Helicobacter pylori prevalence in Leipzig's 1998 school entries: methodology and first results

The non-invasive, stable-isotope-aided Helicobacter pylori (H. pylori) tests--breath and equivalent urine tests--were offered on a voluntary basis as part of the mandatory school entry medical examination to the 1998 school entry cohort of the City of Leipzig (480,000 residents). Parents of participating subjects were asked to fill out a detailed epidemiologic questionnaire. The response rate was 94% (n = 2228 of 2369 school starters born in 1991/92). Parent-completed questionnaires were returned by 1890 (80%) children. The overall H. pylori positive prevalence was 7.2%. The prevalence among children with a test and a parent-completed questionnaire was 6.5%. Prevalences among subsequently tested family members of the positive tested children was 65, 60 and 39% for mothers, fathers and siblings respectively. Though studies have shown that the direct transmission of the bacterium (oral-oral and fecal-oral) is a dominant pathway of infection, the questionnaire analyses indicate associations between H. pylori colonisation and living as well as environmental conditions.

Transmission of Helicobacter pylori among siblings

BACKGROUND

Helicobacter pylori infection causes chronic digestive diseases with a major public-health impact, yet the design of prevention measures is hampered by limited knowledge of transmission pathways. We studied the effect of family composition on H. pylori prevalence among rural Colombian children aged 2-9 years.

METHODS

684 children were screened for H. pylori with the 13C-urea breath test. For each child, birth order, birth spacing, number of 2-9-year-old siblings, and number of H-pylori-positive 2-9-year-old siblings was recorded. Odds ratios were estimated by logistic regression, controlling for hygiene-related exposures, socioeconomic indicators, and the number of children in the household.

FINDINGS

The odds of infection increased with the number of 2-9-year-old siblings in the household (odds ratios 1.4, 2.3, 2.6, and 4.3 for one, two, three, and four to five siblings, respectively). Compared with first-born children, odds ratios for children born second and third to ninth were 1.8 (95% CI 1.0-3.3) and 2.2 (1.0-4.3), respectively. Compared with children born 10 or more years after the next older household member, those born within 4 years were 4.1 times (CI 2.0-8.6) more likely to be infected; the age gap to the next younger household member displayed a weaker effect. The number of H-pylori-positive 2-9-year-old siblings had a particularly strong effect gradient (1.5, 3.2, 5.6, and 7.1, for one, two, three, and four positive siblings, respectively).

INTERPRETATION

Among rural Andean children younger than 10 years, H. pylori infection seems to be transmitted most readily among siblings who are close in age, and most frequently from older siblings to younger ones.

Helicobacter pylori: epidemiology and routes of transmission

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 infection among offspring of patients with stomach cancer

BACKGROUND & AIMS

A positive family history is associated with an increased risk of stomach cancer. We compared the prevalence of Helicobacter pylori infection, a known risk factor for stomach cancer, between subjects with and without parental history of stomach cancer to evaluate a potential role of H. pylori infection in familial aggregation of stomach cancer.

METHODS

A total of 1351 men and women aged 30-74 years who participated in the German Health and Nutrition Survey conducted in the western part of Germany in 1987-1988 were included in the study. Detailed information on sociodemographic factors, nutritional factors, and parental history of cancer was obtained by standardized interviews. Serum samples were analyzed for immunoglobulin G antibodies against H. pylori by enzyme-linked immunosorbent assay.

RESULTS

The prevalence of H. pylori infection was much higher (69%) among subjects with a parental history of stomach cancer than among other subjects (44%). This association persisted after control for potential confounders by multiple logistic regression (adjusted odds ratio, 2.7; 95% confidence interval, 1.3-5.9), and was particularly strong among subjects below age 55 (adjusted odds ratio, 5.1; 95% confidence interval, 1.6-16.1).

CONCLUSIONS

These results suggest that familial aggregation of stomach cancer may be explained at least partly by familial clustering of H. pylori infection.

A dynamic transmission model for predicting trends in Helicobacter pylori and associated diseases in the United States

To assess the benefits of intervention programs against Helicobacter pylori infection, we estimated the baseline curves of its incidence and prevalence. We developed a mathematical (compartmental) model of the intrinsic dynamics of H. pylori, which represents the natural history of infection and disease progression. Our model divided the population according to age, infection status, and clinical state. Case-patients were followed from birth to death. A proportion of the population acquired H. pylori infection and became ill with gastritis, duodenal ulcer, chronic atrophic gastritis, or gastric cancer. We simulated the change in transmissibility consistent with the incidence of gastric cancer and duodenal ulcer over time, as well as current H. pylori prevalence. In the United States, transmissibility of H. pylori has decreased to values so low that, should this trend continue, the organism will disappear from the population without targeted intervention; this process, however, will take more than a century.

