An unvaccinated adult who traveled from Europe to the United States while infectious with measles last year spread the virus to 17 other people, researchers from the US Centers for Disease Control and Prevention (CDC) write in The Journal of Infectious Diseases.

For the report, published late last week, the researchers analyzed case samples and data from the CDC’s Port Health Activity Reporting System and health department investigations to describe subsequent contact-tracing efforts, environmental assessments, and laboratory testing. The team also reviewed flight records to pinpoint relative locations of the index and secondary case-patients at the arrival airport.

Index patient traveled despite symptoms

In May 2025, the CDC was notified of an adult who flew commercially from Europe to Denver International Airport in Colorado, stayed overnight in a hotel, and then boarded another flight to North Dakota. The case-patient had a fever, persistent cough, cold-like symptoms, and conjunctivitis (“pink eye”) during travel, and his rash occurred one day after his domestic flight.

Travelers with fever and other overt signs of transmissible illness, such as coughing or malaise, should be strongly encouraged to delay travel while symptomatic.

Contact investigation identified 135 domestic travelers exposed to the index patient. Fifteen of them (13 adults, two children) were infected during the international (five) and domestic (three) flights and at the airport (seven). The virus then spread to two other people outside of their households, for a total of 17 infections. 

Ten of the 15 secondary case-patients had documented or self-reported receipt of at least one dose of a measles vaccine, while five were unvaccinated. Five case-patients (three unvaccinated, two who self-reported vaccination) were hospitalized. 

Of the two tertiary case-patients, one was confirmed to have received two vaccine doses and was exposed to a secondary case-patient who self-reported vaccination, while the other was unvaccinated and exposed to an unvaccinated secondary case-patient.

“Vaccination is recommended prior to international travel for all travelers aged 6 months or older,” the study authors wrote. “Travelers with fever and other overt signs of transmissible illness, such as coughing or malaise, should be strongly encouraged to delay travel while symptomatic.”

CDC and state researchers reported a similar travel-related outbreak in late January.

A report in Nature details a case of likely direct interspecies mpox virus (MPXV) transmission from a fire-footed rope squirrel to wild sooty mangabey monkeys in a Cote d’Ivoire national park in 2023.

To investigate the outbreak among a group of sooty mangabeys, the team examined molecular evidence from rodents and wildlife carcasses from the area, as well as ecological and behavioral evidence. The researchers have been monitoring the health of chimpanzees, mangabeys, and other wildlife in the park for decades.

“African rodents, especially squirrels, are suspected to be involved in MPXV emergence, but no evidence of a direct transmission to humans or non-human primates has been established,” the researchers, from Germany and Cote d’Ivoire, wrote.

Fecal samples link squirrel, virus to mangabeys

About one third of the mangabeys showed clinical signs of mpox infection, and four infants died. Genomic sequencing showed that the virus from an infected fire-footed rope squirrel that was found dead roughly two miles from the mangabey territory 12 weeks before the outbreak was nearly identical to the one that affected the mangabeys.

Because squirrels and non-human primates are hunted, traded and consumed by humans in West and Central Africa, exposure to these animals probably represents risk for zoonotic transmission of MPXV.

The finding was supported by a 2014 video that showed a mangabey from the infected group eating the same squirrel species and an analysis of fecal samples collected from the mangabeys eight weeks before the outbreak, which contained DNA from the rope squirrel and the virus.

“Our findings indicate that rope squirrels were the source of the MPXV outbreak in mangabeys,” the authors wrote. “Because squirrels and non-human primates are hunted, traded and consumed by humans in West and Central Africa, exposure to these animals probably represents risk for zoonotic transmission of MPXV.”

In a press release from the Helmholtz Centre for Infection Research in Germany, co–senior author Livia Patrono, DVM, PhD, of the center, said, “Identifying the animal sources of the virus and the exposure routes that lead to inter-species transmission are key steps towards understanding spillover mechanisms and developing effective prevention measures to mitigate the risk of transmission to humans.”

• Late last week US Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. appointed two new members to the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP). Sean Downing, MD, and Angelina Farella, MD, both have experience in pediatrics. Downing practices in Sarasota, Florida, and Farella is a pediatrician in Webster, Texas. Farella gained some notoriety during the pandemic as a member of the right-wing medical group America’s Frontline Doctors. She made several television appearances calling for the removal of the COVID-19 vaccine, blamed it for 4,000 uncounted deaths in Texas, and advocated treating COVID-19 with vitamins. “These appointments strengthen ACIP with experienced clinicians who understand how immunization guidance matters for patients and families,” said CDC Acting Director Jay Bhattacharya, MD, PhD in an HHS statement.
• Despite Congress protecting funding streams for research scientists against the latest round of budget cuts, the US National Institutes of Health (NIH) has so far not received approval to spend any of the research funding allocated in a budget bill signed into law on February 3, according to a new report in Nature. The stall is because the White House Office of Management and Budget has been slow to authorize the release of funds. Until the new funds are released, the NIH can issue new research awards only using leftover money from funds approved by Congress last November. According to Nature, the agency has received about one-third of its US $47-billion budget from this measure.
• The Williams Institute at the UCLA School of Law finds that, in 2024, 43% of US adults held at least one stigmatizing belief about people living with HIV (PLWH), an increase from 31% in 2021. This study uses data from the nationally representative General Social Survey to assess HIV stigma. Heterosexual adults, conservatives, and those with lower education were most likely to express stigmatizing views on PLWH. Of note, 26% of those polled expressed blame-based stigma, while 31% expressed fear-based stigma.