This study was the first to investigate the prevalence of H. pylori and its associated risk factors in Hainan Province, China. We used 14C-UBT to detect H. pylori infection in people aged 14 years or older. The results indicated that the overall prevalence of H. pylori infection in Hainan Province was 38.7%, which was significantly lower than the overall prevalence of 44.2% in China (95% CI: 43.0–45.5%) and in line with the global trend of a continuous decrease in H. pylori infection in recent years [6, 7]. This is inextricably linked to China’s high economic growth, high level of universal health coverage, and improved public health conditions [17]. However, we also noted that only 9.7% (355/3632) of the population had previously received H. pylori screening and eradication treatment. This observation suggests that good scientific knowledge of H. pylori can potentially help to improve the awareness of H. pylori and alleviate the existing situation of H. pylori infection.
The prevalence of H. pylori infection was found to increase sharply with age but plateaus in the middle-aged and older age groups above 45 years. This result was similar to several large-scale epidemiological surveys in China [9, 10]. There could be two possible reasons to explain these findings. On the one hand, the rapid economic and health development in China in the last two decades has resulted in relatively few risk factors associated with H. pylori exposure in young people, which has markedly reduced the risk of infection. On the other hand, middle-aged and elderly people have a relatively less stable gastric environment as well as weaker organism resistance, and all of these factors can favor the colonization of H. pylori. However, there is no conclusive evidence regarding the possible relationship between gender and H. pylori infection. For instance, in one study Moshkowitz et al. suggested that H. pylori were more likely to colonize the gastric mucosa in women [18], but our study did not find a significant correlation between the gender and H. pylori infection, and this finding was in agreement with conclusions of several previous studies [8, 9].
Occupation is an important factor influencing H. pylori infection, which was consistent with the results of previous studies [8,9,10,11,12,13,14,15,16,17,18,19]. It is generally believed that occupational groups working in agriculture have a relatively higher risk of H. pylori infection, and multiple reasons may be involved to explain this finding. First, farmers generally have a low level of education and often have poor hygiene habits and lifestyles; and second these individuals often have a low socioeconomic status as well as limited access to medical resources for H. pylori screening and eradication treatment. Moreover, we found regional differences in the prevalence of H. pylori infection in Hainan Province, with economically developed areas (e.g., Haikou City) having significantly higher rates of H. pylori infection in comparison to economically backward areas (e.g.,Wuzhishan City). This observation also indirectly indicated that socioeconomic status was closely related to H. pylori infection.
It is now recognized that oral-oral, fecal–oral is the main transmission route of H. pylori [20]. In China, sharing of meals is an important food culture, but this can effectively increase the risk of H. pylori transmission and infection [14]. This was confirmed in the present study as it was found that people who share tableware are more likely to be infected with H. pylori. In addition, poor hygiene practices can substantially increase the risk of H. pylori transmission and serve as an important factor influencing H. pylori infection [21]. In our study, frequent premeal hand washing was identified as independent protective factors for H. pylori infection. Therefore, introduction of meal sharing and the promotion of personal hygiene as well as health awareness could be useful public health measures for the prevention of H. pylori infection.
A good lifestyle seems to be effective in reducing the risk of H. pylori infection and gastric cancer development [22]. We found that the prevalence of H. pylori infection was significantly lower in participants who participated in regular exercise, had regular meals and maintained a regular diet of fruits and vegetables compared to other populations who did not had such healthy habits, and they were also independent protective factors for H. pylori infection. The possible reasons could be as following (i) the presence of chemicals such as isothiocyanate radicicicin and mustard oleoresin in fruits and vegetables can effectively inhibit the colonization of H. pylori and thereby reduce the inflammatory response of the gastric mucosa [23]. (ii) Regular exercise can enhance the body’s immunity and regular diet can contribute to the stability of the gastric environment, all of which can significantly reduce the risk of H. pylori colonization. In our study, regular betel nut as well as alcohol consumption were associated with increased odds of H. pylori infection. The practice of washing the raw leaves of betel vine and betel nut (used in the preparation of betel nut liquid) in unclean water may explain our findings [24]. We also found that alcohol consumption is an independent risk factor for H. pylori infection. It is well established that home-brewing is more common in Hainan Province, but the production process is crude and the relevant indicators remain untested. A number of previous studies have reported that alcohol consumption has a protective effect or is not associated with H. pylori infection, probably due to increased gastric acid secretion and promotion of gastric emptying after alcohol intake, as alcohol has a powerful and direct antibacterial activity, thus potentially inhibiting the growth of H. pylori in the stomach. In addition, alcohol can promote gastric emptying and reduce the contact time between H. pylori and the gastric mucosa, which in turn can attenuate the rate of H. pylori infection [25, 26]. In particular, red wine was found to prevent H. pylori-induced gastritis in a mouse model [27]. Another study [28] reported alcohol as a significant risk factor for H. pylori infection because alcohol can directly damage the gastric mucosal layer, thus weakening the gastric mucosal defense barrier. Thus, alcohol could theoretically provide a pathway for H. pylori infection, while heavy alcohol consumption may predispose consumers to different social contacts that favor the transmission of H. pylori infection. Therefore, the potential relationship between alcohol consumption and H. pylori infection still requires further longitudinal and epidemiological studies for further explanation.
H. pylori infection serves as an important influencing factor in the development of gastric cancer. For instance, a large cohort study found that the incidence of gastric cancer increased each year with the duration of H. pylori infection [29]. In addition, the risk of gastric cancer as well as the risk of death decreased significantly after H. pylori eradication [30]. Similar to a previous study, we found that a family history of gastric cancer can serve as an independent risk factor for H. pylori infection [31]. Upper gastrointestinal symptoms were identified as one of the important risk factors for H. pylori infection in this study. However, asymptomatic infection is an important feature of most H. pylori-infected patients, who often have developed severe upper GI disease by the time they seek medical attention. Therefore, one should consider upper GI symptoms (e.g., nausea, acid reflux) as an early warning sign of H. pylori infection, which can be an important step for the timely diagnosis and treatment of H. pylori.
The strengths of this study include the fact that this was the first large-scale epidemiological investigation of H. pylori in Hainan Province, China. In addition, the method employed to detect H. pylori infection was highly accurate and specific. Of course, the study has some limitations. First, cross-sectional studies do not accurately reflect the temporal trends in H. pylori infection. Second, outcome and exposure were assessed simultaneously, which does not allow for a temporal relationship to be established. Finally, the age of our subjects was limited to those aged 14 years or older, thus failing to cover the entire age range in Hainan Province.
In conclusion, the prevalence of H. pylori infection in Hainan Province was significantly lower than the overall prevalence in China and closely related to age, local socioeconomic conditions, hygienic status and dietary habits.
