Helicobacter pylori (H. pylori), also termed as "ulcer bacteria”, is a type of bacteria which was first discovered to have a tendency to attack the stomach in 1983 by Warren and Marshall. Infection with H. pylori occurs worldwide, but the prevalence varies greatly among countries and among population groups within the same country. The overall prevalence of H. pylori infection is strongly correlated with socio-economic conditions. Eight in 10 middle-aged adults are affected in many developing countries as compared with 20 to 50 per cent in industrialised countries. The infection is acquired by oral ingestion of the bacterium and is mainly transmitted within families in early childhood. The higher prevalence in older age groups is thought to reflect a cohort effect related to poorer living conditions of children in previous decades.

How someone with H. pylori infection presents?

H. pylori causes chronic inflammation in the stomach and duodenum, and is a common contagious cause of ulcers. Normally, it infects your stomach during childhood. While infections with this strain of bacteria typically don’t cause symptoms, they can lead to diseases including peptic ulcers and an inflammatory condition inside the stomach known as gastritis. The infections are thought to spread from one person’s mouth to another, transferred from faeces to the mouth and can happen when a person does not wash their hands thoroughly after using the toilet. It can also spread through contact with contaminated water or food.

Most people with H. pylori don’t have any symptoms until the infection leads to an ulcer. Initial symptoms may include abdominal pain, especially during the night when the stomach is empty or a few hours after meals. The pain is usually described as a gnawing pain which may come and go with or without nausea and vomiting.

When suspected to have H. pylori infection, your blood or stool may serve as samples to confirm the disease.

H. pylori the main cause of gastric cancer

H. pylori is classified by the World Health Organisation as a definite human gastric carcinogen.Gastric cancer is one of the most common and lethal type of cancer worldwide. It is the fifth leading cancer and the third leading cause of death worldwide, making up 7 per cent of cases and 9 per cent of deaths. In 2012, it occurred in 950,000 people and caused 723,000 deaths.

It occurs twice as often in males as in females.The stomach cancer in Rwanda peaks at age 80+. At 113.4 deaths per 100,000 men in 2013, the peak mortality rate for men was higher than that of women, which was 69.3 per out of 100,000 women. Different hypothesis affirm that feminizing hormone "estrogen” is protecting women from gastric carcinoma.

Infection with H. pylori is recognised as the major cause of gastric cancer and its discovery is arguably the most significant advance made in gastro duodenal pathology. It is the biggest cause of chronic gastritis, and almost certainly the major etiological factor responsible for duodenal ulcer. Those bacteria are adapted to live in the harsh, acidic environment of the stomach because they can change the environment around them and reduce its acidity to survive. The shape of H. pylori allows them to penetrate the stomach lining which is protected by a specialised mucus.

The immune cells can’t really do much as it is not able to reach them and destroy the bacteria, this prolong their life and increase risk of stomach problems.

Research on H. pylori has emphasized on mechanistic and epidemiology to understand how dysregulated and persistent release of H. pylori chemicals lead to the development of chronic inflammation and the cellular events related to carcinogenesis. Stomach cancer, also known as gastric cancer, is cancer developing from the lining of the stomach. It’s now understood that peptic ulcers are not caused by alcohol, stress or eating foods high in acid even if they are exacerbating factors.

Early symptoms may include heartburn, upper abdominal pain, nausea and loss of appetite. Later signs and symptoms may include weight loss, yellowing of the skin and whites of the eyes, vomiting, difficulty swallowing, and blood in the stool among others.

H. pylori and children

Infection of H. pylori is more likely to develop in childhood where many are at its higher risk due to lack of proper food hygiene but most of symptoms start at adolescent age. This increases as we get older therefore prevention of gastric cancer should start at an early age and focus primarily on food hygiene.

The writer is a fifth year medical student at University of Rwanda