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Friday, 22 April 2016 07:00

Peanut Allergies

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peanut allergyThe significant rise in peanut allergies in recent years has puzzled physicians and scientists. In the past decade, peanut allergies have quadrupled in the United States. The scientific community has started to suspect that doctors’ recommendations to parents, regarding when to feed their children peanuts, could be partly to blame for the rise in peanut allergy incidence.

Doctors used to tell parents to avoid feeding their children foods that are often associated with allergies, such as peanuts, eggs, and fish, until their children were about three years old. The idea behind this protocol was that young immune systems may not yet be ready to deal with these potentially problematic foods. In 2008, however, these recommendations changed when the American Academy of Pediatrics decided that delaying the introduction of these foods may in fact increase the chances that allergies develop.

Last year, a long-term study known as LEAP showing that 5 year olds were 81% less likely to be allergic to peanuts if they ate peanuts products like peanut butter before they were 11 months old was published in the New England Journal of Medicine Last month, another study, known as LEAP-On, was published in the same prestigious medical journal that further supports the idea that exposing kids to peanuts early may actually be an effective way to prevent the development of peanut allergies. In addition, the study demonstrated other positive effects that peanuts may have on health.

As in the previous study, this recent research focused on children with a high risk for developing an allergy to peanuts. They found that kids who ate peanut products from infancy until they were 5 years old could avoid peanuts for a full year without affecting their risk of developing a peanut allergy. There were 550 study participants who were asked not to ingest peanut products for one year, from the age of 5 to the age of 6. Once they were 6, these children were tested for peanut allergies, and 21.5% of those who had always refrained from ingesting peanuts were found to be allergic to them, whereas only 2.4% of those who ate peanuts in their first 5 years of life were now allergic.

Enough exposure early on in life therefore seemed sufficient enough to allow children’s immune systems to recognize peanuts as innocuous in the long-term, even if peanut exposure was not consistent afterward. This new study builds on the previous finding that early peanut exposure reduces the risk of developing peanut allergy by showing that this protection can last even through a subsequent avoidance phase.

Several other problems often seen in children, including stomach bugs, eczema, lower respiratory tract infections, and near-sightedness were also found to be lower in the children who ingested peanut products from infancy to the age of 5. Given the latest findings on the relationship between peanut exposure and the likelihood of developing peanut allergies, as well as the correlation between peanut exposure and other health benefits, the American Academy of Pediatrics are working to develop updated guidelines. For now, pediatricians are told to suggest to parents that children be introduced to peanuts between the ages of 4 and 11 months if the children are at risk for developing peanut allergies.

Another recent study, known as EAT, looked at the ability of early exposure to other foods, such as egg, fish, milk, and wheat to desensitize children to allergies to these foods. Though the study clearly showed that early exposure to egg could reduce rates of the development of egg allergy, the findings for the other foods were less clear. Researchers plan to improve their study designs so that they can clarify the specific impacts of early exposures to problematic foods and determine any differences that may exist in the pattern of allergy development for different foods.

Friday, 08 April 2016 07:00

Formula & Allergies

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formular and allergiesThere are a number of reasons why babies may not be able to receive sufficient nutrition from breast milk. To combat the obstacle and ensure that babies are offered proper nutrition easily and early in life, formula was created. Given that breast milk is lacking in certain nutrients, formula provided an opportunity to provide babies with these added nutrients. Indeed, breastfed babies are generally required to take supplements such as vitamin D and iron. In addition, formula creators can formulate the product to address any number of health issues, aiming to provide as many health benefits as possible.

A “hypoallergenic” formula was created by Nestle, which the company claimed provided protection against autoimmune diseases and problematic health issues like asthma. Nestle was granted permission in 2011 by the US Food and Drug Administration (FDA) to market its formula as a product that reduces the risk of developing eczema. However, a new study, published in the British Medical Journal is raising doubts that the formula actually provides the health benefits its creators have been claiming.

