H. pylori is a common bacterium, and approximately 50 percent of the world's population has been estimated to be infected (198). Humans are the principal reservoir. The prevalence of H. pylori infection varies widely by geographic area, age, race, ethnicity, and SES. Rates appear to be higher in developing than in developed countries, with most of the infections occurring during childhood, and they seem to be decreasing with improvements in hygiene practices. H. pylori causes chronic gastritis and has been associated with several serious diseases of the gastrointestinal tract, including duodenal ulcer and gastric cancer. Since its "discovery" in 1982 by Warren and Marshall (1), H. pylori has been the topic of extensive research. A number of studies have used questionnaire components to investigate factors possibly related to the etiology of H. pylori infection. The majority of recent studies have not found tobacco use or alcohol consumption to be risk factors for H. pylori infection. Adequate nutritional status, especially frequent consumption of fruits and vegetables and of vitamin C, appears to protect against infection with H. pylori. In contrast, food prepared under less than ideal conditions or exposed to contaminated water or soil may increase the risk. Overall, inadequate sanitation practices, low social class, and crowded or high-density living conditions seem to be related to a higher prevalence of H. pylori infection. This finding suggests that poor hygiene and crowded conditions may facilitate transmission of infection among family members and is consistent with data on intrafamilial and institutional clustering of H. pylori infection. Understanding the route of H. pylori transmission is important if public health measures to prevent its spread are to be implemented. Iatrogenic transmission of H. pylori following endoscopy is the only proven mode. For the general population, the most likely mode of transmission is from person to person, by either the oral-oral route (through vomitus or possibly saliva) or perhaps the fecal-oral route. The person-to-person mode of transmission is supported by the higher incidence of infection among institutionalized children and adults and the clustering of H. pylori infection within families. Also lending support to this concept is the detection of H. pylori DNA in vomitus, saliva, dental plaque, gastric juice, and feces. Waterborne transmission, probably due to fecal contamination, may be an important source of infection, especially in parts of the world in which untreated water is common. Recent studies in the United States have linked clinical H. pylori infection with consumption of H. pylori-contaminated well water. This area of research is worthy of further investigation. Although H. pylori has been isolated in domestic cats, additional research has suggested that H. pylori is probably uncommon in domestic cats and thus is probably not a major concern for cat owners. Several studies have suggested sheep as a possible source of H. pylori transmission, a hypothesis that deserves additional investigation. The most recent reservoir suggested for H. pylori transmission is the housefly. However, evidence is lacking that H. pylori can be transmitted to humans from flies that have been in contact with H. pylori-infected feces. Nevertheless, the hypothesis is appealing since flies are known to carry many other infectious diseases. Knowledge of the epidemiology and mode of transmission of H. pylori is important to prevent its spread and may be useful in identifying high-risk populations, especially in areas that have high rates of gastric lymphoma, gastric cancer, and gastric ulcer.

Helicobacter pylori: epidemiology and routes of transmission.

Objective. Gastroesophageal reflux disease has been reported to be a common burden on health-care resources in the Western world, but its manifestations in the general population are as yet unclear. The aim of this study was to estimate the prevalence of, and to identify the risk factors for gastroesophageal reflux symptoms (GERS) and erosive esophagitis (EE) in the adult population of two Swedish municipalities. Material and methods. A random sample (n=3000) of the adult population (20–81 years of age) of two Swedish municipalities (n=21,610) was surveyed using a validated postal questionnaire assessing gastrointestinal symptoms. The response rate was 74%. A subsample (n=1000) of the responders was subsequently invited, in random order, for esophago-gastro-duodenoscopy with evaluation of GERS, risk factors and tests for Helicobacter pylori. Results. GERS were reported by 40.0% and EE was found in 15.5% of the population that had undergone endoscopy. Of those with GERS, 24.5% had EE while 36.8% of those w...

