Enlarge / Poster issued by the United States Centers for Disease Control and Prevention advocating for measles immunizations in 1985. (credit: Getty | National Library of Medicine. )

In 2000, after a decadeslong public health battle and a Herculean vaccination program, the US won a coveted status: measles elimination. The designation means that the extremely infectious measles virus is no longer endemic in the US—defined as continuous transmission in the country over 12 or more months while in the presence of an effective disease monitoring system. The country went from having 3 to 4 million children fall ill with the severe infection each year, to tallying just dozens of mostly travel-linked cases.

But in an alarming turn, the country's elimination status is now at risk. Measles cases in the first quarter of 2024 have increased more than 17-fold over the cases seen in the first quarters of 2000 to 2023. Measles vaccination rates among kindergarteners have slipped in that time, too, with vaccination coverage in the last three consecutive years below the 95 percent target that is needed to prevent sustained transmission. Outside the US, measles cases are exploding in the wake of pandemic-related disruptions to routine childhood vaccination programs. Altogether, the conditions are prime for measles to regain its foothold in the country—and the Centers for Disease Control and Prevention is clearly anxious.

"The rapid increase in the number of reported measles cases during the first quarter of 2024 represents a renewed threat to elimination," CDC researchers write in a new analysis of the country's measles cases and surveillance system . The analysis was published Thursday in the CDC's Morbidity and Mortality Weekly Report.

Enlarge / A child with measles. (credit: Greene, Charles Lyman )

Florida health officials on Sunday announced an investigation into a cluster of measles cases at an elementary school in the Fort Lauderdale area with a low vaccination rate, a scenario health experts fear will become more and more common amid slipping vaccination rates nationwide.

On Friday, Broward County Public School reported a confirmed case of measles in a student at Manatee Bay Elementary School in the city of Weston. A local CBS affiliate reported that the case was in a third-grade student who had not recently traveled. On Saturday, the school system announced that three additional cases at the same school had been reported, bringing the current reported total to four cases.

On Sunday , the Florida Department of Health in Broward County (DOH-Broward) released a health advisory about the cases and announced it was opening an investigation to track contacts at risk of infection.

Enlarge / This thin section transmission electron microscopic (TEM) image reveals numerous spheroid-shaped Enterovirus-D68 (EV-D68) virions. (credit: CDC/ Cynthia S. Goldsmith, Yiting Zhang )

2022 was the bad year that wasn't—at least for a mysterious paralyzing condition in children.

In the decade before, hundreds of young, healthy kids in the US abruptly felt their limbs go weak. Debilitating paralysis set in. In recent years, around half of affected children required intensive care. About a quarter needed mechanical ventilation. A few died, and many others appear to have permanent weakness and paralysis.

Researchers quickly linked the rare polio-esque condition to a virus known for causing respiratory infections, often mild colds: enterovirus D68, or EV-D68 for short. Identified decades ago, it's a relative of polio, one of the over 100 non-polio enteroviruses that float around. But when EV-D68 began surging, so did the mysterious paralyzing condition, called acute flaccid myelitis, or AFM. The menacing pair seemed to come in waves every other year, likely starting with a cluster of cases in California in 2012 . In 2014, there were 120 AFM cases in 34 states . In 2016, 153 cases in 39 states. In 2018, 238 cases in 42 states. By contrast, there were just a few dozen cases or so in each of the years in between, cases that were sporadic or unrelated to EV-D68.

Enlarge / Road blockade due to Nipah affected areas at Chathamangalam panjayat on September 8, 2021, in Kozhikode, India. (credit: DeFodi Images News / Getty )

On the morning of September 11, critical care specialist Anoop Kumar was presented with an unusual situation. Four members of the same family had been admitted to his hospital—Aster MIMS in Kozhikode, Kerala—the previous day, all similarly sick. Would he take a look?

He gathered his team of doctors to investigate. Soon they were at the bedsides of a 9-year-old boy, his 4-year-old sister, their 24-year-old uncle, and a 10-month-old cousin. All had arrived at the hospital with fever, cough, and flu-like symptoms. The 9-year-old was in respiratory distress, struggling to breathe properly, and had needed to be put on a noninvasive ventilator , with air pumped through a mask to keep his lungs expanded.

Their symptoms were concerning and mysterious—none of the team could pinpoint what was wrong. But delving into their family history, Anoop and his colleagues soon uncovered a clue. The father of the two young siblings, 49-year-old Mohammed Ali, an agriculturalist, had died less than two weeks previously. And when the team at Aster MIMS got in touch with the hospital that had treated Ali, they found that he had been admitted with similar symptoms, pneumonia and fever.

Enlarge / Transmission electron micrograph of a SARS-CoV-2 virus particle isolated from a patient sample and cultivated in cell culture. (credit: Getty | BSIP )

A remarkably mutated coronavirus variant classified as BA.2.86 seized scientists' attention last week as it popped up in four countries, including the US.

So far, the overall risk posed by the new subvariant is unclear. It's possible it could lead to a new wave of infection; it's also possible (perhaps most likely) it could fizzle out completely. Scientists simply don't have enough information to know. But, what is very clear is that the current precipitous decline in coronavirus variant monitoring is extremely risky.

In a single week, BA.2.86 was detected in four different countries, but there are only six genetic sequences of the variant overall —three from Denmark, and one each from Israel, the UK, and the US (Michigan). The six detections suggest established international distribution and swift spread. It's likely that more cases will be identified. But, with such scant data, little else can be said of the variant's transmission or possible distribution.

Enlarge (credit: Raymond Gehman / Getty Images )

People in the US transmitted the pandemic coronavirus to white-tailed deer at least 109 times, and the animals widely spread the virus among themselves, with a third of the deer tested in a large government-led study showing signs of prior infection. The work also suggests that the ubiquitous ruminants returned the virus to people in kind at least three times.

The findings, announced this week by the US Department of Agriculture, are in line with previous research, which suggested that white-tailed deer can readily pick up SARS-CoV-2 from humans, spread it to each other , and, based on at least one instance in Canada, transmit the virus back to humans .

But the new study , led by the USDA's Animal and Plant Health Inspection Service (APHIS), provides a broader picture of deer transmission dynamics in the US and ultimately bolsters concern that white-tailed deer have the potential to be a virus reservoir. That is, populations of deer can acquire and harbor SARS-CoV-2 viral lineages, which can adapt to their new hosts and spill back over to humans, causing new waves of infection. It's conceivable that viruses moving from deer to humans could at some point qualify as new variants, potentially with the ability to dodge our immune protections built up from past infection and vaccination.