Further evidence for an exceptionally low prevalence of Helicobacter pylori infection among peptic ulcer patients in north-eastern peninsular Malaysia

Epidemiology and role of Helicobacter pylori virulence factors in gastric cancer carcinogenesis

Infection with Helicobacter pylori is associated with the development of gastric cancer. Although the prevalence of gastric cancer has declined throughout years due to improvement in early screening strategy, mortality due to gastric cancer has not changed. Incidence and mortality due to gastric cancer are higher in developing countries as compared to developed countries. Diagnosis and prognosis of gastric cancer are still poor with patients usually diagnosed with cancer at an advanced stage. Eradication of H. pylori is pertinent for the prevention of gastric cancer. However, the rise in antimicrobial resistance among H. pylori isolates has complicated the prevention strategy. H. pylori express multiple virulence factors for survival in the hostile acid gastric environment. The expression of oncogenic protein cytotoxin-associated gene A (CagA), vacuolating cytotoxin A (VacA), and outer inflammatory protein is essential for H. pylori to exert pathogenesis towards the host. Interestingly, <3% of H. pylori-infected subjects develop gastric cancer, suggesting a unique way of interaction between the host's immune response and H. pylori virulence factors. This article is aimed to review the epidemiology and role of H. pylori in gastric carcinogenesis. A better understanding of the interaction between H. pylori virulence factors and host is required for better gastric cancer prevention.

A systematic approach for the diagnosis and treatment of idiopathic peptic ulcers

An idiopathic peptic ulcer is defined as an ulcer with unknown cause or an ulcer that appears to arise spontaneously. The first step in treatment is to exclude common possible causes, including Helicobacter pylori infection, infection with other pathogens, ulcerogenic drugs, and uncommon diseases with upper gastrointestinal manifestations. When all known causes are excluded, a diagnosis of idiopathic peptic ulcer can be made. A patient whose peptic ulcer is idiopathic may have a higher risk for complicated ulcer disease, a poorer response to gastric acid suppressants, and a higher recurrence rate after treatment. Risk factors associated with this disease may include genetic predisposition, older age, chronic mesenteric ischemia, smoking, concomitant diseases, a higher American Society of Anesthesiologists score, and higher stress. Therefore, the diagnosis and management of emerging disease should systematically explore all known causes and treat underlying disease, while including regular endoscopic surveillance to confirm ulcer healing and the use of proton-pump inhibitors on a case-by-case basis.

Absence of Helicobacter pylori is not protective against peptic ulcer bleeding in elderly on offending agents: lessons from an exceptionally low prevalence population

Aim. Helicobacter pylori (H. pylori) infection is exceptionally rare in population from the north-eastern region of Peninsular Malaysia. This provides us an opportunity to contemplate the future without H. pylori in acute non-variceal upper gastrointestinal (GI) bleeding.

Methods. All cases in the GI registry with GI bleeding between 2003 and 2006 were reviewed. Cases with confirmed non-variceal aetiology were analysed. Rockall score > 5 was considered high risk for bleeding and primary outcomes studied were in-hospital mortality, recurrent bleeding and need for surgery.

Results. The incidence of non-variceal upper GI bleeding was 2.2/100,000 person-years. Peptic ulcer bleeding was the most common aetiology (1.8/100,000 person-years). In-hospital mortality (3.6%), recurrent bleeding (9.6%) and need for surgery (4.0%) were uncommon in this population with a largely low risk score (85.2% with score ≤5). Elderly were at greater risk for bleeding (mean 68.5 years, P = 0.01) especially in the presence of duodenal ulcers (P = 0.04) despite gastric ulcers being more common. NSAIDs, aspirin and co-morbidities were the main risk factors.

Conclusions. The absence of H. pylori infection may not reduce the risk of peptic ulcer bleeding in the presence of risk factors especially offending drugs in the elderly.