Robert Boyle and other authors of the study reviewed information from approximately 19,000 participants in 37 different trials between the years of 1946 and 2015 and concluded that there was little evidence to suggest that formula, or the process that is undertaken to create formula confers any protection against allergy-related conditions or autoimmune disease. To make hypoallergenic formula, cow’s milk is heated to break down proteins in a process called hydrolysis.

Proponents of formula’s health benefits have argued that by breaking up proteins, and thereby making them smaller (into what are known as peptides), the proteins have less power to produce allergic reactions. They claim that with less exposure to allergenic peptides could prevent the sensitization that occurs when allergies develop, thereby reducing the risk of allergies and other autoimmune reactions. As a result of their claims, formula is recommended for infants at increased risk for allergies, asthma, eczema, allergic rhinitis, and even type 1 diabetes.

Immune conditions including allergies and asthma have increased in recent years, particularly among young people, which has increased the incidence of chronic disease. There is much evidence to suggest that dietary exposures during infancy may be associated with the development of some of these conditions. Though it is well established that a proper diet is essential for healthy development and the avoidance of chronic diseases, there is still much to learn in terms of what the ideal diet is for infants and children. The specific nutrients and their optimal doses are still debated by scientists and doctors.

Given the findings of the systematic review and meta analysis conducted by Boyle and his colleagues, some scientists are now urging the FDA to reconsider its recommendations regarding the use of formula and suggest that commercial interests may have interfered with the integrity of the scientific investigation of the health benefits of formula. They also point out that claims made about formula in marketing campaigns could undermine mothers’ motivation to breastfeed, which has been established as the healthiest option for feeding infants.

Friday, 18 March 2016 07:00

New Evidence for Vibration Allergies

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vibration allergies march 2016Scientists from the National Institutes of Health (NIH) have discovered a genetic mutation that causes for a very rare type of allergy - an allergy to vibration. The team of scientists, who were specifically housed at the National Institute of Allergy and Infectious Diseases (NIAID) and the National Human Genome Research Institute (NHGRI) published their findings in the New England Journal of Medicine on February 3rd.

Allergy to vibration, known as vibratory urticaria, causes sufferers to break out in itchy hives or skin rashes on areas of the body that endure vibration. Though the allergy tends to lead to only mild symptoms, for those with this particular allergy, everyday activities, such as exercising, riding in motor vehicles, hand clapping, and using towels can pose serious inconveniences. For some, the allergy to vibration can lead to symptoms unrelated to the skin, such as headaches, blurry vision, and fatigue.

To gain some insight into why and how the immune system reacts to vibration as it does in those with vibratory urticaria, the scientists looked at how key immune cells, called mast cells, reacted to vibration. They looked at these cells in a family with multiple generations of vibration allergy sufferers, as well as in other people who did not suffer from the allergy and were not related to anyone with the allergy.

Researchers found that people with vibratory urticaria had higher levels of substances called histamine and tryptase in their blood than those without the allergy. These substances are normally found in mast cells, so the rise of these substances in the blood indicated that mast cells released their contents in response to vibration. In those without vibratory urticaria, these rises in histamine and typtase were not observed in the blood. Vibrations therefore initiated a specific immune response in those allergic to vibrations and not in those without the allergy.

The researchers realized that the symptoms in the family they were studying resembled those of a family described in 1981 by scientists at Yale. To test for a genetic contributor to vibratory urticaria, researchers took DNA samples from both families and identified a mutation in a single gene, the ADGRE2 gene. The mutated form of the gene was present in all family members who were allergic to vibration and in none of those who were not. The mutation was also not found in a database of DNA of 1000 other individuals who did not have vibratory urticaria.

Researchers were therefore convinced that the genetic mutation of ADGRE2 contributes to allergic reactions to vibrations. Further studies have shown how the gene leads to allergy symptoms in response to vibrations. The ADGRE2 gene produces an ADGRE2 protein that is present on immune cells. The protein has two portions that are normally close together and relatively stable. In those with vibratory urticaria, the two subunits of the ADGRE2 protein are less stable and separate more easily in response to vibration. When these cells separate, it signals to the immune system that an immune response is needed. At that point, mast cells are activated, and they release their contents.

