Updated: October 29, 2019
Ebola hemorrhagic fever is a viral disease caused by Ebola virus, a member of the Filoviridae family that results in nonspecific symptoms in early stage. But the disease often causes internal and external hemorrhage as it progresses.
Ebola hemorrhagic fever or Ebola virus disease is a disease caused by four different strains of Ebola virus of the Filoviridae family. These viruses infect humans and nonhuman primates.
The infection is transmitted by direct contact with the blood, body fluids, and tissues of infected animals or people. Intensive supportive care is required for severely ill patients. Ebola virus disease (EVD) is often characterized by onset of fever, intense weakness, muscle pain, headache, and sore throat. Because families and friends are exposed to infectious secretions when caring for an ill individual, it tends to spread quickly among them. The time interval from infection with Ebola to the onset of symptoms ranges from 2 to 21 days.
Ebola is considered a zoonotic virus which means it originates in animals and then spread to humans. Early clinical diagnosis is difficult as the symptoms are nonspecific. However, if the patient is suspected to have Ebola, the patient needs to be isolated, and local and state health departments need to be immediately contacted.
ELISA and/or PCR tests are used for definitive diagnostic tests for Ebola hemorrhagic fever. Viral cultivation and biopsy samples may also be used. There is no standard treatment for Ebola hemorrhagic fever. Only supportive therapy and experimental treatment is available. Currently no vaccine available for Ebola, although several are in development with some success in one vaccine, called Ebola Ã§a suffit.
The time interval from infection with Ebola to the onset of symptoms is 2 to 21 days, although 8 to 10 days is most common.
Symptoms of Ebola virus infection which are similar to those produced by other hemorrhagic fever viruses include:
Additional Ebola symptoms may include:
Symptoms can include bleeding at various sites within or outside of the body in severe cases.
Low white blood cell and platelet counts and elevated liver enzymes are indication of ebola infection. As long as the patient's blood and secretions contain the virus, they are infectious. In fact, Ebola virus was isolated from the semen of an infected man 61 days after the onset of illness.
The cause of Ebola hemorrhagic fever is Ebola viruses in the Ebolavirus and Filoviridae family. Ebola is considered a zoonosis which means that the virus is present in animals and is transmitted to humans. How this transmission occurs at the onset of an outbreak in humans is unknown. It may have developed after handling infected animals found ill or dead, including chimpanzees, gorillas, fruit bats, monkeys, forest antelope, and porcupines.
After someone infected with Ebolavirus becomes symptomatic, the transmission can occur from person to person. An outbreak can be hard to control and may spread rapidly as a person with Ebola may have been in contact with hundreds of people with in 21 days which is the incubation period.
When an Ebola infection occurs in humans, the virus can be spread in several ways to others. Transmission of Ebola between humans can occur through:
There is no evidence that Ebola can be spread via insect bites.
There is a higher risk of becoming infected when:
Patients who survive infection may remain contagious for approximately 21 to 42 days after symptoms abate. However, health care professionals can remove the viruses from semen, breast milk, spinal column, and ocular fluids. The reason why some patients can survive and others die from this disease is unclear. But patients who die usually have a poor immune response to the virus. Symptoms can be severe for a week or two for patients who survive the infection. Recovery is often slow which can take a weeks to months and some survivors have chronic problems such as fatigue and eye problems.
Preliminarily diagnose of Ebola hemorrhagic fever is based on early symptoms and association with other individuals with Ebola.
As samples from patients with Ebola are an extreme bio-hazard risk, testing should be conducted under maximum biological containment conditions. Other diseases should be ruled out before the diagnosis of Ebola. The patient should be isolated if Ebola is suspected and public health professionals should be notified immediately. Ebola virus infections can be diagnosed definitively in a laboratory through several types of tests, including:
Diagnosis is made using IgM and IgG antibodies in more advanced stages of the disease or after recovery. Health care professionals usually perform studies using immunohistochemistry testing, PCR, and virus isolation in deceased patients for epidemiological purposes.
Standard treatment for Ebola hemorrhagic fever is still limited to supportive therapy. Supportive therapy is balancing the patient's fluid and electrolytes, maintaining their oxygen status and blood pressure, and treating such patients for any complicating infections. Any patients suspected of having Ebola hemorrhagic fever should be isolated, and caregivers should wear protective garments.