Helicobacter pylori infection--a boon or a bane: lessons from studies in a low-prevalence population

Helicobacter pylori (H. pylori) infection is etiologically associated with gastric cancer and peptic ulcer diseases which are both important public health burdens which could be largely eliminated by H. pylori eradication. However, some investigators urge caution based on the hypothesis that eradication of H. pylori may result in an increase in the incidence of gastroesophageal reflux disease, esophageal adenocarcinoma, and childhood asthma. The ethnic Malays of northeastern Peninsular Malaysia have long had a low prevalence of H. pylori infection and, as expected, the incidence of gastric cancer and its precursor lesions is exceptionally low. The availability of a population with a low H. pylori prevalence and generally poor sanitation allows separation of H. pylori from the hygiene hypothesis and direct testing of whether absence of H. pylori is associated with untoward consequence. Contrary to predictions, in Malays, erosive esophagitis, Barrett's esophagus, distal esophageal cancers, and childhood asthma are all of low incidence. This suggests that H. pylori is not protective rather the presence of H. pylori infection is likely a surrogate for poor hygiene and not an important source of antigens involved in the hygiene hypothesis. Helicobacter pylori in Malays is related to transmission from H. pylori-infected non-Malay immigrants. The factors responsible for low H. pylori acquisition, transmission, and burden of H. pylori infection in Malays remain unclear and likely involves a combination of environmental, host (gene polymorphisms), and strain virulence factors. Based on evidence from this population, absence of H. pylori infection is more likely to be boon than a bane.

Towards understanding the low prevalence of Helicobacter pylori in Malays: genetic variants among Helicobacter pylori-negative ethnic Malays in the north-eastern region of Peninsular Malaysia and Han Chinese and South Indians

OBJECTIVES

To identify gene polymorphisms that differ between Malays, Han Chinese and South Indians, and to identify candidate genes for the investigation of their role in protecting Malays from Helicobacter pylori (H. pylori) infection.

METHODS

Malay participants born and residing in Kelantan with a documented absence of H. pylori infection were studied. Venous blood was used for genotyping using the Affymetrix 50K Xba I kit. CEL files from 141 Han Chinese and 76 South Indians were analyzed to compare their allele frequency with that of the Malays using fixation index (FST ) calculation. The single nucleotide polymorphisms (SNPs) with the highest allele frequency (outliers) were then examined for their functional characteristics using F-SNP software and the Entrez Gene database.

RESULTS

In all, 37 Malays were enrolled in the study; of whom 7 were excluded for low genotyping call rates. The average FST estimated from the genome-wide data were 0.038 (Malays in Kelantan vs the South Indians), 0.015 (Malays in Kelantan vs Han Chinese) and 0.066 (Han Chinese vs South Indians), respectively. The outlier gene variants present in Malays with functional characteristics were C7orf10 (FST  0.29988), TSTD2 (FST  0.43278), SMG7 (FST  0.29877) and XPA (FST  0.43393 and 0.43644).

CONCLUSION

Genetic variants possibly related to protection against H. pylori infection in ethnic Malays from the north-eastern region of Peninsular Malaysia were identified for testing in subsequent trials among infected and uninfected Malays.

Sociocultural and dietary practices among Malay subjects in the north-eastern region of Peninsular Malaysia: a region of low prevalence of Helicobacter pylori infection

BACKGROUND AND AIM

The prevalence of Helicobacter pylori infection is exceptionally low among the Malays in the north-eastern region of Peninsular Malaysia. The reasons are unknown. Our aim was to compare environmental factors that differed in relation to H. pylori prevalence among Malays born and residing in Kelantan.

METHODS

A case-control study was conducted among Malays in Kelantan who underwent upper endoscopy between 2000 and 2008. Helicobacter pylori status was determined by gastric histology. Sociocultural and dietary factors were assessed using a validated investigator-directed questionnaire administered after 2008, and the data were analyzed using logistic regression analysis.

RESULTS

The study group consisted of 161 subjects (79 H. pylori positive and 82 controls). Univariable analysis identified five poor sanitary practices associated with an increased prevalence of H. pylori infection: use of well water, use of pit latrine, less frequent boiling of drinking water, and infrequent hand wash practice after toilet use and before meals. Multivariable logistic regression analysis identified three variables inversely associated with H. pylori infection: frequent consumption of tea (OR: 0.023, 95% CI: 0.01-0.07), frequent use of "budu" or local anchovy sauce (OR: 0.09, 95% CI: 0.1-0.7), and frequent use of "pegaga" or centenella asiatica (OR: 0.25, 95% CI: 0.1-0.65).

