Seroprevalence and risk factors for Helicobacter pylori infection in Greenlanders

Seroprevalence and Determinants of Helicobacter pylori Infection in the Hispanic Community Health Study/Study of Latinos

BACKGROUND & AIMS

Helicobacter pylori infection is the primary known risk factor for gastric cancer. Despite the global decline in H. pylori prevalence, this infection remains a major public health concern in developing areas, including Latin America. Our study aimed to determine H. pylori seroprevalence and identified its determinants among Hispanics/Latinos living in the United States (U.S.).

METHODS

The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) is a population-based sample of self-identified Hispanics/Latinos (n = 16,144) in four U.S. communities, aged 18 to 74 years, recruited from randomly selected households using a stratified two-stage area probability sample design based on sampling households within sampled census block groups weighted for differential response rates. Anti-H. pylori immunoglobulin G antibodies were measured by an enzyme-linked immunosorbent assay using plasma samples. We calculated adjusted seroprevalence (i.e., predicted margins) from multivariable logistic regression models.

RESULTS

The overall weighted H. pylori seroprevalence was 57% among HCHS/SOL participants, with 38% and 62% seropositivity among U.S.-born and non-U.S.-born individuals, respectively. Age-adjusted prevalence varied by self-reported Hispanic/Latino background, ranging from 47% in Puerto Rican to 72% in Central American backgrounds. Adjusted H. pylori seroprevalence was higher in the following groups: older age, male sex, lower education, non-U.S. born status, smoking, greater number of missing teeth, fewer doctor visits, lower ferritin level, and hepatitis A seropositivity.

CONCLUSIONS

H. pylori seroprevalence in Hispanics/Latinos remains high and differed significantly by Hispanic/Latino background. H. pylori seropositivity is strongly associated with poor socioeconomic conditions. These findings highlight the ongoing importance of this bacterial infection in the U.S.

Stomach Cancer Incidence and Mortality Trends among Circumpolar Nations

BACKGROUND

Stomach cancer incidence and mortality rates are declining across circumpolar nations, but the burden may not be distributed equally across subpopulations, including Indigenous peoples. Our objective was to examine stomach cancer incidence and mortality trends across circumpolar populations.

METHODS

Cancer incidence and mortality data from 1999-2016 were obtained from the Canadian Cancer Registry, Canadian Vital Statistics, CDC WONDER, NORDCAN, Northwestern Russian cancer registries, and National Cancer Reports. The direct method was used to calculate 10-year rolling age-standardized incidence and mortality rates to the world (WHO 2000-2025) and 2011 Canadian standard populations. Standardized incidence rate ratios (SRR) were calculated. Data were stratified by sex, year, and region. U.S. data were broken down by race [White; American Indian/Alaska Native (AIAN)]. Race data were not available from non-U.S. cancer registries.

RESULTS

Most populations showed declining incidence and mortality rates over time. Incidence rates among Greenland males and females, Alaska AIAN males and females, and Northern Canadian both sexes were elevated compared with regional counterparts and remained stable. The largest male SRR was observed among Alaska AIAN versus Alaska Whites [SRR = 3.82; 95% confidence interval (95% CI), 2.71-5.37]. The largest female SRR was observed among Alaska AIAN versus Alaska Whites (SRR = 4.10; 95% CI, 2.62-6.43).

CONCLUSIONS

Despite stomach cancer incidence and mortality rates declining overall, some northern and Indigenous populations experience elevated and stable incidence and mortality rates.

IMPACT

There is a need to address disparities observed among circumpolar subpopulations. Given similarities in incidence, mortality, and risk factor prevalence across circumpolar regions, addressing disparities could benefit from coordinated international action.

Helicobacter pylori Recurrence after Eradication Therapy in Jiangjin District, Chongqing, China

Purpose

To investigate the recurrence rate of Helicobacter pylori infection after eradication in Jiangjin District, Chongqing, China, and to analyze the related causes.

Methods

Outpatients who were eradicated of H. pylori infection with standard therapy between August 2014 and August 2017 were included in this study. The recurrence rate was investigated 1 year later. Data regarding gender, smoking, alcohol intake, frequency of eating out, and treatment strategy were recorded, and their relationships with the recurrence rate were analyzed. Multivariate logistic regression analysis was performed to determine the independent risk factors for H. pylori infection recurrence.

Results

In total, 400 patients (225 males and 175 females) were included in this study. Of them, the recurrence rate of H. pylori infection was 4.75% (19/400), with 5.33% (12/225) in males and 4.57% (7/175) in females, showing no gender difference. The recurrence rate was 7.03% (9/128) in smokers and 3.68% (10/272) in nonsmokers, while it was 6.45% (12/186) in those who drink alcohol and 3.27% (7/214) in those who do not drink alcohol, showing no significant differences. The higher the frequency of eating out, the higher the recurrence rate of H. pylori infection (P = 0.001). There was a statistically significant difference in the recurrence rate between patients receiving treatment alone and patients whose family members also received treatment (6.08% vs. 0.96%, P = 0.035). Drinking and dining out were independent risk factors for H. pylori infection recurrence (P = 0.014 for drinkers and P = 0.015 and P = 0.003 for those who sometimes and often dine out, respectively).

