"Disease X," The Democratic Republic of the Congo, and adventures with Google Translate.

---

Getty Images: beast01

An outbreak in the DRC raises questions. We need answers, not rumors and bad translations.

Officials from the Democratic Republic of the Congo (DRC) have reported an outbreak of an unknown illness that has so far caused 376 people to get sick and 79 to die since late October. The symptoms described resemble those of a typical respiratory pathogen, like influenza. So far, it’s just being called “Disease X.” Many of my colleagues and I are watching this closely. We don’t yet know whether this is the next major problem, or something completely self-contained. Anything is possible.

Whenever reports like this emerge, there are several key points to remember while officials figure everything out:

1. Severity. Early in an outbreak, officials are likely to detect the most severe cases only. Severe cases are what trigger investigations. (Why else would they notice something is amiss?) So, initial reports about an unknown illness tend to reflect the worst end of the spectrum, whatever the problem ends up being.

2. Prevalence. The number of cases is likely far higher than reported. Why? Because only people with moderate or severe illnesses even seek care. Mild or even asymptomatic cases never get evaluated by doctors, so they don’t show up in the statistics. Thus, early summaries often underestimate how many cases there are and overestimate how severe typical cases are.

3. Cause. When we hear about a new mysterious illness, we often assume it’s some kind of microbe like a virus, bacterium, or parasite. But it’s actually unclear whether a new illness is due to an infectious pathogen from some non-human source (bad water, bad food, animals), let alone one that humans can spread. As my friend Dr. Craig Spencer reminded me yesterday, sometimes a confusing combination can occur. For example, in 2021 around 66 children in Gambia died after consuming toxic cough syrups. All of these kids had some kind of respiratory illness, but the virus itself was not the problem. Instead, it was diethylene glycol and ethylene glycol, two toxic compounds that cause kidney failure and even death. So, even if a virus appears to be spreading, we have to think outside the box.

4. Spread. If an illness is caused by a pathogen that humans can spread amongst themselves, the way it spreads (touch, droplets, air) and how contagious it is varies greatly, and might even depend on the environment. For example, a person shedding Covid-19 at their peak contagious period could exhale enough viral particles into a small room to infect a dozen people in mere minutes. But that same person could pass 1,000 people on the sidewalk and infect nobody. There’s a reason why New York City is a great place for a respiratory pathogen to spread: it’s dense and people spend a lot of time in crowded indoor spaces.

5. Epidemiology. Who is affected? Is it kids? Working-aged adults? Seniors? The reason this matters is that generally speaking, older people will have more severe illnesses (there are exceptions). Let’s imagine this were happening in Los Angeles. If 79 older people died in a month, that might be a 2% increase over usual death rates in the region—which would be hard to distinguish from random variation in any similar time period. But if 79 teenagers suddenly died, it would be a 100% increase in usual mortality. So, we have to keep in mind the size of the population being assessed, and their demographics.

Is Google Translate freaking everyone out? Two keywords to notice…

At this stage, we are waiting for more information from DRC officials. Test results are expected as soon as today or this weekend. But in the meantime, there are two keywords floating around in news reports and social media that caught my attention: “raging” and “airborne.”

The DRC’s official press release about the situation this week began as follows: “Since October 24, 2024, a disease of still unknown origin has been raging in Kwango province…” [emphasis added].

I wondered what was meant by raging, because to me, that word implies “spreading like wildfire.” But the press release was initially written in French and translated to English. So I found the original version and discovered that the French word used there was sévit. To me, that verb implied severity of illness, rather than speed of spread, but my French is admittedly mediocre. However, I’ve since confirmed with native French speakers that my impression was right. The word should have been translated differently—something closer to: “has been severely affecting people in Kwango province.”

