Ebola Virus Strikes Terror Once Again

“I’m deeply concerned about the scale and speed of the epidemic.”

Tedros Abhanom Ghebreyesus, Director General of the World Health Organization

“You can’t fight off Ebola the way you fight off a cold. Ebola does in ten days what it takes AIDS ten years to accomplish.”

Richard Preston, American author

My inaugural Germ Gems dealt with the Ebola virus. As I published that post on July 20, 2019, the 50^th anniversary of Neil Armstrong’s landing on the moon, I titled it “How About a Moonshot to End Ebola Virus Infections?” At that time, the idea didn’t seem that farfetched; after all, if humans could make it to the moon and back and eradicate smallpox—a viral infection that killed more people than all wars combined—then defeating Ebola virus certainly seemed achievable. Unfortunately, that hasn’t happened.

Since July 2019 there have been nine distinct Ebola virus outbreaks in Africa, including the current one. (Seven of these outbreaks occurred in the Democratic Republic of the Congo (DRC) and two in Uganda.) The current outbreak started in the DRC in late April and is already the third largest Ebola outbreak on record. Due to its alarming trajectory, on May 17, 2026, the World Health Organization (WHO) declared this outbreak a Public Health Emergency of International Concern (PHEIC).

In this week’s Germ Gems post, I provide an overview of Ebola virus infections and discuss why the current outbreak in the DRC is particularly worrisome.

What is Ebola Virus Disease (a recap)?  Orthoebolaviruses, found mostly in sub-Saharan Africa, are a genus of single-stranded RNA viruses responsible for causing Ebola Virus Disease (EVD) and Ebola Hemorrhagic Fever in humans and other primates. There are six known species of the genus Orthoebolavirus; four cause disease in humans; three are highly lethal.  The highly lethal species are:

• Orthoebolavirus zairense (Zaire virus or Ebola virus): the deadliest species with a human case fatality rate ranging from 50-90%;

• Orthoebolavirus sudanense (Sudan virus): fatality rates ranging around 50%; and

•  Orthoebolavirus bundibugyoense (Bundibugyo virus): an estimated fatality rate of up to 40%.

  (https://www.ama-assn.org/public-health/infectious-diseases/ebola-resources).

Ebola is a zoonotic infection, meaning it originates in animals and then can be transmitted to humans. The elusive animal reservoir for the Ebola virus (EV) is most likely fruit bats.

People can be infected with the EV through contact with a fruit bat or contact with a non-primate animal infected with the virus. Person-to-person contact can occur through direct contact with the bodily fluids of infected or deceased individuals. A common scenario for viral spread is often in healthcare settings or among those preparing the bodies of people who died from EVD for burial. Even though these viruses are not spread through the air (by aerosols), they are highly contagious and can affect a large number of people.

Symptoms of EVD usually begin suddenly after an incubation period of about 2-21 days. Early symptoms resemble influenza or malaria and include fever, fatigue, headache and loss of appetite. The early symptoms are followed by vomiting, profuse diarrhea, abdominal pain, and, in fatal cases, by liver and kidney dysfunction, hemorrhage, shock, and death. (Hemorrhage is a key risk factor for death.)

At the present time, there is one vaccine (Ervebo) that is effective against the Zaire virus. (Adepoju, P., “Ebola vaccines exist, but not for the strain in the current outbreak, Scientific American, May 20, 2026). But, there is no licensed vaccine or treatment for either Sudan virus or Bundibugyo virus, the cause of the current outbreak. Efforts are underway, however, to change that.

A WHO-sponsored clinical trial of two experimental treatments for Ebola Bundibugyo virus disease is in the works. (Callaway, E., “Scientists race to develop Ebola drugs as outbreak surges,” Scientific American, May 18, 2026). In addition, health officials are considering whether the approved vaccine for the Zaire virus could be put in trial for the current outbreak. And then there is a drug produced by Mapp Biopharmaceutical, Inc., a small biotech company based in San Diego, California, that is working with the Biochemical Advanced Research and Development Authority to deliver its drug for potential use in EV patients. (Smith, G., “US Enlists Small Biotech for Experimental Ebola Treatment,” Bloomberg News, May 20, 2026).

