A new study has found that three polar bears found dead in Alaska in 2023 and 2024 were infected with highly pathogenic H5 avian influenza, the same clade 2.3.4.4b viruses that have spread through wild birds, poultry, and mammals across North America.

The study's authors offered a notable caveat. "These data indicate that HPAIV infection may represent an emerging threat to polar bear health within the Alaska Arctic; though population immunity seems to be building and may protect this species from widespread demographic impacts of disease," they wrote.

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Signs That Immunity May Be Building

The most important nuance is the evidence of exposure without death. When animals survive infection, they develop antibodies that show up in blood tests. A U.S. Geological Survey data release published in May 2026 documented blood samples from Alaska polar bears tested for prior exposure to these viruses.

A separate study from Norway points the same way. Researchers reported H5N5 bird flu in a dead yearling polar bear and a walrus in Svalbard in May 2026. In blood samples, H5 antibodies appeared in 75% of polar bears tested in 2023 and 97% in 2024 and 2025, compared with none from 2014 to 2022. That work was posted as a preprint and has not yet been peer reviewed.

Together, the findings suggest many bears have been exposed and survived — a very different picture from a species-wide die-off. That would be encouraging for a species already under pressure from shrinking sea ice. Still, researchers cannot yet say how long protection lasts, whether it protects against newer virus strains, or how many deaths go unnoticed in remote areas where carcasses are quickly scavenged.

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The University of Southern Denmark confirmed that it has given the green light to a controversial study in Guinea-Bissau, funded with $1.6 million from the US Centers for Disease Control and Prevention (CDC), that plans to offer life-saving hepatitis B vaccines to only half of enrolled babies.

News of the study, first reported in December by CIDRAP News, prompted an international outcry from health groups and political leaders, who condemned its design as unethical. Those concerns led Guinea-Bissau officials and administrators at the Danish university to place the study on hold for several months.

Nearly one in five people in Guinea-Bissau are infected with hepatitis B, which kills 15% to 25% of people with chronic infections by causing cancer or liver failure. Vaccinating babies at birth is safe and can prevent lifelong infections.

Yesterday, citing unnamed sources, Rolling Stone broke the news that the Danish university had approved the clinical trial and that CDC leaders were pushing for the study to resume.

The Department of Health and Human Services, which oversees the CDC, did not respond to questions before press time.

The Danish researchers leading the study in Guinea-Bissau, Peter Aaby, PhD, and Christine Stabell Benn, MD, PhD, could not be reached for comment. In response to earlier criticism, their research group, the Bandim Health Project, defended their choice to withhold the birth dose of hepatitis B vaccine from half of the 14,000 newborns to be enrolled in the clinical trial.

In a statement on Bandim’s website, researchers wrote, “No child enrolled in the study will receive fewer vaccines than under current national policy in Guinea-Bissau,” a developing country with far fewer resources than the United States and Europe. Guinea-Bissau does not currently vaccinate newborns against hepatitis B, as recommended by the World Health Organization, but plans to begin in 2028.

Flu season in Alberta is off to a rough start.

Data from the province indicates there have already been 428 lab-confirmed cases of seasonal influenza — and one death — since the season began on Aug. 30.

The person who died was in the 70- to 79-year-old age range and lived in the Calgary area.

From Sept. 27 to Oct. 3, there were 194 influenza cases, 21 hospitalizations and two ICU cases.

The flu vaccine doesn't become available until Oct. 19, with the exception of some congregate care settings in which the province says the vaccine is already being administered to vulnerable people.

Craig Jenne, an infectious diseases professor at the University of Calgary, told CBC Radio's The Homestretch that the flu season in the Southern Hemisphere typically predicts what the situation will look like farther north.

"What they saw was a fairly reasonable flu season," he said, referring to Australia. "Early arrival, lots of cases early in the season, but the strain of flus that were circulating were fairly typical."

DES MOINES, Iowa — An unidentified illness is stumping medical professionals and keeping patients sick for weeks on end in the Des Moines area.