Association of Helicobacter pylori infection with gastric cancer

BACKGROUND

Helicobacter pylori has generated public health interest since its identification in 1983. Past studies have suggested that the bacterium plays a role in the pathogenesis of gastric cancer. More recent studies support the conclusion that the association of H. pylori with gastric cancer is causal. The purpose of this article is to review the available evidence supporting the association of H. pylori with gastric cancer.

METHODS

We performed a critical review of the relevant literature published in the English language on H. pylori and gastric cancer using MEDLINE, Index Medicus for the years 1985 to 1997. The reference lists of selected articles also were reviewed to capture citations for further pertinent studies.

RESULTS

H. pylori is thought to be the major cause of chronic atrophic gastritis. H. pylori gastritis is worldwide in distribution. H. pylori is now categorized by the International Agency for Cancer Research as a group 1 carcinogen, i.e., an agent that is carcinogenic to humans. Several reports from the United States have found the highest frequencies of gastric cancer in geographic areas and populations with the highest rates of acquisition of H. pylori infection. The high prevalence of H. pylori infection has been documented most notably in blacks and Hispanics, who also are at high risk for gastric cancer.

CONCLUSIONS

New studies that focus on the epidemiology and pathology of H. pylori improve our understanding of its relationship with gastric cancer and advance the development of gastric cancer prevention and control strategies that are proposed.

Does maternal smoking hinder mother-child transmission of Helicobacter pylori infection?

Evidence for early childhood as the critical period of Helicobacter pylori infection and for clustering of the infection within families suggests a major role of intrafamilial transmission. In a previous study, we found a strong inverse relation between maternal smoking and H. pylori infection among preschool children, suggesting the possibility that mother-child transmission of the infection may be less efficient if the mother smokes. To evaluate this hypothesis further, we carried out a subsequent population-based study in which H. pylori infection was measured by 13C-urea breath test in 947 preschool children and their mothers. We obtained detailed information on potential risk factors for infection, including maternal smoking, by standardized questionnaires. Overall, 9.8% (93 of 947) of the children and 34.7% (329 of 947) of the mothers were infected. Prevalence of infection was much lower among children of uninfected mothers (1.9%) than among children of infected mothers (24.7%). There was a strong inverse relation of children's infection with maternal smoking (adjusted odds ratio = 0.24; 95% confidence interval = 0.12-0.49) among children of infected mothers, but not among children of uninfected mothers. These results support the hypothesis of a predominant role for mother-child transmission of H. pylori infection, which may be less efficient if the mother smokes.

Fecal and oral shedding of Helicobacter pylori from healthy infected adults

CONTEXT

Helicobacter pylori commonly infects humans; however, its mode of transmission remains unknown.

OBJECTIVE

To determine how humans-the primary host for H pylori-shed the organism into the environment.

DESIGN

Controlled clinical experimental study conducted from February through December 1998.

SETTING

Clinical research unit of a hospital in northern California.

PATIENTS

Sixteen asymptomatic H pylori-infected and 10 uninfected adults.

INTERVENTION

A cathartic (sodium phosphate) and an emetic (ipecac) were given to all infected subjects and an emetic was given to 1 uninfected subject.

MAIN OUTCOME MEASURE

Confirmed H pylori isolates cultured from stool, air, or saliva before and after catharsis and emesis and from vomitus during emesis. Isolates were fingerprinted using repetitive extragenic palindromic (REP) polymerase chain reaction and species identity was confirmed by sequencing the 16s ribosomal RNA gene.

RESULTS

All vomitus samples from infected subjects grew H pylori, often in high quantities. Air sampled during vomiting grew H pylori from 6 (37.5%) of the 16 subjects. Saliva before and after emesis grew low quantities of H pylori in 3 (18.8%) and 9 (56.3%) subjects, respectively. No normal stools and only 22 (21.8%) of 101 induced stools grew the organism, although 7 (50.0%) of 14 subjects had at least 1 positive culture (2 stool culture samples were contaminated by fungus and were not included). Fingerprints of isolates within subjects were identical to one another but differed among subjects. No samples from uninfected subjects yielded H pylori.