These findings by NIH researchers clarify details of immune system responses generally and allergic reactions specifically. Researchers hope to find out how the subunits of the ADGRE2 protein act once vibrations are over because that information could help them better understand the allergy to vibration and potentially treat it. They also plan to study more families with vibratory urticaria to develop a more comprehensive view of this intriguing allergy.

vitamin d allergiesVitamin D, also known as the sunshine vitamin, has long been linked to allergies. Studies have shown that children who live farther from the equator are more likely to develop allergies and suffer higher rates of hospital admissions due to allergic reactions.  From November through February, it is thought that people in the north (at a latitude above 35°) cannot synthesize vitamin D because they are not sufficiently exposed to sun.

Children and adolescents with lower levels of vitamin D in their blood are more sensitive to allergens than those with higher vitamin D levels. In 2012, a study published in the Journal of Pediatrics demonstrated that infants with vitamin D deficiency are at higher risk for allergies and eczema than those with sufficient levels of the vitamin. Further, the severity of allergy in infants was shown to be linked to the severity of vitamin D deficiency.

Now, researchers at the Mount Sinai School of Medicine have discovered that one’s exposure to vitamin D may impact their likelihood of developing allergies even before they are born. The recent study, published in The Journal of Allergy and Clinical Immunology on February 11th, showed that women who eat foods that are rich in vitamin D during pregnancy are less likely to have children who will develop allergies. This finding is consistent with previous reports that maternal vitamin D levels are related to the likelihood that children will wheeze at the age of 3.

This new study examined 1,248 American women and their children from the first trimester until children were approximately 7 years old. Children with a reduced risk for developing allergies had mothers who had consumed higher amounts of vitamin D. Vitamin D can be found in dairy products including milk and eggs, as well as in other foods such as fish, mushrooms, and cereal. Women who consumed at least the amount of vitamin D that would be found in 8 ounces of milk per day were shown to confer the allergy benefits to their children. These children had a 20% reduced risk of hay fever in their school years.

Vitamin D likely reduces the chance of developing allergies because of its effect on the immune system, which has been demonstrated in a number of ways. Vitamin D has been shown to quickly rid the body of hives and other allergy symptoms. This vitamin is critical to the proper functioning of T-cells, which are a major part of the immune system.

The finding that vitamin D can protect a fetus from eventually developing allergies is a promising discovery in the allergy field. However, it should be noted that vitamin D supplements did not have the same effect as vitamin D found in foods. In other words, pregnant women had to eat foods containing vitamin D to confer the allergy benefit to their children. However, the research linking vitamin D supplements to allergies and asthma has produced a large mix of results.

Whereas some scientists have supported the idea that vitamin D supplements taken by pregnant women can reduce the risk that their children will develop allergies and asthma, others have shown that adults who took vitamin D supplements as infants were in fact more likely to develop allergies than those who did not take the supplements. One study showed that vitamin D supplements were effective in both preventing and treating seasonal allergies, but other studies found that vitamin D supplements had no effect on the likelihood of developing allergies. Scientists therefore believe that further research is needed before we can truly understand the impact of vitamin D supplements on allergies. It may be the case that higher doses of the supplements are needed to achieve the same effect as consumed vitamin D.

For now, it is likely that clinicians will recommend that pregnant women consume vitamin-D rich foods during pregnancy. Not only are the recent data on the protective effect of vitamin D against allergies promising, but vitamin D has a number of other health benefits and is therefore a critical component of our diets.

Friday, 19 February 2016 07:00

Allergies & Anxiety

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allergies and anxietyScientific research has shown that having allergies makes it more likely that people will suffer certain anxiety disorders, such as generalized anxiety disorder (GAD) and panic attacks. According to a new study published in Pediatrics, children who suffer from allergies starting at a young age are at an increased risk for anxiety and depression. Specifically, seasonal allergies seem to be the culprit for this group of people with a higher likelihood for anxiety and depression, and the more allergies these people have, the higher their risk. For those allergic children who suffered anxiety or depression, the degree of anxiety or depression varied from very mild to disorders that required treatment. However, allergic rhinitis, which involves allergy symptoms that specifically affect the nose, was specifically linked to the highest scores of anxiety and depression.

