Nearly every story this week comes back to a single idea. Infectious diseases do not always advance on their own. They advance when humans stop holding the line. From Ebola in the Democratic Republic of the Congo to measles in Pennsylvania, this week was less about microbes than about the systems we build to contain them.
The premise that runs underneath all of it is that infectious disease is the default. If humans do nothing, infectious diseases spread. They emerge. They increase. Risk communication, vaccine acceptance, functioning public health institutions, even something as unglamorous as cooling tower maintenance, all of that is part of holding the line. When those systems hold, humans win and civilization wins. Where they fray, the pathogens are already there, waiting to come back.
Ebola in the DRC: no longer just an outbreak
The Ebola outbreak in the Democratic Republic of the Congo is now the third largest on record, and it is still climbing. We are firmly in the expansion stage. This remains a game of catch up, where responders are chasing transmission rather than getting ahead of it.
Cases now sit around 1,800, with more than 600 deaths, for a case fatality ratio near 34 percent. This is an undercount. There are more cases out there than the official numbers capture, because testing still lags, even though it has improved somewhat.
We now have another infected American, a humanitarian worker with Samaritan's Purse. Some of you will remember that Samaritan's Purse was also involved in the 2014 to 2016 outbreak in West Africa, when two of their personnel were infected, including Dr. Kent Brantly, who was famously transferred to Emory for care. The open question is what happens to this patient. Do they go to Germany, as the last infected American did, or are they allowed to use the Ebola treatment centers that we built here in the United States at taxpayer expense? It appears that this patient is now in Germany.
There is also a fifth province now involved, Tshopo. At least one case there has no travel link to known cases elsewhere in the outbreak zone. That tells you there is very likely an undetected chain of transmission seeding this new province.
Healthcare workers are bearing an inordinate burden. As of now, 112 healthcare workers have been infected and 32 have died. This is precisely why personal protective equipment and safe treatment settings matter so much. Healthcare workers are canaries in the coal mine. When they start getting infected in numbers like this, it is a signal that they do not have the resources they need and that things are going wrong. Not unrelated, there is a healthcare worker strike threatening recent progress, and it could stall the clinical trials underway to evaluate a monoclonal antibody, remdesivir, and obeldesivir. All of that is up in the air while a strike continues.
There is a deeper failure here. This same region experienced an Ebola outbreak between 2018 and 2020, the second largest on record. Yet there does not appear to have been sustained risk communication in the years since. People's memory has faded, and we are seeing the same resistance and the same misinformation recur. Misinformation is the single biggest ally of this outbreak, and it has to be addressed directly.
A couple of guardrails need to stay intact. This is an area where malaria is also endemic, and you cannot let malaria services collapse. During the 2014 to 2016 outbreak, the collapse of malaria control is estimated to have caused as many deaths as Ebola itself, more than 10,000. It is critical not to forget the other infectious disease threats that already plague parts of the DRC.
For all of that, keep Ebola's limits in mind. This is not a pathogen that will go pandemic. It is very constrained in its ability to spread. The real worst-case scenario is not global spread. It is that this region becomes a place where Ebola is endemic, a frontier where Ebola is simply common. That is the outcome responders are trying to avoid.
Broken risk communication, healthcare worker strikes, transmission outrunning testing, a fifth province drawn in, the third largest outbreak on record, and regional endemicity as the worst case. Taken together, this is no longer simply an Ebola outbreak. It is a test of whether the international community remembers the lessons of the last one and chooses to act proactively.
Cyclospora: a fast outbreak with no source and no clear advice
Cyclospora is all over the headlines in the United States right now, and it is an unusual situation: a fast-growing outbreak with an unknown source, no traceback, and no clear advice to give people.
A quick primer. Cyclospora is a parasitic protozoal infection spread by produce. The produce becomes contaminated when irrigation water carries human fecal matter. It has been surging across the country this summer. Michigan is at around 2,000 cases with several dozen hospitalizations, roughly four times higher than the state reported last year. Sixteen other states are also reporting cases, and no common source has yet to be identified.
