Ebola is a deadly viral disease endemic to certain parts of Africa. It was first identified in the DRC, or the Democratic Republic of Congo, near a river called the Black River. Ebola means black in the local dialect. Outbreaks of the disease seem to appear from nowhere, infect and kill thousands, and then disappear again. It must have an animal host, most probably a species of bat, but this has not yet been proven. Recently, a species of African fruit bat was discovered to harbor the Bombali strain of Ebola, but it’s not yet known if Bombali can cause disease in humans. There are five main types of Ebola:
- Tai Forest
Of these, the Zaire strain is the most deadly. Its death rate is as high as 90 percent. Sudan isn’t as bad, killing about half of its victims. The Reston strain doesn’t cause disease in humans, but it’s still highly lethal to other primates. Symptoms include high fever, headache, body pain, dehydration resulting from severe vomiting and diarrhea and pain in the stomach. Death is typically from shock and mass organ failure. Ebola is deadly mainly because it attacks so quickly, devastating the body’s systems before the immune system can ramp up enough antibodies to fight it. Survivors of Ebola appear to be at least somewhat immune from another attack of the same strain for at least a decade after recovery. However, a survivor of one strain of Ebola is not necessarily protected from infection by another.
Ebola has no known source within the United States, but the infection has appeared here in the past. In 2014, a travelling male Liberian national transmitted the Zaire strain to two nurses caring for him in a Dallas hospital. Both survived, mainly due to aggressive supportive care. The Liberian man died. Ebola does not appear to be generally airborne, but it’s extremely contagious. All body fluids are contaminated with it. Just touching an Ebola patient can transmit it. It can also enter the body through the eyes, nose, mouth and through sexual intercourse. There is some evidence that the virus can persist in male semen for an unknown period of time even after the patient has totally recovered. Even after full recovery, some people still experience headaches, fatigue and visual problems.
In the past, Ebola wasn’t treatable with any known drugs. It had no vaccine. Epidemics were often fueled by very old African customs that included close contact with the body after death. In many African cultures, it’s a sign of love and respect to prepare a loved one’s body for burial. The body surfaces of a patient who just died of Ebola are teeming with live, infectious viral particles. These particles can infect a new victim with just a touch and then from there, a transfer to the eyes, nose or mouth. The tiniest break in the skin can also allow the virus to enter. The virus can also live on objects, like bedding and clothing, and can infect a person in that way.
Earlier this year, four African nations licensed a new vaccine for Ebola Zaire, called Ervebo. Ervebo prevents infection in 97.5 percent of those people who receive it. Ervebo appears to reduce the risk of death in patients already infected at the time the vaccine is given, too. Ervebo is effective only against the Zaire strain, but since it’s the one most likely to kill the most people, this is satisfactory.
Although all strains of Ebola, except for Reston, cause similar disease in humans, they are still distinct from one another as far as vaccines and drug treatments are concerned. Very specific immune factors are involved. This means that a vaccine or drug for one strain will not be effective for another. It also means that it’s possible for the same person to get all five Ebola strains. One strain doesn’t necessarily confer immunity to another. There is another deadly viral disease, dengue fever, endemic to Africa and Central and South America. It also has four different strains, and it’s possible for the same person to recover from one strain and still be susceptible to the other three.
Supportive care measures for Ebola virus infection include:
- Intravenous fluids and electrolytes
- Medications for pain, diarrhea and to support blood pressure
- Antibiotics for other bacterial infections
A New Drug Treatment for Ebola Zaire
Inmazeb is the trade name for a new drug developed to fight the Zaire strain of Ebola. Inmazeb is a combination of three monoclonal antibodies that disable the virus and stop it from entering cells, where it takes over and directs the human cell to produce more Ebola virus. The antibodies do this by identifying and attaching to certain proteins on the surface of the virus.
Because the proteins on the surface of the virus are so specific, Inmazeb can only target the Zaire strain. It’s entirely possible to create a monoclonal antibody therapy drug for all the Ebola strains, but these are not yet available. One day, a combination drug that targets all four of the Ebola strains that cause disease in humans may be available. Inmazeb offers the real hope of survival from a deadly disease. At least for now, that’s enough.