Conclusions

The overall recurrence rate after H. pylori eradication by standard therapy in Jiangjin District is 4.75%. Reducing the frequency of eating out and family members receiving treatment may reduce the recurrence of H. pylori infection.

The epidemiology of Helicobacter pylori infection in Europe and the impact of lifestyle on its natural evolution toward stomach cancer after infection: A systematic review

BACKGROUND

Helicobacter pylori is a recognized cause of stomach cancer, but only a fraction of infected subjects develop cancer. This systematic review 1, summarizes the prevalence of infection with this bacterium in Europe; and 2, reviews the possible impact of particular lifestyles in progression from infection to stomach cancer.

MATERIALS AND METHODS

A systematic literature search was conducted in two databases by two independent investigators. Studies describing prevalence of infection among European healthy adult populations and worldwide studies analyzing the impact of lifestyle factors in association with H. pylori on stomach cancer risk were included.

RESULTS

Variable H. pylori infection prevalence was observed depending on region and study period. The lowest infection prevalences were found in Northern Europe, while the highest were in Eastern and Southern Europe, up to 84% in Portugal and Poland. Studies on smoking, salt, and meat consumption demonstrated increased risks of developing stomach cancer among H. pylori-infected individuals, while studies relating the intake of fruit, vegetables, and vitamins demonstrated decreased risks, but the levels of significance differed importantly between studies. No significant interaction could be found for alcohol consumption or physical activity.

CONCLUSIONS

Recent data showed remaining high H. pylori infection rates in several European regions. This systematic review suggests that a number of correctable lifestyle factors could impact the disease progression toward H. pylori-associated stomach cancer. However, additional research is required to determine the potential role of targeted interventions in reducing stomach cancer development after H. pylori infection.

Peptic Ulcer Disease and Helicobacter pylori Infection in Different Siberian Ethnicities

BACKGROUND

The high prevalence of Helicobacter pylori (H. pylori) infection in eastern Siberia is consistently established. In the same geographic area, however, fragmentary information is available on the epidemiology of the peptic ulcer disease (PUD).

AIM

To assess the prevalence of H. pylori infection (including CagA status) and PUD in different eastern Siberian ethnicities.

PATIENTS AND METHODS

An endoscopy population of 3149 eastern Siberian dyspeptic patients was considered [1727 Europoids and 1422 Mongoloids (Evenks = 792; Khakases = 630)]. H. pylori status was assessed by urease test and/or serum anti-H. pylori IgG and/or histology. CagA status was serologically assessed (anti-CagA antibodies).

RESULTS

All the Siberian ethnicities featured high rates of H. pylori infection (Europoids = 87.1%, Evenks = 88.6%, Khakases = 85.4%). Among the 1504 H. pylori-positive Europoids, the prevalence of CagA-positive status (68.7%) was significantly higher than that featured by the 1240 H. pylori-positive Mongoloid ethnicities (46.9%; p < .001 for both comparisons). Peptic ulcer disease significantly prevailed among Europoids (prevalence among Europoid Evenks and Khakases: 8.9% and 8.3%, respectively; prevalence among Mongoloid Evenks and Khakases = 1.0% and 4.4%, respectively).

CONCLUSIONS

eastern Siberian populations feature consistent high rates of H. pylori infection, but different prevalence of peptic ulcer disease. In particular, Europoids featured a prevalence of both CagA-positive status and peptic ulcer disease significantly higher than that of the Mongoloid ethnicities. These results suggest that both environmental factors (coexisting with the H. pylori infection) and host-related variables modulate the clinicopathological expression of the H. pylori -associated gastric diseases.

Surveillance of infectious diseases in the Arctic

OBJECTIVES

This study reviews how social and environmental issues affect health in Arctic populations and describes infectious disease surveillance in Arctic Nations with a special focus on the activities of the International Circumpolar Surveillance (ICS) project.

METHODS

We reviewed the literature over the past 2 decades looking at Arctic living conditions and their effects on health and Arctic surveillance for infectious diseases.