This recent study, which followed almost 600 children between the ages of one and seven, examined allergy symptoms in children who had gotten skin tests at ages one, two, three, four, and seven and had the parents of these children complete behavioral assessments. The behavioral assessments included 160 questions aimed at identifying anxiety and depression in children. These questions related to children’s emotions and behaviors that may have demonstrated fear, nervousness, worry, or sadness. Based on the data, researchers concluded that that four year olds suffering from classic allergy symptoms, such as itchy eyes, sneezing, wheezing, and skin inflammation, are more likely to be depressed or anxious than seven year olds with the same symptoms.

Though the results of the study appear robust, controlling for several patient factors, including gender and race, they do not provide clarification on why the association between allergies and anxiety and depression exists. The researchers speculate that allergies could cause chemical changes in the brain in areas involved in mood, thereby leading to anxiety and depression. However, they also acknowledge that anxiety and depression in this group may simply be due to the impact allergies have on their lives. For instance, often feeling sick and having to get shots or take medications may be the culprit for increased anxiety and depression in these children.

Regardless of the specific reasons that young children with allergies are more likely to develop anxiety and depression than those without such allergies, researchers believe that when anxiety and depression do occur, it is linked to the children’s tendency to ‘internalize.’ Internalizing behavior involves directing feelings inward. People who internalize tend to inflict harm on themselves when they are frustrated or upset rather than externalizing, and taking their emotions out on others. Specific internalizing behaviors include substance abuse, overeating, and anorexia. Certain groups of youths are more likely to display internalizing behaviors. For instance, both bullies and those being bullied are more likely to internalize. Youths who are obese are also at a higher risk for internalizing behavior. Because internalizing tends to be more socially acceptable than externalizing, it can go unnoticed as a problem for long periods of time.

Given the important role of internalizing in anxiety and depression among those with allergies, some physicians now advise that children who suffer from allergies should be monitored for behavioral issues, as well as signs of anxiety and depression. More research on the reason that those with allergies suffer from anxiety and depression at a more frequent rate than those without allergies will help clarify what specific risk factors predispose children to these disorders. New information should also help parents ensure that their children get proper treatment for their allergies while minimizing the likelihood that they develop anxiety or depression.

Friday, 05 February 2016 07:00

Is There A Link Between Asthma and Autism?

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asthma allergiesAutism and autism spectrum disorder involve impairments in communication and social interaction and are thought to result from abnormal brain development. This type of abnormal brain development is most likely due to a combination of genetic and environmental factors. The rate of autism diagnosis has increased significantly since 1980, as has the diagnosis of asthma. Nonetheless, because autism is primarily thought to be a manifestation of abnormalities in the brain, its potential link to asthma is not intuitive.

However, research has shown that women who are diagnosed with asthma or allergies while in her second trimester of pregnancy is at an increased risk for having a child with autism. Further, a new study, published in the medical journal Pediatrics in January, found that mothers who take certain types of asthma medications while they are pregnant are slightly more likely to have children with autism than those not exposed to such medications. This effect was seen regardless of whether a woman was using drugs for asthma during her first, second, or third trimesters, or even during preconception.

The United Sates Centers for Disease Control and Prevention (CDC) estimates that autism currently affects approximately one out of every 68 children in this country. Not all asthma medications were found to be associated with autism in offspring. Even more important is that failing to manage asthma during pregnancy can be much more dangerous than the drugs used to manage the disease.

The drugs studied in this study were drugs called beta-agonists. Such drugs tend to influence the muscles around the airways, relaxing them so that breathing becomes easier. The beta-agonist asthma medications that are often used are: salmeterol, also known as Serevent, formoterol, also known as Foradil, and albuterol, which is often used as a rescue inhaler during an asthma attack. The former two drugs are more often used to prevent asthma attacks. Because the drugs are able to cross the placenta, they can biologically impact the growing fetus during its development.

