r/ContagionCuriosity

A Detroit-bound flight from Paris was diverted to Canada on Wednesday night after U.S. Customs discovered a passenger from a country currently affected by the outbreak was allowed on the plane.

There have been 131 deaths associated with the outbreak and 543 suspected cases, with 33 confirmed cases in the Democratic Republic of Congo, as well as two confirmed cases in Uganda.

The U.S. has issued travel restrictions for Congo, Uganda and South Sudan.

Air France said the passenger was taken off the flight in Montreal, and then the rest of the passengers returned to Detroit Metro Airport on Thursday night.

There was no medical emergency on board and it's not believed the passenger was showing active symptoms.

One woman on board said about halfway through the flight, the captain told them they were being diverted and then flight attendants started putting on (sic) mass.

They didn't really tell us why," Deborah Mistor said. "The captain said that it was the U.S. government not allowing us to land in Detroit."

Mistor was on Air France flight 375 when it was diverted to Montreal with no explanation.

"By that point, the flight attendants all had masks on, which no one had prior to the announcement. So it was really concerning, like, what is going on here? Why are we not being allowed to land?" she said.

Mistor said the only information given came from a flight attendant, saying that a passenger from the Democratic Republic of Congo was on board, an area hit by the Ebola outbreak. U.S. CBS confirmed in a statement that the passenger shouldn't have been on the flight.

"This particular passenger did not have any active symptoms or showing any signs of any Ebola activity," Mistor said.

Dr. Matthew Sims, the medical director of infectious disease research for Corewell Health East, said people shouldn't panic.

"It doesn’t spread super easily. It tends to spread more in areas of the world where you just don't have that tracking in place," he said.

On Sunday, the World Health Organization declared the oubreak in Africa a public health emergency of international concern. Then Monday, the CDC ordrered a 30-day entry restirction on non-US Passport holders who've been in the DRC, Uganda or South Sudan in the past 21 days.

Neither airline has offered us any information whatsoever. No health officials offered us any info," Mistor said. "Should we be concerned? Was that person exposed? Was this just an overabundance of caution? What steps should we be taking to protect ourselves or anyone around us

Officials are looking into how the passenger was allowed to board the flight.

One person who recently returned to Ontario from East Africa is being tested for the Ebola virus, the province says.

In a statement to CTV News, a spokesperson for the Ontario Ministry of Health said the person is currently in the hospital.

“Out of an abundance of caution, clinicians are testing the patient for a range of possible infectious diseases, including Ebola virus, given their recent travel history, in accordance with established clinical protocols. All appropriate infection prevention and control measures are in place,” the statement notes.

The spokesperson added that there are no current confirmed cases of Ebola in the province.

It is unclear when the person came back to Canada and what symptoms they are experiencing.

The latest Ebola outbreak in the Democratic Republic of Congo and Uganda has resulted in at least 134 deaths and more than 500 suspected cases.

The outbreak is caused by the Bundibugyo virus, an Ebola strain that has no approved vaccine.

The World Health Organization declared the outbreak a public health emergency of international concern over the weekend. Officials are worried about the scale and speed of the outbreak.

The disease is spread through direct contact with bodily fluids or tissues of an infected person or animal experiencing symptoms. Officials noted that it is not spread through air or casual contact.

Global Affairs Canada said it was not aware of any Canadians in Congo and Uganda who are affected by the Ebola outbreak. About 3,600 Canadians are registered as being in the two African countries.

The federal government has advised Canadians not to travel to the eastern Ituri and North Kivu provinces of Congo.

There are now 600 suspected Ebola cases after the outbreak in Congo and Uganda, the World Health Organisation has said.

WHO Director-General Tedros Adhanom Ghebreyesus said the risk of the disease spreading nationally and regionally was now high - but low at a global level.

He said 51 cases had so far been confirmed in the northern provinces of Ituri and North Kivu in Congo, "although we know the scale of the epidemic is much larger".

Uganda had also told the UN health agency of two confirmed cases in Uganda's capital, Kampala, he added.

"There are several factors that warrant serious concern about the potential for further spread and further deaths," he said.

"First, beyond the confirmed Ebola cases, there are almost 600 suspected cases and 139 suspected deaths. We expect those numbers to keep increasing, given the amount of time the virus was circulating before the outbreak was detected.

"Second, the epidemic has expanded, with cases reported in several urban areas. Third, deaths have been reported among health workers, indicating healthcare-associated transmission. Fourth, there is significant population movement in the area."