RESULTS

In regards to other regions worldwide, the Arctic climate and environment are extreme. Arctic and sub-Arctic populations live in markedly different social and physical environments compared to those of their more southern dwelling counterparts. A cold northern climate means people spending more time indoors, amplifying the effects of household crowding, smoking and inadequate ventilation on the person-to-person spread of infectious diseases. The spread of zoonotic infections north as the climate warms, emergence of antibiotic resistance among bacterial pathogens, the re-emergence of tuberculosis, the entrance of HIV into Arctic communities, the specter of pandemic influenza or the sudden emergence and introduction of new viral pathogens pose new challenges to residents, governments and public health authorities of all Arctic countries. ICS is a network of hospitals, public health agencies, and reference laboratories throughout the Arctic working together for the purposes of collecting, comparing and sharing of uniform laboratory and epidemiological data on infectious diseases of concern and assisting in the formulation of prevention and control strategies (Fig. 1). In addition, circumpolar infectious disease research workgroups and sentinel surveillance systems for bacterial and viral pathogens exist.

CONCLUSIONS

The ICS system is a successful example of collaborative surveillance and research in an extreme environment.

The diagnosis and treatment of Helicobacter pylori infection in Arctic regions with a high prevalence of infection: Expert Commentary

Helicobacter pylori infection is a major cause of peptic ulcer and is also associated with chronic gastritis, mucosa-associated lymphoid tissue (MALT) lymphoma, and adenocarcinoma of the stomach. Guidelines have been developed in the United States and Europe (areas with low prevalence) for the diagnosis and management of this infection, including the recommendation to ‘test and treat’ those with dyspepsia. A group of international experts performed a targeted literature review and formulated an expert opinion for evidenced-based benefits and harms for screening and treatment of H. pylori in high-prevalence countries. They concluded that in Arctic countries where H. pylori prevalence exceeds 60%, treatment of persons with H. pylori infection should be limited only to instances where there is strong evidence of direct benefit in reduction of morbidity and mortality, associated peptic ulcer disease and MALT lymphoma and that the test-and-treat strategy may not be beneficial for those with dyspepsia.

Community-driven research on environmental sources of H. pylori infection in arctic Canada

The role of environmental reservoirs in H. pylori transmission remains uncertain due to technical difficulties in detecting living organisms in sources outside the stomach. Residents of some Canadian Arctic communities worry that contamination of the natural environment is responsible for the high prevalence of H. pylori infection in the region. This analysis aims to estimate associations between exposure to potential environmental sources of biological contamination and prevalence of H. pylori infection in Arctic Canada. Using data from 3 community-driven H. pylori projects in the Northwest and Yukon Territories, we estimated effects of environmental exposures on H. pylori prevalence, using odds ratios (OR) and 95% confidence intervals (CI) from multilevel logistic regression models to adjust for household and community effects. Investigated exposures include: untreated drinking water; livestock; dogs; cats; mice or mouse droppings in the home; cleaning fish or game. Our analysis did not identify environmental exposures associated clearly with increased H. pylori prevalence, except any exposure to mice or mouse droppings (OR = 4.6, CI = 1.2-18), reported by 11% of participants. Our multilevel models showed H. pylori clustering within households, but environmental exposures accounted for little of this clustering; instead, much of it was accounted for by household composition (especially: having infected household members; number of children). Like the scientific literature on this topic, our results do not clearly implicate or rule out environmental reservoirs of H. pylori; thus, the topic remains a priority for future research. Meanwhile, H. pylori prevention research should seek strategies for reducing direct transmission from person to person.

Breast-feeding and Helicobacter pylori infection: systematic review and meta-analysis

Objective

To quantify the association between breast-feeding and Helicobacter pylori infection, among children and adolescents.

Design

We searched MEDLINETM and ScopusTM up to January 2013. Summary relative risk estimates (RR) and 95 % confidence intervals were computed through the DerSimonian and Laird method. Heterogeneity was quantified using the I2 statistic.

Setting

Twenty-seven countries/regions; four low-income, thirteen middle-income and ten high-income countries/regions.

Subjects

Studies involving samples of children and adolescents, aged 0 to 19 years.

Results

We identified thirty-eight eligible studies, which is nearly twice the number included in a previous meta-analysis on this topic. Fifteen studies compared ever v. never breast-fed subjects; the summary RR was 0·87 (95 % CI 0·57, 1·32; I2=34·4 %) in middle-income and 0·85 (95 % CI 0·54, 1·34; I2=79·1 %) in high-income settings. The effect of breast-feeding for ≥4–6 months was assessed in ten studies from middle-income (summary RR=0·66; 95 % CI 0·44, 0·98; I2=65·7 %) and two from high-income countries (summary RR=1·56; 95 % CI 0·57, 4·26; I2=68·3 %). Two studies assessed the effect of exclusive breast-feeding until 6 months (OR=0·91; 95 % CI 0·61, 1·34 and OR=1·71; 95 % CI 0·66, 4·47, respectively).

Conclusions

Our results suggest a protective effect of breast-feeding in economically less developed settings. However, further research is needed, with a finer assessment of the exposure to breast-feeding and careful control for confounding, before definite conclusions can be reached.

