Helicobacter pylori Infection – A Boon or a Bane: Lessons from Studies in a Low-Prevalence Population

The prevalence of Helicobacter pylori infection varies globally from one geographical region to another with a greater prevalence generally being reported from developing countries [1,2]. South-East Asia is a cultural-diverse region rich with multiple ethnics and indigenous communities. One of the larger ethnic groups is the Malays (Melayu) who are a member of the Austronesian family, largely populating the Peninsular Malaysia, Sumatra, and Borneo. In the first half of the 20th century, it was noted that peptic ulcer and gastric cancer were rare in the ethnic Malays but not in the Chinese or Indian populations living in this region [3]. With the discovery of H. pylori being the etiological agent underlying gastric cancer, the ethnic Malays were also reported to have a low prevalence of H. pylori infection besides a low gastric cancer rate [4–6]. The population of the northeastern region of Peninsular Malaysia (state of Kelantan – Fig. 1) consists of 90% ethnic Malays and, over many centuries, has had minimal to no interactions with populations from the nearby Indonesian archipelago or with more recent migrants. A population genotyping study indicates that the Malays from this region are genetically distinctive from Malays of other parts of the Peninsular [7]. Despite the fact that the region (i.e., state of Kelantan) is among the lowest in coverage of clean water and sanitation facilities in the country [8], this unique Malay population has a prevalence of H. pylori infection that is probably the lowest in the world [9]. Studying this population may provide important insights to public health problems related to H. pylori infection especially in gastric cancer prevention. Figure 1 Map of Peninsular Malaysia showing the northeastern region (State of Kelantan). The reasons for the exceptionally low prevalence of H. pylori are intriguing and remain elusive [10]. One postulation is that this Malay population may have passed through bottlenecks in which its founding population was uninfected. Another possibility is that local practices or environmental factors may limit transmission or inhibit the infection. Unidentified genetic or host factors intrinsic to this population may also result in them being less susceptible to H. pylori infection or cancer as a whole. Studying this unique population also provides some insights into answering the contentious issue on whether eliminating H. pylori infection has potentially detrimental effects? While H. pylori infection is known to be etiologically associated with dire consequences including peptic ulcer disease and gastric cancer among others, its absence has been postulated to be causative in the rise of other morbidities including gastroesophageal reflux disease, distal esophageal cancers, and childhood asthma [11]. This review examines the evidence from available studies conducted on the Malay population in northeastern Peninsular Malaysia in an attempt to shed some light on this issue and also discusses the potential reasons for the exceptionally low prevalence of H. pylori infection.