What is causing the current outbreak? In 1976, in what is now known as the DRC and the Sudan, scientists identified the first Orthoebolavirus—the Sudan virus. Since that discovery, there have been more than 35 recorded Ebola virus outbreaks—the vast majority occurring in Central and West Africa. Traditionally, the Zaire virus has been the most common strain behind outbreaks as well as the most deadly. The Bundibugyo virus—a rarer species of the Ebola virus—is the cause of the current outbreak. (Fieldhouse, R., Basu, M, “Ebola outbreak is a global health emergency: what happens next,” Nature, May 18, 2026).

The Bundibugyo species has caused two previous documented outbreaks. The current outbreak, with more than 670 cases and 160 deaths as of May 21, 2026, is fast-spreading with “significant uncertainty” about the number of infections and the extent of its spread. (Mogensen, J.F., “An Ebola outbreak is spreading fast. Should you be worried?,” Scientific American, May 20, 2026). Nonetheless, public health experts stress that as serious as this outbreak is that “the risk of a pandemic-level threat is low, with minimal danger to the U.S.”

Part of the reason that risk of a pandemic-level threat to the U.S. is likely to remain low is due to the biology of the virus itself. People usually become infected with orthoebolaviruses  through contact with bodily fluids—not a particularly efficient mode of transmission as compared to SARS-CoV-2 which can spread through the air (aerosols).  In addition, unlike an airborne infection like the flu that can be transmitted from people who are infected but asymptomatic, people infected with orthoebolaviruses are not thought to be infectious until after the onset of symptoms.

As Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, said, “Not every pathogen has the ability to cause a pandemic.” Nonetheless, she cautioned, “There are many types of public health emergencies that fall short of a pandemic that are still important. Ebola does not have pandemic potential, but it clearly is an epidemic disease and has massive regional importance.” (Even though the WHO declared the current outbreak a PHEIC, its Director-General stressed it “does not meet the criteria of pandemic emergency.”)

Controlling this outbreak. There is no widely available diagnostic test, no treatment, and no vaccine for this species of EV. (Cohen, J., “Scientists play catch-up to startling Ebola outbreak,” Science, May 18, 2026).  With past Ebola outbreaks, rigorous control measures have managed to stop its spread. The DRC itself “has stopped more than a dozen previous outbreaks despite a lack of drugs or vaccines simply by isolating patients and identifying and quarantining their contacts.”

At present, the global risk remains low. Nonetheless, U.S. health officials have now put enhanced screening measures in place for travelers to the U.S. from the affected areas.  As Secretary of State Marco Rubio said: “Our No. 1 objective on Ebola…has to be we can’t have it affect the United States. We can’t have Ebola cases coming here.” (Helmore, E., “US temporarily bans green-card holders from entering country from African nations,” The Guardian, May 23, 2026).

To that end, on May 18, 2026, the U.S.  issued travel restrictions that for the next three weeks that bar non-U.S. passport holders who have been to the DRC, Uganda, or the South Sudan from entering the U.S. On May 22, 2026, it enhanced these restrictions by temporarily banning green-card holders from entering the country if they had traveled to any of these three African nations in the last 21 days.

Given EV’s high transmissibility, travelers to the affected regions should avoid contact with sick people, and if they become symptomatic, should report their symptoms immediately. Infection control experts recommend that healthcare workers dealing with Ebola patients wear head coverings, as well as goggles, masks or face shields, gloves, gowns, and rubber boots.

What’s the U.S. Centers for Disease Control and Prevention’s role in this outbreak? In the past, the U.S. Centers for Disease Control and Prevention (CDC) would have been at the forefront of the public health organizations addressing public health emergencies just like this. But, there’s little evidence that the CDC and WHO are even coordinating their approaches to this EVD PHEIC.

The CDC has, however, 25 staff stationed in the DRC and claims it will send more technical experts to help. And, the U.S. had promised to fund up to 50 Ebola treatment units in the outbreak area. According to Secretary Rubio: “The United States has an ironclad commitment to ensuring this response is fully resourced, rapid, and cooperative between key global health and humanitarian partners. (Soucheray, S., “At least 600 Ebola cases suspected as US pledges to fund 50 treatment clinics,” CIDRAP News, May 20, 2026).  Let’s hope that is true.