CONCLUSIONS

Under the assumption that sanitary, sociocultural, and dietary habits have not changed over the years, we can conclude that an increased risk of H. pylori was associated with unsanitary practices whereas protection was associated with consumption of tea and locally produced foods, "pegaga" and "budu." These dietary factors are candidates for future study on the effects on H. pylori transmission.

Barrett's Esophagus in an Area with an Exceptionally Low Prevalence of Helicobacter pylori Infection

Objective. This study was undertaken to gain an insight into the relationship between Helicobacter pylori (H. pylori) infection, Barrett's esophagus and reflux esophagitis in an area of exceptionally low prevalence of H. pylori infection. Methods. A total of 1895 consecutive upper endoscopies performed between January 2005 and July 2007 were reviewed. 120 cases of columnar-lined esophagus and endoscopic esophagitis were evaluated. H. pylori infection was determined using the urease test and/or histology. Results. The rate of endoscopic esophagitis was 5.49% (80 Malays, 24 non-Malays) while histological reflux esophagitis was found in 3.75% (56 Malays, 15 non-Malays). Barrett's esophagus was present in 0.79% (11 Malays, 4 non-Malays). H. pylori infection was present in 8/120 or 6.67% subjects. Conclusion. The low rate of Barrett's esophagus in this population does not support the hypothesis that the absence of H. pylori infection is more than a minor risk factor for Barrett's esophagus.

Incidence of esophageal carcinoma among Malays in North-Eastern Peninsular Malaysia: an area with an exceptionally low prevalence of Helicobacter pylori infection

BACKGROUND

Obesity, gastroesophageal reflux, and Barrett's esophagus have all been linked to esophageal adenocarcinoma. In addition, the decline in Helicobacter pylori (H. pylori) infection in affluent societies has also been suggested to be a major factor in the recent rise in the incidence of esophageal adenocarcinoma. If H. pylori infection has a protective role, populations with a naturally low prevalence of H. pylori infection such as the ethnic Malays of Northeastern Peninsular Malaysia should have high rates of esophageal adenocarcinoma.

AIM

To test this hypothesis, we investigated the incidence of esophageal carcinoma among the ethnic Malays of the state of Kelantan in Northeastern Peninsular Malaysia.

METHODS

The pathology services in the state of Kelantan are provided by two main hospitals. The histopathological records of both hospitals were systematically examined to retrieve all cases of esophageal carcinoma diagnosed between 2004 and 2008. Incidence rates were determined based on the most recent population census.

RESULTS

The age-standardized incidence rates (per 100,000 population) of esophageal adenocarcinoma among Malay men and women were 0.75 and 0.69, respectively. The corresponding rates for squamous cell carcinoma of the esophagus were 0.66 and 1.34, respectively.

CONCLUSIONS

The low rates of adenocarcinoma and squamous cell carcinoma of the esophagus in the study area, despite the fact that H. pylori infection is virtually absent, does not support the hypothesis that the absence of H. pylori infection is a pivotal factor in the pathogenesis of these cancers.

Epidemiology of Helicobacter pylori among multiracial community in Northern Peninsular, Malaysia: effect of age across race and gender. ASIAN PAC J TROP MED. 2011;4:72-75. [PMID: 21771421 DOI: 10.1016/s1995-7645(11)60037-0]

OBJECTIVE

To study the epidemiology of Helicobacter pylori (H. pylori) infection according to age group.

METHODS

H. pylori infection data among 1 965 consecutive patients referred to the Endoscopy Unit collected at Sungai Petani Hospital for oesophagogastro-duodenoscopy (OGD). The patients were divided into 9 age groups (10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89 and 90-99 years). In addition these groups were further divided into three minor group namely young adults (10-39), older adults (40-69) and geriatric groups (70-99).

RESULTS

Overall prevalence of infection of H. pylori was analyzed and found that the prevalence increase with age (P<0.05). When the patients divided by ethnic and gender group with age, prevalence rate among young adults and older adults significantly higher (P<0.05) compared to geriatric groups across all races and gender (P<0.05). Furthermore, significantly higher number of males were infected compared to female (P<0.05) but such trend was only observed among older adult groups. In addition, there is a significant differences in H. pylori infection prevalence rates among ethnic groups (highest in Indians adults, followed Chinese and low in Malays, P<0.05).

