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Allergies in kids: What’s changed, and what’s dirt got to do with it

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Whenever I am asked what I do for a living, the phrase “I’m an allergist” is almost immediately followed by “So, where are all of these allergies coming from?”


Maybe I’ll get sick of that question some day, but I haven’t yet. As a clinician and researcher on and public health, I first explain that when a society begins to become aware of a disease, the reported prevalence will go up. This is understandable. People who have medically unexplained symptoms wonder “Could I have this allergy that’s being talked about?” and try on the diagnosis. Sometimes an allergy really is at the root of their problems, and sometimes it’s not.


For example, at least 50% of patient-reported food allergies are only presumed. They have not been evaluated thoroughly enough to know for sure whether the patient is allergic. Research also demonstrates that, in many cases, we presume wrongly. The symptoms fit better with an intolerance than an allergy, or the events were coincidental. While 11%-12% of patients currently report a food allergy, only about 5% of adults and 8% of children likely have true food allergy. Around 8% of patients report a penicillin allergy, but fewer than five out of 100 patients who report a penicillin allergy can be shown to be allergic when tested.


Many people next ask whether are genetic, but in one’s family appear to explain only 10%-40% of a person’s increased risk for allergies. Allergic diseases are also increasing at rates that are inconsistent with genetic diseases.


More interesting is that there appear to have been different waves in which allergies appeared in historical records. Hay fever (environmental allergies) first appeared in the 1800s, followed by more recent increases in asthma and


What’s changed, and what’s dirt got to do with it?


So if genetics don’t fully explain the rise in allergy, what does? Some of the most consistent risk factors for allergic diseases include overuse of antibiotics; acute viral respiratory infections in childhood; birth by cesarean section; nutritional disorders; second-hand smoke exposure; pollution; and the environment where you grew up


To organize these risks into categories, two conceptual hypotheses currently seem to be of value – the barrier hypothesis and the hygiene hypothesis.


Imagine that your immune system is an army behind a castle wall. The castle wall is your skin, your respiratory tract and your gastrointestinal tract. The army is composed of your white blood cells in addition to other cells in the body that can activate these gung-ho Marines to defend you.


The central tenet of the barrier hypothesis is that when our skin, respiratory tract and gastrointestinal tract are chronically injured, your castle wall is broken down. The soldiers of the immune system are activated to aggressive defense, yet allergens can penetrate, and people can begin to experience allergic inflammation in those areas. This has been most clearly demonstrated with the allergic skin disease known as eczema.


Research has also shown that activities in these barrier sites can flavor the immune response and profile of a person, especially in childhood. Many risk factors for allergic disease, such as viral infections, nutritional disorders, smoke exposure and pollution, affect the health of our barriers. Studies have indicated that up to 50% of childhood eczema, a barrier disease, can be prevented simply by applying protective emollients like petroleum jelly to protect babies’ skin when we bathe them.


The role of hygiene in allergy


The central tenet of the hygiene hypothesis is that we have gone a bit too far and inadvertently killed off our good bacteria along with the bad. As our society progressed from one that was chronically burdened with infectious diseases caused by poor sanitation, the thinking goes, we reduced our exposures to the things that gave our immune system an appropriate training and tolerance. Historically, our totally rational fear of dying from a cholera epidemic led to sewage and water management, but may have kicked off the allergy epidemic.


Our overuse of antibiotics and C-sections affects the set of organisms called the microbiome that an infant is exposed to growing up. Both have been shown to increase the risk of childhood allergic diseases.


Growing up in a rural area exposed to farm animals appears to confer a decreased risk of allergies and asthma for your entire lifetime, even among genetically similar populations. Studies in mice have shown that inhaling certain molecules from soil-dwelling bacteria can set off a beneficial cascade promoting an immune system which focuses more on threats rather than nonthreats, such as allergens.

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Vaccinations appear to be a crucial exception to the rule of the hygiene hypothesis. They confer protection against diseases without any associated increase in the risk of allergic disease, likely because they, unlike antibiotics, are very specifically targeting only the worst disease-causing organisms.


Our current prescription


The data currently paints a picture that we might prevent allergies in the future by protecting our barriers and introducing the right tolerizing exposures at the right time, such as early introduction of peanuts. However, I can’t currently tell you how much dirt or what kinds of bacteria your child needs to safely experience while growing up. It’s too soon for that, but many wonderful scientists around the world are working on these questions, thanks to support from a variety of governments and foundations.


Until then, I will share with you the broad-brush advice that I currently give my friends and patients.


  • Let your kids play outside, get dirty, try new foods and be exposed to a variety of things. Advocate for them to have outside recess time in school as much as possible.

  • Use plain soap and water; you don’t need to sanitize everything.

  • Talk to your doctor about watchful waiting to respond to an illness, rather than take antibiotics.

  • Be judicious about what you put on your body’s barriers, and become an advocate for clean air, clean water and a clean environment for everyone.

  • Get all of your routine vaccinations. The healthiest children in the U.S. are the ones who are fully vaccinated.



Cosby Stone, Instructor in Allergy/Immunology, Vanderbilt University Medical Center, Vanderbilt University


This article is republished from The Conversation under a Creative Commons license. Read the original article.


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Sick hospital workers often expose patients to contagious illness

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Hospital workers often come to work with contagious respiratory illnesses, against the recommendations of public regulators, a Canadian study suggests.


Nearly all of the 2,093 care workers in the study who had such symptoms came to work at some point while sick.