Dr Tedros said the outbreak of the rare Ebola strain, known as Bundibugyo, is likely to have started a couple of months ago.

He said there was a suspected death on 20 April but that investigations were continuing.

"WHO has a team on the ground supporting national authorities to respond. We have deployed people, supplies, equipment and funds," he said, adding that $3.9m in emergency funding from the agency had now been approved to support the response.

Congo was expecting shipments from the US and UK of an experimental vaccine for different types of Ebola, developed by researchers at Oxford, Jean-Jacques Muyembe, a virus expert at the National Institute of Biomedical Research, said on Tuesday.

"We will administer the vaccine and see who develops the disease," he said.

Health experts said the delayed detection of the virus, large movements of population in the affected areas, along with the preexisting humanitarian crisis, complicated the response. Parts of eastern Congo are in the hands of armed rebels, hampering the delivery of aid.

Congo had said the first person died from the virus on 24 April in Bunia, but the confirmation did not come for weeks. The body was repatriated to the Mongbwalu health zone, a mining area with a large population.

"That caused the Ebola outbreak to escalate," said Congo's health minister Samuel Roger Kamba.

Dr Anne Ancia, the head of the WHO team in Congo, said authorities still had not identified "patient zero".

There was a long road ahead, she said, adding that cuts in funding had "a marked detrimental effect on humanitarian actors".

Whenever pathogens like H5N1, Ebola, or more recently, Andes Hantavirus hit the news, social media is bombarded with questions about what the pathogen's estimated R0 is, or speculative statements citing that since the pathogen has an R0 of, 2.2, for example, it is certainly going to become the next pandemic. I wanted to write this post to serve to define R0, describe its limitations, and caution against its broad application as a predictor of pandemic risk. I have also seen several posts with SIR, SEIR, or SEIRD models, which while valuable in context, also have major limitations in their applications. Diseases are not always predictable, and pathogens' behaviors cannot simply be distilled down to R0 and compartmental models. This may be a quite lengthy post, but I do think the information is incredibly valuable.

What R0 Actually Means

R0, or the Basic Reproduction Number, is the average number of secondary infections caused by one infected individual in a fully susceptible population under a specific set of conditions. Keep that last phrase in mind there, specific set of conditions.

R0 is hardly a fixed biological constant. It changes with healthcare infrastructure, population density, infection control practices, behavior modifications, among other factors. A pathogen does not always have one single R0.

The Average Can Hide A Lot

Imagine two pathogens, Pathogen A and Pathogen B. Both have an R0 of 2.0.

• In an outbreak of Pathogen A, each infected person infects two others.
• In an outbreak of Pathogen B, nine infected people infect no one, and one infected person infects 20 in a superspreader event.

Both pathogens have an R0 of 2.0 but their real world behavior is drastically different. This is where the dispersion parameter (k) comes in.

What is k?

The dispersion parameter (k) describes the distribution of R0s around the average. In plain terms, R0 tells you the average number of people infected, while k tells you whether that average is shared by most cases or by a small number of superspreaders. For many emerging pathogens, k is just as informative as R0.

For a given pathogen with an R0 of 2.0:

• If k = 10, most people infect 2 others
• If k = 0.1, most people infect nobody, and a few people infect many others

A pathogen can have an R0 of >1 and still fail to spark an outbreak. Maybe k is very small, so there are superspreader events that cause an explosive start to the outbreak, but focus on high-risk groups and interventions tamps the spread of the pathogen much more effectively. K describes the heterogeneity of transmission and can paint a much better picture than R0 alone when assessing risk for broad disease spread.

Secondary Attack Rate (SAR)

Another measure we consider when assessing the likelihood of disease spread is the secondary attack rate. SAR is the proportion of susceptible contacts who will go on to develop disease after exposure to an index case. In diseases where household SAR is quite low, it suggests that while transmission is possible, it is quite inefficient. Again, it is so much more than just R0.

Compartmental Modeling

S(usceptible), E(xposed), I(nfectious), R(ecovered) [and sometimes D(ead) or I(nfectious) again, or V(accinated)] models are what are called compartmental models. Compartmental models simulate populations moving between some defined compartments. In the case of these SIR, SIRV, SIRS, SEIR, SEIS, SEIRD, SEIRV, and on and on, the population is moving between being susceptible, exposed, infectious, recovered, or any other iteration.