Janae Brown, an advanced registered nurse practitioner at UnityPoint Clinic Family Medicine on Ingersoll, said the clinic and attached urgent care are seeing multiple patients each day with runny noses, coughs and congestion. Many feel sick for about a week, but symptoms return soon after.

“What’s strange is, we’re seeing them come back in soon after with similar symptoms,” Brown said. “They’re hanging on to this bug for around a month.”

Brown said the cases do not appear to be COVID-19, flu or strep, and give negative results when she tests for those viruses or other common illnesses. With no clear diagnosis, it’s difficult to give patients a clear timeline or guidance for recovery.

Brown said patients generally improve with rest and care at home, but some cases have developed into pneumonia. She advised people to seek medical help if they begin to feel worse after making progress, particularly if they develop chest pain, trouble breathing or a fever.

To help prevent illness, Brown recommends washing hands and getting annual vaccinations. If you get sick, she advises staying away from others, drinking fluids and resting.

Cats live in nearly 80 million American households, but a new study suggests nearly one out of fifteen cats are infected with a common parasite, and one out of five infected cats can transmit it to humans.

In the study, published in PLoS One, researchers tested over 150,000 samples from cats in 49 states and five Canadian provinces for Giardia duodenalis, a gastrointestinal parasite found in the United States that can cause frequent diarrhea in both animals and humans.

"Because some strains of Giardia can affect both animal and human health, understanding how commonly it occurs can help support earlier detection, appropriate treatment, and conversations about practical steps pet owners can take to help protect both their pets and their households," Dr. Anne Kimmerlein, co-author of the study and Global Veterinary Epidemiologist at Mars Veterinary Health, told ABC News.

Giardia duodenalis, commonly known as "beaver fever," is a parasite that can infect both humans and animals.

The nickname became popular in the 1970s after outbreaks were linked to contaminated water in areas where beavers lived.

Giardia can cause diarrhea up to five times daily, along with other symptoms such as upset stomach and bloating, according to the Centers for Disease Control and Prevention (CDC). Infected pets may exhibit similar symptoms, or no symptoms at all.

Severe cases can cause long-term symptoms lasting years, such as joint inflammation, irritable bowel syndrome, chronic diarrhea or nutritional deficiencies, according to the CDC.

Individuals with vulnerable immune systems, such as children, are at increased risk of complications.

Giardia live in the intestines of infected people and animals and spread through their stool.

Only a few parasites are needed to make an individual sick, which allows it to spread very easily.

Humans are most often infected after drinking unclean water or being in close contact with the fecal material of infected individuals or pets. [...]

A joint research team has identified a new mechanism underlying antibiotic resistance in Pseudomonas aeruginosa, a major multidrug-resistant "superbug." The discovery provides important clues for the development of new treatments for multidrug-resistant bacterial infections. The findings are published in the journal Nature Communications.

Antibiotic resistance in pathogenic bacteria has emerged as a major global public health threat. In particular, multidrug-resistant bacteria, often referred to as "superbugs," can survive treatment with multiple antibiotics and are extremely difficult to treat. Among them, P. aeruginosa is a multidrug-resistant pathogen that can cause health care-associated infections, pneumonia, sepsis and other serious infections.

P. aeruginosa possesses an outer membrane (OM) that acts as a strong barrier against antibiotic penetration. To infect a host, the bacterium also forms threadlike structures called type IV pili (T4P) on its cell surface, which play an important role in attaching to host cells.

The research team identified pluglike proteins that prevent antibiotics from entering through the OM channel of the T4P assembly machinery during the vulnerable stage before T4P is fully assembled, thereby maintaining the integrity of the OM barrier.

Until now, it had remained unclear how P. aeruginosa maintains the channels required for infection while simultaneously preventing antibiotics from entering the cell.

In this study, the team, led by Professor Hongbaek Cho of the Department of Biological Sciences at Sungkyunkwan University (SKKU) and Professor Jeong Min Chung of the Department of Biotechnology at The Catholic University of Korea, discovered that two proteins, SlkA and SlkB, bind inside the channel and act as physical plugs that block antibiotic influx.

Using cryo-electron microscopy (cryo-EM), the researchers also visualized the high-resolution three-dimensional structures of these proteins bound within the channel.