CONCLUSIONS

Helicobacter pylori can be cultivated uniformly from vomitus and, occasionally, from saliva and cathartic stools. The organism is potentially transmissible during episodes of gastrointestinal tract illness, particularly with vomiting.

Helicobacter pylori: characteristics, pathogenicity, detection methods and mode of transmission implicating foods and water

Helicobacter pylori is an organism involved in the pathogenesis of human active chronic gastritis, peptic and duodenal ulcer diseases and gastric cancer. This review article covers this emerging human pathogen in terms of its phenotypic and genotypic characteristics, methods for culturing, its role in gastric pathogenicity, evidence involving its mode of transmission, difficulty in its isolation and detection methodology. In terms of transmission, both foodborne and waterborne pathways have been speculated as the mode of transmission for H. pylori as the patterns of the infection are consistent with those from fecal-oral and oral-oral transmission. Therefore, it is important to also evaluate methods for the detection of H. pylori from specifically food products and water. The detection of this pathogen has proved difficult since changes in cell morphology, metabolism and growth patterns occur when H. pylori is exposed to different environmental stimuli. The development of a viable but non-culturable coccoid (VNC) form is observed. These VNC forms do not undergo cellular division and cannot be cultured by traditional methods, increasing the difficulty in their detection. Since both viability and virulence in the VNC form of H. pylori are retained, the examination of food products and water for these forms is critical. Current methods include filtration, immuno-separation (IMS), polymerase chain reaction (PCR), probe hybridization, immuno-staining, autoradiography and ATP bioluminescence.

Epidemiology of Helicobacter pylori: transmission, translocation and extragastric reservoirs

Although H. pylori infection is endemic and despite more than 10 years of research, the mode and route of transmission remain elusive. This may, in part, be due to the inherent problems of detecting H. pylori noninvasively. The prevalence of infection varies between countries and is closely related to Growth Domestic Product. An age-cohort effect and data from longitudinal studies suggest that the incidence of infection is much higher in children than adults. In developing countries the prevalence of infection is often more than 80% in young adults, in contrast to less than 10% for similar age groups in developed countries. The observations of mosaicism (in the VacA gene) and a panmycytic population structure imply exchange of genetic material either in or outside of the host, which is supported by the increasing recognition of polyclonal infection and suggests that secondary infection occurs after primary acquisition. In addition, in children persistent primary infection may sometimes occur only after previous (repeated) exposure and/or transient colonisation of the gastric mucosa. H. pylori and other gastric Helicobacter spp are always noninvasive, but other human nongastric Helicobacter spp have sometimes been isolated from the systemic circulation in immunocompromised patients. For nonhuman hosts, intestinal Helicobacter spp are thought to translocate more frequently from the colon to the liver. Within the human host, the oral cavity is the principal extragastric reservoir, although case reports suggest that H. pylori may sometimes be found beyond the 2nd part of the duodenum. The hypothesis that H. pylori is a zoonosis or transmitted as coccoid forms by a vector (pets, houseflies) is not supported by recent research showing that H. pylori is entirely unable to support an aerobic or anaerobic metabolism and that coccoid forms are non-viable. H. pylori is primarily acquired in infancy, most probably via the oroorogastric route, from other family members or close contacts encountered after weaning or socialisation. Further studies to support or refute this hypothesis are required.

Rare incidence of interspousal transmission of Helicobacter pylori in asymptomatic individuals in Japan

PCR-restriction fragment length polymorphism electrophoretic patterns of amplified ureB and ureC of Helicobacter pylori were compared between spouses after digestion with restriction endonucleases. Twenty of 21 couples, both members of which were positive for H. pylori, showed ureB and ureC patterns that differed between spouses. We concluded that in Japan, interspousal transmission of H. pylori occurs rarely.

