In 1976, an outbreak of a viral illness was identified in Sudan. Patients would present with symptoms of high fever, headache, vomiting, diarrhoea and a spotted rash, but would rapidly deteriorate in health. Within days, patients showed signs of decreased blood clotting, such as bleeding from intravenous line sites, having blood in their vomit and stool, or bleeding from essentially any bodily orifice. If untreated, patients would die within two weeks of shock (very low blood pressure), kidney failure or bleeding into the brain. The outbreak killed 151 people before it disappeared.
Later in the year, a headmaster at a school in Zaire developed a similar disease after travelling to the Ebola River. He died two weeks later. Soon after, people he came in contact with after his trip died of similar symptoms. The World Health Organisation investigated this epidemic and realised that the disease was caused by a new type of virus, which was named ebola virus. Due to its symptoms, the disease caused by the virus is named ebola haemorrhagic fever.
Since the discovery of the disease, occasional ebola outbreaks were seen in various parts of Africa, mainly around Congo and Uganda. Each time, the disease would rapidly claim the lives of hundreds of people and then vanish. This is because ebola virus was so effective in killing people (with a death rate of 90% in one outbreak), that it would kill the infected person before they spread the disease further.
The virus can be spread through any bodily fluid, including blood, tears, semen and sweat. Because of this, once an infected patient is brought into hospital, the disease can spread rapidly throughout the building and infect many patients and hospital staff if proper precautions are not taken. Fortunately, the virus is not known to spread when the patient is in the incubation period (when they are infected but have not shown symptoms yet).
The origin of the virus has been traced back to fruit bats (like many other serious viruses). Fruit bats have extremely powerful immune systems to protect their cells from the harmful metabolites produced by flying, allowing bats to harbour deadly viruses without succumbing to them. These viruses have also evolved to withstand the high temperatures produced by flying (which involves significant muscle work), meaning they can easily survive the high fevers they cause in humans. The transmission from bats to human in modern times is likely attributed to deforestation and humans encroaching into the bats’ native territory.
The current epidemic that originated from West Africa is the biggest ebola outbreak so far, having infected over 9000 people and claiming the lives of over 4500 people (October 14, 2014). However, this is likely a grossly underestimated number. The epidemic is focussed mainly in Guinea, Sierra Leone, Liberia and surrounding countries, but has infected foreign workers and volunteers who have been repatriated to be treated in their home country.
Despite a robust effort from the WHO to try and curb this epidemic, the infection rate continues to climb due to various factors, such as traditional funeral rites involving touching the deceased person’s body, which is still infective after death. There are currently no effective vaccines or treatments and the only thing that can be done is supportive treatment in an intensive care unit where the patient can be adequately hydrated and monitored. Like with most communicable diseases, the most effective treatment is preventing the disease from spreading through education, rigorous infection control protocols and improved healthcare systems in the affected countries.