We do know that there does not seem to be an international travel link driving this major outbreak. People who travel to areas of Central and South America where cyclospora is endemic can certainly bring it home, and that appears to explain many of the California cases, but it does not explain the Michigan outbreak. We are in peak season, spring and summer, and that part is normal. What is abnormal is that no one can identify the source, which means there is no concrete "avoid this" to give the public. In past outbreaks we could point to raspberries, basil, or bagged lettuce. This time we cannot, and it is already changing behavior. I was at dinner recently with people who would not eat the lettuce on their plates because they were scared.
Part of the difficulty is technical. Unlike Salmonella or E. coli, cyclospora does not lend itself to an easy genomic traceback. One expert likened sorting its genetics to reading War and Peace versus a quick read. On top of that, our foodborne surveillance system, FoodNet, has been scaled back significantly since July 2025. It is run by the CDC, and the focus now is really on Salmonella and E. coli (it used to cover cyclospora). It is not yet clear exactly what role that scale back played in this outbreak, but it certainly did not help, and the fact that CDC reporting lags state reporting is its own problem.
On the clinical side, the treatment for cyclospora is Bactrim, but the diagnosis is often missed because clinicians do not order the right test. It requires a specific stool test. The illness can be prolonged and severe in people who are immunocompromised. This is all unfolding during the World Cup. I do not see a clear linkage between the two, and it has not meaningfully affected the tournament, but expect cyclospora to stay in the headlines until the driver is finally found.
A few other foodborne items deserve a mention. There is an E. coli outbreak traced to frozen blueberries sold at Publix. Infant botulism cases continue to occur in connection with powdered formula, with four cases reported in the latest cluster. And Fox News has reported that many US beaches are under swimming warnings because of high E. coli and coliform counts. The reporting described fecal contamination that could actually be smelled at many beaches, which puts swimmers at real risk if they enter contaminated water.
Measles: an endemic disease reestablishing itself in real time
I no longer think of measles as an outbreak. I think of it as an endemic disease reestablishing itself in real time.
We now have more than 2,200 cases in the United States, and the number is still rising. That is nearing the total for all of 2025, and we are only in July. About 6 percent of cases have been hospitalized. That is lower than last year, but it is not trivial, because this is a fully preventable disease. My home state of Pennsylvania has passed 100 cases, which is a modern record.
This is exactly where you can see that measles is the default. Do nothing, and you get what is happening in Pennsylvania. We are watching this virus reestablish endemicity in front of us.
One thing that genuinely annoyed me this week: someone offered me the population denominator, telling me Pennsylvania has roughly twelve million people and only about a hundred cases, as if that made the number small. It does not. That hundred is very high, because the relevant baseline is zero. The denominator does not matter. Every case of measles occurring in Pennsylvania, or anywhere in the United States, is essentially voluntary. It reflects people choosing a lower standard of living.
Development and disease are intertwined. We do not have a development problem in the United States, but the data are clear that when there is war or disruption, measles rises, and each standard deviation increase in development tracks with roughly a one-third standard deviation drop in measles. We are not being forced into this situation by war or collapse. We are choosing to lower ourselves toward that level in pursuit of what amounts to a nihilist ideology that refuses to recognize the value of vaccines.
People's behavior is shifting in response. Around 74,000 older adults have sought to check their measles status, spending money and effort to manage a risk that was actively brought back. That is a change in healthcare economics as much as anything else. We are also seeing outbreaks in congregate settings, including ICE facilities in Tucson, Arizona, which are fertile ground for measles, and predictably we are seeing communication problems around those outbreaks as well.
Remember that the line against measles was already built. It was built in the 1960s when the vaccine was developed. What is happening now is that people are erasing that line. When you erase the barrier of herd immunity in front of a pathogen that is simply waiting outside it, the outcome is not a mystery.
Vaccine policy and preparedness
The through line in vaccine policy this week is that the institutions built to safeguard vaccines are being remade, not to improve them, but to denigrate them, because the people doing the remaking are vaccine skeptics.
Consider the nominee for Assistant Secretary for Preparedness and Response, Sean Kaufman, who had a Senate hearing this past week. He is a vocal opponent of mRNA vaccines and of the hepatitis B vaccine. The proposal is to put this person in charge of the nation's emergency vaccine stockpiles, reporting to RFK Jr., who himself does not even accept the germ theory of disease. That is not accidental. RFK Jr. himself is moving to add many conditions to the COVID vaccine injury tables by fiat, likely insulated from judicial or legislative challenge, which opens the door to unfounded claims and makes vaccine development far more hazardous.