(C. M. Macal, \"To agent-based simulation from System Dynamics,\" Proceedings of the 2010 Winter Simulation Conference, Baltimore, MD, USA, 2010, pp. 371-382, doi: 10.1109/WSC.2010.5679148.)

These models rely on R0 to determine the transmission rates, which we discussed earlier relies heavily on assumptions. These models are fairly inflexible, and assume homogenous mixing of populations, stable populations, and average contact rates. We know this is not possible to compartmentalize. Depending on the population, R0 may differ, k may differ, and therefore, all of the assumptions we rely on for modeling these scenarios are not as simple as S, I, and R.

Bottom Line

I think it is great to see laypeople interested in epidemiology and infectious disease dynamics. I would argue (though I am biased as it is my field) it is one of the most interesting fields there is. The advent of social media has empowered people to fear monger, mislead, misinform, and flat out lie. I caution you all to not try and distill these things down to metrics that do not consider real life. Remember, an R0 of 2 can look like a single superspreader event, or it can look like a protracted outbreak. Bundibugyo Ebola and Andes Hantavirus are absolutely things to watch and have some level of concern about, but jumping to the conclusion that they are imminent pandemic-causers based simply on an R0 of >1 is not something I would advise. It just really is not that simple.

Some reading below that I think is valuable to further explain these concepts:

https://pmc.ncbi.nlm.nih.gov/articles/PMC10227392/

https://pmc.ncbi.nlm.nih.gov/articles/PMC7442271/

https://wwwnc.cdc.gov/eid/article/25/1/17-1901_article

https://pmc.ncbi.nlm.nih.gov/articles/PMC3935673/

https://www.sciencedirect.com/science/article/pii/S0010482521004510

About 220 cases of diphtheria have been recorded around the country — the biggest outbreak of the disease since national records began in 1991.

Health practitioners across the country are preparing for more cases and are encouraging people to check their vaccinations are up to date.

Federal Health Minister Mark Butler says the federal and states governments are now working on a support package primarily aimed at boosting vaccination rates.

Update: Milti-million federal vaccine campaign has been launched.

The $7.2 million package will include money for the National Critical Care and Trauma Response Centre for a surge workforce to administer booster vaccinations and treatments, as well as procuring additional vaccines and antibiotics.

Federal Health Minister Mark Butler said while the package was primarily for the Northern Territory, he would be writing to other affected states to see if they also needed Commonwealth support.

ABC Misinformation Fact Check

As of 11 May 2026

• 98.9% locally acquired cases (192/194)
• 81.8% resided in areas classified as ‘remote’ and ‘very remote’
• 15.1% resided in ‘outer regional’ areas
• 24.7% (48/194) have been hospitalised, including a likely death in the NT, the first for almost a decade.

The predominant clinical presentation has been cutaneous diphtheria (69.1%), with respiratory diphtheria accounting for 29.9% of cases. Proportion of respiratory diphtheria is increasing.

Bird flu has been detected in a dead polar bear in the Arctic Svalbard archipelago, marking the first time that the virus has been found in the species in Europe.

The Norwegian Veterinary Institute confirmed the finding on Tuesday, alongside avian influenza in a deceased walrus from the same region, which is roughly halfway between the North Pole and mainland Europe.

The findings are part of a trend where highly pathogenic avian influenza virus is increasingly being detected in mammals in Europe,” the institute said in a statement.

“At the same time, the virus has spread to new areas in recent years, including the Arctic, where it may have consequences for vulnerable populations and ecosystems."

[...]

The Norwegian institute said mammals can be infected with avian influenza through direct contact with birds or other mammals, and that it is investigating whether the virus detected in the polar bear and walrus was specifically adapted to mammals.

The detected virus is of the subtype H5N5 which has in recent years been found in Svalbard in birds, Arctic foxes and a walrus.

The first case of a polar bear being infected with bird flu was confirmed in December 2023.

The bear, which was infected with the H5N1 subtype, was found dead near Utqiagvik, one of the northernmost communities in Alaska.

At the time, the Alaska Department of Environmental Conservation told local media that it was likely the bear had been scavenging on the carcasses of infected birds.

[...]

Andean antivirus could spread to densely populated areas.

An American exposed to the deadly hantavirus while on a cruise from Argentina said on Monday that she is not being allowed to leave a federal quarantine unit in Nebraska.

