Ebola Viral Disease (EVD) is one of many RNA viruses that can infect humans. All viruses reproduce by hijacking the cellular machinery and making the cell produce new viruses instead of normal proteins. Ebola is one of a group of filoviruses (string-like viruses) that produce a deadly hemorrhagic fever, resulting in the deaths of over 50% of victims.
Ebola is not new. Periodic epidemics have broken out in West and Central Africa since the 70’s, where it is a “zoonosis” or animal-borne disease. The animal hosts include bats, non-human primates (monkeys and chimpanzees) and other creatures, some of which are consumed by humans as “bush meat”. Because of this natural reservoir, total eradication of Ebola has proven impossible.
Up until now, the epidemics have had little geographic spread, often being limited to remote villages where the disease infects a few individuals and then dies out. This time, however, Ebola has stricken large urban areas in Guinea, Sierra Leone and Liberia. The latter two countries have been devastated by decades of civil wars, which left their governments and health systems in disarray.
Ebola is not airborne, although it can be transmitted on large droplets. Transmission depends on direct contact with blood, sweat, vomitus, diarrhea, semen and vaginal secretions. Once introduced, the virus invades and destroys epithelial cells, resulting in massive bleeding and diarrhea. As the person becomes sicker, the viral load (the number of viruses) increases, making terminally ill patients particularly dangerous to others. At this time, there are no specific proven medications or vaccines against Ebola, although both have been fast-tracked by pharmaceutical companies.
Over 5,000 people have died from Ebola and over 13,000 have been infected in West Africa. These unprecedented numbers pose an enormous public health challenge. In Africa, the treatment consists of isolation and hydration, often under very primitive conditions. Over 50% of those infected die from the disease. For the U.S., infection remains only a plane flight away.
Several notorious cases have been treated in the U.S., eight out of nine of whom have survived as of press time. Although not required, specialized bio-containment units (four of which exist around the U.S.) can accommodate up to 12 cases. In the U.S., control measures consist of screenings of visitors from West Africa who have already been screened in their home countries. People who have been to West Africa who are not symptomatic will still be monitored twice daily by public health workers for 21 days. Quarantine will vary depending on the level of exposure in West Africa.
The first question you will be asked at a health care provider in the U.S. is whether you have traveled to West Africa in the last month, specifically to Guinea, Sierra Leone or Liberia. You will then be asked if you have been in contact with anyone who has traveled there who might have Ebola. Since only symptomatic people can be infectious, you will then be asked if you have fever, nausea, vomiting, diarrhea, joint and muscle pains, headache or unusual fatigue. The extent of fever has shifted from 101.5 degrees Fahrenheit to 100.4 and now to “subjective fever from baseline”. Should your travel history and symptoms suggest Ebola, you will be isolated and the necessary laboratory work obtained.
Ebola scares the public, and rightfully so. Any disease that kills over 50% of its victims and has no specific treatment must be a source of concern. That being said, actions should be based on science and logic, not on fear. In the end, the development of an effective vaccine and eradication of the disease among humans in West Africa will constitute our best defense in the U.S.