In U.S if any patient is diagnosed with Ebola, special hospitals certified to treat Ebola patients to avoid spreading of the disease to hospital workers. Then they contact the CDC immediately for information for experimental vaccines, treatment protocols, and patient care and/or transfer to an appropriate facility. Experimental medical treatments of Ebola infections include immune serum, antiviral drugs, possible blood transfusions, and supportive care in an intensive care hospital facility approved by the CDC to treat Ebola infections.
Because Ebola infections can spread rapidly to others and because patients can easily infect health care workers, only highly trained personnel are recommended by the CDC and other agencies to treat Ebola patients. This treatment involves high-level barrier techniques to protect all health care professionals that include hospital care workers, nurses, doctors, lab technicians, janitors, and hospital infectious-disease-control personnel.
The specialists who may treat Ebola-infected patients are emergency medicine specialists, infectious disease specialists, critical care doctors and nurses, pulmonologists, hematologists, hospitalists, and hospital infection-control personnel.
The virus can results in coagulation abnormalities, including gastrointestinal bleeding, development of a rash, cytokine release, damage to the liver. It also results in massive viremia which is large number of viruses in the blood that leads to damaged vascular cells that form blood vessels.
Coagulation factors are compromised and the microvascular endothelial cells are damaged or destroyed as the massive viremia continues. This resulting in diffuse bleeding internally and externally. Bleeding from the mucosal surfaces like nasal passages and/or mouth and gums and even from the eyes termed conjunctival bleeding occurs. This uncontrolled bleeding leads to blood and fluid loss and can cause hypotensive shock that causes death in many Ebola-infected patients.
Organ failures, severe bleeding, jaundice, delirium, shock, seizures, coma, and even death can happen in Ebola hemorrhagic fever. Those patients fortunate enough to survive Ebola hemorrhagic fever still may have complications that may take many months to resolve. Survivors may experience weakness, fatigue, headaches, hair loss, hepatitis, sensory changes, and inflammation of organs such as the testicles and the eyes.
Some may have Ebola linger in their semen for months and others may have the virus latently infect their eyes. Ebola viruses are detected in semen of male patients for as long as six months after they survive the infection. Although the chance of being infected with Ebola from semen is very low, utilizing condoms for at least six months is usually recommended.
As the reason of infection is unknown, stopping infection is still difficult. The main way to prevent getting Ebola hemorrhagic fever is to not travel to areas where it is endemic and by staying away from any patients who may have the disease. Healthcare workers may protect themselves from infection by strict adherence to barriers to the virus such as wearing gloves, gowns, goggles, and a mask.
Preventing transmission can be achieved by:
World Health Organization (WHO) has given license for two promising Ebola vaccines:
GlaxoSmithKline has developed this vaccine in collaboration with the United States National Institute of Allergy and Infectious Diseases (NIH). It uses a chimpanzee-derived adenovirus vector with an Ebola virus gene inserted.
This was developed by the Public Health Agency of Canada in Winnipeg with NewLink Genetics, a company, located in Ames, IA. The vaccine uses a weakened virus found in livestock, one of its genes has been replaced by an Ebola virus gene.
The Ebola ca Suffit vaccine had 100 percent efficacy in the trial, which took place in Guinea and involved 4,000 people. The full results of this trial were published in Lancet in February 2017.
However, currently these vaccines are not available. But it will be available in future as soon as possible and in sufficient quantities to protect critical front line workers and to make a difference in the epidemic's future evolution.
Although a relatively safe and effective vaccine is now available to clinicians under certain conditions, research are still going on. The antibody generated against the glycoprotein in the vaccine may only be effective against one strain of Ebola, but not against the other strains.
The following are several references that we update periodically to provide recent information about Ebola viruses and Ebola disease:
World Health Organization: http://www.who.int/csr/don/13-may-2017-ebola-drc/en/
Centers for Disease Control and Prevention: https://www.cdc.gov/vhf/ebola/index.html
Centers for Disease Control and Prevention, 2014-2016 West Africa outbreak: https://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/