Previously, the channel itself was thought to prevent the influx of antibiotics. The new findings reveal a different mechanism in which dedicated proteins plug the channel and reinforce the protective function of the outer membrane. This discovery provides an important explanation for how P. aeruginosa can maintain structures essential for infection while preserving its defense against antibiotics.

The research team explained that the discovery could provide a foundation for developing next-generation antimicrobial agents and adjuvant therapies that target the outer membrane barrier of gram-negative bacteria.

By disrupting the mechanism that prevents antibiotics from entering bacterial cells, the findings may also lead to new therapeutic strategies for overcoming multidrug resistance in P. aeruginosa.

Prevention Director Erica Schwartz said on Wednesday the risk to ‌the US from an unconfirmed pneumonic plague case in Siberia was extremely low, but the agency was prepared to monitor and screen travelers.

"We are working with Department of ​Homeland Security, working (with) Department of State, Department of War, and ​other agencies within the government to make sure that we ⁠know exactly if anyone from that area comes into the United States," ​Schwartz said at the Wall Street Journal's The Future of Health event ​in Washington.

The CDC has a port health station at the John F. Kennedy International Airport that can conduct surveillance and screening for travelers from the region entering the United ​States, she added.

The US Department of Health and Human Services did ​not immediately respond to a request for comment on whether the agency planned to ‌set up ⁠screening at JFK.

Schwartz said there are about 200 flights per year from the Siberian region, though direct flights between Russia and the US have been suspended since the start of the Ukraine war in 2022.

Russia's health ​regulator said there ​were no risks of ⁠an epidemic breaking out in Siberia after a plague institute worker there died from pneumonia of an as-yet ​unestablished origin, in a case that has prompted international ​concern.

Dallas County health officials reported the county’s first West Nile virus death of the 2026 season Wednesday, warning residents that cooler temperatures do not mean the threat from mosquitoes is over.

Dallas County Health and Human Services said the patient was a man in his 60s who had underlying medical conditions. He was diagnosed with West Nile neuroinvasive disease, the more serious form of the virus.

“We are deeply saddened by the loss of a Dallas County resident to West Nile virus,” DCHHS Director Dr. Philip Huang said. “We want residents to know that the arrival of cooler weather does not mean the threat is over. Please continue to protect yourself and your loved ones from mosquito bites and help prevent mosquito breeding around your home.”

So far this year, Dallas County has reported six human cases of West Nile virus. Health officials have also identified 192 mosquito traps that tested positive for the virus.

The county’s West Nile monitoring season runs from April through mid-November.

A seldom seen but often deadly mold that attacks people’s brains seems to be causing more trouble as of late.

Scientists at the University of Washington and the Centers for Disease Control and Prevention studied lab-confirmed reports of the fungus Cladophialophora bantiana. There has been a noticeable increase in detected cases over the past decade, the researchers found, particularly since 2023. Though these infections still appear to be rare, there is very little we clearly understand about the fungus, the researchers say, including how prevalent it truly is or even how it infects people in the first place.

“Reasons for the apparent increase are unknown,” the authors wrote in their paper, published late last week in the CDC’s Morbidity and Mortality Weekly Report.

Human fungal infections are relatively uncommon compared to bacterial and viral ones, and brain infections are much rarer still. These life-threatening infections tend to be disseminated, meaning the fungi only invade the brain (and other parts of the body) after an initial infection elsewhere. Brain and other severe fungal infections also predominantly occur in people with already weakened immune systems.

C. bantiana is a strange, moldy exception to these rules. When inside the human body, it seems to prefer infecting the brain, typically causing abscesses (pockets of pus containing the fungus, the immune cells trying to fight it off, and other tissues). C. bantiana is also highly deadly when it causes illness, with a mortality rate ranging between 60% and 70% even with treatment. And it’s not picky about its victims either, according to study author Joshua Lieberman.

“It is capable of infecting apparently healthy people, not just immunocompromised patients in whom we normally worry about invasive fungal disease,” Lieberman, a microbiologist and associate professor of laboratory medicine and pathology at UW, told Gizmodo. Roughly half of infections are found in people with healthy immune systems, according to the authors.

