Helicobacter pylori (H. pylori) is a very common — and yes, contagious — type of bacteria that infects the digestive tract. Typically, the bacteria enter the mouth and work their way into the gastrointestinal tract.

The germs may live in saliva. This means someone with the infection can pass it on through kissing or oral sex. You can also become infected through fecal contamination of food or drinking water.

Although H. pylori infections are typically harmless, they’re responsible for most ulcers in the stomach and digestive tract. These ulcers can lead to more serious complications, such as stomach cancer.

Read on to learn how you can get H. pylori, what the symptoms are, and how it’s treated.

H. pylori is present inabout 60 percent of the world’s population. A 2014 study in the Central European Journal of Urology suggests that as many as 90 percent of people with an H. pylori infection may carry the bacteria in their mouth and saliva.

This means that the infection can spread through oral sex (in addition to kissing) and may also be a likely cause of urethritis. Urethritis is an inflammation of the urethra that’s treated with antibiotics.

Research has also found that H. pylori may lead to a range of serious health problems, including certain types of gastric cancers and gastric ulcers. In 2018, researchers reported that H. pylori may also play a role in the development of Parkinson’s disease.

As common as H. pylori is, evidence suggests its prevalence may be falling, primarily in developed nations and in children. That said, this bacterial infection continues to be a concern among many ethnic minorities.

A 2018 report in the journal Gastroenterology notes another concern: Worldwide resistance of H. pylori to antibiotics may be growing dramatically.

H. Pylori is highly contagious

H. pylori infection can be spread through kissing, oral sex, and contaminated food or drinking water.

If you’re taking antibiotics to treat H. pylori, you’re still contagious until tests show the infection is gone.

Living in highly crowded conditions or in areas without a consistently clean water supply raises the risk of H. pylori infection. Unsanitary conditions at home or in the community can also increase the chances of developing this infection.

These conditions tend to be more common in developing countries, which is why H. pylori remains a greater threat in these regions than in areas with more reliable sources of clean drinking water.

In addition, living with family members or others who have the H. pylori infection can make you more vulnerable. People taking antibiotics to treat an H. pylori infection are still contagious until tests confirm the infection is gone.

It’s not always clear how H. pylori is passed from one person to another, but good personal hygiene is one way to help reduce your odds of infection. Thorough and frequent handwashing is important, especially after using the bathroom and before eating or cooking.

You should also make sure your food is clean and has been prepared and cooked properly. Likewise, make sure your drinking water is safe and clean.

Be especially mindful of these preventive measures if you spend time in a part of the world where public sanitation is a challenge, and clean sources of drinking water and food are scarce.

If you live with someone with H. pylori, help make sure they complete their treatment program as prescribed by their physician. A person is still contagious until they finish their course of antibiotics and tests show the infection is gone.

Most people with H. pylori don’t have symptoms. It’s not clear why the infection causes problems for some individuals and not for others. If you have the infection, but show no signs of it, you may simply have a greater resistance to the bacteria’s impact on your system.

When symptoms are present, they can include:

  • abdominal pain that’s more acute when you’re hungry
  • a stomach ache or burning sensation in your gut
  • nausea
  • reduced appetite
  • unexplained weight loss
  • gas
  • bloating

If the abdominal distress doesn’t subside or if it’s accompanied by black, tarry stools, or black vomit that looks like coffee grounds, you should see a doctor immediately. Trouble swallowing is also a sign of a worsening H. pylori infection.

If you have H. pylori but no symptoms, you’re still contagious

If you have no obvious systems, but still have the H. pylori infection, you can pass it along to someone else.

A person undergoing treatment is still contagious until they finish their course of antibiotics and tests show the infection is gone.

H. pylori infections are diagnosed with a combination of a physical exam and certain lab tests. The lab tests look for the actual bacteria or signs that your body is fighting the infection.

These tests include:

  • Blood test. This test checks for antibodies that indicate the presence of an H. pylori bacterial infection.
  • Stool test. A small stool sample is sent to a lab and examined for any abnormal bacteria.
  • Breath test. This test is given after you swallow a urea pill containing carbon molecules. If carbon molecules are found, it indicates that your body is making an enzyme called urease. This enzyme makes stomach acid less acidic and weakens the stomach’s mucous lining.

Treating an H. pylori infection usually requires antibiotics to kill the harmful bacteria. In most cases, a combination of two different antibiotics is prescribed.

You’ll be retested after you finish your course of antibiotics to make sure the infection is gone. Some infections require an additional round of antibiotics.

Other medications may also be helpful. Among them are:

Antibiotics are the most effective means of treating H. pylori symptoms. However, some natural H. pylori treatments can help ease your symptoms, too.

The nature of your treatment plan will depend on several key factors, most importantly the severity of your infection and symptoms. Other considerations include:

  • your age
  • your overall health and medical history
  • your tolerance or resistance to certain medications
  • the prognosis of your infection

Once treatment has started, you should expect to see your doctor for a follow-up appointment in about four weeks. You’ll be tested again to see how well you’re responding to treatment and if the infection has cleared up.

If you still have the infection, an additional round of antibiotics may be necessary. Your doctor may consider a different combination of antibiotics and other medications to get the desired results.

Complications of an H. pylori infectioncan include ulcers, as well as stomach cancer and esophageal cancer. If no complications arise, your prognosis is usually good following proper treatment.

Reinfection risks are low — about 1 to 2 percent for men, and 5 to 8 percent for women and children. You won’t be contagious if tests show the infection is gone.

H. pylori is a common bacterium that may cause you no symptoms or complications. An H. pylori infection can be serious, but it’s treatable.

The key is to respond quickly to signs of an infection. Be sure to tell your doctor if you think you’ve been exposed to the bacteria.

For example, if you might have been exposed during recent travels or by spending time with someone who’s infected. This may prompt your doctor to test for H. pylori if they haven’t yet considered it.

Also keep in mind that for antibiotics to be effective, they need to be taken as prescribed by your doctor. Continue to take the full course of antibiotics, even if your symptoms go away. An infection can linger despite the fact that you may be feeling better.

Also, be sure to follow up with your doctor after completing your antibiotic treatment to confirm that the H. pylori infection is gone.