Ebola

By Aileen Marshall

Are you like me and you’ve heard about the Ebola virus in the news, but didn’t really pay attention? Do you wonder if there’s anything to worry about? In doing the research, it seems there is little chance to be infected in the US. Here is a summary of what’s going on with the current outbreak.

First, a little history. The first outbreak was identified in 1976. It was named after the Ebola River, near the first outbreak, in Zaire, now known as the Republic of Congo. That original epidemic caused 280 deaths, with an 88% fatality rate—WHO (World Health Organization) helped to contain that plague. There were later outbreaks in the Republic of Congo in 1995, 2003, 2007 and 2012 and in Uganda in 2000. Each killed several hundred people, with fatality rates ranging from 60 to 90%. The current outbreak is in Guinea, Liberia, Sierra Leone and Nigeria. Over 2000 deaths have occurred in this outbreak.

Ebola Hemorrhagic Fever (EHF) is caused by the Ebola virus. This virus is a member of the family Filoviriadae, the genus Ebolavirus. The specific species is the Zaire ebolavirus. Although it is not known for sure, the most likely animal reservoir is fruit bats. The bats will carry the virus, but not get sick. They will bite into a piece of fruit, leaving their saliva on it, and drop it to the ground. Some other animal, perhaps a dog or a monkey will touch or eat the fruit and become infected. The animal then passes the disease along to a human by some contact. A person can get the virus from an animal bite, or handling the animal or the meat. Once Ebola is in a human host, it spreads from person to person by contact with bodily fluids. Many healthcare workers in West Africa have contracted the disease either by not having enough personal protective equipment (PPE) such as masks or gloves, re-using infected needles, or not hand washing due to lack of running water. It is important to note that Ebola can only be contracted through direct contact with an infected person’s bodily fluids. Ebola is not airborne, like the flu. So it is unlikely for anyone here to get Ebola unless they are in direct contact with someone recently infected in Africa.

Ebola can be difficult to diagnose early, since the symptoms are much like that of other common infections: fever, fatigue, headaches, joint and muscle pain, and abdominal pain. Later, diarrhea and vomiting occur. Symptoms appear between two and 21 days from infection. Later, in the bleeding phase, a rash, red eyes, bruising and bloody vomit appear, usually between five and seven days after the first symptoms appear. The virus is caused by internal bleeding.

Because the early symptoms are vague and flu-like, diagnosis can be difficult. It is suspected if a patient has had recent contact with an infected person. If so, the patient must be quarantined immediately. There are tests that detect antibodies in a blood sample, but, some of the tests are not available in under developed areas like West Africa.

Currently, there are no approved treatments or vaccines for EHF. The numbers of infected people are not enough to have spurned interest from the pharmaceutical companies. However, because the current outbreak having spread so much further than the previous ones, WHO has declared an emergency situation. It encouraged all medical regulatory agencies to fast track any medicines or vaccines in development. There are a few drugs getting ready to go to Phase I clinical trials.

Currently treatments to support patients’s immune systems are administering fluids, electrolytes, painkillers, anti-emetics, oxygen, etc., and treating concurrent infections.

There are two drugs being developed as treatments: ZMapp and TKM-Ebola. These have been approved by the FDA to be used in this current emergency situation. ZMapp is a combination of three different monoclonal antibodies that bind the virus in the blood. It’s still in early stage of development, it’s not known if it works, it has not yet completed Phase I clinical trials. TKM-Ebola uses small interfering RNAs. Both of these drugs have been tested in monkeys and guinea pigs, with promising results.

Another treatment that has been used is to give a blood transfusion from an Ebola survivor. The reasoning is that the survivor must have developed antibodies against the virus. WHO has encouraged this as the first treatment of choice, although it has not been systematically studied in humans.

There are two promising vaccines that have been effective in non-human primates in preclinical research. The most promising one is rVSV. It’s a vector from vesicular stomatitis virus carrying a glycoprotein from the Ebola virus. It has produced one year of protection in monkeys. Human trials of this vaccine were started in September. These trials came about due to collaboration and support from the National Institutes of Health, Glaxo Smith Kline, the Public Health Agency of Canada, Wellcome Trust and the British Medical Research Council. Phase I clinical trials using another possible vaccine ChAd3, also just started. It’s a disabled virus from chimpanzee derived replication defective adenovirus. However, this vaccine requires booster shots, which are difficult to do in current outbreak countries.

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