CONCLUSIONS

The overall prevalence of H. pylori did increase with age group across ethnicity and gender, in Northern Peninsular Malaysia.

Helicobacter pylori infection among Aborigines (the Orang Asli) in the northeastern region of Peninsular Malaysia

Whether the exceptionally low prevalence of Helicobacter pylori (HP) infection reported among Malays is also present among aborigines (the Orang Asli) living in northeastern Peninsular Malaysia is unknown. We studied asymptomatic Orang Asli from settlements situated 210 km from the city of Kota Bharu. The HP infection status was confirmed by a validated serology test. Nineteen percent of 480 Orang Asli tested positive for HP infection. The prevalence was 40.6% in the birth cohort of the 1940s and declined steadily in later cohorts to under 10% among 12-30 year olds. This may be related to the phases of relocation from the jungles into resettlement camps and ultimately into designated villages near rivers. The low prevalence pattern after the 1970s was probably partly a result of improvement in sanitation and hygiene practice in these villages but other unidentified factors may also be operating.

Risk factors associated with dyspepsia in a rural Asian population and its impact on quality of life

OBJECTIVES

The epidemiology and impact of dyspepsia in rural Asia remains uncertain. We aimed to determine the prevalence epidemiology and impact of dyspepsia in a rural Malaysian community.

METHODS

A door-to-door survey was conducted in a representative rural population in Malaysia. Dyspepsia was defined according to the Rome II criteria, and health-related quality of life (HRQOL) was assessed using the Euroqol (EQ-5D) instrument.

RESULTS

Of 2,260 adults, 2,000 (88.5%) completed the survey. The mean age of respondents was 40.4+/-15.3 years, 62.7% were women, 79.0% were ethnic Malays, 8.4% had been educated up to the tertiary level, 49.7% were unemployed, and 63.4% resided in village-type housing with 49.1% having >8 residents per household. Dyspepsia was prevalent in 292 (14.6%) adults, and they had lower mean EQ-5D utility scores compared with healthy controls (0.91+/-0.17 vs. 0.97+/-0.08, P<0.0001). Dyspepsia was found to be associated with female gender (15.8 vs. 12.7% males, P=0.058), Chinese ethnicity (19.7 vs. 14.2% non-Chinese), higher education levels, medium-range incomes (19.1% medium range vs. 13.3% low range), non-village-type housing (16.3 vs. 13.5% village-type house, P=0.08), nonsmokers (18.7 vs. 13.7%, P=0.015), non-tea drinkers (19.5 vs. 12.3%, P<0.0001), regular analgesia intake (27 vs. 12.7%, P<0.0001), and adults with chronic illness (26.6 vs. 11.1%, P<0.0001). Logistic regression analysis showed that higher levels of education, i.e., secondary (odds ratio (OR) 2.13, 95% confidence interval (CI)=1.15-3.93) and tertiary (2.70, 95% CI=1.30-5.62) education, non-village housing (OR 1.36, 95% CI=1.02-1.80), regular analgesia (OR 2.22, 95% CI=1.60-3.09), and chronic illness (OR 2.83, 95% CI=2.12-3.77) were independent risk factors for dyspepsia. Conversely, regular tea drinking (OR 0.59) seemed to have an inverse relationship.

CONCLUSIONS

Dyspepsia in rural Malaysians is associated with a lower HRQOL. Epidemiological risk factors include a higher socioeconomic status, regular analgesic consumption, and chronic illness.

Chronic atrophic antral gastritis and risk of metaplasia and dysplasia in an area with low prevalence of Helicobacter pylori

INTRODUCTION

The Northeastern region of Peninsular Malaysia is an area with exceptionally low prevalence for Helicobacter pylori infection. The risk of intestinal metaplasia and dysplasia in patients with chronic atrophic gastritis (CAG) and its association with Helicobacter pylori is unknown in this region.

METHODS

This was a cross-sectional study on gastric biopsies from 234 consecutive patients (mean age 53.5 [14.8] years) who underwent upper gastrointestinal endoscopy between January 2006 and December 2006.

