Enlarge (credit: Andrew Burton/Getty )

The Arctic—that remote, largely undisturbed, 5.5 million square miles of frozen terrain—is heating up fast. In fact, it’s warming nearly four times quicker than the rest of the world, with disastrous consequences for the region and its inhabitants. Many of these impacts you probably know from nature documentaries: ice caps melting, sea levels rising, and polar bears losing their homes. But good news! There is another knock-on effect to worry about: the warming landscape is rewiring viral dynamics, with the potential to unleash new pathogens.

An underappreciated consequence of climate change is how it will exacerbate the spread of infectious disease. As the world heats up, many species are expected to up sticks and meander many miles away from their typical habitat, bringing various pathogens along with them for the ride. This means that previously unacquainted viruses and hosts will meet for the first time, potentially leading to viral spillover—where a virus jumps from one reservoir host to a new one, like our old friend SARS-CoV-2.

Enlarge (credit: KATERYNA KON )

Vertebrates such as ourselves rely on a complicated, multi-layer immune system to limit the impact of pathogens. Specialized B and T cells play a central role by recognizing specific pathogens and providing a memory of past infections.

Obviously, single-celled organisms like bacteria and archaea can't take the same approach. But that doesn't mean they're defenseless. They also have an adaptive defense system that maintains a memory of past infections (and happens to make a great gene editing tool ). Now, researchers have found that a family of related proteins is used to fight viruses in organisms ranging from bacteria to humans. While the effects it triggers vary among organisms, it appears to be capable of recognizing a wide range of viruses.

Finding family members

Mammals have a family of immune proteins called STAND (for reasons that are unimportant) that are part of what calls the innate immune system. This arm of our immune system doesn't recognize specific pathogens; instead, it recognizes general features of infection, such as molecules that are found on the surface of most bacteria.

Enlarge / Burkholderia pseudomallei grown on sheep blood agar for 24 hours. B. pseudomallei is a Gram-negative aerobic bacteria, and it's the causative agent of melioidosis. (credit: Getty | CDC/Courtesy of Larry Stauffer, Oregon State Public Health Laboratory )

The fourth person affected by a bacterial outbreak linked to imported aromatherapy room sprays sold at Walmart last year occurred in a previously healthy 5-year-old boy in Georgia, who died of the infection. That's according to new information presented Tuesday at the International Conference on Emerging Infectious Diseases (ICEID), hosted by the Centers for Disease Control and Prevention in Atlanta.

The tragic new details of the boy's cases—presented by epidemiologist Jessica Pavlick of the Georgia Department of Public Health—have newfound significance for the US. In the year since the boy's death, the tropical soil bacterium behind his deadly infection has been found in environmental samples in southern Mississippi . The bacterium— Burkholderia pseudomallei —is now considered endemic to the Gulf Coast region, creating an ever-present threat to people in the area.

Tragic infection

For years, CDC researchers have suspected that B. pseudomallei could already be lurking in soil and water in the continental US, rather than being brought in via imported animals and products (like the room sprays), as well as travelers and migrants. In recent years, the US has averaged about 12 cases of B. pseudomallei infection, which causes a disease called melioidosis.

Enlarge / Burkholderia pseudomallei grown on sheep blood agar for 24 hours. B. pseudomallei is a Gram-negative aerobic bacteria, and it's the causative agent of melioidosis. (credit: Getty | CDC/Courtesy of Larry Stauffer, Oregon State Public Health Laboratory )

For years, health officials in the US noted sporadic, mysterious cases of a foreign bacterial infection, called melioidosis. The infection—which is difficult to diagnose, tricky to treat, and often deadly—was thought to only strike travelers or those who came in contact with contaminated imported goods or animals. Yet, now and then, an American would inexplicably fall ill—no recent travel, no clear links.

Now, health officials have a definitive explanation. And it confirms a dreaded, long-held suspicion: The deadly bacterium is foreign no more. Rather, it's a permanent US resident entrenched in American soil.

Three samples taken from soil and puddle water in the Gulf Coast region of southern Mississippi tested positive for the bacterium, officials from the Centers for Disease Control and Prevention announced Wednesday . The sampling was part of an investigation into two mysterious cases in the area that occurred in 2020 and 2022. The positive test results mark the first time that investigators have caught the deadly germ in US environmental samples, though they've been looking for it for years.

Enlarge / The bacteria, Ca. Thiomargarita magnifica , discovered in the French Caribbean mangroves is a member of the genus Thiomargarita . (credit: Tomas Tyml)

Clinging to sunken debris in shallow, marine mangrove forests in the French Caribbean, tiny thread-like organisms—perfectly visible to the naked eye—have earned the title of the largest bacteria ever known.

Measuring around a centimeter long, they are roughly the size and shape of a human eyelash, batting away the competition at 5,000 times the size of garden-variety bacteria and 50 times the size of bacteria previously considered giant. In human terms, this is akin to coming across a person as tall as Mount Everest.

Views of the sampling sites among the mangroves of Guadeloupe archipelago in the French Caribbean, April-May 2022. (credit: Pierre Yves Pascal)

Olivier Gros, a biologist at the University of the Antilles, discovered the prokaryotes in 2009, noticing them gently swaying in the sulfur-rich waters among the mangroves in the Guadeloupe archipelago. The bacteria clung to the leaves, branches, oyster shells, and bottles that sunk into the tropical swamp, Gros said in a press briefing.