Introduction
Epidemiology of H. pylori Infection
Prevalence of H. pylori infection
Country | N studied cases | Age range (years) | Pre-valence | Ref. |
---|---|---|---|---|
Developing Countries
1
: | ||||
Bangladesh
| 181 | 20-44 |
92%
| [95] |
Brazil
| ||||
- rural | 40 (children) | < 20 |
77.5%
| - rural |
164 (adults) | 20-90 |
84.7%
| [96] | |
- urban | 363 | > 20 |
63.4%
| [97] |
- poor urban community | 204 | 18-80 |
80%
| [98] |
Colombia (rural) | 684 | 2-9 |
69%
| [99] |
China
| ||||
- Southern China | 1727 | N/A |
44.2%
| [9] |
- Hong Kong | 397 | 36-65 |
58.6%
| [100] |
- Changle of Fujan | 1456 |
80.4%
| [100] | |
Egypt
| ||||
- Alexandria (northern) | 169 mothers | N/A |
88%
| |
169 children | < 1 |
13%
| ||
1.5 |
25%
| [101] | ||
- Cairo (central) | 52 | < 6 |
33%
| |
56 | > 6 |
60%
| [102] | |
- Assiut (southern) | urban | N/A |
87%
| |
rural | N/A |
40%
| [103] | |
- poor urban area | schoolchildren | N/A |
72.4%
| [104] |
India
| 238 | 3-70 |
79%
| [13] |
Mexico
| 11605 | 20-90 |
66%
| [61] |
Nepal (rural) | 1142 | 4-93 |
56.8%
| [69] |
407 | 2 mo-12 yr |
48%
| [105] | |
Peru
| 104 | 0-17 |
50%
| [70] |
Russia
| 213 | 20-75 |
88%
| [106] |
- St. Petersburg 1995 | 307 | 2-19 |
44%
| |
- St. Petersburg 2005 | 370 | 2-19 |
13%
| [18] |
Saudi Arabia
| 557 | 5-10 |
40%
| [107] |
> 20 |
70%
| |||
Taiwan
| 823 | 1-40+ |
54%
| [78] |
Developed Countries
1
: | ||||
Australia (urban Melbourne) | 273 | 19-47 |
23%
| [32] |
Denmark
| 3589 | 30-60 |
25.9%
| [108] |
Germany (western) | 260 | 18-61 |
39.2%
| [60] |
Israel (rural) | 377 | 30-90 |
72%
| [109] |
Japan
| 4361 | 19-69 |
30%
| [110] |
Netherlands
| 254 (employees) | 11-89 |
27.2%
| [111] |
New Zealand
| 579 workers: | 40-64 |
56%
| |
- Europeans | 190 |
35.8%
| ||
- Maori | 195 |
57.4%
| ||
- Pacific Islanders | 194 |
73.2%
| [64] | |
Spain
| 332 | > 18 |
43%
| [112] |
- mountain | 1782 |
54%
| ||
- coastal | 154 |
30%
| ||
South Korea
| 161 | 20-75 |
75%
| [113] |
Switzerland
| 176 natives | 10-20 |
7.3%
| [81] |
20 immigrants |
30%
| |||
United Kingdom
| ||||
- England | 267 (healthy) | > 18 |
41%
| [114] |
467 (all males) | 18-65 |
37.5%
| [115] | |
- Northern Ireland | 4742 | 12-64 |
50.5%
| [116] |
- South Wales | 1796 | 45-59 |
70%
| [117] |
United States
| ||||
- South Carolina | 938 army recruits | 17-26 |
26%
| |
324 blacks |
44%
| |||
47 Hispanics |
38%
| |||
536 whites |
14%
| [66] | ||
- California | 556 | 20-39 |
27%
| [67] |
- Texas | 246 blacks | 15-80 |
70%
| |
239 whites |
34%
| [59] |
Incidence of H. pylori infection
Transmission of H. pylori infection
I. Direct transmission [For a detailed review, see Ref. [11]]
1) Oral-oral transmission
2) Gastro-oral transmission
3) Fecal-oral transmission
II. Indirect transmission
Hypothesis | Evidence/Example studies | Ref. |
---|---|---|
Food
| ||
- Contaminated food prepared under unhygienic conditions is a probable mechanism for transmission. | A positive correlation was reported between prevalence of infection and consumption of food from street vendors in Peru. | [70] |
- The daily amount of raw vegetables is a risk factor, which possibly implies a role for water too. | In the Colombian Andes, frequent consumption of raw vegetables was associated with likelihood of infection. | [99] |
- Sheep and cow milk can be vehicles for transmission. | See below (under Animals) | |
Animals
| ||
- Several animal species were suggested as H. pylori reservoirs. | H. pylori was isolated from: | |
- pigtailed monkeys | [120] | |
- rhesus monkeys | [121] | |
- cats | [122] | |
- sheep | [123] | |
- cockroaches | [124] | |
- houseflies (but the housefly hypothesis was challenged) | ||
- Working with animals may increase risk, and animal-to-human transmission is possible. | H. pylori was suggested as zoonotic, occupational infection to meat and abattoir workers. | |
In Colombian Andes, children who had contact with sheep had higher prevalence odds. | [99] | |
Dore et al. stated that animals, especially sheep and dogs, could transmit H. pylori to humans (shepherds) in Sardinia. | [129] | |
- H. pylori can be recovered from animal products. | H. pylori was recovered from sheep and cow milk. | |
- Experimental animal colonization is possible. | Bacillary forms of H. pylori were used to colonize germ-free piglets. | [130] |
Water
| ||
- Water contamination is a risk factor for H. pylori infection. | Many reports, mostly from developing countries, suggested contaminated water sources as risk factors. Examples include studies performed in Peru, Chile, and Kazakhstan. | |
- Water from running, municipal, and underground sources, as well as wastewater has been suggested as reservoir for H. pylori. | - Municipal water | [105] |
- Well water | [133] | |
- Running water | ||
- Wastewater | [135] | |
- H. pylori even survives in chlorinated water. | [136] | |
- H. pylori proteins and DNA can be detected in water. | - by immunological methods | [137] |
- by PCR | ||
- by hybridization methods | [139] | |
- Viable H. pylori can be detected and isolated from water. | - as individual cells | [140] |
- associated with biofilm | ||
- cultured | [135] |