Lessons learnt from the epidemiology of Helicobacter pylori infection in Malaysia: JGHF Marshall and Warren Lecture 2017

Abstract

The study of Helicobacter pylori in Malaysia has given several important insights into the epidemiology of the infection and pathogenesis of disease. Malaysia has a multiracial Asian population with three major Asian races living together-Malay, Chinese, and Indian. Races remain fairly distinct because of a paucity of interracial marriages. The "Racial Cohort Hypothesis" proposes that the infection occurs within racial groups rather than between. As such, the high prevalence among Indians (> 50%) and Chinese (40-50%) reflects the high prevalence in their countries of origin even though migration had taken place more than two generations before. The Malays have a comparatively low prevalence of about 10-20%. Despite the high prevalence of H. pylori, the Indians have a low gastric cancer incidence of less than 10 per 100 000 per year. This is in contrast to the Chinese who has an incidence in excess of 20 per 100 000 per year. We have called this the "Indian Enigma." The reason for this enigma is unclear and is the result of interaction between bacterial virulence factors, host susceptibility, and environmental factors. Phylogenetically, Chinese bacterial strains are distinct from Indians and Malays and are predominantly hpEastAsia/hsp EAsia. CagA EPIYA motifs among Chinese belong predominantly to the more virulent ABD motif. There is no clear distinguishing profile among host genetic factors. Environmental factors particularly diet may play an important role. Indians consume chilies and curries, which may be gastro protective, whereas Chinese consume more preserved and salted foods, which are thought to be carcinogenic.

Helicobacter pylori infection may increase the severity of nonalcoholic fatty liver disease via promoting liver function damage, glycometabolism, lipid metabolism, inflammatory reaction and metabolic syndrome

“…H. pylori is a Gramnegative microaerophilic bacterium affecting >50% of humans worldwide, with a higher prevalence in developing countries [16,17]. A JGHF Marshall and Warren Lecture in 2017 about the epidemiology of H. pylori infection in Malaysia (three major Asian races living together -Malay, Chinese and Indian) reported that the H. pylori prevalence was high in Indians (>50%) and Chinese (40-50%), while a comparatively low prevalence occurred in Malays (10-20%) [18]. Moreover, at the same year, a systematic review and meta-analysis mentioned that the H. pylori infection is highly endemic in East Asian countries, with 54% of prevalence in China, Japan, Taiwan and Korea in 2015 [19].…”

Worldwide Prevalence and Risk Factors of Helicobacter pylori Infection in Children

“…Another study on the Iranian population found a pooled prevalence of 54%, with 42% in children concluding that more than half of this population was infected by H. pylori during the last decades [ 108 ]. A study performed in Malaysia, which stratified the population according to races living in this area, concluded that Chinese and Indians have the highest prevalence rate of H. pylori infection (40–50%) compared to 10–20% in native Malays [ 109 ]. Another study performed on children from China pointed out a prevalence of 18.6% [ 110 ].…”

“…Similar prevalence was also identified by Zhou et al in Chinese schoolchildren aged 7–12 years (24.1%) [ 111 ]. These findings are enigmatic since, despite the increased H. pylori prevalence, Indians, unlike the Chinese, have a much lower gastric cancer incidence of less than 10 per 100,000 per year [ 109 ]. Lapidot et al assessed H. pylori infection and intestinal microbiome in healthy Israeli children aged between 6–9 years and identified 57% of the participants to be positive for H. pylori infection [ 112 ].…”

Helicobacter pylori Infection: Prevalence, Demographic Characteristics, Clarithromycin Resistance and Evaluation of the In-House Rapid Urease Test in Sungai Buloh Hospital, Malaysia

“…It is postulated, that these countries were the origin of these ethnicities, which had subsequently passed down the H. pylori infection through generations born in Malaysia, or after their migration to Malaysia. This is further supported by the paucity of interracial marriages, leaving the ethnicities remaining fairly distinct, and encouraged transmission of infection within the racial group (Goh 2018;Pue & Sulaiman 2013). Other causes for the differences in prevalence amongst ethnicities may be attributed to the virulence factors of H. pylori strains, which are distinct to different ethnicities, host susceptibility factors, and (Goh 2018).…”

“…This is further supported by the paucity of interracial marriages, leaving the ethnicities remaining fairly distinct, and encouraged transmission of infection within the racial group (Goh 2018;Pue & Sulaiman 2013). Other causes for the differences in prevalence amongst ethnicities may be attributed to the virulence factors of H. pylori strains, which are distinct to different ethnicities, host susceptibility factors, and (Goh 2018). In our study, although we did not show any statistically significant difference between ethnicity and infection, the proportion of infected patients appeared to be highest among Indians.…”