This map of the world shows the percentages of H. pylori infection.
After innumerable epidemiologic studies of H. pylori infection patterns worldwide, one factor emerges as the most important determinant of infection: poverty. Does this mean that everyone who has an H.pylori infection is poor,or that all poor people are infected? Definitely not. So how does poverty cause H. pylori infection? It doesn’t, actually, but impoverished communities have characteristics that may facilitate the spread of the H. pylori infection from person to person. These factors, which include overcrowding, poor sanitation,insects,lack of adequate facilities with which to boil water or thoroughly cook food, and consumption of contaminated produce,allow the organism to travel easily from person to person.
Person-to-person contact is the main route of infection and that, rather than getting H. pylori from the environment, most people tend to become infected by other members in their households. Upon examination of all members of a given family,it became apparent that most people were infected in infancy or early childhood, and that the risk was greatest when the mother was infected, implying that parents transmit the bacterium to their children. Several things that mothers do for their children may explain this high rate of infection among children in the developing world .In India,where mothers moisten their nipples with saliva before feeding their infants,the rate of infection is much higher than among neighboring Pakistani women, who do not.Also,in Ethiopia,where baby food is not affordable or commonly available, mothers partially chew the food that they feed their babies, which may explain why over 80 percent of Ethiopian children are infected before the age of six.
Poor Sanitation and Contaminated Food
While person-to-person contact is thought to be the most likely cause of infection,other factors are undoubtedly at work. Fecal-oral exposure is one route by which many people become infected with H. pylori.Because H. pylori is shed in the feces of infected persons, poor sanitation leads to increased exposure. This is particularly true in impoverished agricultural areas where soil is fertilized with human sewage. Growing food in fecally-contaminated soil may lead to increased rates of infection, particularly when the food is either poorly cooked or uncooked (such as salad vegetables).
In addition to person-to-person contact, other sources of infection have been identified. In Peru, a country with very high rates of H. pylori infection, contaminated drinking water was found to be one source of transmission.In one study,more people who drank water from their city’s water supply were infected than those who used well water. Further studies in Peru demonstrated that H. pylori was indeed present in the drinking water, and that people who boiled their water had lower rates of infection than those who did not. This suggests that H. pylori infection can also be spread through drinking water, particularly in countries in which water sanitation is poor and drinking water is not sanitized in the home by boiling or chlorination.
Insects may be another source of food contamination. Houseflies have been repeatedly implicated as agents in the spread of H. pylori. The bacterium can live for up to 12 hours on the body of a housefly,and for more than 24 hours in its intestine. As flies move across food or other surfaces, they leave droppings that contain bacteria, which can then be ingested and lead to infection.Along a similar vein,feces of cockroaches that have been fed H. pylori cultures can be found to contain the bacterium for up to 24 hours, suggesting that food contaminated with the fecal material of these insects can transmit the bacterium to humans, particularly if the food is not properly cooked or washed with clean water.