Childcare attendance and Helicobacter pylori infection: systematic review and meta-analysis

Helicobacter pylori infection is acquired predominantly during childhood. Childcare promotes interpersonal contact and may be an important determinant of infection. The aim was to quantify the association between childcare attendance and H. pylori infection in childhood or adolescence. PubMed was searched up to July 2012 to identify eligible studies. The DerSimonian and Laird method was used to compute summary odds ratio (OR) estimates and 95% confidence intervals (CIs); heterogeneity was quantified with the I statistic and explained through stratified analyses and metaregression. Sixteen studies compared participants attending childcare with those not exposed. The summary OR was 1.12 (95% CI: 0.82-1.52, I=77.4%). Summary estimates were similar for crude and adjusted estimates, and higher when the infection was evaluated in children of 3 years or younger (OR=2.00, 95% CI: 0.94-4.29, I=55.0%). Studies based on the detection of stool antigens yielded higher estimates (OR=2.65, 95% CI: 1.24-5.66, I=36.4%). Those conducted in settings with a high prevalence of H. pylori infection yielded stronger associations (OR=1.44, 95% CI: 0.94-2.20, I=74.3%). In multivariate metaregression, there was no significant association with any of these variables; taking them into account contributed to a reduction of I to 67%. The role of childcare as a risk factor for H. pylori infection is confirmed by our results, especially in settings with a high prevalence of infection. However, the association was moderate, and the effect of the type of childcare setting or the duration or the intensity of exposure was seldom addressed, leaving considerable scope for improving our understanding of how this modifiable exposure contributes towards H. pylori infection.

Cancer patterns in Inuit Nunangat: 1998-2007

OBJECTIVES

To compare cancer incidence patterns between residents of Inuit Nunangat and the rest of Canada.

STUDY DESIGN

Cancer cases were geographically linked to either Inuit Nunangat or the rest of Canada using postal codes or other geographic information. Population estimates were derived from the 2001 and 2006 censuses.

METHODS

Cancer cases were combined from 1998 to 2007 for Inuit Nunangat and the rest of Canada. Age-standardised incidence rates were calculated for all site cancers and sub-sites by sex. Standardised rate ratios between these 2 areas were calculated for all site cancers and sub-sites.

RESULTS

The age-standardised incidence rate for all cancer sites (1998-2007) was 14% lower for the Inuit Nunangat male population and 29% higher for the female population by comparison to the rest of Canada. Cancers of the nasopharynx, lung and bronchus, colorectal, stomach (males), and kidney and renal pelvis (females), were elevated in the Inuit Nunangat population compared to the rest of Canada, whereas prostate and female breast cancers were lower in the Inuit Nunangat population.

CONCLUSIONS

Cancers with potentially modifiable risk factors, such as buccal cavity and pharynx, nasopharynx, lung and bronchus, and colorectal cancer were elevated in the Inuit Nunangat population compared to the rest of Canada. Besides greater smoking prevalence within Inuit Nunangat by comparison to the rest of Canada, distinct socioeconomic characteristics between respective area populations including housing, and income may have contributed to incidence differentials. This study demonstrated that a geographic approach can be used in cancer surveillance when populations of interest are spatially distinguishable, and reside across distinct jurisdictions whose combined cancer registries will not completely provide information to identify the population of interest.

Prevalence and incidence of Helicobacter pylori Infection in a healthy pediatric population in the Lisbon area

BACKGROUND

Helicobacter pylori is mainly acquired in childhood. Although adult studies reported a high prevalence of H. pylori infection in Portugal, the actual rate in children remains unknown. This study aimed to determine the prevalence and the incidence of H. pylori infection in an asymptomatic pediatric population of the Lisbon area and to correlate prevalence with sociodemographic determinants.

MATERIALS AND METHODS

Helicobacter pylori infection was determined by stool antigen test in 844 asymptomatic children (age 0-15 years; 49.4% boys). For the incidence study, H. pylori-negative children in the prevalence study were followed-up every 6 months over a 3-year period.

RESULTS

The global prevalence of H. pylori infection was 31.6%, increasing with age (19.9, 37.0 and 51.5%, in age groups 0-5, 6-10, and 11-15, respectively), but was similar among genders (34.5% in boys and 28.4% in girls). Older age and attendance of nursery/kindergarten during preschool constituted independent risk factors. The overall estimated incidence was 11.6 per 100 child-years (CY). Although 47.5% of children acquired H. pylori infection before 5 years of age, the mean age of acquisition was 6.3. The incidence of infection was similar among the three age groups (11.5, 13.0, and 10.5 per 100 CY, in age groups 0-5, 6-10, and 11-15, respectively).

