Today I am addressing a disease you will almost certainly never get, or even see! However, it is among the most feared infections on the planet, and certainly one of the most deadly ones. Its most common strains have the highest fatality rates of any human pathogenic virus, roughly 50% - 90%.The Ebola virus causes the disease known as Ebola Hemorrhagic Fever. The name comes from the Ebola River Valley in the Democratic Republic of Congo (formerly Zaire), near the site of the first recognized outbreak at a Flemish mission hospital. Outbreaks actually occurred simultaneously, in both Zaire and Sudan, in 1976. Ebola can affect both humans and non-human primates. It remained largely obscure until 1989, when several widely publicized outbreaks occurred among monkeys in the United States. It is transmitted through all body fluids, and has an incubation period of 2 to 21 days from exposure. The virus interferes with the endothelial cells, which line the inside of blood vessels. As the blood vessel walls are destroyed, the platelets are unable to coagulate, and those infected essentially bleed to death and die from shock. The disease is indeed frightening. There is a rapid onset of fever, malaise, muscle pain, headaches, and inflammation of the pharynx. Vomiting and bloody diarrhea develop, along with a rash with bleeding at needle sites and bodily orifices. What animal or insect is the host, or natural reservoir, for this virus? The answer is unknown despite extensive study, but it seems to reside in the rain forests on the African continent and in the Western Pacific. Although non-human primates (such as monkeys, chimpanzees, and gorillas) have been a source of infection for humans, they are not thought to be the source. It is believed that they, like humans, are infected directly from the natural reservoir or through a chain of transmission. The most promising theory is that bats are the host. They drop partially eaten fruits and pulp, and then land-based mammals feed on these fallen fruits. The first human patient in an epidemic would have become infected through contact with just such an infected animal. The virus can then be transmitted in several ways. Most commonly, people are exposed to Ebola virus from direct contact with the blood and or secretions of an infected person, and in this way, the virus is often spread through families and friends who care for the patient. Victims can also be exposed through contact with medical equipment (including needles) that has been contaminated with infected secretions. A major source of spread during Ebola outbreaks is through healthcare workers in clinics and hospitals. All epidemics have occurred in sub-optimal hospital conditions, where the practice of basic hygiene and sanitation are often lacking. In modern hospitals, with disposable needles, knowledge of basic hygiene, and barrier nursing (isolation) techniques, Ebola has never spread on a large scale. With one notable exception, outbreaks of Ebola among humans have been restricted to Africa. In 1989, cases of severe illness and death were reported among monkeys imported from the Philippines to a research facility in Reston, Virginia. While several research workers became infected from these monkeys, they did not become ill, as this particular strain of Ebola fortunately does not appear to cause harm to humans. In Africa, however, other strains of the virus have actually destroyed local populations. When outbreaks have occurred, governments and individuals quickly respond to quarantine the area. In Zaire, there were outbreaks among humans in 1976 and again in 1994. In the Sudan, there was an outbreak in 1976, again in 1979, and 2000 and 2004. A scientist became infected while conducting an experiment on a wild chimpanzee in the Ivory Coast in 1994. The most recent outbreak occurred in Uganda in 2007. Treatment for Ebola is mainly supportive. Invasive procedures are avoided, as they lead to more bleeding. Instead, treatment focuses on replacing electrolytes and fluids, giving coagulation factors to help stop bleeding, maintaining oxygen levels, and treating complications. To date, there is no vaccine for humans, but vaccines for non-human primates have been successful. If this virus isn't scary enough, its high mortality rate has made it a potential agent for biological warfare. In the early 1990's, members of Japan's Aum Shinrikyo cult considered using Ebola as a terror weapon. Their leader led about 40 members to Zaire under the guise of offering medical aid to Ebola victims in a presumed attempt to acquire a virus sample. Wikipedia reports that Aum Shinrikyo did obtain Ebola virus from Zaire in 1994, but it was never used. Given the lethal nature of Ebola, and since no approved human vaccine or treatment is available, it is classified as both a biosafety level 4 agent, and a category A bioterrorism agent by the Centers for Disease Control and Prevention. The attention gathered from the outbreak in Reston prompted an increase in public awareness, leading to numerous fictional works, including the (great!) 1995 movie, "Outbreak." Ebola has not been a major problem here in the United States. Let us hope that there are no more tragic outbreaks in Africa, or anywhere in the world. Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 8301 E. Florence Ave., Suite 100, Downey, CA 90240.
********** Published: April 28, 2011 - Volume 10 - Issue 2