Laboratory studies on these drugs show that they can affect the development of brain cells, or neurons. Nonetheless, scientists who have looked at national databases in Denmark found that only 4% of children diagnosed with autism had been exposed to beta-agonist drugs. This finding demonstrates that the vast majority of autism cases are caused by something other than beta-agonist drugs. Further, the study published in Pediatrics only shows that babies exposed to beta agonists have a slightly increased risk for autism but does not demonstrate a causal link between these drugs and the disorder.

There are a number of other drugs for asthma that are not beta-agonists, and doctors may recommend some of these medications to pregnant women as alternatives to beta-agonists. For quick relief of asthma symptoms, corticosteroids, which are anti-inflammatory drugs, and anticholinergics, which are bronchodilators, may be used. These drugs tend to get rid of coughing, wheezing, and chest tightness in the short-term. For long-term control of asthma, leukotriene modifiers can block chemicals that cause inflammation, whereas mast cell stabilizers can minimize the release of chemicals that lead to inflammation. Theophylline is a bronchodilator that specifically reduces nighttime symptoms of asthma. Finally, for those who do not respond to inhaled drugs, immunomodulator injections may be recommended. These injections tend to be used for patients whose asthma is related to allergies.

When asthma is not well controlled in pregnant women, outcomes for babies have been shown to be poor. Babies born to mothers with uncontrolled asthma are more likely to be born before they are full term and to be born at a low birth weight. These babies are also more likely to end up being admitted to the neonatal intensive care unit. The drugs that are used to control asthma help ensure that the mother and baby are getting sufficient oxygen, which is critical for their health. It therefore important that pregnant women who are taking asthma medications do not just stop taking their medications without speaking with their physicians.

Friday, 22 January 2016 07:00

Can You Be Allergic to Wi-Fi?

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can you be allergic to wifiThough the medical community has not acknowledged it as a legitimate allergy, people have begun to claim that they suffer from allergies to Wi-Fi. Over the years, a number of health risks associated with our smart devices have been revealed – including insomnia, neck pain, and brain changes. According to the World Health Organization (WHO), Electromagnetic Hypersensitivity Syndrome (EHS) is a disorder that involves a number of non-specific symptoms that affect those who are exposed to electromagnetic fields. The apparent existence of EHS may be confused with an allergy for Wi-Fi, and EHS has itself come under scrutiny as a legitimate disorder.

Because the symptoms said to be involved in EHS, including headaches, fatigue, dizziness, rashes, and heart palpitations, are so common and caused by a number of different factors, it is difficult to determine if EHS is a true condition. People claim to suffer the symptoms when exposed to a number of devices, including mobile phones, televisions, and Wi-Fi routers. WHO has attempted to determine what specific environmental triggers could lead to EHS and have considered things such as excessive noise, air pollution, and fluorescent lights emanating from screens. However, no causal association has been persuasively identified.

Recently, a woman in the UK blamed an allergy to Wi-Fi for her daughter’s suicide. She claimed that both she and her daughter had become ill because of the Wi-Fi in their house, suffering from bladder pain, headaches, and fatigue and had thus discontinued Wi-Fi at home. However, according to the woman, her daughter continued to suffer because of the use of Wi-Fi at her school. She claimed her daughter did not intend to commit suicide and blamed the school, and especially the principal, who refused to accommodate the “Wi-Fi allergy” by allowing the girl to participate in activities only in areas free of Wi-Fi, for her daughter’s untimely death. Nonetheless, the medical examiner investigating the girl’s case did not find any evidence to suggest that the suicide was a result of either a Wi-Fi allergy or EHS.

In a separate case in France, a woman was able to collect $900/month in disability benefits as a result of her apparent EHS, the first time the legal community appeared to legitimize the syndrome. The court case sparked controversy and concern among the medical community, who generally do not believe that EHS is appropriately viewed. Specifically, research has shown that the syndrome that is termed EHS does not seem to have any true connection to exposure to electromagnetic or radiofrequency signals. WHO has therefore suggested that EHS be renamed “idiopathic environmental intolerance with attribution to EMF.”

