Helicobacter pylori (H. pylori) is a type of bacteria that infects the stomach lining and is one of the most common infections worldwide being present in nearly 50% of the world human population. The prevalence of H. Pylori is higher in some countries. Central American countries have a prevalence of 50-70% while in the U.S. is it found in 30-40% of the population. Infection is linked to lower social economical status, poor hygiene especially with food preparation, and travel to countries with high rates.

What is Helicobacter Pylori?
H. pylori is a spiral-shaped bacterium that thrives in the acidic environment of the stomach. It is transmitted primarily through contaminated food or through saliva. Transmission of H.pylori is oral-oral or by saliva. This may be from kissing, sharing utensils, and food contaminated with saliva. Generally, it is not a fecal-orally transmitted bacteria as very little of the bacteria makes it to the colon alive (remember, it needs an acidic environment). Once inside the stomach, H. pylori burrows into the stomach lining and disrupts the mucous lining that protects the stomach, leading to inflammation and increased susceptibility to damage from stomach acid.
Symptoms of Chronic H. Pylori Infection
Before discussing chronic infection, let’s cover an acute or new infection. When a person initially contracts H. pylori, he or she will typically have significant new or worsening in chronic heartburn. Many people carry this bacteria without any symptoms, however, one may not be aware that conditions and symptoms may be related to a chronic H. pylori infection.
My personal experience with acute H. pylori: I contracted H. pylori while at a wedding in Mexico: Initially, I had a night of the most severe acid reflux I ever had in my life to the point it was burning up to my throat followed by several days of the most severe sore throat I have ever had and a burning sensation to my posterior nasal cavity. I felt sick and oddly, when I cleared by throat and blew my nose large chunks of something came out. I recall the day when 1/3 of the wedding guests sitting at the poolside were drinking hot tea and saying they were sick with a severe sore throat. About 10 days later a persistent searing burning sensation to my upper stomach developed. I also had moments of severe lightheadness in which I thought I may pass out (this made me think I had fish worms from eating ceviche). I could not eat anything except fresh fruits and vegetables without having nausea resulting in an aversion to all meats and dairy.
When someone is infected with H. Pylori for many months or years, the acute symptoms have likely resolved. While some individuals with H. pylori may remain asymptomatic, chronic infection can lead to noticeable symptoms, including:
Abdominal discomfort or pain: Often described as a dull or burning sensation in the upper abdomen.
Nausea and vomiting: Persistent nausea and occasional vomiting may occur.
Bloating and indigestion: Chronic inflammation of the stomach lining can cause gastrointestinal discomfort.
Unexplained weight loss: This may be a sign of ulcers or more severe complications.
Loss of appetite: A lack of desire to eat can stem from persistent stomach discomfort.
Rashes: Any new, persistent rash should be considered possible H. Pylori.
Concerning skin conditions, presence of H. pylori should be considered when psoriasis is present. In a 2017 one study, people who have psoriasis had a prevalence of 72% while controls had an infection rate of 33.3%.1 The study also found that the more severe the psoriasis was, the more likely H. Pylori was to be present.1 The following year, another study found the same result of H.pylori more lively to be present in people with psoriasis and the psoriasis more severe in those with the infection.2
Complications of Chronic H. Pylori Infection
Once H. pylori is eradicated, chronic complications do not occur. If left untreated, chronic H. pylori infection can lead to:
Peptic ulcers: Erosions in the stomach or duodenal lining caused by inflammation and acid damage.
Gastritis: Chronic inflammation of the stomach lining, which may cause long-term discomfort.
Stomach cancer: Chronic infection is a significant risk factor for gastric cancer, particularly in regions where H. pylori prevalence is high.*
Iron deficiency anemia: The bacteria’s impact on stomach acidity and nutrient absorption can lead to iron deficiency.
