Helicobacter pylori: The Stomach Bacteria, Explained

Helicobacter pylori — the famous "stomach bacteria" — is one of the most widespread infections in the world: about one person in two carries it, often since childhood and without any symptom. It is also one of the most requested tests in our medical analysis laboratory in Tangier. Here is what it causes, how it is detected, and the point almost everyone misses: why the post-treatment check is not done with a blood test.

What does H. pylori do in the stomach?

This bacteria has a rare ability: it survives stomach acidity and settles there for years. In most carriers it causes nothing perceptible. In others, it sustains chronic inflammation of the stomach lining (gastritis) which can cause burning or stomach pain, bloating, nausea — and can be complicated by ulcers. Over the very long term, an untreated infection increases the risk of certain serious stomach diseases: that is precisely why doctors treat the bacteria when they find it. Another lesser-known consequence: by hindering iron absorption, it can contribute to iron deficiency and anaemia visible on the blood count.

Which tests detect H. pylori?

Several methods exist, and they do not say the same thing:

• blood serology detects antibodies: it says you met the bacteria at some point, not whether it is still there — antibodies persist long after the bacteria is gone;
• stool antigen testing detects the bacteria itself: a positive result means an active infection;
• biopsy during gastroscopy, performed by the gastroenterologist, examines the stomach lining directly.

Your doctor chooses the method for your situation — simply bring your prescription to the laboratory and we will tell you the required preparation (some stomach medicines sometimes need suspending before the test: never do this on your own, ask the prescriber).

Treatment — and the point everyone misses: the control

Treatment combines several medicines prescribed by the doctor for a precise duration; followed properly, it eliminates the bacteria in the vast majority of cases. What matters next is verifying it is really gone, a few weeks after the end of treatment — and that is where the difference between tests becomes concrete: serology stays positive for a long time even when the bacteria is eliminated. Eradication control is therefore done with stool testing (or a breath test depending on the case), never with a simple blood test. A patient who "stays positive" on serology after treatment is not necessarily still infected.

Frequently asked questions

How is H. pylori caught?

Most often in childhood, within the family, through saliva or contaminated water and food. That is why several members of the same family often carry it — if one is treated, the doctor may suggest testing relatives who have symptoms.

Which symptoms should bring this bacteria to mind?

Stomach burning or pain that lasts or returns, persistent bloating or nausea, iron deficiency anaemia without another explanation. But many carriers have no symptom at all — screening is decided with the doctor.

Should I fast before the test?

Not for blood serology. For stool testing, medication preparation is what matters: some stomach treatments can distort the result if not suspended — check with your prescriber, and our team reminds you of the instructions at drop-off.

Positive serology: am I sick?

Not necessarily. Antibodies say you met the bacteria, not that it is still present or causing lesions. The doctor interprets, if needed ordering a stool test to know whether the infection is active.

Does the treatment work?

Yes, in the vast majority of cases when followed completely and to the end. Failures exist (resistant bacteria, interrupted treatment): that is what eradication control detects, so the doctor can adapt if needed.

What about children?

The infection is often acquired in childhood, but screening and treating children follows particular rules: it is the paediatrician's decision, never a routine test to do on your own.

To go further: our articles on fasting before a blood test and the value of an annual blood checkup.