TIME Infectious Disease

Getting Sick From Planes Is Way Less Likely Than You Think

interior of plane
Martial Colomb—Getty Images

From Ebola to the common flu, viruses don't jump from 32D to 12C all that easily

The person next to you on your eight-hour flight is clearly not feeling well—coughing, running to the lavatory frequently. Great, you think. I’m going to catch some horrible virus.

Actually, probably not. Although most of us would swear that we caught a flu as the result of air travel, airliners are not great at spreading infectious diseases among passengers. (Bacteria is another story, though. See the 6 Germiest Places on a Plane for what to be careful about.) According to a Centers for Disease Control and Prevention (CDC) investigation, if a suspected tuberculosis carrier was aboard a jet, the agency wouldn’t expect exposure to possible infection to extend beyond two rows in either direction.

Airliners are, however, very good at delivering infectious diseases to entire countries. The SARS breakout in Canada in 2003, which sickened 400 people and killed 44, was traced to a single airline passenger—the index patient—who traveled from Hong Kong to Toronto and fell ill after she arrived home. Most of the cases were hospital-acquired, however, including healthcare workers themselves. SARS seemed to have skipped the airline passengers altogether.

Likewise, the chance of catching Ebola from a fellow passenger is remote. The virus is spread through direct contact with infected bodily fluids, not by sitting in a middle seat. “The one thing we have as an advantage is the lack of airborne transmissibility,” says Dr. David R. Shlim, president the International Society of Travel Medicine. “It’s not likely to get in an airplane and then float down the aisle.”

The World Health Organization, which plays traffic cop to the planet’s disease vectors, has warned reasonably for travel restrictions for anyone suspected of having Ebola. Airport and health authorities in Lagos and Monrovia are screening passengers for symptoms before they board and anyone stricken with such symptoms is unlikely to be able to travel, although it’s certainly not impossible. In the U.S., the CDC mans quarantine stations at international airports, such as John F. Kennedy in New York City and Newark Liberty in New Jersey, that act as the front-line defense against infectious visitors.

The bigger issue is that a virulent illness—SARS, MERS, and perhaps some superbug lurking somewhere waiting for a ticket out—can be delivered around the globe with relative ease given the expansion in air travel. A million passengers a day enter the United States, according to the Customs and Border Protection agency. “Diseases that used to smolder can now move more quickly. You can get anywhere in 24 hours,” says Shlim. “All the public health officials know about that and are concerned about it.” Consider chikungunya, a mosquito-borne virus that causes fever and joint pain. According to the CDC, the chikungunya virus reached the Americas via the islands of the Caribbean in late 2013. “There is a risk that the virus will be imported to new areas by infected travelers,” the CDC notes. Sure enough, a case was discovered in Florida this year.

The WHO hasn’t gone so far as recommending a travel embargo to the Ebola-affected nations, but that would be the logical progression if the outbreak can’t be reined in with the current program, called Ebola Virus Disease Outbreak Response Plan. During Canada’s SARS outbreak, the WHO issued a travel advisory that recommended that tourists avoid the Toronto area. It’s not known whether the advisory stopped SARS from spreading, but it did severely damage Canada’s tourism industry before being withdrawn after a few days after the Canadian government protested the advisory.

Stopping the movement of people is the ultimate way of keeping a viral disease in check geographically. But in the more connected world of global logistics it will be increasingly difficult to do so. Although ebola is terrifying in that there is no widely available remedy, there’s no reason to change your flight plans, even to Africa.

That doesn’t mean people won’t. “I can’t think of any example of one person got on a plane and 30 people got off sick,” Shlim notes. The biggest concern on your next jet ride isn’t going to be Ebola. It’s more like measles, which is very contagious. The risk there isn’t from a third-world passenger arriving from Africa. It’s more likely a 7-year American kid who hasn’t been vaccinated.