Angela Perryman, 47, received a federal quarantine order, a copy of which she provided to The New York Times, on Monday, after making plans to self-isolate in Florida. It requires her to stay at the National Quarantine Unit in Omaha until the end of May.

Ms. Perryman said she has been tested once for the hantavirus, and the results were negative. She is not experiencing symptoms, she said, although she did have brief conversations on the ship with a passenger who later died from the illness.

It was not immediately clear why Ms. Perryman was being required to stay, though federal law authorizes health officials to impose quarantines to prevent the spread of disease. Representatives from the Department of Health and Human Services and the Nebraska Quarantine Unit did not immediately respond to requests for comment.

Federal health officials have previously said that the 18 American passengers from the cruise ship would need to be screened and monitored at the quarantine unit for several days. Officials had suggested that passengers might not be required to stay for the virus’s full 42-day incubation period.

“At some point, they may be able leave their medical centers to continue quarantines at home, depending on how they are doing,” Captain Brendan Jackson, a U.S. Centers for Disease Control and Prevention official, said in a news conference last week after the passengers arrived in Omaha and Atlanta.

He said that each would have an “individualized decision plan.”

Ms. Perryman said she and the 17 other passengers were told during a video conference call with federal officials on Sunday that if they did not remain at the unit voluntarily, they would receive a mandatory quarantine order keeping them there.

Her order came on Monday, authorized by Jay Bhattacharya, acting director of the Centers for Disease Control and Prevention. Citing federal public health law, it requires her to remain in the Nebraska facility for 21 days after her arrival, a period that expires on May 31.

That three-week period is when the risk of becoming symptomatic from the hantavirus is the highest.

The National Quarantine Unit at the University of Nebraska Medical Center in Omaha is the only federally funded facility of its kind. Two passengers from the ship were originally sent to a facility in Atlanta, but have since been moved to Omaha.

Someone in Colorado has died from a Hantavirus case not related to the cruise.

WASHINGTON, May 18 (Reuters) - The U.S. Centers for Disease Control and Prevention said on Monday ‌that one American tested positive for Ebola as part of its work in the Democratic Republic of Congo, where there is an outbreak of a rare strain of the virus, but advised that the immediate risk in the U.S. was low.

The CDC did not name the individual, but the Serge Christian mission organization said one of its medical missionaries, Dr. Peter Stafford, was exposed while treating ​patients at Nyankunde Hospital in the DRC.

A number of Americans who are in the Democratic Republic of the Congo are believed to have had exposure to suspected cases in the country's latest Ebola outbreak, with several deemed to have had high-risk exposures, sources have told STAT. At least one of these individuals may have developed symptoms.

One source said that there are not yet test results for any of the individuals, but the U.S. government is reportedly trying to arrange to transport them out of the DRC to somewhere they can be safely quarantined, and cared for, if they prove to have been infected. It’s not clear if that would be in the United States; there is some discussion of perhaps taking the individuals to an American military base in Germany, a source said.

The sources spoke on condition of anonymity, because they had not been authorized to discuss the situation publicly.

Already, the outbreak’s suspected case count is at least 246 cases, with 80 deaths, including at least four health workers.

The Centers for Disease Control and Prevention held a hastily called news conference on Sunday to discuss the outbreak, which the World Health Organization has declared a public health emergency of international concern (PHEIC). But when specifically asked whether any Americans have been exposed to Ebola, and whether the government is planning on extricating them from the DRC, the CDC’s incident manager, Satish Pillai, did not answer the questions.

Neither the State Department nor the Department of Health and Human Services have responded to repeated requests from STAT for information about the situation.

“We don’t discuss or comment on individual dispositions,” Pillai said. “It is a highly dynamic situation, and at this point, what I would say is, we continue to assess [and] we will continue to keep you posted as we learn more.”

Pillai said the CDC is assessing the needs on the ground and is working to deploy experts to help with the response.

Despite the lack of official answers, STAT has been told that the U.S. government has been reaching out to the health care institutions that have high-containment treatment facilities able to quarantine people who have had high-risk exposures to Ebola, and isolation beds where they can be cared for, if they become ill.

One of the sources who spoke to STAT said the situation is fluid, with numbers changing daily. But what is clear, the individual said, is that there is an effort afoot to get some Americans out of the DRC quickly.