Leana Wen, the former Baltimore City health commissioner, published an op-ed in the Washington Post documenting how CDC leadership has meddled with the science around certain test designs. The important point is not the technical nuance of how you might tweak a trial for more statistical validity. The real aim is to erode public confidence in vaccine data altogether. When the general public sees this kind of manufactured debate, they conclude that nothing about vaccine data can be trusted, and that is exactly what the anti-vaccine movement wants.
The Advisory Committee on Immunization Practices is in shambles, and it is in shambles by design. At the same time, there is a hopeful counterweight in the courts, which appear to be separating somewhat from the administration's position. Courts are affirming that schools can maintain vaccine entry requirements and that employers can maintain vaccine requirements for employment. That is a good thing, and it is encouraging to see the judiciary defend sound vaccine policy.
The absurdity of the movement was on full display this week in its platforming of Andrea Shaw, a mother charged with murder in the deaths of her twins, who is blaming the vaccines and claiming they suffocated her children. There is no biological plausibility to that claim. It lays bare an anti-human ideology. This is a movement that is, by its own logic, avowedly anti-human.
Legionnaires' disease in New York City: a preventable failure of maintenance
New York City has a growing cluster of Legionnaires' disease on the Upper East Side. There is a grim symmetry to it, arriving 50 years after the disease was first described in Philadelphia in 1976. The latest figures I have seen are around 46 cases and 22 hospitalizations, and the cluster is still growing.
Legionnaires' is fundamentally an industrial disease. The culprit is almost always building cooling towers. Officials are now sampling those towers, running cultures and PCR, and remediating the ones that test positive. It is important to finish that work and to interpret the data carefully. Many towers may be PCR positive at low levels or with non-viable bacteria without being the actual source, so we will have to see what the full picture reveals. Legionella thrives in warm water in cooling towers, and New York has seen this before, including an outbreak in Harlem last year.
This is not a benign illness. It can cause a severe pneumonia, especially in older people and those who are immunocompromised, and patients sometimes present late enough that antibiotics can no longer help. The durable lesson for a city of apartment towers is straightforward. Cooling towers must be maintained and routinely tested. This should be standard of care, not something you investigate only after an outbreak, because Legionnaires' is among the more preventable outbreaks we face. The technology is not futuristic. It is just maintenance. And it applies beyond cooling towers to hot tubs, another known source. The natural state of the world is not disease control. Disease control is something societies actively create and maintain.
When systems fail together: congregate settings and the Eaton Fire
There is a useful reminder in data from the Eaton Fire in Los Angeles in January 2025. When large numbers of evacuees were placed into congregate settings, disease spread. Among evacuees and staff there were 104 cases of norovirus, 56 of COVID, 29 of flu, and additional cases of nonspecific respiratory illness.
The lesson is that congregate settings spread infection, and that disasters compound. You have a fire, you evacuate people, you place them together, and disease takes hold. That is the default. You have to assume it will happen and put technology and planning in place to minimize the impact.
Ticks: refusing preemptive surrender
Finally, a strong and comprehensive piece ran in the New York Times, by Jonathan Mingle, about ticks. What I appreciated most was its framing that humans are currently in a state of what it called preemptive surrender to ticks.
We do not need to be in preemptive surrender to ticks, or to anything. This is a civilizational question. Can we master the problem of tick-borne illness? The answer is yes. We will start to see Lyme disease vaccines and other countermeasures, and those will be part of how we handle the resurgence of tick-borne disease. Surrender is a choice, and it is the wrong one.
The common thread
I noticed these stories precisely because they are the exceptions. Most days, vaccines prevent outbreaks, surveillance systems detect threats, and public health infrastructure quietly and thanklessly does its job. The challenge is keeping it that way.
That is the common thread through this week. Civilization is not self-sustaining. The systems that protect us from infectious disease have to be maintained, defended, and renewed. When they are, outbreaks stop or never occur at all. When they are not, the microbes remind us why those systems existed in the first place.