A psychiatrist at George Washington University in Washington D.C. says that EHS it not recognized as a real medical disorder and that those who apparently suffer from EHS are more likely to be suffering from a psychiatric condition. In this case, the patient would be said to be suffering from a somatization disorder. Of particular concern is that the likelihood of people believing they suffer a disease or disorder is much more likely when people first know of, or believe in the existence of that disorder. A study demonstrating this phenomenon exposed subjects to a fake Wi-Fi signal after showing half the subjects a BBC series that claimed that Wi-Fi signals were dangerous. Those who saw the series were significantly more likely to develop symptoms associated with EHS. The tendency for people to believe they are sick after being exposed to something they believe should sicken them has serious implications with respect to the growing concern about EHS and Wi-Fi allergies.

As a result, the medical community has appeared to become more vocal about their belief that people cannot really be allergic to Wi-Fi. As evidence for their position, they point out that the radiofrequency signals to which we are constantly exposed are quite weak and that there is no good evidence to show that they do true damage. Given the growing concern of health risks associated with the Internet and smart devices, as well as the known health risks posed by some devices and technologies associated with radiation, it is likely that research into any potential health threat that the Internet or relevant devices could pose will continue. Though allergies to Wi-Fi appear a far-fetched idea, it is not out of the question that the growing use of the Internet may pose new health risks in indirect ways.

sesame allergiesThough sesame allergies affect less than 1% of the United States’ population, somewhere between 300,000 and 500,000 people in the U.S. are allergic to sesame. According to allergists, many more people are afflicted in the U.S. today than a decade or two ago. The most common symptom associated with sesame allergy is hives, with hives, stomach problems, and respiratory problems also occurring quite frequently.

The allergy appears to now be as serious and as frequent to other common allergies, like those to tree nuts. Tree nuts include walnuts, cashews, hazelnuts, almonds, pistachios, and Brazil nuts. Further, recent research has shown that those allergic to tree nuts are at a higher risk for also suffering from a sesame allergy than those who are not allergic to tree nuts. One study found that 70% of those who were allergic to sesame were allergic to tree nuts, and 65% were allergic to peanuts. A study on children conducted in Boston determined that kids with tree nuts allergies were three times more likely to be allergic to sesame seeds as well.

The growing prevalence of sesame allergies could be due to greater awareness of the allergen or due to more people actually experiencing it. With respect to the latter reason, one explanation that has been posed for the rise in the number of allergic reactions to sesame is the enhanced popularity of Middle Eastern foods. Whereas sesame seeds were once most commonly associated with bagels in the U.S., they are now found in a number of foods that can be purchased in grocery stores and that are served in restaurants. Hummus, falafel, and halvah for instance, are now popular foods in the U.S. and contains sesame.

A major concern with regard to the growing number of allergy cases related to sesame is that sesame is often not found on the label of foods that contain sesame. A number of cases have been reported where identifying the problematic food was quite difficult due to a lack of knowledge about the presence of sesame. Tahini, for instance, contains sesame that has been transformed into either a paste or a powder, and it is often not explicitly said to contain sesame. Similarly, many foods with sesame often account for that ingredient by including the term “spice” or “natural flavoring” on the label. Some foods more common to the U.S. historically that often serve as sources for sesame include: breads (especially hamburger buns and pizza crust), noodles, cookies, pretzels, crackers, oils, margarine, soups, ice cream, salad dressing, energy bars, and pastries.

Other countries, such as Canada, Australia, New Zealand, and several European nations are required to list sesame on their food labels. However, because the Food Allergen Labeling and Consumer Protection Act, passed by Congress in 2004 did not include sesame because it was not known to be a major contributor to allergic reactions. The foods included were instead: milk, eggs, peanuts, tree nuts, fish, shellfish, wheat, and soy. Because the idea of the Act was to cover 90% of all food allergies, many argue that our new knowledge regarding sesame allergies constitutes a need to add it to the list.