These efforts are likely made more difficult by the fact that one of the facilities that can quarantine people suspected of being infected with a high-consequence pathogen like Ebola and care for them if they are infected is currently housing Americans who were passengers on the MV Hondius, the cruise ship on which there was a recent hantavirus outbreak.

The Ebola outbreak was declared a PHEIC overnight Sunday Geneva time, by WHO Director-General Tedros Adhanom Ghebreyesus. Tedros declared the PHEIC without yet having convened an expert panel to advise him on the situation — an unprecedented move that speaks to the gravity of the unfolding situation.

Confirmation that an Ebola outbreak is underway in northeastern DRC only came Friday from DRC’s National Public Health Institute.

Daniel Jernigan, who led the CDC’s National Center for Emerging and Zoonotic Infectious Diseases until he quit last summer in protest over the firing of former CDC Director Susan Monarez, said the current signs point to an outbreak that may take quite some time to bring under control. It is unusual for Ebola outbreaks to be this large when they are first declared, a fact that suggests tracing all the chains of transmission will be a daunting task.

“There is a lot that we don’t know here, and it has happened very quickly, and the numbers suggest that it’s not going away anytime soon,” Jernigan said.

The WHO said Sunday that the first known suspected case, a health worker, developed symptoms on April 24. A health care worker is unlikely to be the first case in an outbreak; the more probable scenario is that someone infected — either by a bat or by another infected person — brought the virus into a health care setting while seeking care. Either way, the outbreak had been smoldering for some time before the cause of the rising tide of illness was deemed to be caused by Ebola.

Two infected people from DRC traveled — independently of one another — to Kampala, the capital of neighboring Uganda, where one died. At present, there is no indication of ongoing transmission in Uganda, the WHO said.

An Ebola species called Bundibugyo is responsible for the outbreak. This marks only the third detected Bundibugyo outbreak on record; the previous two were in 2007 and 2012.

[...]

https://archive.is/JqHUd

Asymptomatic mpox infections among men who have sex with men (MSM) may be far more common than previously recognized and could be playing a role in ongoing transmission, according to a study published last week in Nature Communications. Researchers estimate that actual infections may outnumber diagnosed cases by 33 to one.

The findings challenge the assumption that most mpox cases are spread by people with symptoms.

1% had asymptomatic mpox

For the study, researchers led by teams at the University of California (UC) at Berkeley and Kaiser Permanente Southern California tested for mpox in MSM in Los Angeles during routine sexually transmitted infection (STI) screening from May to November 2024. Then they monitored the same group of MSM for clinically diagnosed mpox.

Among nearly 8,000 eligible participants, only 15 laboratory-confirmed mpox cases were identified through standard clinical testing. But when the team tested for mpox DNA in 1,190 specimens collected from the routine STI tests, they found infections in six men who never presented with mpox symptoms or received an mpox diagnosis.

“We used the specimens from routine testing for other sexually transmitted diseases to test for mpox and found roughly 1% of men had asymptomatic infections without knowing it,” lead study author Joseph A. Lewnard, PhD, associate professor of epidemiology at the UC Berkeley School of Public Health, said in a news release. “From the testing, we estimated that only about one in every 33 infections gets diagnosed,” meaning infections exceeded reported cases by a 33-fold margin.

Undiagnosed cases may drive 31% to 44% of spread

These cryptic infections likely contribute to under-the-radar mpox spread. The authors estimate that undiagnosed infections may account for at least 31% to 44% of all transmission events and, under “realistic modelling assumptions,” potentially much more.

The findings run counter to current guidance from the Centers for Disease Control and Prevention, which has advised that people with symptoms primarily drive mpox spread, despite a lack of connection to a symptomatic partner.

“We have not known how mpox is transmitted, and why the cases seem to have very few connections to other cases,” senior study author and Kaiser Permanente scientist Sara Y. Tartof, PhD, MPH, said in the news release. “These findings help resolve a fundamental question in the epidemiology of mpox by suggesting that infected people pose a risk of transmitting the disease to others even in the absence of clinical symptoms."

Vaccination may reduce disease severity

The researchers also found that pre-exposure immunization with the Jynneos vaccine was associated with 72% effectiveness against diagnosed mpox. The finding that previously vaccinated men accounted for five of the six subclinical infections identified through routine STI testing suggests that vaccination may help protect against mpox by reducing disease severity, which aligns with previous research.

“Unvaccinated people face risk of severe disease if they are exposed to mpox,” Lewnard said. “And our findings suggest this risk is greater than we previously understood.”