*In recent years some medical communities consider the presence of this bacteria in asympotmatic people to be a colonization that may be beneficial. This is not supported by the 1994 WHO and International Agency for Research on Cancer (IARC) decision to designate this bacteria as a group 1 carcinogenic organism.3 Any group 1 carcinogens have been proven to cause cancer and others with this designation include cigarette smoke, alcohol, and many industrial chemicals.
Chronic H. Pylori Infection & Dementia
Several new studies are looking at the possibility of H. pylori as a modifiable risk factor for the development of dementia. “In a population-based cohort of 4,262,092 patients aged 50 years or older without dementia, of clinically apparent Helicobacter pylori infection in the previous 2 years or more was associated with an 11% increased risk for Alzheimer's disease (AD) compared with no exposure to CAHPI (clinically apparent H. pylori infection). A secondary analysis found a similarly increased risk for non-AD dementia with CAHPI exposure.”4,5.
It may seem odd that a stomach bacteria would contribute to brain dysfunction. H. pylori does this by bacteria-derived outer membrane vesicles (OMVs) which act as natural carriers of virulence factors. The vesicles have the ability to stread beyond the gut and cross the blood-brain-barrier (BBB). Virulent OMVs may travel up the vagus nerve (a large nerve that directly connects the brain to the GI tract) or through the blood stream. Due to their small size, they can can cross the BBB where they are taken up by the BBB cells, the astrocytes. OMVs then activate astrocytes and other glial cells (brain’s immune system and nerve lining cells) resulting in inflammatory effects leading to neuronal dysfunction. These inflammatory changes exacerbate amyloid-β pathology (this is a waste-product brain protein which may be forming at a higher rate and/or not being cleared by the brain’s immune cells) resulting in cognitive decline.6
What to do?
If you think you may have an H. pylori infection, you should get tested. There are multiple tests available but unfortunely no test is 100% sensitive at picking up the infection. When a negative test occurs, a repeat test should be considered. Use of stomach-acid-lowering medications in the two weeks prior to testing lowers the sensitive of the test as these medications lower the amount of the bacteria present and available to allow for a positive test.
References:
Mesquita PM, Diogo A Filho, Jorge MT, Berbert AL, Mantese SA, Rodrigues JJ. Relationship of Helicobacter pylori seroprevalence with the occurrence and severity of psoriasis. An Bras Dermatol. 2017 Jan-Feb;92(1):52-57. doi: 10.1590/abd1806-4841.20174880. PMID: 28225957; PMCID: PMC5312179.
WC, Upala S, Sanguankeo A. Association between Psoriasis and Helicobacter pylori Infection: A Systematic Review and Meta-analysis. Indian J Dermatol. 2018 May-Jun;63(3):193-200. doi: 10.4103/ijd.IJD_531_17. PMID: 29937554; PMCID: PMC5996629.
IARC Working Group on the Evaluation of Carcinogenic Risks to Humans Schistosomes, liver flukes and Helicobacter pylori. Lyon, June 7-14, 1994. IARC Monogr Eval Carcinog Risks Hum. 1994;61:1–241.
H pylori Infection Linked With Increased Alzheimer's Risk - Medscape - January 02, 2024.
Douros A, Ante Z, Fallone CA, Azoulay L, Renoux C, Suissa S, Brassard P. Clinically apparent Helicobacter pylori infection and the risk of incident Alzheimer's disease: A population-based nested case-control study. Alzheimers Dement. 2024 Mar;20(3):1716-1724. doi: 10.1002/alz.13561. Epub 2023 Dec 13. PMID: 38088512; PMCID: PMC10984501.
Xie J, Cools L, Van Imschoot G, Van Wonterghem E, Pauwels MJ, Vlaeminck I, De Witte C, El Andaloussi S, Wierda K, De Groef L, Haesebrouck F, Van Hoecke L, Vandenbroucke RE. Helicobacter pylori-derived outer membrane vesicles contribute to Alzheimer's disease pathogenesis via C3-C3aR signalling. J Extracell Vesicles. 2023 Feb;12(2):e12306. doi: 10.1002/jev2.12306. PMID: 36792546; PMCID: PMC9931688.
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