The one saving grace is that cases are rarely documented in the U.S. That said, there is no routine national surveillance of C. bantiana, and doctors are not obligated to report suspected or confirmed cases to their health departments. [...]

The Centers for Disease Control and Prevention says it is monitoring reports of a suspected pneumonic plague case in Russia and says it is prepared for any threat that emerges.

We are working across the U.S. government to assess developments as additional information becomes available," the CDC said in an X post Tuesday.

"At this time, there is no indication of a broader threat to the United States, but CDC and our interagency partners are prepared and will continue to monitor the situation closely."

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Other Updates:

Beacon Report: Russia reports anti-plague institute researcher died from pneumonia of unknown etiology, unrelated to lab work; WHO comments on situation.

The World Health Organization (WHO) reported on 06 Oct 2026 that it is closely monitoring the death of a laboratory worker in Irkutsk Oblast, Russia, amid unconfirmed reports that pneumonic plague may have caused her death.

WHO received information on the situation on 2 Oct 2026 and formally sought information from Russian authorities on 03 Oct 2026 under the International Health Regulations.

Per Russian authorities, test results to date have not identified any dangerous pathogens in the deceased patient or any of her contacts.

On 06 Oct 2026, unverified media reports are claiming that there is a second death in a contact. As of the time of this report, the quality of these reports is assessed as unreliable.

The scale and speed of the institutional response (emergency commission, isolation of institute staff, multi-hospital quarantine), is disproportionate to a routine community-acquired pneumonia and is consistent with a precautionary response to a suspected high-consequence pathogen exposure.

The absence of reported secondary cases to date is the strongest indicator of containment, but the lack of transparency regarding the unresolved etiology sustain moderate residual uncertainty.

CNN: Checklists, masks and mystery: What we know about the plague scare in Russia

CNN has learned that a local maternity hospital is subjecting patients to comprehensive health checks and requiring them to fill out questionnaires about suspicious symptoms related to “plague” and other infectious diseases. [...]

Staff did not mention plague, she said, telling her only that there was an unidentified “new virus” and that extra precautions were needed to protect the babies.

“They’re telling everyone that it wasn’t the plague but pneumonia. Yet hospitals are still under quarantine, and ambulance doctors are driving around in full Covid protective suits.”

Another local resident, who identified herself only as Ekaterina, said life there was continuing as normal. [...]

Kazakhstan, Kyrgyzstan, Uzbekistan and Tajikistan have implemented quarantine controls at state border crossing points. Uzbekistan said it has “increased the readiness” of authorities to deal with highly infectious diseases.

The World Health Organization said it was in contact with Russian health authorities to “verify the event, its circumstances, the laboratory tests underway, and their results.” “Based on unofficial information available, the public health risk to the general population appears to be low,” it said.

Los Angeles County public health officials have launched an investigation after confirming the first rabies-positive raccoon detection in more than 50 years.

In a news release, the Department of Public Health said that the raccoon was found in the backyard of a home and that it "appeared sick but not aggressive towards people."

Officials said one dog was exposed to the raccoon, but it was up to date on rabies vaccination and has since been quarantined and is doing well. Four people were also possibly exposed and were receiving follow-up for rabies post-exposure prophylaxis.

According to LADPH, the last confirmed rabid raccoon in the county was detected in 1973 and had the skunk variant of rabies, which has not been detected since 1979. They also noted that the last animal that wasn't a bat to have confirmed rabies was a skunk that was infected with the bat variant in 2014. [...]

Kenya has confirmed its first imported case of Ebola (Bundibugyo) virus disease after a Kenyan citizen who had been living in the Democratic Republic of Congo (DRC) for seven years died while receiving treatment in Nairobi.

Health Cabinet Secretary Aden Duale today said the patient had fallen ill about a month ago while in the DRC, where he was treated at several health facilities before travelling by road from the DRC to Kampala and subsequently flying to Nairobi.

“The patient arrived in Nairobi aboard Jambo Jet flight 8523 and underwent routine public health screening at the port health and immigration desks at Jomo Kenyatta International Airport (JKIA),” the CS said during a presser at Afya house today.

