Where Germs Lurk on Planes

It's a common complaint: Fly on a crowded plane and come home with a cold. What's in the air up there?

Airlines are deploying state-of-the-art filtration systems to contain flu and cold viruses from spreading. Scott McCartney joins Lunch Break to discuss how to avoid getting sick while flying. Photo: AP.

Air travelers suffer higher rates of disease infection, research has shown. One study pegged the increased risk for catching a cold as high as 20%. And the holidays are a particularly infectious time of year, with planes packed full of families with all their presents—and all those germs.
Air that is recirculated throughout the cabin is most often blamed. But studies have shown that high-efficiency particulate air (HEPA) filters on most jets today can capture 99.97% of bacterial and virus-carrying particles. That said, when air circulation is shut down, which sometimes happens during long waits on the ground or for short periods when passengers are boarding or exiting, infections can spread like wildfire.

One well-known study in 1979 found that when a plane sat three hours with its engines off and no air circulating, 72% of the 54 people on board got sick within two days. The flu strain they had was traced to one passenger. For that reason, the Federal Aviation Administration issued an advisory in 2003 to airlines saying that passengers should be removed from planes within 30 minutes if there's no air circulation, but compliance isn't mandatory.
Much of the danger comes from the mouths, noses and hands of passengers sitting nearby. The hot zone for exposure is generally two seats beside, in front of and behind you, according to a study in July in the journal Emerging Infectious Diseases, published by the U.S. Centers for Disease Control and Prevention.
A number of factors increase the odds of bringing home a souvenir cough and runny nose. For one, the environment at 30,000 feet enables easier spread of disease. Air in airplanes is extremely dry, and viruses tend to thrive in low-humidity conditions. When mucous membranes dry out, they are far less effective at blocking infection. High altitudes can tire the body, and fatigue plays a role in making people more susceptible to catching colds, too.
Also, viruses and bacteria can live for hours on some surfaces—some viral particles have been found to be active up to a day in certain places. Tray tables can be contaminated, and seat-back pockets, which get stuffed with used tissues, soiled napkins and trash, can be particularly skuzzy. It's also difficult to know what germs are lurking in an airline's pillows and blankets.
Research has shown how easily disease can spread. Tracing influenza transmission on long-haul flights in 2009 with passengers infected with the H1N1 flu strain, Australian researchers found that 2% passengers had the disease during the flight and 5% came down within a week after landing. Coach-cabin passengers were at a 3.6% increased risk of contracting H1N1 if they sat within two rows of someone who had symptoms in-flight. That increased risk for post-flight disease doubled to 7.7% for passengers seated in a two-seat hot zone.
The epidemic of severe acute respiratory syndrome (SARS) in 2002-03 suggested a wider exposure zone, however. On one flight studied, one passenger spread a particular strain to someone seated seven rows away, while people seated next to the ill passenger didn't contract the disease.
That said, most people sitting near someone who is ill probably won't get sick. "When you get aboard an aircraft, most of us don't have a say on who we sit next to. But that doesn't doom you to catching the flu," said Mark Gendreau of Boston's Lahey Clinic Medical Center.
In 2005, he was part of a team that published a paper in the Lancet that concluded the perceived risk for travelers was higher than the actual risk, and that's still the case today, he said.
Even so, there are some basic precautions passengers can take to keep coughs away.

Hydrate. Drinking water and keeping nasal passages moist with a saline spray can reduce your risk of infection.
Clean your hands frequently with an alcohol-based hand sanitizer. We often infect ourselves, touching mouth, nose or eyes with our own hands that have picked up something.
Use a disinfecting wipe to clean off tray tables before using.
Avoid seat-back pockets.
Open your air vent, and aim it so it passes just in front of your face. Filtered airplane air can help direct airborne contagions away from you.
Change seats if you end up near a cougher, sneezer or someone who looks feverish. That may not be possible on very full flights, but worth a try. One sneeze can produce up to 30,000 droplets that can be propelled as far as six feet.
Raise concerns with the crew if air circulation is shut off for an extended period.
Avoid airline pillows and blankets (if you find them).
"If you take the proper precautions, you should do quite well," said Dr. Gendreau. "In most of us, our immune system does what it was designed to do—protect us from infectious insults."
Hidden Dangers in Security
You think the plane is bad? Security checkpoints harbor a host of hazards as well, researchers say.

Jason Schneider Airport security areas can make it easy to get sick. People are crowded together, and plastic storage bins that hold personal effects are not cleaned after each screening.

People get bunched up in lines, where there is plenty of coughing and sneezing. Shoes are removed and placed with other belongings into plastic security bins, which typically don't get cleaned after they go through the scanner.
A National Academy of Sciences panel is six months into a two-year study that is taking samples at airport areas to try to pinpoint opportunities for infection.
With limited resources, airports and airlines have asked researchers to help figure out where best to target prevention, said Dr. Mark Gendreau of Boston's Lahey Clinic Medical Center who is on the panel.
Check-in kiosks and baggage areas are other prime suspects in addition to security lines, he said.
Corrections & Amplifications
In a 2009 study, coach-cabin passengers were at a 7.7% increased risk of contracting the H1N1 flu strain if they sat within two seats of someone who was infected. A graphic that orginally appeared with this column incorrectly said such passengers were at a 7.5% increased risk.