RESULTS

There were 137 (59%) men and 185 (79%) Malay patients. Among 234 biopsies, CAG was found in 99 and non-atrophic gastritis in 135. Intestinal metaplasia and dysplasia were detected in 8 and 6 atrophic gastritis biopsies, respectively, and in 10 and 3 of non-atrophic gastritis biopsies, respectively. H. pylori were detected in 16 (9 Malays, 7 non- Malays) biopsies (p=0.024); intestinal metaplasia was detected in 4 biopsies (p=0.3) and dysplasia in 5 biopsies (p=0.3). Of the 218 biopsies negative for H. pylori, intestinal metaplasia was found in 14 and dysplasia in 4. The risk of intestinal metaplasia as well as dysplasia was associated with presence of H. pylori infection (p=0.029 and p<0.001 respectively).

CONCLUSION

Even in a setting of low prevalence of H. pylori, intestinal metaplasia and dysplasia were significantly associated with H. pylori infection. The frequency of intestinal metaplasia and dysplasia was similar different between biopsies with atrophic gastritis and non-atrophic gastritis.

Review article: Helicobacter pylori-negative duodenal ulcer disease

BACKGROUND

Helicobacter pylori infection rates in duodenal ulcer (DU) patients may be lower than previously estimated.

AIM

To review the real prevalence of H. pylori-negative DUs and its possible causes.

METHODS

Bibliographical searches in MEDLINE looking for the terms 'H. pylori' and 'duodenal ulcer'.

RESULTS

Mean prevalence of H. pylori infection in DU disease, calculated from studies published during the last 10 years including a total of 16 080 patients, was 81%, and this figure was lower (77%) when only the last 5 years were considered. Associations with H. pylori-negative DU were: (1) False negative results of diagnostic methods, (2) NSAID use (21% in studies with <90% infection rate), (3) Complicated DU (bleeding, obstruction, perforation), (4) Smoking, (5) Isolated H. pylori duodenal colonization, (6) Older age, (7) Gastric hypersecretion, (8) Diseases of the duodenal mucosa, (9) Helicobacter'heilmanii' infection and (10) Concomitant diseases.

CONCLUSION

In patients with H. pylori-negative DU disease, one should carefully confirm that the assessment of H. pylori status is reliable. In truly H. pylori-negative patients, the most common single cause of DU is, by far, the use of NSAIDs. Ulcers not associated with H. pylori, NSAIDs or other obvious causes should, for the present, be viewed as 'idiopathic'. True idiopathic DU disease only exceptionally exists.

Contemplating the future without Helicobacter pylori and the dire consequences hypothesis

Helicobacter pylori is a serious chronic transmissible pathogen that causes gastric structural and functional damage and is a major cause of morbidity and mortality worldwide. H. pylori is one of the digestive tract pathogens that has traveled with mankind since before humans moved out of Africa. Some have suggested that the long association of H. pylori with humans means there must be a benefit and suggest dire consequences will follow its eradication. Fortunately, there are now sufficient experiences with the outcome of treatment and with populations where the infection disappeared long ago to support the conclusion that H. pylori is a serious chronic transmissible pathogen that no one needs, deserves, or desires. The dire consequence hypotheses have proven to be erroneous attempts to blame some of the problems facing the modern world on a pathogen that was and is responsible for much suffering, morbidity, and mortality. It is time to join together to eradicate it and to let H. pylori join smallpox and polio on the hit list of undesirables.

Thoughts about populations with unexpected low prevalences of Helicobacter pylori infection

Helicobacter pylori is one of the few remaining major pathogens that accompanied humans on their travels from Africa. A recently published study reports the unexpected finding of a low H. pylori prevalence among pregnant women in Zanzibar (Farag, T.H., Stolzfus, R.J., Khalfan, S.S., Tielsch, J.M., 2007. Unexpectedly low prevalence of Helicobacter pylori infection among pregnant women on Pemba Island, Zanzibar. Trans. R. Soc. Trop. Med. Hyg. 101). The apparent epidemiology of higher prevalence with higher socioeconomic status and decrease with age are unprecedented. As with many 'unexpected' events, a search of the literature reveals evidence of low prevalence populations in Java and Malaysia, with clues dating back to the mid-twentieth century. Why some populations apparently lost H. pylori infection remains an open question. However, the tools needed to resolve the dilemma are readily available and we hope investigators will soon rise to the challenge.