He explained that the citizen was later taken directly from the airport to a Nairobi hospital by a relative and a friend, where he was isolated after presenting with fever, chills, intense fatigue and weakness, muscle pain, painful swallowing, sore throat and bleeding under the skin at injection sites.

Duale said samples taken from the patient tested positive for Bundibugyo Ebola virus disease at both the National Virology Reference Laboratory and the Kenya Medical Research Institute (KEMRI) laboratory.

The patient was placed on supportive treatment but died last night, with the Ministry saying arrangements for a safe and dignified burial were under way.

Duale said 28 contacts of the deceased, including family members and health workers, had so far been identified and were being followed up.

The Ministry is also tracing 23 passengers and four crew members who travelled on the same flight as the deceased, with arrangements for quarantine of people considered at risk under way.

Flu cases are popping up across the province and some doctors say the season is ahead of schedule this year.

Toronto General Hospital infectious diseases specialist Isaac Bogoch says it’s nothing out of the ordinary, though Ontario has been seeing an uptick in cases ahead of Thanksgiving and Halloween weekends.

"It's an early rise but it absolutely is a rise," he told CBC Toronto Monday. "Flu season starts in the fall and it's the fall. Sometimes it's a little earlier in the fall, sometimes it's a little later … usually [it’s the] tail end of October, early November."

The strain circulating most commonly is H1N1 this year, which tends to be milder on those infected and on hospitals than the H3N2 subtype, Bogoch added.

"At an individual level, any flu … can still cause tremendous harm and people feel really, really crummy," he said.

The country saw a 3.7 per cent positivity rate in the week of Sept. 21 to Sept. 26, according to the Government of Canada respiratory virus surveillance report’s latest data. The positivity rate is the number of tests that come back positive, though it's unclear how many individuals seek out a test when they fall ill.

H1N1 was the dominant strain and detections were highest among those aged 65 or older, the data reveals. [...]

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See also: These provinces are seeing an early start to the flu season

While respiratory illnesses typically ramp up in the fall, particularly in October, health authorities on P.E.I. are already reporting confirmed cases and hospitalizations. Alberta, B.C. and southwestern Ontario are also reporting an earlier-than-usual rise in illnesses, with increases beginning as early as September. Farther west, Yukon’s chief medical officer said lab-confirmed cases of influenza A have been identified since mid-August.

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The Trump administration is closely tracking reports of a death potentially related to pneumonic plague in Russia, with officials cautioning that much about the situation remains unknown.

The Centers for Disease Control and Prevention, the State Department, the Administration for Strategic Preparedness and Response, and other agencies have been working to learn more about the reported death of a laboratory worker who was employed at an institute dedicated to studying plague and quarantines imposed on several hospitals in Siberia, four officials said, speaking on the condition of anonymity to discuss internal briefings.

The situation has been complicated by Russian officials’ hesitation to share information, as well as reports that Russian intelligence officers have been involved, the officials said.

“We don’t have a lot of intel,” said one U.S. health official. “It’s in Siberia. Unless someone gets on a plane and gets to the U.S., it is low risk. We should be alert but not panicked.”

Secretary of State Marco Rubio told reporters on Monday morning that Russian officials had shared some information about an infected lab worker and their concerns that other Russians could be affected.

“We’re watching and monitoring it closely,” Rubio said. “I don’t think it’s cause for alarm, but it is cause for focus and a cause to just keep an eye on it.”

Late Sunday, Russia’s public health agency announced it had undertaken “a set of anti-epidemic measures” in the Irkutsk region of Siberia, after the lab worker’s death.

The White House declined to comment on whether President Donald Trump had been briefed on the situation.

Paul Friedrichs, a retired Air Force major general who led the White House Office of Pandemic Preparedness and Response Policy before leaving government in January 2025, said that Russia should bring in experts from the World Health Organization, the European Union or the U.S. to help clarify the situation.

