Ebola

 There seems little concern about the Ebola outbreak in Congo.  What I see is a horrible disease usually fatal and easily spread.

Your reaction is understandable. Ebola has a fearsome reputation because it combines a high fatality rate with dramatic symptoms and the possibility of person-to-person transmission.

What may be creating the impression of indifference is that public health officials are worried, but they are worried in a very specific way. The current outbreak in the Democratic Republic of the Congo has in fact been declared a Public Health Emergency of International Concern by the WHO, and international agencies are treating it as a major crisis.

The distinction is between local danger and global danger.

Ebola is not "easily spread" in the way measles, influenza, or COVID are. Transmission generally requires direct contact with the bodily fluids of a symptomatic person or with contaminated materials. Casual contact, sharing air in a room, or simply passing someone on the street is usually not enough. That makes outbreaks difficult but not impossible to contain.

The concern in Congo is that this particular outbreak is occurring amid conflict, population displacement, weak medical infrastructure, attacks on health workers, and mistrust of authorities. Those conditions make contact tracing and isolation much harder. Current reports describe the outbreak as growing rapidly and potentially becoming one of the largest Ebola epidemics ever recorded.

Another complication is that this outbreak involves the Bundibugyo strain of Ebola. Unlike the more familiar Zaire strain, there is currently no licensed vaccine or specific treatment for Bundibugyo, although vaccines and treatments are being tested.

So the picture is a bit paradoxical:

    For people in the affected regions, the danger is very serious.

    For neighboring countries, the risk is significant and requires vigilance.

    For the world as a whole, health authorities still assess the risk as relatively low because Ebola's mode of transmission makes sustained international spread much less likely than with airborne diseases.

In a way, Ebola is almost the opposite of COVID. COVID was often mild in individual cases but spread extraordinarily easily. Ebola is often devastating in individual cases but is much harder to transmit. That difference largely explains why an Ebola outbreak can kill thousands without producing the same level of worldwide public alarm.

It can also, it seems, infect animals and thereby presents a reservoir.

Yes, and epidemiologists take that very seriously.

One reason Ebola has never been eradicated is that it is not solely a human disease. It is a zoonosis—a disease that can move between animals and humans. The leading suspects for the natural reservoir are several species of African fruit bats, which appear able to carry the virus without becoming seriously ill themselves.

That creates a different problem from diseases such as smallpox. Smallpox had no significant animal reservoir, so once human transmission was interrupted, the virus had nowhere to hide. Ebola can apparently persist in wildlife and then "spill over" into humans again years later.

What's interesting is that many of the animals people first associate with Ebola—gorillas, chimpanzees, monkeys—are probably not true reservoirs. They often die from the infection just as humans do. They are more like additional victims. Fruit bats are thought to be the species in which the virus can circulate for long periods.

The existence of an animal reservoir is one reason why outbreaks keep recurring in Central Africa despite decades of public-health efforts. Even if every human case in an outbreak were successfully isolated and treated, the virus could still be reintroduced from wildlife.

That said, the reservoir cuts both ways. It means Ebola may never disappear completely, but it does not mean it spreads efficiently among humans. The virus seems to rely on occasional jumps from wildlife and then chains of close-contact human transmission. If it were both permanently established in wildlife and as contagious as measles, the history of the disease would look very different indeed.

In some ways, rabies is a useful comparison. Rabies persists because of animal reservoirs, yet human epidemics remain limited because transmission between people is uncommon. Ebola is not the same disease, but the reservoir problem is conceptually similar.

What is the mortality rate of the present strain?

The answer depends on whether you mean the Bundibugyo strain in general or the current Congo outbreak.

Historically, Bundibugyo Ebola has been somewhat less lethal than the more famous Zaire strain. Previous Bundibugyo outbreaks had case-fatality rates ranging from about 25–40%, with some estimates extending to 30–50%.

For the current 2026 Congo outbreak, the observed mortality has climbed as the epidemic has progressed:

    Early June: about 20% of confirmed cases died.

    Mid-July WHO figures: about 39%.

    Mid-August reports: about 46–47% (roughly 2,300–2,500 deaths among 5,000+ confirmed cases).

So if you ask, "What fraction of known infected people are dying in this outbreak right now?" the answer is roughly one-half. That is alarmingly high, though still below the worst historical Ebola outbreaks, where mortality sometimes exceeded 70% and occasionally approached 90% in areas with little supportive care.

One subtle point: the rising mortality rate does not necessarily mean the virus itself is becoming more deadly. WHO and other experts attribute much of the increase to people being diagnosed late, dying before reaching treatment centers, and the difficulties of providing care in conflict-affected regions.

From a public-health perspective, a disease that kills about half its recognized victims is terrifying. The reason it has not become a global catastrophe is not that it is mild, but that it remains relatively difficult to transmit compared with airborne infections. A virus with Ebola's lethality and measles' transmissibility would be a very different sort of threat indeed.

I assume transport restrictions are in place?

Yes, but perhaps not in the way one might expect.

The WHO has consistently advised against broad border closures and trade restrictions, arguing that they often do more harm than good. Their concern is that if official crossings are closed, people may simply use informal routes that are harder to monitor, while medical supplies and aid workers have more difficulty reaching affected areas.

What has happened instead is a patchwork of measures:

    Health screening at airports and border crossings in affected regions.

    Restrictions on movement within some affected areas. For example, M23 rebel authorities recently imposed movement restrictions in territories they control.

    Entry restrictions, quarantine requirements, or waiting periods imposed by some countries. Canada, for example, has barred certain recent visitors to the DRC, while the United States has imposed screening and waiting-period requirements for people recently in the DRC.

An interesting detail is that Congo itself reopened Bunia airport, near the outbreak's epicenter, after initially suspending flights, relying on screening and hygiene measures rather than a prolonged shutdown.

This reflects a long-standing debate in epidemiology. Intuitively, one thinks, "Close the borders." Yet for diseases like Ebola, which spread through close contact rather than through the air, rapid identification of cases, contact tracing, isolation, safe burials, and community cooperation often matter more than stopping all travel.

Your concern is not misplaced, though. The current outbreak has already crossed into Uganda and has produced a few imported cases outside Africa. The fear is less that a jetliner will seed a worldwide pandemic and more that continued movement through a region with conflict, displacement, and weak health infrastructure makes local containment much harder.

One thing that stands out to me is that this outbreak is testing a public-health principle that became controversial during COVID: whether travel restrictions mainly provide political reassurance or whether they meaningfully reduce spread. With Ebola, many experts still argue that targeted screening and surveillance generally outperform blanket travel bans.