Though there have not been many deaths related to sesame allergy, there have been allergic reactions severe enough that they could have led to death if not treated properly and promptly. As a result, last year, the Center for Science in the Public Interest proposed that the Food and Drug Administration (FDA) require that foods containing sesame or have cross contact with sesame during the manufacturing process have “sesame” on the food’s label.

Another concern related to sesame allergy is that exposure to sesame is not limited to foods. Certain beauty products, such as moisturizing creams and lipsticks also contain sesame and so can lead to allergic reactions, especially in those who would understandably not suspect the presence of sesame in their cosmetics. It is therefore important to educate those at risk for sesame allergy on the various ways they may be exposed to sesame and ensure that those people are protected from severe allergic reactions with medications. For those at risk for anaphylaxis, carrying an EpiPen is generally advised.

Friday, 18 December 2015 07:30

Allergic Reactions to Insect Stings

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allergic reactions to insect stingsMany people are allergic to insect stings, which can be associated with a number of insects including honeybees, sweatbees, bumblebees, paper wasps, white-faced hornets, yellow hornets, yellow jackets, harvester ants, fire ants, and jack jumper ants. Less often, allergies can also occur to proteins found in the saliva of other insects, including mosquitos, horseflies, and kissing bugs.

Stinging insect allergy can occur in response to insect venom and has the potential to be fatal if it causes anaphylaxis and disrupts the breathing process. This type of reaction occurs in approximately 0.4-0.8% of children and 3% of adults, leading to about 40 annual deaths in the United States. However, when it does not cause anaphylaxis, stinging insect allergy is not and manifests in non-respiratory ways.

There are three main ways that the relevant insect venom tends to affect those with stinging insect allergy. For systemic reactions that include anaphylaxis, other systems may also be impacted. These systems include the gastrointestinal tract, the respiratory system, the heart, and the brain. A second potential outcome is a systemic reaction that is isolated to the skin, impacting skin all over the body. Finally, the venom could cause a local reaction, leading to swelling that is focused around the area where stings occurred.

When systemic reactions occur, they usually happen fairly quickly after the sting and often involve highly noticeable symptoms such as anaphylaxis. On the other hand, local reactions may occur over a day or two, and it may take up to about 10 days for the associated swelling to go away.

There main ways to prevent allergic reactions to insect venom are to avoid insect stings and to undergo venom immunotherapy (VIT). The latter is an effective way to prevent anaphylactic reactions in certain patient populations that have demonstrated allergic reactions to insect venom. In this case, patients are usually screened with tests such as skin tests to assess their suitability for VIT, though screening tests are not generally a recommended preventative measure for insect venom allergies.

When VIT is employed, 95-98% of systemic reactions are successfully prevented, and the therapy may also minimize local reactions. Rarely, VIT itself causes allergic reactions and can cause anaphylaxis, so patients undergoing this preventative measure must be monitored for about half an hour following each session of therapy. This form of therapy is usually started at a low dose (0.1-1 mg weekly) and is increased incrementally (to about 100 mg). The highest VIT dose is thought to be equivalent to about 2 insect stings and would thus ideally protect against at least the relevant amount of venom. Therapy is usually used for 3 to 5 years but is generally extended in high risk patients who continue to have severe reactions or are frequently exposed to insects.

Because the best way to ensure that allergic reactions to insect venom do not occur is to avoid stings, there are a number of recommendations for how to do so. Removing nests from places where patients spend a lot of time, such as the home, is an important first step. Wearing closed shoes and clothing that covers the skin while outdoors can also be effective. Wearing muted colors and scents is a less intuitive means for preventing insect stings but can work because insects are attracted to bright colors and can track strong scents. Areas like bushes and attics should be approached with caution when attempting to avoid insect stings.

When stings do occur and are followed by an allergic reaction, the type of reaction dictates what type of treatment should be undergone. Local reactions can be treated with cold compresses and analgesics to help manage any pain occurring as a result of the sting, as well a antihistamines for itchiness. However, if anaphylaxis occurs, an epinephrine needs to be administered to reverse the dangerous respiratory symptoms.