TIME Infectious Disease

Hand Sanitizers Don’t Lower School Absences

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A new study shows hand sanitizer doesn't keep kids in school Paul Velgos—Getty Images

Putting hand sanitizers in schools and encouraging kids to use them doesn’t lower the rate of school absences, according to new research published Tuesday in the journal PLOS Medicine.

“These findings suggest that in high-income countries, where clean water for hand washing is readily available, putting resources into extra hand hygiene by providing hand sanitizer in classrooms may not be an effective way to break the child-to-child transmission of infectious diseases,” the study authors conclude.

The team of New Zealand researchers randomly assigned 68 primary schools to either have alcohol-based hand sanitizers in the classroom or not. All of the students in the participating schools underwent a 30 minute session on hand hygiene. The kids were also told that they should use the hand sanitizer after they coughed or sneezed, as well as when they left the classroom.

Despite the high level of encouraged use of the dispensers, the researchers found that there was no difference in the rates of school absences between the schools with dispensers and the schools without. Still, the study had some limitations. During the study period, there was an flu going around in the region—which means that the population was likely hearing public health messages about flu prevention in other places, making the effectiveness of their specific intervention difficult to parse.

For now, a good bar or soap and water, for those lucky enough to use them liberally, should do the trick.

 

TIME Germs

Bumping Fists Spreads Fewer Germs Than a Handshake, Study Says

From right: U.S. President Barack Obama and First Lady Michelle Obama bump fists at an election night rally at the Xcel Energy Center on June 3, 2008 in St. Paul, Minn. during his first presidential campaign.
From right: U.S. President Barack Obama and First Lady Michelle Obama bump fists at an election night rally at the Xcel Energy Center on June 3, 2008 in St. Paul, Minn. during his first presidential campaign. Scott Olson--Getty Images

Plus, they're cooler

President Barack Obama’s famous fist bumps may have health benefits as well as a cool factor, because a new study shows that greeting someone with your knuckles is much more hygienic than shaking their hand.

Dr. Dave Whitworth, of Aberystwyth University in Wales, tested the germ-carrying potential of various greetings by high-fiving, fist-bumping, and shaking hands with with a PhD student. One wore a glove covered in bacteria, the other wore a clean glove.

They found that handshakes transferred the most germs, with high-fives transferring only half as many and fist-bumps transferring 90% less, which means that fist-bumping instead of shaking hands could help limit the spread of illness.

The study will be published in the August issue of the American Journal of Infection Control.

Dr. Whitworth hypothesized that fist-bumps are more hygienic mostly because they minimize the surface area of hand-to-hand contact, and they’re usually quicker than handshakes.

“People rarely think about the health implications of shaking hands,” he said in a statement. “If the general public could be encouraged to fist-bump, there is genuine potential to reduce the spread of infectious diseases.”

Plus, if we all fist-bump, then we’d never have to deal with that limp-fish thing again.

TIME Germs

You Asked: Is the 5-Second Rule Legit?

The Five Second Rule
Illustration by Peter Oumanski for TIME

When food hits the floor, some say you have 5 seconds to retrieve it before filth hitches a ride. Here’s what germ experts have to say about that

Donut down! You quickly grab your grub, certain you’ve satisfied the 5-second rule with time to spare. But is your fallen food safe to eat?

Past research shows roughly 70% of women would say yes, along with 56% of men, says Paul Dawson, a food scientist at Clemson University who has lab-tested the legitimacy of the 5-second rule. Unfortunately, snacking on stuff that has touched the ground is always a risky proposition, he says.

“I compare picking up dropped food and eating it to not wearing a seat belt,” Dawson says. You could drive a lifetime without wearing a safety belt and never have an accident, but that doesn’t mean you’re safe not wearing one, he explains.

Dawson and his team tested the time it takes harmful bacteria like salmonella to transfer from various surfaces—wood, tile, carpet—to either dry foods (bread) or moist ones (bologna).

