if 100 people exit quarantine after 21 days, five may still become sick with Ebola. However, a 25 day period isolation means there is a 99% chance that someone exposed to Ebola won’t have Ebola, or only one person in a hundred may still become sick with Ebola after 25 days of isolation. [Sources: Transmission dynamics and control of Ebola virus disease (EVD): a review Gerardo Chowell^12* and Hiroshi Nishiura³ BMC Medicine 2014, 12:196 and Osong Public Health Res Perspect. 2011 Jun;2(1):3-7. doi: 10.1016/j.phrp.2011.04.001. Epub 2011 Apr 12. Incubation period of ebola hemorrhagic virus subtype zaire. Eichner M¹, Dowell SF, Firese N].

While fever is an early symptom of being infected with Ebola, it is possible to be infected and have no symptoms whatsoever. In a study [Source: Lancet. 2000 Jun 24;355(9222):2210-5.Human asymptomatic Ebola infection and strong inflammatory response. Leroy et al.] Clinicians checked the blood for evidence of Ebola infection in individuals who were family members of symptomatic patients, and who lived continuously with them taking care of them without any physical protection such as gloves. The study showed that asymptomatic, replicative Ebola infection can and does occur in human beings. It seems that people who get infected with Ebola and either are asymptomatic or symptomatic and recover have a different immune response than people who get infected and become very ill and die. The issue then is whether asymptomatic individuals infected with Ebola can infect others. The risk of transmission via blood products donated by such individuals or via semen should be taken into consideration in public-health policy since infectious filovirus have already been found in semen from symptomatic patients 2–3 months after symptoms [Source: Lancet. 2000 Jun 24;355(9222):2210-5].

Taking temperatures at an airport is giving the public a false sense of security. Fever is not specific, as it is an early manifestation of Ebola and many other infections. Someone infected with Ebola may never have a fever. Fevers are not constant throughout the course of the day, but go up and down. Inexpensive temperature dots could be placed on the wrist of travellers as they check in for flight, and checked prior to boarding and disembarking. Should they get a temperature in flight, they could be isolated in one of the plane’s bathrooms, equipped with hazmat suit and respirator with an intercom.  Although healthcare workers are at greater risk for being infected with Ebola, I see no reason not to quarantine all travellers from West African countries where Ebola is present. Furthermore, why not restrict travel to and from West Africa to those risking their lives trying to stop the epidemic there?

Let’s look at the assumption that Ebola cannot be transmitted through the air. Evidence exists that Ebola Zaire virus infects pig’s lungs, and that pigs can infect non-human primates through respiratory transmission of the virus.. Therefore, pigs could theoretically be a source of aerosolized transmission of Ebola to humans in West Africa. This study also showed that the non-human primates did not infect each other through respiratory tracts, i.e., the air. [Source: Transmission of Ebola virus from pigs to non-human primates. Sci Rep 2012, 2:811]. Weingartl et al].  Another study demonstrated there was evidence of possible aerosol route of transmission between non-human primates (Transmission of Ebola virus (Zaire strain) to uninfected control monkeys in a biocontainment laboratory ,[Source: N.Jaax et al, The Lancet, Volume 346, Issue 8991, Pages 1669 - 1671, 30 December 1995]. What this underscores is that we don’t know enough about Ebola to make sweeping generalizations about whether it can or cannot be transmitted through the air.

Humans sitting or standing within close proximity to each other could transmit Ebola virus by sneezing droplets of infected fluid onto another person. The viral load, or numbers of viral particles in a sample, is extremely high in body fluids of infected individuals when they become symptomatic. It takes as few ten Ebola viruses out of the millions in each airborne droplet of a sneeze to infect those who breathe it in.  

It also is evident that air travel is a major mode of dissemination of airborne illnesses, such as influenza.  A study demonstrated that the post 9/11 restriction of air travel in the United States delayed the dissemination of that year’s influenza by 2 weeks. There were no travel restrictions imposed in France in 2001, and consequently, there was no change in the timing of the arrival of influenza, in France. Given the number of deaths each year from influenza, perhaps it makes sense not to let sick people with fevers fly in general. [Source: PLoS Med. 2006 Sep;3(10):e401.Empirical evidence for the effect of airline travel on inter-regional influenza spread in the United States. Brownstein JS¹, Wolfe CJ, Mandl KD].

One possible explanation for the role of direct physical contact in transmission is the presence of abundant virus particles and antigens in the skin in and around sweat glands. Source: [J Infect Dis. 1999 Feb;179 Suppl 1:S36-47]. The nurses infected with Ebola while caring for Mr. Duncan (the West African patient who flew into Dallas) were said to have made some mistake in protecting themselves.  It is possible that Ebola could have been transmitted through the skin of Mr. Duncan, particularly later in the course of his illness when his viral load was the greatest.  Simply touching a cadaver is an independent risk factor for contracting Ebola.

As yet, we know far too little to presume the following: that 21 days is sufficient to adjudge a person Ebola virus-free; that screening for temperatures at airports protects the American people; that lack of symptoms indicates no possibility of infection; and that Ebola cannot be transmitted through the air. We do know that at least 25 day isolation would add significant protection; that blood tests are the most reliable  way to confirm an infection with Ebola, and that much more research needs to be done on how this virus is spread. Until we know enough, we need to set a much higher bar for containment before we risk further spread of deadly pathogens.

Perhaps, the only way to know if someone is infected with Ebola is to take serial blood samples spaced over one month, 30 days which is 5 days past the 25 days of isolation necessary to eliminate 99% of people, exposed to Ebola, who will become symptomatic. We do not know how many people who are asymptomatic after the period of isolation are not infected with Ebola unless their blood is checked for presence of the viral RNA and/or have specific antibodies to the Ebola virus at the end of their confinement.

Ultimately, the mass vaccination of vulnerable people in West Africa and those brave healthcare volunteers who are risking their lives to save the rest of us is key to ending the spread of Ebola. Until then, public health policy and public trust, must be dictated by the science about what we know and will learn about the mode of transmission of Ebola.