CONCLUSIONS

The prevalence of H. pylori infection in the Portuguese pediatric population is still high. Although this study confirmed that the highest acquisition rate occurs at young age, it showed that in high-prevalence populations, older children can also acquire H. pylori infection at a rate similar to that of young children.

Risk factors for Mycobacterium tuberculosis infection among children in Greenland

OBJECTIVE

To examine the risk factors for Mycobacterium tuberculosis infection (MTI) among Greenlandic children for the purpose of identifying those at highest risk of infection.

METHODS

Between 2005 and 2007, 1797 Greenlandic schoolchildren in five different areas were tested for MTI with an interferon gamma release assay (IGRA) and a tuberculin skin test (TST). Parents or guardians were surveyed using a standardized self-administered questionnaire to obtain data on crowding in the household, parents' educational level and the child's health status. Demographic data for each child--i.e. parents' place of birth, number of siblings, distance between siblings (next younger and next older), birth order and mother's age when the child was born--were also extracted from a public registry. Logistic regression was used to check for associations between these variables and MTI, and all results were expressed as odds ratios (ORs) and 95% confidence intervals (CIs). Children were considered to have MTI if they tested positive on both the IGRA assay and the TST.

FINDINGS

The overall prevalence of MTI was 8.5% (152/1797). MTI was diagnosed in 26.7% of the children with a known TB contact, as opposed to 6.4% of the children without such contact. Overall, the MTI rate was higher among Inuit children (OR:  4.22; 95% CI: 1.55-11.5) and among children born less than one year after the birth of the next older sibling (OR:  2.48; 95% CI: 1.33-4.63). Self-reported TB contact modified the profile to include household crowding and low mother's education. Children who had an older MTI-positive sibling were much more likely to test positive for MTI themselves (OR:  14.2; 95% CI: 5.75-35.0) than children without an infected older sibling.

CONCLUSION

Ethnicity, sibling relations, number of household residents and maternal level of education are factors associated with the risk of TB infection among children in Greenland. The strong household clustering of MTI suggests that family sources of exposure are important.

Influence of sociodemographic factors on Helicobacter pylori prevalence variability among schoolchildren in Leipzig, Germany. A long-term follow-up study

BACKGROUND

Until the beginning of this decade the assumption was that the Helicobacter pylori prevalence increases with the age of the population under consideration. More and more epidemiological studies have been suggestive of constancy in Helicobacter pylori prevalence, but to date there has been no long-term follow-up study in a large group of children confirming this hypothesis.

METHODS

Following up our study of H. pylori among school starters and 2nd graders in 1998 and 2000, we conducted a third phase of this study in 2006 using the [13C]-Urea Breath Test and a detailed parent-completed epidemiological questionnaire to evaluate the development of prevalence among the overall population of 8th graders in the city of Leipzig (n = 1,905), and especially of the subgroup of participants who took part in all three study phases (n = 751).

RESULTS

The overall H. pylori prevalence was 6.5% and had not significantly changed since 1998 and 2000 (6.1%, 5.7% respectively). However, we noticed a significant lower prevalence in the subgroup that participated in all study phases (2.7%). Moreover, we observed a dependence of prevalence on distribution of sociodemographic risk factors such as foreign nationality of at least one parent, birth outside of Germany, low parental education and unemployment, and > or = 2 older siblings.

CONCLUSION

The variability in prevalence is most likely a result of unequal sociodemographic family backgrounds.

Influence of family size and birth order on risk of cancer: a population-based study

BACKGROUND

Family size and birth order are known to influence the risk of some cancers. However, it is still unknown whether these effects change from early to later adulthood. We used the data of the Swedish Family-Cancer Database to further analyze these effects.

METHODS

We selected over 5.7 million offspring with identified parents but no parental cancer. We estimated the effect of birth order and family size by Poisson regression adjusted for age, sex, period, region and socioeconomic status. We divided the age at diagnosis in two groups, below and over 50 years, to identify the effect of family size and birth order for different age periods.

RESULTS

Negative associations for increasing birth order were found for endometrial, testicular, skin, thyroid and connective tissue cancers and melanoma. In contrast, we observed positive association between birth order and lung, male and female genital cancers. Family size was associated with decreasing risk for endometrial and testicular cancers, melanoma and squamous cell carcinoma; risk was increased for leukemia and nervous system cancer. The effect of birth order decreased for lung and endometrial cancer from age at diagnosis below to over 50 years. Combined effects for birth order and family size were marginally significant for thyroid gland tumors. Especially, the relative risk for follicular thyroid gland tumors was significantly decreased for increasing birth order.

CONCLUSION

Our findings suggest that the effect of birth order decreases from early to late adulthood for lung and endometrial cancer.