For the study, published in the Journal of Infection Control & Hospital Epidemiology, nurses, doctors, and support staff at nine across Canada filled in online illness diaries during four flu seasons, recording symptoms such as a runny or stuffy nose, fever, cough or scratchy throat.


Of the 1,036 participants who had contagious respiratory illnesses during the study period, 52% reported working on every scheduled day of work and 94.6% reported working at least one day of their illness.


The most common reason given for working while sick was that the illness seemed mild and manageable. Compared to other care workers, physicians were more likely to work while sick and nurses were less likely.


But nurses who thought their managers expected them to show up unless they were too sick were more likely to feel obligated to work.


For most people, in fact, feeling obligated was a driving factor behind their decision to come to work sick, as was their perceptions of what managers expected from them. Younger workers, and workers without paid sick leave, were more likely to say they could not afford to stay home.


“It is only by knowing these reasons that managers and employers can take steps to mitigate the risk of infection to other people,” said Brenda Coleman, senior study author of the study from the Dalla Lana School of Public Health, University of Toronto, in email to Reuters Health. Eleven percent of the hospital workers said they had come to work even while feeling miserable because they had “things to do.” Physicians were under-represented in the study, and self-reporting of the illnesses may also confound the results, the authors acknowledge in their report.


The US Centers for Disease Control and Prevention advises workers to take seven days off or consider temporary reassignment if they have a fever and respiratory symptoms.


The research team suggests that changing sick leave policies and cultural norms could help reduce the risk of disease transmission from sick health care workers to patients.


Also needed, the researchers say, is an understanding of how to balance the costs and risks of absenteeism by sick workers against the costs and risks of illness transmission associated with working while ill.


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First two cases of Ebola confirmed in Congo’s South Kivu: Officials

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A woman and her child were the first two cases confirmed with in Congo’s South Kivu region this week, opening a new front in the fight against the outbreak.


Health officials said on Friday that the latest cases were more than 700 km (430 miles) south of where the outbreak was first detected.


has killed at least 1,900 people in Democratic Republic of Congo over the past year. This is the second biggest toll ever and militia violence combined with local resistance have made the outbreak harder to contain.


The 24-year-old woman had been identified as a high-risk contact of another case in Beni, more than 700 km north, last month, according to a government statement issued on Friday.


She travelled by bus, boat and road with her two children to Mwenga, in South Kivu, where she died on Tuesday night, according to a slide from a presentation by health officials.


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Research shows how nordic walking may benefit breast cancer patients

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Nordic walking, an aerobic activity performed with walking poles similar to ski poles, may benefit patients with breast cancer, according to a review of existing research.


The low-impact exercise improved swelling, physical fitness, disability and quality of life, the study authors conclude in the European Journal of Cancer Care.


“The main strategy in rehabilitation for women with is a change of habits, where physical exercise is a fundamental tool,” said study co-author Jorge Torres of the Faculty of Educational Sciences and Sports at the University of Vigo in Pontevedra, Spain.


“It’s not easy to turn a sedentary person into an amateur athlete, so sports such as Nordic walking are accepted more easily,” Torres told Reuters Health by email, particularly since the activity doesn’t require expensive equipment, can be done in a group with others, and is easy to learn.


Introduced in the 1980s as a summer training exercise that was similar to cross-country, or Nordic, skiing, Nordic walking became more widespread in the 2000s. It’s now part of some exercise-based rehabilitation programs, especially in Northern Europe where it is more common, Torres noted.


He also owns a personal training company, Vigo Entrena, that creates physical activity programs for people with specific needs, including injuries, obesity, pregnancy, postpartum and women with breast cancer, and he specializes in Nordic walking training.


To see if this form of exercise helps women treated for to reduce side effects like arm swelling, and offers other benefits of exercise, Torres and his colleagues analyzed nine studies. Four studies were randomized controlled trials comparing Nordic walking to other activities; the other studies focused on specific effects of Nordic walking.


Periods of exercise in the studies ranged from 30 to 80 minutes and were performed on one to five days a week for up to 12 weeks.


In eight of the nine studies, Nordic walking had a positive effect on a number of symptoms, including lymphedema, fitness, upper-body strength, disability and perceptions of pain and swelling.


A handful of studies also showed improvements in depression, self-efficacy for managing pain and improvements in physical activity levels. They didn’t find any adverse effects, and the study participants seemed to stick with the programs.


The biomechanical gesture of Nordic walking, compared to just walking, seemed to counteract some of the side effects that can come from cancer treatment, such as shoulder-arm mobility and postural problems, the study team writes.


“(Many) health professionals and therapists do not realize that there are contraindicated exercises during breast cancer rehabilitation and that alternatives such as Nordic walking can be very effective,” Torres said.


“Nordic walking is a structured form of physical activity which nowadays has been shown to be ‘more complete’ than basic walking,” said Marco Bergamin of the University of Padova in Italy, who wasn’t involved in the research review.


“Another important point that is less stressed by these authors: quality of life,” Bergamin said in an email. “Nordic walking gives huge benefits because breast cancer patients are survivors, and from a socio-psychological point of view, that really impacts their life.”


Future studies should also investigate the intensity, frequency, duration, and length of exercise needed to help breast cancer patients, said Lucia Cugusi of the University of Cagliari in Italy, who also wasn’t involved in the review.


“What is most evident is the growing interest of the scientific community in tracking the needs, interests and preferences of patients,” Cugusi said by email.


“Offering them novel forms of physical activity that are both effective and engaging has become one of the new and stimulating research fields in cancer therapy and management.”


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