Many Americans are quite frightened by the possibility of an Ebola outbreak happening here. These fears are being fanned by some irresponsible reporting by certain media outlets. As I posted earlier, the probability of even a small outbreak (say 10 people infected in the U.S.) is negligible; the healthcare system and public health infrastructure are too good. The more likely scenario is that a person infected in Western Africa may inadvertently fly to the U.S. while they are still asymptomatic, and then become sick here; this is what happened to Mr. Duncan. It is important to identify and hospitalize such a person as soon as possible. Mistakes were made in delaying medical care for Mr. Duncan.
The challenges of containing Ebola virus disease (EVD) have been compared to the emergence of AIDS in the 1980s. Unlike AIDS, the patient has to be symptomatic to be contagious. Similar to AIDS, there has to be direct contact with the contagious individual to have viral transmission.
A further explanation of direct contact may help to assuage fears.
First there must be a source of Ebola virus. More dangerous sources (i.e. potentially containing high levels of virus) are the blood, vomit, diarrhea, and urine from a symptomatic individual. Less dangerous sources (i.e. probably containing lower levels of virus) are the sweat, saliva, mucous, tears, semen and breast milk from a symptomatic individual.
Second there must be entry into your blood stream. There are two modes of entry: (1) broken skin (e.g. cuts on your skin), and (2) mucous membranes (mouth, nose, eyes).
Thus, direct contact means that one of the source fluids must splash, spray, or be deposited on to broken skin or into your mouth, eyes or nose. The higher the virus content and the larger the entry point, the greater chance you will be infected.
Note that there is no airborne transmission of EVD. Thus, you cannot get EVD if someone vomits a few rows in front of you on an airplane. You cannot get EVD if you walk through the apartment of someone who had EVD as long as you don't touch anything and you get rid of your shoes.
If EVD is not so contagious then why do health workers wear so much protective garb (Figure 1)? In a nutshell, because EVD is so lethal with a mortality rate approaching ~70% of all people infected. Thus, it is critical for workers to take the utmost precautions when they are working in the presence of EVD patients or handling their bodily fluids. The goal of the protective suit is to prevent direct contact between EV-containing bodily fluids and any part of the skin (which may contain very small cuts or abrasions) or any mucous membranes (nose, mouth, eyes). It should be emphasized that a sick Ebola patient will secrete/excrete an extreme volume of bodily fluids including blood because of the nature of the disease.
The infected nurse in Spain was handling the bodily fluids of the sick Spanish priest and evidently, she may have broken protocol and wiped her face (i.e. mouth, nose, or eyes) with a soiled glove.
Meanwhile in Dallas, none of the people who were in the presence of Mr. Duncan or in his apartment including his relatives and the medical personnel who took him to the hospital have fallen ill (see Update at bottom; this statement is no longer true). By the end of this week they will be approaching the approximate 21-day limit for symptoms to appear.
Finally, Ebola Virus (EV) is susceptible to a variety of disinfectants. It is possible to clean an area contaminated with the virus by washing with a bleach solution. In addition, alcohol, heat, and gamma radiation can kill the virus. EV needs a moist environment to survive for a prolonged period i.e. won't survive on a dry surface for long.
In summary, if proper protocol is followed, the situations in Dallas and Spain should be resolved. The key is quick identification and isolation, and patients can be identified quickly because they become ill so fast.
UPDATE (10/12/14):
The first American has contracted EVD in the U.S. She is one of the nurses who was caring for Mr. Thomas Duncan. This infection most likely arose through a breach in protocol. Removal of soiled garments is one area in which workers must be extremely careful, especially those who are working with EVD patients for the first time.
The director of the CDC, Dr. Thomas Friedan, had the following statements:
"We don't know what occurred in the care of the index patient, the original patient, in Dallas, but at some point there was a breach in protocol, and that breach in protocol resulted in this infection," CDC director Dr. Thomas Frieden told a news conference.
"We are evaluating other potential healthcare worker exposures because if this individual was exposed, which they were, it is possible that other individuals were exposed," he said.
The worker was in close contact with Duncan and initial testing shows that the level of virus in her system is low. The CDC will conduct a secondary test to confirm the results from a lab in Austin that showed Ebola infection, he said.
"Unfortunately it is possible in the coming days that we will see additional cases of Ebola," he said.
Figure 1. The intimidating protective suit of Ebola virus disease health workers is necessary to avoid direct contact.
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