Why are we told always to finish a course of antibiotics?

By Jonathan Crowe

Most of us have at one time or another been prescribed a course of antibiotics by our GP. But how many of us heed the instruction to complete the course – to continue taking the tablets or capsules until none remain? Very often, our strict adherence to the prescription fades in line with our symptoms: the prescription may last for, say, seven days, but we’re often feeling much better after just two or three. So why bother continuing to take the antibiotic? After all, if we’re feeling better, the antibiotic has done its job, right? Well, you may think so. But, in fact, stopping a course of antibiotics early can have potentially lethal consequences. How can that be?
To answer this question, we must travel inside our body to mingle with the bacteria the antibiotics have been prescribed to kill. At face value, all the bacteria in a given population might seem identical. But look a little deeper, and you’ll see subtle differences. And one difference is the way in which they respond to a given antibiotic.
I described in a previous post how antibiotics are designed selectively to attack bacteria rather than causing harm to our own cells, which must necessarily get exposed to the antibiotic as it travels through our body in search for the alien intruder within. But different bacteria, even from within the same population, may respond differently to a particular dose of antibiotic. The ‘weak’ ones may be susceptible to a relatively low dose – they may be killed after just a few days of exposure to the antibiotic; by contrast, others may be much more resilient, and will still be alive after a few days of treatment.
The important point here is that the population as a whole is made up of bacteria exhibiting a range of tolerances – at one end of spectrum, a few real weaklings; at the other, a few really resilient ones. And, in between, we find many average, run-of-the-mill individuals, who can hold out against the antibiotic for so long – but not for very long. (I saw the same kind of distribution within a population when we grew some tomato plants this summer: some were noticeably short, some were unusually tall, but a majority hovered somewhere in between.)
But what’s causing this difference in tolerance? I mentioned in a previous post that each time a genome is copied there’s a chance a mutation (an error) will creep in to one of the genes making up that genome. Well, every time a bacterium reproduces it has to make a copy of its genome to pass on to its offspring – and, every time, there’s a chance an error will creep in. The chances are that the variation in tolerance to antibiotics that we witness in this population of bacteria is due to slight variations in their genomes; it could be that our resilient individuals show this resilience because they picked up mutations not present in their weak or average cousins.
Now, let’s return to our bacterial infection and imagine that we’ve started to take a course of antibiotics. It takes just a day or two to kill the real weaklings. And, in three or four days, even the Mr Averages will start to feel the proverbial heat. At this point, the population as a whole will have gone into noticeable decline, and we may start to feel much better as the number of alien invaders reduces.
But what has actually happened by the three or four day stage? The population as a whole may have shrunk in size – we’ll have rid ourselves of the few real weaklings and the larger number of Mr Averages – but we’ll be left with the few hangers-on at the other end of the spectrum, the real bruisers.
Before we started taking the antibiotics, the antibiotic-resilient bacteria (our ‘bruisers’) were fighting for a share of the available food with all the other members of the population. (It’s important to note that, when I talk of ‘weak’ or ‘resilient’ individuals I’m only referring to their tolerance level to antibiotics, not their ability to scavenge for food, and other aspects of survival in an antibiotic-free world.) In essence, the bruisers were being kept in check by everyone else – they remained in the minority because the whole population, including the weaklings and the Mr Averages, was growing at about the same rate. Now, three or four days in, the bruisers suddenly find themselves with much less competition for food. Imagine going to the buffet table at a wedding with 200 guests, all of whom are vying for a slice of the pie (quite literally), versus going to the same-sized buffet table with the same amount of food at a wedding attended by just 20 guests. At which wedding are you most likely to be able to fill your proverbial boots?
Now let’s consider what happens after day three or four, once the supply of antibiotic has stopped. At this point, remember, there are just a relatively small number of antibiotic-resilient bacteria left, but no weak or average ones. When the resilient bacteria suddenly find themselves the guests at an unexpected banquet – with competition for food gone – they do what bacteria do best: they reproduce. And without the previous competition for food, they can do so rapidly. So, we’ve suddenly gone from a mixed population in which the majority didn’t take kindly to antibiotics and only a few were the bruisers, to one in which virtually everyone is unusually tolerant to antibiotics. And this is where the real danger can lurk.
I mentioned above that the resilient bacteria may exhibit their resilience because they have accumulated more errors in their genomes than their weak or average cousins as successive generations have reproduced. As this resilient population now continues to thrive, it risks accumulating even more errors. And one of those errors could be what it takes to tip the balance from the bacterium being highly-tolerant of the antibiotic to it being completely resistant. You don’t need to be a medical expert to realise that complete resistance to an antibiotic is a really bad thing. If a bacterium has overwhelmed our immune system, and we don’t have an antibiotic to act as a back-up defence system, we have no weapons left to fight with.
If we carry on taking our antibiotics as prescribed, the story ends quite differently: even the resilient bacteria lose the will to live in the end. But we have to keep up the pressure by finishing the course of antibiotics. That way, any resilient individuals don’t get to dominate, and we reduce the risk of one of them picking up a mutation that makes them virtually invincible – but which is potentially lethal for us. In future, you know what you need to do…

Over 40% of cancers due to lifestyle, says review

By Michelle Roberts Health reporter, BBC News

Booze, cigarettes and inactivity are collectively bad

Nearly half of cancers diagnosed in the UK each year - over 130,000 in total - are caused by avoidable life choices including smoking, drinking and eating the wrong things, a review reveals.