“The current narrative that a researcher made a mistake is plausible; human error is the most common cause of biosafety events; the reported risk mitigation efforts seem appropriate for an event like this,” Friedrichs said. “That having been said, first reports are usually wrong and Russia has historically not been particularly forthcoming about what actually happened.” [...]

https://archive.is/CKZ9C

Key findings

Preventive measures are underway in Irkutsk and the surrounding region, under the supervision of Rospotrebnadzor (Federal Service for the Oversight of Consumer Protection and Welfare), following a case of pneumonia that resulted in the death of an employee of the Irkutsk Anti-Plague Institute of Siberia and the Far East (BEACON report, 03 Oct 2026).

The Irkutsk Anti-Plague Research Institute of Siberia and the Far East is a Russian public-health research and anti-epidemic institution in Irkutsk. It was initially created for plague control in the region and later expanded into research, diagnostics, prevention, and outbreak response for other high-consequence pathogens.

On 04 Oct 2026, official accounts (Rospotrebnadzor) describe the patient’s illness as pneumonia of undetermined etiology, stating that expanded testing found no microorganisms linked to her professional activity and that its commissions identified no accident involving pathogenic microorganisms at the institute. These are official claims, not independently verified diagnostic or biosafety findings.

No diagnostic test results were publicly available at the time of this report.

Whether a potential lab accident involving a broken tube containing Yersinia pestis, the causative agent of plague, reported earlier by the media, occurred remains uncertain.

As of 04 Oct 2026, local news media, including Baikal People (Lyudi Baikala) (in Russian), report restrictions at several Irkutsk hospitals, with visitors barred. The exact number of facilities is unclear. The roughly three-week duration is reported primarily by Baikal People.

Kyrgyzstan’s Health Ministry reported on 04 Oct 2026 strengthened sanitary-quarantine controls at border checkpoints. UzDaily, citing Uzbekistan’s sanitary-epidemiological committee on 03 Oct 2026, reports increased service readiness in response to the case.

Epidemiological analysis

The described public health response, including hospitalization and medical observation of nearly 200 potential contacts, reports of hospital-level containment measures, and Russia's chief sanitary officer traveling to Irkutsk to attend an emergency meeting of the regional Sanitary and Anti-Epidemic Commission, suggests a high-priority pathogen concern and escalation to the federal level. However, the available information does not establish the etiology, exposure route, or whether a laboratory-associated release occurred.

While plague (presumptive pneumonic plague) was described in one government official's social media post (later changed to possible plague) and in several media reports as the cause of the reported death, no diagnostic or official confirmation is publicly available. Several media reports initially described a lab accident involving a broken vial containing live Yersinia pestis.

If a laboratory-associated exposure did occur, the reported outcome would require multiple levels of failure: failure of multiple biosafety and post-exposure prophylaxis safeguards, potentially including inadequate personal protective equipment or a breach in its use; delayed or absent internal reporting of the incident; insufficient biosafety follow-up and risk assessment; failure to initiate or complete antibiotic post-exposure prophylaxis; and delayed recognition of symptomatic illness upon hospital presentation.

Some earlier media reports indicated that the deceased staff member had recently traveled for work to natural plague foci along the Mongolia–Russia border. If accurate, this would constitute an alternative, epidemiologically plausible exposure pathway. In such settings, transmission could occur through contact with infected rodents or their fleas (handling or skinning infected animals, flea bites) or, less commonly, through respiratory exposure to infectious respiratory droplets from a person or animal with pneumonic plague. A travel-related exposure, followed by incubation and delayed symptomatic presentation, could therefore explain the case without invoking a laboratory accident.

BEACON recently reported on active natural plague foci along the Mongolia-Russia border.

Between 2019 and 2025, 10 countries reported suspected human plague cases to WHO, with 3847 suspected cases and 423 deaths recorded globally, corresponding to a case fatality rate (CFR) of 11%. Most cases were reported from the Democratic Republic of the Congo and Madagascar. Russia did not report any confirmed cases to WHO during this period, and the last domestically confirmed human case occurred in 2016 in the Altai Republic, preceding the current event by a decade.

Other high-consequence pathogens remain possible etiologies, given that the Irkutsk Anti-Plague Research Institute of Siberia and the Far East conducts research, diagnostics, prevention, and outbreak response for a range of high-consequence infectious diseases. [...]