The National Academies

The National Academies: What You Need To Know About Infectious Disease

What You Need To Know About Infectious Disease

Helicobacter Pylori

Helicobacter pylori, or H. pylori, are bacteria that live in human gastric mucosa. The bacteria produce an enzyme that neutralizes the stomach’s digestive acids, allowing the bacteria to live in harsh, acidic conditions. About half of the human population has an H. pylori infection, making it one of the world’s most common bacterial infections. While the exact origins and transmission of H. pylori are unknown, it is most likely transmitted through contact with infected saliva or feces. It may also be spread through contaminated food or water. Most often the infection is acquired during childhood.

Most H. pylori infections do not produce symptoms. However, because the bacteria affect the gastrointestinal tract and digestive system, some infections can lead to abdominal pain, vomiting, nausea, bloating, and loss of appetite. H. pylori infection is the major cause of peptic ulcer disease, and it also increases the risk of gastritis (inflammation of the stomach lining) and duodenal ulcers. Symptoms of these diseases are similar to those already mentioned and can also include bloody or black vomit and stools.

Treatment of H. pylori usually involves a combination of antibiotics over a period of 10 to 14 days. Sometimes supplemental medicines that reduce stomach acids are used to reduce symptoms and increase the effectiveness of antibiotics.

There are no specific, proven ways of preventing infection. No vaccine is available, and there are no recommended drugs for preventing infection. It is advised that people follow the normal precautions for preventing many infectious diseases—handwashing with soap frequently throughout the day, drinking clean water, and eating food that has been properly prepared and cooked.


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What do you know about infectious disease?

Which are larger?

  • Correct!

    Bacteria are 10 to 100 times larger than viruses.

  • Sorry, that’s incorrect.

    Bacteria are 10 to 100 times larger than viruses.

Infectious Disease Defined


An organism in which a parasite that is pathogenic for some other organism lives and reproduces without harming its host.

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