Tobacco is the biggest culprit, causing 23% of cases in men and 15.6% in women, says the Cancer Research UK report.
Next comes a lack of fresh fruit and vegetables in men's diets, while for women it is being overweight.
The report is published in the British Journal of Cancer.
Its authors claim it is the most comprehensive analysis to date on the subject.
Lead author Prof Max Parkin said: "Many people believe cancer is down to fate or 'in the genes' and that it is the luck of the draw whether they get it.
"Looking at all the evidence, it's clear that around 40% of all cancers are caused by things we mostly have the power to change."
Weighty matters

For men, the best advice appears to be: stop smoking, eat more fruit and veg and cut down on how much alcohol you drink.

For women, again, the reviews says the best advice is to stop smoking, but also watch your weight.
Prof Parkin said: "We didn't expect to find that eating fruit and vegetables would prove to be so important in protecting men against cancer. And among women we didn't expect being overweight to be more of a risk factor than alcohol."
In total, 14 lifestyle and environmental factors, such as where you live and the job you do, combine to cause 134,000 cancers in the UK each year.

Former cancer patient Jackie Gledhill: "My lifestyle had really gone downhill - I did go out for walks but it wasn't enough"

About 100,000 (34%) of the cancers are linked to smoking, diet, alcohol and excess weight.
One in 25 of cancers is linked to a person's job, such as being exposed to chemicals or asbestos.
Some risk factors are well established, such as smoking's link with lung cancer.
But others are less recognised.
For example, for breast cancer, nearly a 10th of the risk comes from being overweight or obese, far outweighing the impact of whether or not the woman breastfeeds or drinks alcohol.
And for oesophageal or gullet cancer, half of the risk comes from eating too little fruit and veg, while only a fifth of the risk is from alcohol, the report shows.
For stomach cancer, a fifth of the risk comes from having too much salt in the diet, data suggests.
Some cancers, like mouth and throat cancer, are caused almost entirely by lifestyle choices.

But others, like gall bladder cancer, are largely unrelated to lifestyle.
The researchers base their calculations on predicted numbers of cases for 18 different types of cancer in 2010, using UK incidence figures for the 15-year period from 1993 to 2007.

In men, 6.1% (9,600) of cancer cases were linked to a lack of fruit and vegetables, 4.9% (7,800) to occupation, 4.6% (7,300) to alcohol, 4.1% (6,500) to overweight and obesity and 3.5% (5,500) to excessive sun exposure and sunbeds.

In women, 6.9% (10,800) were linked to overweight and obesity, 3.7% (5,800) to infections such as HPV (which causes most cases of cervical cancer), 3.6% (5,600) to excessive sun exposure and sunbeds, 3.4% (5,300) to lack of fruit and vegetables and 3.3% (5,100) to alcohol.
Dr Rachel Thompson, of the World Cancer Research Fund, said the report added to the "now overwhelmingly strong evidence that our cancer risk is affected by our lifestyles".
Dr Harpal Kumar, chief executive of Cancer Research UK, said leading a healthy lifestyle did not guarantee a person would not get cancer but the study showed "we can significantly stack the odds in our favour".
"If there are things we can do to reduce our risk of cancer we should do as much as we possibly can," he said.
Glyn Berwick, of Penny Brohn Cancer Care, which specialises in offering nutrition and exercise advice, agreed.
"We know from years of experience the positive impact that changing lifetsyles can have."
The president of the Royal College of Physicians, Sir Richard Thompson, said the findings were a wake-up call to the government to take stronger action on public health.
"The rising incidence of preventable cancers shows that the 'carrot' approach of voluntary agreements with industry is not enough to prompt healthy behaviours, and needs to be replaced by the 'stick' approach of legislative solutions," he said
The government said it was intending to begin a consultation on plain packaging by the end of this year.
Diane Abbott, Shadow Public Health Minister, said: "The government is failing on all the main public health issues.
"And the message from Labour, the Tory-led Public Health Committee, campaigners like Jamie Oliver and even some the government's own policy panels is clear: the government's approach to tackling lifestyle-related health problems is completely inadequate."
Public Health Minister Anne Milton said: "We all know that around 23,000 cases of lung cancer could be stopped each year in England if people didn't smoke.
"By making small changes we can cut our risk of serious health problems - give up smoking, watch what you drink, get more exercise and keep an eye on your weight."