Helicobacter pylori is closely related with gastritis, peptic ulcer, gastric cancer and gastric MALT lymphoma, and it may participate in a variety of parenteral diseases. Infection rates of Helicobacter pylori is still high, so effectively eradication is necessary. At present, the eradication therapy has achieved very good curative effect. However, relapse after eradication is unoptimistic. This study has made an analysis for reinfection after eradication of Helicobacter pylori Infection include the retrospective and prospective studies, aims to explore the epidemiological data and related risk factors of Hp reinfection in China.

In the retrospective study,we choose the people received regular eradication therapy, successfully eradicated helicobacter pylori more than six months, but 4 to 8 weeks after drug withdrawal ,the detection result of helicobacter pylori were negative to ensure that the results of the study is the reinfection, not residual. Even more noteworthy is during the treatment and detection again, the patients must not received any eradication therapy of Hp. What's more , before the detection, they also has not used antibiotics, bismuth agent and the traditional Chinese medicine with antibacterial effect in 1 monthor and has not used H2RA and PPI in 2 weeks to prevent affecting the accuracy of the results. At the same time, we also investigated the patient's general situation, conomic conditions, living conditions, personal health and lifestyle to explore related risk factors of Hp reinfection in China. In the prospective study, we detected Hp by C-UBT after regular eradication therapy of Hp for 4 weeks, 8 weeks and 6 months to prospect the reinfection of Hp.It also can make up the defects of retrospective study.

Inclusion Criteria:

-1、Retrospective study：

1. Received regular eradication therapy, 4 to 8 weeks after drug withdrawal , detected of helicobacter pylori and the results were negative
2. Eradication program and original disease is unlimited
3. Without any eradication therapyof Hp during the treatment and detection again
4. before the detection has not used antibiotics, bismuth agent and the traditional Chinese medicine with antibacterial effect in 1 monthor and has not used H2RA and PPI in 2 weeks.

2、Prospective study

1. Infected with H. pylori that detected by C-UBT
2. With out alimentary tract hemorrhage,ulceration and complications of eradication
3. Eradication program and original disease is unlimited

Exclusion Criteria:

1. Pregnancy or breast-feeding women
2. With the major disease which would influence the research such as liver disease, heart disease, kidney disease, malignant tumor and alcohol poisoning
3. Participated in other drug research in the past three months
4. The patient can't express himself correctly such as mental illness and severe neurosis and can't cooperation this test

In the retrospective study,people who has infected helicobacter pylori and successfully eradicated it more than six months detected helicobacter pylori by the C-urea breath test in order to evaluate the reinfection In the prospective study,people who has infected helicobacter pylori received regular eradication therapy after the 4 weeks, 8 weeks and 6 months detected helicobacter pylori by the C-urea breath test in order to prospect the reinfection