Here’s what they found: The length of time food spends on the floor does increase the amount of bacteria that latches on. Also, specific food-floor combinations (especially moist food on tile) result in a greater transfer of germs. But regardless of the snack-surface specifics, a significant amount of unhealthful gunk jumps from the ground to your food pretty much instantaneously, Dawson explains.

“I stand by the zero-second rule,” he says. “If bacteria is present on the ground, it will be transferred to your food.”

Recently, biomedical scientist Anthony Hilton and colleagues at Aston University in the UK repeated Dawson’s experiment with different sickness-causing bacteria like E. coli and Staphylococcus aureus. The results didn’t change.

“The majority of bacteria transfer to the food immediately on impact,” Hilton says. “The quicker you pick up your food, the fewer bacteria will transfer.” But that doesn’t mean a speedy recovery of your fallen treat will keep you safe from germs, he adds.

What about food falling on other surfaces—like your desk at work? It all depends on whether illness-causing bacteria are present, Dawson says. According to a University of Arizona study, the average office desk harbors hundreds of times more germs than the average office toilet seat.

Consider yourself warned.

TIME Germs

Why You Should Let Kids Eat Dirt

Gardening Hands - let your kid eat dirt
Getty Images

Kids who are exposed to more germs before age one are less likely to have allergies and asthma a new study shows

Infants who are exposed to unsavory things like rodent and pet dander, roach allergens and household bacteria during their first year are actually less likely to suffer from allergies and asthma, Johns Hopkins researchers say.

A new study published in the Journal of Allergy and Clinical Immunology shows that being exposed to allergens before a child turns one can benefit allergies. To reach these findings, the researchers studied 467 inner-city infants in Boston, New York and St. Louis. They tracked their health over three years, and visited their homes to calculate the levels of a variety of allergens. They also conducted allergy tests on the children and collected bacteria from dust gathered in their homes.

The kids who lived in homes with mouse and cat dander as well as cockroach droppings during their first year had lower rates of wheezing by age 3. The kids with a greater amount of bacteria in their homes were also less likely to wheeze and were less likely to have environmental allergies.

Kids who were completely free of allergies were also most likely to grow up in homes with the highest amount of allergens and bacteria in them. In contrast only 8% of kids with both allergies and asthma were exposed to the substances by the time they were 1.

It’s possible you’ve heard of the “hygiene hypothesis,” which is the speculation that the reason Americans have so many allergies is because we are, quite simply, too clean. Kids are kept in such sterile environments that they never build immunities to common allergens.

A significant amount of research has shown that kids who grow up living on farms with livestock, or with a pet are less likely to develop asthma or allergies. Prior research has also suggested that it’s not necessarily dust that provides a protective benefit, but the microbes that are in our guts that influence our immune system and ability to fight off infections.

The new findings support a growing body of evidence that a little exposure to germs here and there never hurt anyone, and in fact, could actually be protective.

TIME Science

Science Confirms the Five-Second Rule Is Actually a Real Thing

Broken wineglass and food plate falling on table
Getty Images

It's still best to keep your food on your plate

Research at the U.K.’s Aston University has confirmed the old adage that food dropped on the floor for five seconds is clean—or at least it’s less likely to be dirty than if it sits there.

To test out the rule, students dropped toast, pasta, biscuits, and candy onto a floor that had been exposed to common bacteria and measured how much of the bacteria transferred when it was left on the surface for durations ranging from three to 30 seconds.

The results found that food left on the floor for less time does indeed get exposed to less bacteria. But more importantly, the texture of the floor that food is dropped on to is the most significant factor in how much bacteria is transferred.

Carpet is actually the cleanest surface to drop food onto, contrary to its connotations as a fibrous home for germs. It carries “the lowest risk of bacterial transfer onto dropped food,” Professor Anthony Hilton explains. Laminate and tiled floors are the worst offenders for dropped food infection.

That said, we’re not taking any chances.

(h/t Geekosystem)

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