NR 503 Week 3: Current Event

NR 503 Week 3: Current Event

A 2005 study published in Nature and directed by Eric Leroy tested more than 1,000 small vertebrates in central Africa and found evidence of asymptomatic Ebola infection in three species of frugivorous bats, which led him to believe that perhaps these animals that sometimes they hunt to consume their meat, were the reservoir of the virus (Kupferschmidt, 2017). Humans can become infected by hunting and eating infected meat or by direct contact with bats. Once infected, the human can transmit the virus to others. Moreover, Ebola has an incredible ability to take over the body fluids of men who have survived the disease long after they have healed. In fact, one study found that more than half of men who survived the West African epidemic tested positive for Ebola in semen a year or more after recovery (CDC, 2016). In one case, the analysis yielded a positive result no less than 565 days after the cure (CDC, 2016). Because of the risk of the disease spreading, survivors are advised to avoid having unprotected sex until their semen has twice tested negative for the presence of the virus.

It is estimated that each infected person infects an average of two other people (Doucleff, 2014). The bodies of deceased people remain highly infectious for about seven days. Although Ebola has often been classified as a hemorrhagic fever, WHO and other experts begin to avoid the term as not all individuals present with visible hemorrhages (WHO, 2014). In fact, the evolution is as follows: the first symptoms (tiredness, nausea, fever, headache) are similar to those of diseases such as influenza and malaria, which makes early diagnosis difficult. As the infection progresses, muscle aches, fever and headache become more pronounced and diarrhea and vomiting appear. Often, there is bleeding from the nose or gums. Death occurs within two weeks after the onset of the first symptoms (WHO, 2014).

The rVSV-ZEBOV vaccine, specific for the Zaire strain and not yet approved, was developed by the National Microbiology Laboratory of Canada, tested in Guinea and Sierra Leone during the 2014-2016 epidemic and then purchased by the company. Pharmaceutical Merck, which holds the rights. 100% of the people vaccinated did not develop the disease. However, it was the end of the outbreak and the actual efficacy of this compound must still be proven (Medaglini & Siegrist, 2017). The first trials with the candidate vaccines show that they are safe and that they induce an immune response. What is not yet known is the level of protection and the duration of it. Even if the vaccines do not confer lasting protection, they can be used in future outbreaks to protect the most exposed populations (health workers, among others). Moreover, there is currently no approve vaccine or specific treatments for Ebola. For now, the most effective way to limit in part the mortality caused by the virus is to provide intensive support care, which consists in restoring liquids and electrolytes lost by diarrhea and vomiting.

CDC (2016). Virus Linger Longer than Expected in Semen. Retrieved on July 8, 2018 from https://www.cdc.gov/media/releases/2016/p0830-ebola-virus-semen.html

Doucleff, M. (2014). No, Seriously, How Contagious Is Ebola?. Public Health. Retrieved on July 12, 2018 from https://www.npr.org/sections/health-shots/2014/10/02/352983774/no-seriously-how-contagious-is-ebola

Kupferschmidt, K. (2017).Hunting for Ebola among the bats of the Congo. Since AAAS.  (361)6398. doi:10.1126/science. Aan6907

WHO (2014). Ebola Response Team. Ebola virus disease in West Africa — the first 9 months of the epidemic and forward projections. N Engl J Med.371:1481-1495