What is Ebola hemorrhagic fever?
Ebola hemorrhagic fever is a viral disease caused by Ebola virus (a member of the Filoviridae family or filoviruses) that results in nonspecific symptoms (see symptom section of this article) early in the disease and often causes internal and external hemorrhage (bleeding) as the disease progresses. Ebola hemorrhagic fever is one of the most life-threatening viral infections; the mortality rate (death rate) may be very high during outbreaks (reports of outbreaks range from about 25%-100% of people infected, depending on the Ebola strain). Because most outbreaks occur in areas where high-level intensive care supportive public health services are not available, survival rates are difficult to translate to potential outbreaks in Ebola-affected areas with more resources.
What is the history of Ebola hemorrhagic fever?
Picture of the Ebola virus, viewed with an electron microscope; SOURCE: CDC/Frederick Murphy
Ebola hemorrhagic fever first appeared in Zaire (currently, the Democratic Republic of the Congo or DRC or Congo) in 1976. The original outbreak was in a village named Yambuku near the Ebola River after which the disease was named. During that time, researchers identified the virus in person-to-person contact transmission. Of the 318 patients diagnosed with Ebola, 88% died. The second outbreak occurred in Nzara, South Sudan, in 1976, with 151 deaths.
Since that time, there have been multiple outbreaks of Ebola virus, and researchers have identified five strains; four of the strains are responsible for the high death rates. The four Ebola strains are termed as follows: Zaire, Sudan, Tai Forest, and Bundibugyo virus, with Zaire Ebola virus being the most lethal strain. Researchers have found a fifth strain termed Reston in the Philippines. The strain infects primates, pigs, and humans and causes few if any symptoms and no deaths in humans. Most outbreaks of the more lethal strains of Ebola have occurred in sub-Saharan West Africa and mainly in small- or medium-sized towns. Health care professionals believe bats, monkeys, and other animals maintain the non-human virus life cycle in the wild; humans can become infected from handling and/or eating infected animals.
Once an Ebola outbreak is recognized, African officials isolate the area until the outbreak ceases. However, in the outbreak that began in West Africa in March 2014, some of the infected people reached larger city centers before the outbreak was recognized; this caused further spread. The infecting Ebola virus detected during this outbreak was the Zaire strain, the most pathogenic strain of Ebola. Health agencies are terming this outbreak as an "unprecedented epidemic." This epidemic spread quickly in the West African countries of Guinea and Sierra Leone. In addition, countries of Liberia, Nigeria, Senegal, Uganda, and Mali all reported confirmed infections with Ebola. In addition, a few infections or flare-ups of Ebola virus infection appeared in the United States, Spain, and the United Kingdom (see for example, the case of Pauline Cafferkey, a nurse who became infected); most of the people with Ebola in these countries either were imported infections from West Africa or were newly spread infections from treating patients who originally became infected in Africa. Another outbreak occurred in the DRC in May 2018 in Bikoro, a small town 80 miles from Mbandaka, with 46 reported infections and 26 deaths. Unfortunately, the large city of Mbandaka, with over 1 million people, has recorded at least three people with Ebola. The DRC hopes to isolate or stop the spread of Ebola in the two areas by vaccinating anyone who may have had some physical contact with an infected person with a new chimeric virus vaccine that in 2015 showed good results in Ebola-infected patients.
Health officials now report over 1,000 deaths due to Ebola in areas like Butembo in the Congo (DRC) and neighboring countries in an ongoing outbreak over the last 9 months. This outbreak is difficult to control because it is happening in a war zone where cooperation between countries to control the outbreak is uncoordinated and even considered unwelcome.