I also happened to notice that the entire English version was created using Google Translate. I know because I pasted the French text into the app and got a nearly verbatim readout back, virtually identical to the text in the screenshot below (with a few words changed). Even parts of the wonky formatting from Google Translate were retained from the cut-and-paste job. Look, the DRC has a lot of expertise in dealing with outbreaks and I respect their abilities on the medicine and epidemiology. But with the world hanging on every word, perhaps officials could do better than Google Translate. Maybe the WHO could help them out here…

The other word that’s getting bandied about is “airborne.” I’ve heard mixed reports on what was said during an Africa CDC call yesterday, but it seems that an expert opining that this may be a respiratory virus was mistranslated or misunderstood as having said “airborne.” Now, it could very well be that this illness is caused by a pathogen that can spread by respiratory droplets and/or aerosols. But we don’t know that and it seems like there may be a high-stakes game of translation/telephone happening here.

Ultimately, in moments like these, we need to think before we spread rumors, and keep a close eye on developments as they emerge.

Some thoughts on the epidemiology.

We also learned yesterday about some of the demographics of the cases (see below). Among hospital cases, at least, the case fatality rate (deaths/cases) has been somewhat higher in 5-9-year olds compared to younger children and infants (0-4 years). Meanwhile, adults age 25 and older have had many documented cases (29.6% of them), but they account for only 3.5% of the in-hospital deaths. Take a look (the data below appear to include all known cases in the region, but only hospital deaths, which seem to be 27 of the 79 deaths):

Hospital data. Data: Democratic Republic of the Congo. Formatting/translation: Inside Medicine.

There are a few possible explanations for this breakdown:

1. Biology: Some pathogens (like Dengue Fever) are worse on reinfection, due to the immune system’s enhancement of the disease. So, older kids are more likely to have had prior exposures. And in the case of influenza and other pathogens, a stronger immune system might be responsible for an overly aggressive response (sepsis or cytokine storm) in which the counterattack becomes as or more deadly as the disease itself. Meanwhile, in some diseases, animal bites could be responsible and younger children and infants may be more protected from serious bites and multiple exposures because they spend more of their time supervised and indoors.

2. Exposures. As above, if a toxin is responsible, it could be that older children were given some medicine that has associated toxicity, like the 2021 Gambia outbreak.

3. Healthcare seeking behavior. It’s possible that only a small fraction of the cases are showing up to healthcare facilities, and that the age distribution of that behavior is not equal. For example, infants get sick all the time, so a flu-like illness might not warrant a trip to the doctor every time.

Could it be Ebola or Marburg?

I would be surprised if this disease turns out to be either Ebola or Marburg virus. First, the kinds of exposures it takes to spread those pathogens are far more typical in adults. Second, we learned about all these cases at once. Ebola and Marburg last 2-3 weeks and only become contagious near the end of the bouts. Usually, officials learn about one or two very sick patients (with bleeding and fever) which leads to an aggressive investigation/search for more cases in the area. The cases are carefully followed until their outcomes are known. In other words, the ramp-up of new Ebola or Marburg cases often happens over an excruciatingly long two or three week period, with outcomes trickling in a few at a time. Here, we were given a tranche of cases and outcomes all at once. That just does not comport with the usual Ebola or Marburg pattern.

There are many other possibilities here. The big question is whether this is some new pathogen (if it is one at all), or a variation on an old one. Unknown.

Now would be a bad time to defund public health.

Whatever is happening in the DRC, the United States can likely help. Expertise from the NIH (prior research), the CDC (surveillance and testing), and other federal assets ranging from the Department of Defense to the Biomedical Advanced Research and Development Authority (BARDA) might provide DRC officials who already possess the necessary expertise with the logistical tools they need (and lack) to mount the best possible response. “Relationships. Access. Transparency,” is what is needed, according to Dr. Spencer.

Indeed, now would be a bad time to, as RFK Jr. advocated recently, “give infectious diseases a break” for a few years—since that detente won’t be reciprocated.

Turning away from public health investments in this realm seems like a recipe for another pandemic, if not due to this particular outbreak, then perhaps the next one.

Special thanks to Dr. Craig Spencer for his input and expertise.

---

Poll of the Week results.

Here are the results from the last week’s reader poll. Thanks for your votes. The correct answer is that around 6,200 hospitals in the US accept Medicare.

Feedback! Have any ideas for next week’s Poll of the Week? Any great articles you’ve read elsewhere that you want to share with the Inside Medicine community?