Understanding Ebola Virus: A Global Health Threat and Challenge
Ebola virus disease (EVD) is a deadly disease and is caused by an infection with four of five viruses of the genus Ebolavirus. The Ebola virus (EBOV) is currently the most dangerous of the known-EVD causing viruses. This virus has been spread widely around the world for millions of years until it was first discovered in 1976. In general, for the various types of the Ebola virus, the most likely reservoir hosts involved are various species of bats and fruit bats. The first outbreak occurred in a village near the Ebola River in Africa after which the virus was named. Since then, the virus has been infecting humans from time to time, causing multiple outbreaks in Africa. And the largest Ebola outbreak, which began in West Africa in 2014, spread to urban areas and across borders within weeks and became a global epidemic within months. It lasted two years and infected thousands of people, more than half of whom died. The virus causes hemorrhagic fever that could lead to death in a few days. EBOV is transmitted from wild animals to humans and from person to person through body fluids, blood, feces and vomit. The fatality rate after infection is as high as 90%. When the virus enters the human body, the immune system becomes activated and produces antibodies in response to neutralize it. However, if the immune system is unable to resist, the virus will spread, leading to impaired innate and adaptive immune responses and uncontrollable viral replication. The main causes of death are stroke, myocardial infarction, hypovolemic shock, or multiple organ failure. There's no cure for Ebola, though researchers are working on it. The first vaccine against Ebola virus disease, Ervebo, was approved by the U.S. FDA in December 2019 and was supported by a study conducted during the largest outbreak in Africa. Beyond promising vaccine candidates, the U.S. FDA has currently approved two drug therapies for the treatment of Ebola virus. These two drugs block the virus from binding to cell receptors, thereby preventing its entry into the cell. In February of this year, new outbreaks of Ebola broke out in Guinea and the Democratic Republic of Congo (DRC). So far, at least 18 people have been infected in Guinea and nine have died. Recent preliminary analyses of viral genome sequences by three research teams revealed that the virus causing the current case is nearly identical to the strain that caused the last pandemic. This shocking finding suggests that the current outbreak was probably triggered by someone who was infected 5-6 years ago and has unwittingly harbored the virus in their body this entire time. Ebola virus is likely to be latent in the human body for a long time, which will bring new challenges to the prevention and treatment of Ebola. The findings of the latest outbreak serve as a platform for further research efforts to better understand the mechanism of the virus, which is expected to reveal its mystery and avoid future EVD-related disasters.