Unexpectedly low prevalence of Helicobacter pylori infection among pregnant women on Pemba Island, Zanzibar

Helicobacter pylori is strongly associated with peptic ulcer and gastric cancer and may be the most common human bacterial infection. The epidemiology of H. pylori has been poorly studied in Africa, where its relevance to disease has not been fully appreciated. Following a cross-sectional study design, H. pylori infection was measured by (13)C-urea breath test among 857 pregnant women attending antenatal care clinics. Location, water use practices, anthropometry, and social and demographic variables were assessed as covariates. The prevalence of H. pylori infection was 17.5%. Multiple logistic regression showed that H. pylori was positively associated with location of enrollment clinic along the main road leading from the southern seaport (odds ratio (OR)=2.5), presence of costlier household lighting in the home (OR=1.6) and height (10 cm) (OR=1.5). The prevalence of H. pylori infection was unexpectedly low for a developing country population, where prevalence is typically very high. Higher prevalence along the road from the southern seaport suggests that infection was imported from the mainland. The reason for very low prevalence should be investigated further because the discovery of bacterial or dietary factors that limit infection in this population could have useful public health applications.

Precise role of H pylori in duodenal ulceration

The facts that H pylori infection is commoner in duodenal ulcer (DU) patients than in the normal population, and that eradication results in most cases being cured, have led to the belief that it causes DU. However, early cases of DU are less likely than established ones to be infected. H pylori-negative cases are usually ascribed to specific associated factors such as non-steroidal anti-inflammatory drugs (NSAIDs), Crohn’s disease, and hypergastrinaemia, but even after excluding these, several H pylori-negative cases remain and are particularly common in areas of low prevalence of H pylori infection. Moreover, this incidence of H pylori negative DU is not associated with a fall in overall DU prevalence when compared with countries with a higher H pylori prevalence. In countries with a high H pylori prevalence there are regional differences in DU prevalence, but no evidence of an overall higher prevalence of DU than in countries with a low H pylori prevalence. There is no evidence that virulence factors are predictive of clinical outcome. After healing following eradication of H pylori infection DU can still recur. Medical or surgical measures to reduce acid output can lead to long-term healing despite persistence of H pylori infection. Up to half of cases of acute DU perforation are H pylori negative. These findings lead to the conclusion that H pylori infection does not itself cause DU, but leads to resistance to healing, i.e., chronicity. This conclusion is shown not to be incompatible with the universally high prevalence of DU compared with controls.

Ideology of Helicobacter pylori prevalence in peptic ulcer disease in an inner-city minority population

GOALS AND BACKGROUND

The prevalence of Helicobacter pylori infection among patients with peptic ulcer disease has been reported to range from 61 to 94%. Recent studies show a reduction in the prevalence of H. pylori infection in patients with peptic ulcer disease. This study was conducted to determine the prevalence of H. pylori infection in peptic ulcer disease in an inner-city hospital in Washington, DC.

METHODS

Medical records of all patients who had undergone upper gastrointestinal endoscopy from July 1997 through June 1999 were reviewed. All patients who had gastric ulcer and/or duodenal ulcer on upper gastrointestinal endoscopy were studied. Demographic characteristics, history of nonsteroidal antiinflammatory drug ingestion, alcohol consumption, and associated diseases were studied. H. pylori was considered to be present if CLOtest and/or histopathology were positive for H. pylori. Patients with negative pathology for H. pylori or negative pathology and CLOtest were considered negative for H. pylori.

RESULTS

One-hundred fifty-six patients were found to have gastric and/or duodenal ulcers. Fifty-one ulcer patients did not meet the inclusion criteria and were excluded. Among the 105 patients who were included in the study, gastric ulcers were found in 48 patients (45.7%), duodenal ulcers were found in 46 patients (43.8%), and both gastric and duodenal ulcers were found in 11 patients (10.5%). H. pylori was present in 66.7% of gastric ulcer patients and in 69.5% of duodenal ulcer patients. Antral histology and CLOtest were in agreement 96% of the time.

CONCLUSIONS

At the District of Columbia General Hospital, an inner-city hospital serving predominantly an African-American community, the prevalence of H. pylori in ulcer patients compares similarly to other more recent studies that have found a decreased prevalence of this bacterial infection in ulcer patients. This suggests that the treatment of H. pylori in minority patients is reducing the proportion of ulcers due to this bacterium, as has been seen with the majority population.