High prevalence of gastroesophageal reflux symptoms and esophagitis with or without symptoms in the general adult Swedish population: a Kalixanda study report.

Despite its decreasing trend in Japan, gastric cancer remains an important public health problem. Although the age standardised rates of gastric cancer have been declining for decades, the absolute numbers are increasing because of the rapid aging of the population. A large proportion of Japanese gastric cancers are detected at an early stage, with a better overall survival rate. As with Western developed countries, a change in the social environment such as reduced salt use and increased fresh vegetable and fruit intake as well as improvement of food storage may play an important part in the decline. Differences in Helicobacter pylori infection rates between generations presumably have contributed to the generation related variation in the declining trends. It is expected that most gastric cancers in Japan may be preventable by lifestyle modification such as salt reduction and increased fruit and vegetable intake, together with avoidance of smoking and countermeasures against H pylori infection so that the level now evident in Western developed countries can be reached.

https://pmj.bmj.com/content/postgradmedj/81/957/419.full.pdf

Epidemiology of gastric cancer in Japan

Recent developments in the epidemiology of Helicobacter pylori.

BACKGROUND: Helicobacter pylori-associated gastrointestinal diseases have been widely recognized. The aims of this study were to investigate the interval change of seropositivity of H. pylori between 1998 and 2005 in Korean adult population and to find the factors related to H. pylori infection. METHODS: Between January and December of 2005, a total of 15,916 health check-up subjects (aged > or = 16 years) from all parts of South Korea responded to the questionnaire, and the prevalence of H. pylori was investigated by measuring anti-H pylori IgG antibodies. The seropositivity in asymptomatic subjects (aged > or = 16 years) was compared with that of 1998, which was surveyed by the Korean H. pylori Study Group. RESULTS: The overall seropositivity rate (aged > or = 16 years) was 56.0%, and 13.9% of seropositive subjects were found to have a history of H. pylori eradication therapy. With the exclusion of subjects who had a history of H. pylori eradication and current gastrointestinal symptoms, the seropositivity rate of H. pylori became 59.6% in 8020 subjects. Seroprevalence of H. pylori was significantly higher in subjects aged 50-59 years, males, low income group, and subjects from provinces. The seroprevalence in 2005 (59.6%) significantly decreased compared with that of 1998 (66.9%), and the decrease was significant in subjects aged < 70 years, Seoul and Gyeonggi province (which is close to Seoul). CONCLUSIONS: The seroprevalence of H. pylori in asymptomatic health check-up adult subjects in 2005 decreased to 59.6% from 66.9% in 1998, probably as a result of the improvement of socioeconomic status and hygiene.

Seroprevalence of Helicobacter pylori in South Korea.

The cross sectional study describes the prevalence of infection with Helicobacter pylori as determined by a serodiagnostic assay in over 3000 asymptomatic subjects, in two age groups 25-34 years and 55-64 years, from 17 geographically defined populations in Europe, North Africa, North America, and Japan, using a common protocol for blood collection and serological testing. In all populations combined, the prevalence of infection was higher in the older age group (62·4%) than in the younger age group (34·9%). There was no difference in prevalence of infection between men and women. Subjects with higher education had considerably lower levels of infection (34·1%) compared with subjects with education up to secondary level (46·9%) or those with primary education only (61·6%). This trend was confined to the older of the two age groups. In contrast a trend of increasing prevalence of infection with increasing body mass index was confined to the younger of the two age groups. There was no effect of smoking or alcohol consumption on the prevalence of infection after adjusting for the other risk factors. There was considerable variation in the prevalence of infection between the 17 populations but, within populations, low education standard was consistently and positively associated with the prevalence of infection.

/pdf/epidemiology-of-and-risk-factors-for-helicobacter-pylori-1imhtfuabe.pdf

J Tycznski

Papers

Epidemiology of, and risk-factors for, helicobacter-pylori infection among 3194 asymptomatic subjects in 17 populations.