Helicobacter pylori, the bacteria that afflicts half of the world’s population and about whose transmission little is known

The Conversation

If there is a cosmopolitan and universal bacteria, it is Helicobacter pylori (H. pylori): can affect people all over the world and of all ages, although it is more common and acquired earlier in less developed countries.

Half of the world’s population is believed to be infected by it, no less.

In some cases it can persist and cause disease in the stomach and duodenum. And, incredible as it may seem, despite being so widespread, it still we know very little about how it is transmitted.

A special bacteria

These gastric microorganisms were observed for the first time more than 100 years ago, and their relationship with gastritis became evident in the 1970s. In 1982, Marshall and Warren identified and cultivated the stomach bacteria called Campyobacter pyloridiswhich was later classified as Helicobacter pylori.

This bacteria has special characteristics that allow it to survive in a very hostile environment such as the stomach and thus cause some diseases. It has been linked to chronic gastritis, many ulcers, and stomach cancer, as well as lymphoma.

Little is known about the transmission

It is not known exactly how the infection is transmitted. H. pylorialthough it is probably produced through fecal-oral or oral-oral exposure between different people.

Humans appear to be the main reservoirs of H. pylori, although it has also been found in captive primates and domestic cats. The latter may have viable bacteria in their saliva and gastric juice, which they could transmit to humans.

Sheep can also house H. pylori in their milk and gastric juice, which perhaps explains the fact that shepherds have infection more frequently than their descendants.

Fecal-oral transmission is also possible. The use of contaminated water in less developed countries can serve as an environmental source of the bacteria. H. pylori It can survive in water for several days, which allows us to find traces of it in the water of areas where infection is frequent.

Children who swim in rivers, streams, pools or eat uncooked vegetables can become infected more easily. The bacteria has also been found in the feces of African children, where by five years of age almost all of their inhabitants are infected.

The more siblings, the more infections

The clustering of infections in some families suggests the possibility of transmission between people. For example, spouses with H. pylori They are more likely to infect their relatives (wives and children) than the uninfected.

In a study carried out in Colombia, it was found that the risk of infection was related to the number of children between two and nine years of age who lived in the same home. It was even shown that younger children were infected more frequently when older children in the same household were also infected.

Colonies have been isolated H. pylori genetically identical in people from the same family and in those living within the same institution, suggesting the possibility of transmission between people living together.

In addition to familial transmission that occurs in developed countries, it can also occur between unrelated people who live in countries with a high frequency of infection.

Helicobacter in dental plaque

Oral-oral transmission of the bacteria has not been confirmed, although it has been identified in dental plaque. However, dentists and dental hygienists who are exposed through their work do not have H. pylori more frequently. It is also known that infected gastric secretions can be a source of transmission of this bacteria.

Different medical devices, such as endoscopes and their accessories, can transmit H. pylori after having been in contact with them. Digestive system doctors and nurses may be at greater risk of becoming infected, which could occur due to their exposure during their work to infected gastric secretions.

To reduce this risk of accidental or occupational transmission, they must be properly disinfected after use with patients.

Hereditary susceptibility

The existence of hereditary susceptibility to infection by H. pylori It is not proven, although individuals of some ethnicities and races present infection more frequently than others. For example, Hispanics and African Americans have higher rates of infection than Caucasian Americans. These differences are not completely explained by the social or economic differences between them.

The possibility of susceptibility to infection is also pointed out in studies done on twins. Thus, those who have grown together have a higher infection concordance than those who have grown separately. Therefore, the role of the environment during childhood seems to be important in the acquisition of H. pylori.

More studies are needed

Not many things are still known about H. pyloria bacteria on which more research is needed to know how we can avoid its transmission.

The fecal-oral and oral-oral routes between different people seem to be the most probable forms of transmission, although it is still not clear. Luckily, once the infection is cured, a new one is not common.

This low rate of reinfection supports the existence of a lower risk of acquiring this bacteria during adult life. Immunity acquired after the first infection may also be important.