eosinophilic gastrointestinal disorders ( egids ) such as eosinophilic esophagitis ( eoe ) and eosinophilic gastroenteritis ( ege ) have recently shown an increasing trend in japan . egids are characterized by chronic mucosal inflammation with dense infiltration of eosinophils in esophageal squamous epithelium and gastrointestinal mucosal epithelium , and considered to be caused by local allergic reactions , possibly to foods or airborne antigens . helicobacter pylori ( h. pylori ) infection is accepted as an important pathogenic factor in chronic gastritis , peptic ulcer diseases , gastric cancers , and mucosa - associated lymphoid tissue ( malt ) lymphoma in humans . in japan , the rate of h. pylori infection has steadily decreased , partly due to improved sanitation . egids are frequently accompanied by various types of allergic diseases such as bronchial asthma , and considered to be related to over - activation or dysregulation of th2-mediated immune reactions . on the other hand , for protection against bacterial infection , th1-type immune response is believed to be important and activated by a bacterial infection . however , because of recent improvements in environmental cleanness , the chance of bacterial infections has remarkably decreased in japanese children . in cases of h. pylori infection , the reduced chance of bacterial infection may result in failure to activate th1 immune response , thus causing an imbalance between that and th2 immune response . when considering this background , the decreasing rate of h. pylori infection may have some link to the increasing prevalence of egids in japan . there are few reports on the relationship between egids ( especially ege ) and h. pylori infection , thus we performed a case - control study to clarify that infection rates in japanese patients with egids . eighteen patients with eoe and 22 with ege diagnosed based on consensus diagnostic guidelines in japan were enrolled . for each , 3 normal age- and gender - matched control subjects ( n  =  120 ) were randomly selected from individuals who received an annual medical check - up between april 2010 and december 2011 at the shimane institute of health science . pylori antibody were measured in serum samples obtained from all patients and controls using eia , according to the supplier s instructions ( e - plate eiken h. pylori antibody , eiken chemical co. , ltd . , this study was approved by the ethical committee of shimane university faculty of medicine and carried out in accordance with the declaration of helsinki . the mean ages of the eoe and ege patients were 50.9    17 and 49.2    20 years , respectively , similar to previously reported studies in japan . the percentages of male patients were higher , especially in the eoe group ( table  1 ) . none of the patients enrolled in this study had been treated by administration of systemic glucocorticoids . among the eoe cases , 22.3% were diagnosed as h. pylori - positive , while 55.5% of the matched controls were positive . thus , the rate of h. pylori infection was significantly lower in patients with eoe as compared to the normal controls , while the odds ratio ( or ) for those patients to be infected was 0.22 ( p<0.05 ) . as for ege cases , 22.7% were diagnosed as h. pylori - positive , while 48.5% of the matched controls were positive , again showing a significantly lower rate of infection in patients with ege as compared to the normal controls ( fig .  1 ) . the or for ege patients to have an h. pylori infection was 0.31 ( p<0.05 ) . eoe and ege are allergic digestive diseases characterized by chronic inflammation along with dense mucosal infiltration of eosinophiles . increasing numbers of patients with eoe have been reported in western countries , while many cases of ege have been reported in japan . it is considered that th2-mediated allergic response and th2-type cytokines , including il-5 , 13 , 15 , and eotaxines , are involved in development of these diseases . during an immune response , different groups of t helper ( th ) cells , termed th1 and th2 , release different patterns of cytokines . th1 cells mediate cell - mediated immunity , as well as production of opsonizing and complement - fixing antibodies by b cells , while th2 cells induce production of high levels of antibodies , including ige , as well as eosinophilia . it has been speculated that particular allergic conditions such as bronchial asthma and allergic rhinitis are increasing because of an imbalance between th1 and th2 type immune responses due to a modern clean lifestyle , which is termed the hygiene hypothesis . th2 cytokines suppress th1 responses , while th1 cytokines inhibit th2 responses and vice versa . the immune system of neonatal humans is thought to have a th2 bias that gradually diminishes during the first 2 years of life in non - allergic individuals . for development of a normal well - balanced immune system , th1 stimulus from the environment is necessary . without a balanced immune system , allergic diseases are prone to occur because of the continuing th2 bias . however , because of improved sanitation and the reduced chance to have a bacterial infection during childhood , individuals have a higher chance to continue to with a skewed th2 immune response . h. pylori infection is considered to be an important pathogenic factor in chronic gastritis , peptic ulcer disease , gastric cancer , and malt lymphoma . due to improved sanitation and the reduced chance of infection during childhood , h. pylori infection is rapidly decreasing in japan , along with peptic ulcer diseases and gastric cancers . however , this decreased rate of h. pylori infection has led to increases in cases of gastric acid secretion and gastroesophageal reflux diseases . moreover , recent studies have suggested that a decrease in h. pylori infections may predispose individuals to various allergic diseases . th1-mediated response is activated in cases of infection , thus th2 type immune response is expected to be continuously skewed in infected individuals , who are likely to become prone to th2 type allergic responses . common pathological conditions including exaggerated th2 response to environmental and food allergens are considered to play important roles in the pathogenesis of egids , and dellon et  al . recently reported that h. pylori infection was inversely associated with esophageal eosinophilic infiltration . in summary , we confirmed the decreased rate of h. pylori infection in japanese patients with eoe as compared to the control subjects . in addition , our findings are the first to show that the h. pylori infection rate is lower in ege as well as in eoe patients . our results are limited by the relatively small sample size , and the fact that other bacterial and viral infections were not investigated . the specific role of the decreased rate of h. pylori infection should be confirmed in a larger scale prospective study .
recent studies have suggested that decrease in helicobacter pylori infection may predispose to allergic diseases . however , there are few reports of the relationships of eosinophilic gastrointestinal disorders ( egids ) , especially eosinophilic gastroenteritis ( ege ) , with h. pylori infection . 
 we investigated the possible influence of h. pylori infection on egids in japanese patients . 
 we performed a case - control study to investigate the prevalence of h. pylori infection in patients with egids . 
 eighteen with eosinophilic esophagitis ( eoe ) and 22 with ege were enrolled . for each patient , 3 age- and gender - matched normal controls ( n  =  120 ) were randomly selected from a population who received a medical check - up between april 2010 and december 2011 at the shimane institute of health science . 
 the mean ages of the eoe and ege patients were 50.9    17 and 49.2    20 years , respectively . 
 males were more frequently seen in the eoe group , while there was no significant gender difference in regard to ege . of the patients with eoe , 
 22.3% were infected with h. pylori , as compared to 55.5% of their age- and sex - matched normal controls . 
 the odds ratio for eoe patients to have an h. pylori infection was 0.22 ( p<0.05 ) . 
 in addition , 22.7% of the patients with ege and 48.5% of their matched controls were infected with h. pylori , with odds ratio for ege patients to have an h. pylori infection shown to be 0.31 ( p<0.05 ) . in conclusion , 
 the prevalence of h. pylori infection was significantly lower in ege and eoe patients in japan as compared to normal control subjects .