A "screen-and-treat" approach for Helicobacter pylori infection: a population-based study in Vammala, Finland

BACKGROUND

To accelerate the decline of Helicobacter pylori infection, and to study the significance of the possible risk factors for H. pylori infection in Finland, we started a voluntary H. pylori"screen-treat-retest-and-retreat" program for all young adults at primary health care in Vammala, Finland after a pilot study in 1994 including 504 subjects aged 15-75.

MATERIALS AND METHODS

A total of 3326 aged 15-40 in 1996, and 716 aged 15 and 584 aged 45 in 1997-2000 were screened for H. pylori using serology. Helicobacter pylori positive were treated, cure was verified by serology.

RESULTS

The eradication rates were 93.8%, 82.2%, and 77.6% per protocol in pilot study in 1994, in subjects invited in 1996 and 1997-2000, respectively. Helicobacter pylori seroprevalence rates were calculated to have decreased from 36% to 14% in pilot study, from 12% to 4% among subjects invited in 1996, from 3% to 2% among subjects aged 15 and from 27% to 12% among subjects aged 45 in 1997-2000. An epidemiologic questionnaire in 1996 revealed that crowding in the childhood household, low education of the mother, current smoking and alcohol consumption, unfavorable housing conditions, and sick leaves due to dyspepsia were independently associated with H. pylori infection.

CONCLUSIONS

This intervention with high participation rates resulted in a significant decline in calculated H. pylori seroprevalence rates. Although the low prevalence of H. pylori infection may limit the cost efficiency of the program, the intervention is expected to reduce the burden of H. pylori-associated diseases.

Childhood hygienic practice and family education status determine the prevalence of Helicobacter pylori infection in Iran

BACKGROUND

Management of Helicobacter pylori, a causative agent of gastrointestinal diseases is an important health problem in most countries. The main reasons include poorly defined epidemiological status and unrecognized mode of bacterial transmission. Our objective was to investigate the prevalence of H. pylori infection in a representative population of Iran and to evaluate possible risk factors for the H. pylori infection.

MATERIALS AND METHODS

In this cross-sectional study, 2561 healthy individuals aged 18-65 years (mean age, 35.5 years) were selected out of 12,100,000 inhabitants of Tehran province by cluster sampling. Infection with H. pylori was evaluated by detection of anti-H. pylori IgG antibody in serum. Sociodemographic status of each subject was determined by filling up a questionnaire.

RESULTS

Prevalence of H. pylori infection was 69% and was correlated with increasing age. The highest infection rate (79.2%) was seen in individuals 46-55 years old. No association was detected between H. pylori positivity and gender. Low education of the study subjects; low father's and mother's education; poor tooth brushing habit; crowded families in childhood; and lack of household bath, hygienic drinking water, and swage disposal facility in childhood were determined as possible risk factors.

CONCLUSIONS

The rate of prevalence of H. pylori infection was higher than developed countries. Low socioeconomic status, poor sanitary indications, and crowded families in childhood were related to high prevalence of H. pylori infection in Iran. Accordingly, fecal-oral and oral-oral routes could be considered as the main pathways of transmission of H. pylori.

Carnitine palmitoyltransferase IA polymorphism P479L is common in Greenland Inuit and is associated with elevated plasma apolipoprotein A-I

Carnitine palmitoyltransferase IA, encoded by CPT1A, is a key regulator of fatty acid metabolism. Previously, a loss-of-function mutation, namely, c.1436 C-->T (p.P479L), was reported in CPT1A in the homozygous state in Canadian aboriginal male with presumed CPT1A deficiency. To determine the population frequency of this variant, we determined CPT1A p.P479L genotypes in 1111 Greenland Inuit. Associations between genotype and variation in plasma total cholesterol, triglycerides, LDL, HDL, apolipoprotein (apo) B, and apoA-I was also investigated. We found the L479 allele occurs at a high frequency in this sample (0.73), while it was completely absent in 285 nonaboriginal samples. This suggests that the original proband's symptoms were not likely due to the CPT1A p.P479L mutation because it is very common in Inuit and because symptoms suggesting CPT1A deficiency have not been reported in any carrier subsequently studied. However, CPT1A p.P479L was associated with elevated plasma HDL and apoA-I levels. The association with increased levels of HDL and apoA-I suggest that the polymorphism might protect against atherosclerosis.

Cancer patterns in Inuit populations

Inuit people inhabit the circumpolar region, with most living in Alaska, northwest Canada, and Greenland. Although malignant diseases were believed to be almost non-existent in Inuit populations during the beginning of the 20th century, the increasing life expectancy within these populations showed a distinct pattern, characterised by a high risk of Epstein-Barr virus-associated carcinomas of the nasopharynx and salivary glands, and a low risk of tumours common in white populations, including cancer of the prostate, testis, and haemopoietic system. Both genetic and environmental factors seem to be responsible for this pattern. During the second half of the 20th century, Inuit societies underwent major changes in lifestyle and living conditions, and the risk of lifestyle-associated tumours, especially cancers of the lung, colon, and breast, increased considerably after changes in smoking, diet, and reproductive factors. This Review will briefly summarise the current knowledge on cancer epidemiology in Inuit populations, with emphasis on the characteristic Inuit types of cancer.