Helicobacter pylori associated gastric pathology

Helicobacter pylori (HP), undoubtedly, the most common world-wide infection plays an important role in pathogenesis of peptic ulcer. Proof for a causal role for HP in peptic ulcer rests in two major points; 1) the majority of ulcer patients are HP infected and the prevalence of this infection for both gastric ulcer (GU) and duodenal ulcer (DU) is much higher than for gender- and age-adjusted controls and 2) the cure of HP infection dramatically reduces ulcer recurrence. Conclusions regarding the mechanisms by which HP induces peptic ulcer are restricted mainly to studies observing the consequences of its eradication by antibiotics combined with gastric inhibitors or bismuth agents. Several specific virulence factors such as cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) as well as other noxious substances including ammonia, lipopolysaccharide (endotoxin), platelet activating factor (PAF), nitric oxide (NO) and others have been implicated in gastritis and were found to be significantly more frequent in gastric cancer than in gender- and age-matched controls, especially in younger generation. Chronic inflammation, atrophic gastritis, intestinal metaplasia, impaired defense mechanisms combined with hypergastrinemia, deficiency of vitamin C in the stomach , excessive oxygen metabolites and epithelial cell proliferation have been associated with gastric cancer. This multi-step pathway originally proposed by Correa and his colleagues, long before the HP was discovered in the stomach, leads to cancer but may be reversed by eradication of HP. This is, however, a controversial issue because gastric atrophy and intestinal metaplasia may be also caused by other factors such as bile reflux, dietary irritants, and autoimmunity. The implication of HP in MALT-lymphoma is based on the observations that eradication of HP in early stage of low-grade of this tumor leads to complete remission. The significance of HP in non-ulcer dyspepsia remains questionable and requires further studies.

Helicobacter pylori infection and host cell responses

It is well known that Helicobacter pylori is able to colonize the gastric mucosa, causing a chronic and persistent infection with complications, such as peptic ulcer and gastric cancer. This review places emphasis on some epidemiological aspects of Helicobacter pylori infection and its mode of transmission. At the same time, invasive and non-invasive methods of diagnosis of Helicobacter pylori infection are illustrated. More space is devoted to the host response following invasion of the stomach. In this respect, the role played by different growth factors and polyamines in the course of Helicobacter pylori disease is discussed also in relation to the result of eradicating treatment. On the other hand, an accurate description of the host immune responses against Helicobacter pylori organism and/or their components (e.g. lipopolysaccharides) is reported. Finally, since Helicobacter pylori has been classified as a class I carcinogen, current researches are focussed on the Helicobacter pylori-induced carcinogenesis.

Isolation of Helicobacter pylori from vomitus in children and its implication in gastro-oral transmission

OBJECTIVE

The route of transmission of Helicobacter pylori (H. pylori) is unclear. Gastro-oral transmission via contaminated vomitus has been proposed as an important mode of transmitting H. pylori, especially in children. This pilot study attempted to isolate H. pylori from the vomitus of children.

METHODS

Children presenting for evaluation with gastroenteritis-associated vomiting were studied. Fresh vomitus samples were collected for detection of H. pylori by bacteriological culture and polymerase chain reaction, (PCR). A rapid, whole blood test was used to determine the H. pylori status of patients.

RESULTS

A total of 18 children with mean age of 6 yr were studied; four had a positive serology test. Among these four children, H. pylori was isolated from vomitus by culture in one child and by PCR in two. An 18-month-old girl with negative serology had H. pylori detected in vomitus by PCR. Six months later, she had seroconversion confirmed, suggesting that she had an acute H. pylori infection on initial presentation.

CONCLUSIONS

This is the first study reporting successful isolation of H. pylori from naturally produced vomitus. The result implies that transmission of H. pylori infection by vomitus, especially in children, is possible.

Enteric lesions in SCID mice infected with "Helicobacter typhlonicus," a novel urease-negative Helicobacter species

BACKGROUND AND PURPOSE

Several rodent helicobacters have been associated with chronic active hepatitis or inflammatory bowel disease. Severe combined immunodeficient (SCID) mice appear to be inherently susceptible to disease attributable to these emerging pathogens. With the advent of polymerase chain reaction (PCR) analysis, it has become clear that several as yet unidentified Helicobacter species may also colonize rodents, but their capacity to cause disease is unknown.

METHODS

A Helicobacter species isolated from feces of a BALB/c mouse and provisionally named "H. typhlonicus" was used to inoculate helicobacter-free 4-week-old SCID mice (n = 11 males and 11 females). At various weeks after inoculation, mice were sacrificed and liver and intestinal specimens were collected for histologic examination and PCR analyses.

RESULTS

The C.B-17 scid/scid mice inoculated with "H. typhlonicus" developed moderate to severe proliferative typhlocolitis, similar to that seen in SCID mice infected with H. hepaticus or H. bilis. However, in contrast to mice infected with H. hepaticus or H. bilis, lesions of chronic active hepatitis were not detected in mice inoculated with "H. typhlonicus." A similar disease syndrome developed in SCID mice cohabitated with B6D2F1 mice naturally infected with a novel Helicobacter species that was genetically identical to "H. typhlonicus."