Different treatment plans may be indicated for distinct patient populations suffering from insect sting allergy. Though it is often suggested that pregnant women adhere refrain from taking medications they took before pregnancy, both VIT and anaphylaxis interventions can continue in pregnant women. However, patients who take beta-blockers or angiotensin converting enzyme inhibitors may be more susceptible to anaphylaxis from VIT so are generally encouraged to undergo an alternative treatment plan. Children with skin reactions to insect venom are less likely than adults to eventually suffer severe reactions. The assessment of children and adults for suitability for VIT therefore differs.

Friday, 04 December 2015 07:30

The Role of Platelets in Allergic Reactions

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the role of platelets in allergic reactionsThere are a number of cells of the immune system that are involved in allergic reactions. Relatively recently, platelets were added to the list of known immune cells that contribute to the body’s response to allergens and to underlie aspects of asthma. Platelets are the smallest cells that travel within the blood and are shaped like plates when they are inactive. One microliter of blood usually contains somewhere between 150,000 and 450,000 platelets.

Platelets are traditionally viewed as functioning to stop blood flow, which they do by clumping together to form blood clots. Given this function, it is important that we have enough platelets so that we are not at risk for losing too much blood should we cut ourselves. However, too many platelets can cause cardiovascular issues. Given their role in thrombosis, or blood clotting, platelets are also often referred to as thrombocytes.

In the 1980s, seminal scientific research demonstrated that the role of platelets is not limited to blood clotting. The work showed how platelets can also kill some parasites. This other function of platelets was realized when scientists observed the presence of certain receptors, called IgE receptors, on the surface of platelets. IgE receptors are antibodies whose main function is to fight parasitic infections.

Also in the 1980s, other scientists observed that platelets appeared depleted in rabbits suffering airway constriction due to allergies. These observations were the initial findings that helped confirm that platelets have a broader role than their role in blood flow and clotting.. It is now clear that platelets play a direct role in allergic reactions. Specifically, they impact other cells of the immune system during inflammatory reactions to help recruit leukocytes into tissues. Not only do their coordinate inflammation responses, but they are also activated by other inflammatory mediators. When platelets are depleted, leukocytes are not as populous within tissues as when platelets are present in normal amounts.

Because of their specific role in inflammation, platelets are critical in inflammatory diseases other than allergies, such as asthma. Research in both animals and humans has demonstrated that platelets are also associated with the pathogenesis of aspirin-exacerbated respiratory disease (AERD), which is an inflammatory disease that involves not only asthma but also nasal polyposis and pathognomonic respiratory reactions when aspirin is ingested.

When asthma occurs, changes in platelet activity are often observed, including changes in the amount of platelet secretion, as well as the molecules that are expressed on the surface of platelets. Asthma and allergies are also associated with abnormalities of both the aggregation and adhesion of platelets to one another.

In this scenario, platelets have been referred to as “exhausted platelets” that may have been activated too often during allergic responses and are thus unable to respond appropriately when needed for clotting functions. Accordingly, people with allergic disease often have what is referred to as a mild hemostatic defect, where it takes them longer to stop bleeding when they are cut than those without allergies. On the flip side, this group of people may also experience cardiovascular benefits as a result of their reduced clotting. Some research has suggested that these people have less calcified arteries.

The specific activities of platelets within the immune system lead to the pathogenesis of asthma in a few different ways. First, platelets cause bronchoconstriction. They do this by releasing what is known as spasmogens, which included chemicals like serotonin. Second, they lead to the remodeling of the walls of the airway by signaling to a number of relevant cells to modify their activities. Third, they cause inflammation of the airway, which is often accompanied by the release of free radicals. Free radicals are physiologically destructive and often associated with poor health.

The blood-related effects that are seen in patients with allergy and asthma are likely a result of reduced platelet survival time, which can be reversed with glucocorticosteroid medications. However, given that platelet activity can both help and harm people, depending on the context in which the platelets are activated, as well as on the specific needs of the person, it is important not to aim to minimize or maximize platelet activity but instead to find a balance that optimizes outcomes. As more research helps clarify the specific role of platelets in allergies and asthma, new treatments options that involve platelet activity will likely be developed.

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