Prevalence and risk factors for Helicobacter pylori infection in Chinese populations

BACKGROUND

The prevalence of Helicobacter pylori is higher in developing countries. The aim of this study was to investigate the prevalence and risk factors of H. pylori infection in areas with high prevalence of gastric cancer in Jiangsu Province, China.

METHODS

A prospective epidemiologic survey of H. pylori infection was accomplished in a natural population of 1457 individuals in Xiangshui and Gaoyou counties, Jiangsu Province, China. Questionnaires and laboratory tests for H. pylori infection ((13)C-urea breath test and serum IgG antibodies to H. pylori) were used and performed, respectively.

RESULT

Among 1371 subjects who completed questionnaires and H. pylori detection, 851 (62%) were H. pylori positive. The prevalence reached a peak at the age of 30-40 years (67%). There was no sex difference. The annual family income level was shown to be positively correlated with the risk of H. pylori infection. The prevalence of H. pylori infection was also associated with family size, education level, and several diet-related factors, such as the number of times cooked rice and potatoes eaten per week, and a family history of stomach diseases. Compared to nonsymptomatic individuals, people with dyspeptic symptoms (nausea, vomiting, and belching) presented a low prevalence of H. pylori infection. No association between H. pylori prevalence and smoking or drinking was found. Using multivariate logistic regression analysis, annual family income and education level were the independent predictors for H. pylori infection.

CONCLUSION

High prevalence of H. pylori infection was found in areas with a high risk of gastric cancer and was related to several risk factors. The underlying mechanisms need to be further investigated.

Helicobacter pylori infection in Canadian and related Arctic Aboriginal populations

In 2006, the Canadian Helicobacter Study Group identified Aboriginal communities among Canadian population groups most at risk of Helicobacter pylori-associated disease. The objective of this systematic review was to summarize what is known about the H pylori-associated disease burden in Canadian and related Arctic Aboriginal populations to identify gaps in knowledge. Six health literature databases were systematically searched to identify reports on H pylori prevalence in Canadian population groups, or any topic related to H pylori in Canadian Aboriginals, Alaska Natives or Aboriginals of other Arctic regions. Identified reports were organized by subtopic and summarized in narrative form. Key data from studies of H pylori prevalence in defined populations were summarized in tabular form. A few Arctic Aboriginal communities were represented in the literature: two Canadian Inuit; one Canadian First Nation; two Greenland Inuit; one Russian Chutkotka Native; and several Alaska Native studies. These studies uniformly showed elevated H pylori prevalence; a few studies also showed elevated occurrence of H pylori-related diseases and high rates of treatment failure. Based on the evidence, it would be warranted for clinicians to relax the criteria for investigating H pylori and related diseases in patients from Arctic Aboriginal communities, and to pursue post-therapy confirmation of eradication. Additional community-based research is needed to develop public health policies for reducing H pylori-associated health risks in such communities.

Effect of sibling number in the household and birth order on prevalence of Helicobacter pylori: a cross-sectional study

BACKGROUND

Infection with Helicobacter pylori (H. pylori) is acquired mainly in childhood, with studies demonstrating this is related to living conditions. Effects of sibling number and birth order on prevalence of infection have not been extensively studied.

METHODS

The authors performed a cross-sectional survey of adults, aged between 50 and 59 years, previously involved in a community-screening programme for H. pylori in Leeds and Bradford, UK. Prevalence of H. pylori was assessed at baseline with urea breath test. All individuals who were alive, and could be traced, were contacted by postal questionnaire in 2003 obtaining information on number of siblings and birth order. Data concerning childhood socioeconomic conditions were stored on file from the original study.

RESULTS

3928 (47%) of 8407 original participants provided data. Prevalence of infection increased according to sibling number (20% in those with none vs 63% with eight or more). Controlling for childhood socioeconomic conditions and birth order using multivariate logistic regression, infection odds were substantially increased with three siblings compared with none [odds ratio (OR) 1.51; 95% confidence interval (CI) 1.06-2.15], and a gradient of effect continued up to eight or more siblings (OR 5.70; 95% CI 2.92-11.14). Odds of infection also increased substantially with birth order, but the positive gradient disappeared on adjustment for sibling number and childhood socioeconomic conditions.

CONCLUSIONS

: In this cross section of UK adults, aged 50-59 years, sibling number in the household, but not birth order, was independently associated with prevalence of H. pylori infection.