CONCLUSION

"Helicobacter typhlonicus" joins a growing list of helicobacters that are capable of inducing enteric disease in immunodeficient mice.

Helicobacter pylori in the natural environment

The presence of Helicobacter pylori (H. pylori) in the natural environment has been demonstrated in a number of studies. However, its route of infection into humans is unknown. To study this further, we attempted to detect H. pylori in the natural environment in a region of Japan with a high infection rate. Tap and well water and field soil samples were collected from around the residences of subjects who had participated in an epidemiological survey in 1996. Samples of water from rivers and ponds, and specimens of flies and cow faeces were collected in the region. DNA was extracted from the water, field soil and faecal samples after selective collection of H. pylori by the immunomagnetic-bead separation technique. H. pylori-specific DNA was detected in water, field soil, flies and cow faeces by nested polymerase chain reaction (PCR), and the ureA partial sequences of the PCR products were aligned. The nucleotide sequences of the samples amplified by PCR were highly homologous (96-100%) with the H. pylori sequence in the GenBank database and the H. pylori-specific DNA sequences were highly homologous with each other. These findings suggest the existence of H. pylori in the natural environment and a possible transmission route.

Helicobacter pylori antibody profile in household members of children with H. pylori infection

Intrafamilial spread is implicated as a major route for acquisition of Helicoobacter pylori infection. Investigating H. pylori cytotoxin-associated protein (CagA) and vacuolating toxin (VacA) antibodies within family members enabled the authors to evaluate this possibility further. Serum samples were collected prospectively from household members after their index children were diagnosed with active H. pylori infection. Serum samples were evaluated for anti-H. pylori immunoglobulin G antibody using the enzyme immunoassay (IEA) method and for H. pylori CagA and VacA antibodies with the commercially available immunoprobing Western blot kit. Ten different families participated in the study, including 10 pediatric patients and 31 household members. All patients and 28 household members (90%) were seropositive for H. pylori antibody by IEA and Western blot tests. Overall, 17 subjects (41.4%) were CagA positive, 14 (34.1%) were VacA positive, 11 (26.8%) were positive for both antibodies, and 22 (53.6%) were negative for both antibodies. A significant association in bacterial antibody profile was found between the patient index members and all household members (Cohen's kappa and Mentel-Haenszel methods). In four families, more than 66% of the household members harbored the same antibody profile, and in two families a completely different profile was observed. Moreover, a similar H. pylori antibody profile between the index patient and the mother was found in six families, and between the index patient and the father in two families. The data strongly suggest an intrafamiliar transmission for H. pylori infection.

Helicobacter pylori in animals affecting the human habitat through the food chain

Helicobacter pylori (HP) is the causative agent of many gastrointestinal diseases. Horses, calves, pigs, rabbits, and chickens were evaluated for HP presence, and the pathogenetic effect on their gastric mucosa. The large-sized animals all resulted positive. No positive cases were observed in rabbits and chickens. Chronic inflammatory response to the infection with the development of acquired lymphoid tissue associated to the mucosa was revealed. The recognition of HP in animals living near the human habitat such as animals for slaughter and for technical zootechnic and alimentary use, before the witnessing of the transmission of this infection such as a zoonosis or an anthropozoonosis, can contribute to research on a common source for human and animals as reservoir. It is possible to consider that the intraspecies transmission of infection occurs by vomit, the mucus acting as a vector, while the interspecies one is due to the faecal contamination of the food chain.

Transmission of Helicobacter pylori infection

Helicobacter pylori infection is one of the most common bacterial infections worldwide. It is accepted as the major cause of chronic gastritis, peptic ulcer, carcinoma of the distal part of the stomach and gastric lymphoma. However, how and when the infection is acquired remain largely unknown. Identification of mode of transmission is vital for developing preventive measures to interrupt its spread, but studies focused on this issue are difficult to implement. From epidemiological studies, it is known that there are great differences in the prevalence of infection in different populations and in ethnic groups originating from high prevalence regions. This is likely related to inferior hygienic conditions and sanitation. In developing countries, infection occurs at a much earlier age. In developed countries, the prevalence of infection is related to poor socioeconomic conditions, particularly density of living. Humans seem to be the only reservoir of H pylori, which spread from person to person by oral-oral, fecal-oral or gastro-oral routes. Most infections are acquired in childhood, possibly from parents or other children living as close contacts. Infection from the environment or from animals cannot be entirely excluded.