A new model for the transmission of Helicobacter pylori: role of environmental reservoirs as gene pools to increase strain diversity

Twenty-five years after the first successful cultivation and isolation of Helicobacter pylori, the scientific community is still struggling to understand the way(s) this bacterium is transmitted among the human population. Here, both epidemiologic and microbiologic evidence addressing this matter is reviewed and explored to conclude that most H. pylori successful colonizations are derived from direct person-to-person contact and that even though exposure of humans to H. pylori from environmental sources is a very common event, in most occasions the host is able to fight off infection. In addition, under a new model developed here, we propose that the near elimination of environmental reservoirs is the main responsible for the lower prevalence observed in the more industrialized countries by acting on two levels: by decreasing the number of direct infections and by diminishing the number of intraspecies recombination events for producing strain variation within H. pylori.

Seroprevalence of Helicobacter pylori infection among schoolchildren and teachers in Taiwan

BACKGROUND

Helicobacter pylori are associated with chronic antral gastritis that is related to duodenal ulcer, gastric ulcer, and probably gastric adenocarcinoma. Infection of H. pylori during childhood is considered an important risk factor for gastric carcinoma in adult life.

MATERIALS AND METHODS

To examine the epidemiologic characteristics of H. pylori infection among schoolchildren in central Taiwan, a community-based survey was carried out using stratified sampling in 10 elementary schools and three junior high schools including students and theirs teachers. Serum specimens of 1950 healthy schoolchildren (aged 9-15 years old) and 253 teachers who were randomly sampled were screened for the H. pylori antibodies by enzyme-linked immunosorbent assay. Statistical analysis was performed by using the SPSS for Windows statistical software system.

RESULTS

A total of 332 subjects were H. pylori antibodies positive, giving an overall prevalence of 15.1%. The age-specific seropositive rates were 11.0% in 9-12 years age group, 12.3% in 13-15 years age group, and 45.1% in the teacher group. The older the age, the higher the seroprevalence (OR = 11.53; 95% CI = 6.73-19.74; p < .001 for children vs. teachers). There was no difference in the seroprevalence of H. pylori infection by gender, ethnicity, geographical area, socioeconomic level, parental education, sibship size, family members, and source of drinking water.

CONCLUSION

The teachers had a much higher prevalence of H. pylori antibodies. The finding suggests that these teachers (adults) might be infected in their early childhood and implies that the poor environmental and hygienic conditions might be responsible for it. It seemed that poor water supply system, sewage disposal, and other environmental hygiene in adult might play some roles in H. pylori infection in Taiwan (before early 1980s).

Number of siblings and the risk of solid tumours: a nation-wide study

We analysed the effects of number of siblings on the risk of solid tumours using the Swedish Family-Cancer Database, including population-based information on over 11 million individuals and more than 178 000 cancer patients diagnosed between 1958 and 2004. Incidence rate ratios (RRs), estimated by Poisson regression models, were adjusted for age, sex, birth cohort, area of residence and socioeconomic status. Having eight or more siblings vs none increased the risk of stomach cancer (RR=1.83, 95% confidence interval (CI), 1.44–2.34). Anal cancer diagnosed before age 40 showed the strongest association with the total siblings (RR=3.27, 95% CI, 2.04–5.26 for five or more siblings vs none). Endometrial (RR=0.76, 95% CI, 0.70–0.82), testicular (RR=0.71, 95% CI, 0.62–0.82), skin cancer (RR=0.82, 95% CI, 0.69–0.97) and melanoma (RR=0.72, 95% CI, 0.65–0.79) showed strong decreased risks for five or more siblings vs none. Prostate cancer risk for those with five or more older siblings vs none was 1.38 (95% CI, 1.23–1.55). Having five or more younger siblings was most strongly associated with stomach cancer (RR=1.59, 95% CI, 1.29–1.95) and melanoma (RR=0.68, 95% CI, 0.59–0.79). We conclude that sibship characteristics are strong correlates of cancer risk at several sites; plausible interpretations include socioeconomic status.

Epidemiology of Helicobacter pylori infection

Differences may occur in the mode of transmission of Helicobacter pylori between developed and developing countries: direct human-to-human contacts have been suggested as the primary route in the former while the fecal-oral route, also, through contaminated water, in the latter. Data on intrafamilial transmission of H. pylori among children continue to be produced. The importance of low socioeconomic conditions on the acquisition of H. pylori infection has been confirmed in a number of population-based studies. Due to the improvement of living standards, the prevalence of the infection has fallen dramatically in many countries. It varies from 8.9 to 72.8% among children from developed and developing countries, respectively, the re-infection rate being also significantly higher in the latter. Conflicting data have been reported on the effect of breastfeeding against H. pylori colonization in infancy as well as on the occupational risk for acquiring H. pylori. This review summarizes recent results from the literature on these topics.