Observations of racial differences in the prevalence of Helicobacter pylori in Malaysia have been intriguing. The Indians and Chinese consistently have a higher prevalence compared to the Malays. The racial cohort theory has been proposed to explain these differences where transmission and perpetuation of infection takes place within a racial group rather than between races, races being separate owing to the low rate of interracial marriages. Studies have demonstrated distinctive bacterial strains between races. Phylogenetic studies have shown that H. pylori isolates amongst Chinese and Indians are distinctive while Malays have Indian and other strains suggesting a more recent acquisition of the bacterium from Indians. H. pylori is recognized as the major causative factor in peptic ulcer disease and gastric cancer. Despite the high prevalence of H. pylori, Indians have a relatively low prevalence of peptic ulcer disease and a low incidence of gastric cancer. This paradox with regards to gastric cancer has been termed the "Indian enigma". Bacterial strain differences between races may be putative but this observation may also indicate gastroprotective environmental factors or a lower genetic susceptibility to develop cancer in the Indians.
The new millennium has seen distinct changes in the pattern of gastrointestinal disease in the Asia-Pacific region. These changes are important as more than half of the world's population come from the region and therefore impact significantly on the global disease burden. The highest incidence of gastric cancer (GCA) has been reported from Asia and GCA remains a very important cancer. However time-trend studies have shown a decrease in GCA incidence in several countries in Asia. A rise in cardio-esophageal cancers as seen in the West has not been reported. On the other hand, colorectal cancer has been steadily increasing in Asia with age-standardized incidence rates of some countries approaching that of the West. The pattern of acid-related diseases has also changed. Gastroesophageal reflux disease is a fast emerging disease with an increasing prevalence of reflux esophagitis and reflux symptoms. The prevalence of peptic ulcer disease has at the same time declined in step with a decrease in H. pylori infection. Many of the changes taking place mirror the Western experience of several decades ago. Astute observation of the epidemiology of emerging diseases combined with good scientific work will allow a clearer understanding of the key processes underlying these changes. With rapid modernization, lifestyle changes have been blamed for an increase in several diseases including gastroesophageal reflux disease, nonalcoholic fatty liver disease and colorectal cancer. A worrying trend has been the increase in obesity among Asians, which has been associated with an increase in metabolic diseases and various gastrointestinal cancers. Conversely, an improvement in living conditions has been closely linked to the decrease in GCA and H. pylori prevalence.
Gastroesophageal reflux disease (GERD) is a common disease in the West, which now appears to be also increasing in prevalence in the Asian Pacific region. The reasons for this changing epidemiology are two-fold: an increased awareness among doctors and patients, and/or a true increase in the prevalence of the disease. Prevalence rates of reflux esophagitis (RE) of up to 16% and prevalence of GERD symptoms of up to 9% have been reported in the Asian population. However, the frequency of strictures and Barrett's esophagus remain very low. Non-erosive reflux disease (NERD) appears to be the most common form of GERD among Asian patients accounting for 50-70% of cases with GERD. Among Asian patients differences can also be discerned among different ethnic groups. For example, in Malaysia where a multiracial society exists, RE is significantly more common among Indians compared to Chinese and Malays whereas NERD is more frequently seen in the Indian and Malays compared to the Chinese. The reasons for these differences are not known but may indicate both genetic factors and environmental factors peculiar to the particular racial group. GERD has also been increasing in the region demonstrating a time-lag phenomenon compared to the West. Differing predisposition to GERD among different ethnic groups would mean that such an increase would be more prominent among certain racial groups.
Chronic pancreatitis is a difficult disease to treat. Worldwide, alcohol is the most common aetiology but based on recent studies it is clear that genetic susceptibility plays an important role in determining disease. Several important genetic mutations have been identified. The prevalence of chronic pancreatitis appears to be lower in Asia although very high rates have been reported in parts of India. Severe intractable pain is the predominant presenting complaint of patients. The natural history of the disease and the onset of exocrine and endocrine insufficiency depend on the classification of disease as early onset, late-onset or alcohol associated. Complications of chronic pancreatitis are important and include pseudocyst formation, bile duct and duodenal strictures.
Helicobacter pylori infection has many different clinical outcomes. Not all infected persons need to be treated. Therefore, indications for treatment have to be clear, and several consensus guidelines have been formulated to aid the medical practitioner in this decision-making process. Triple therapy with a proton pump inhibitor (PPI), in combination with amoxicillin and clarithromycin is the established treatment of choice. For patients with penicillin hypersensitivity, metronidazole can be substituted for amoxicillin. Bacterial resistance to antibiotics is a major factor adversely affecting treatment success. Resistance to metronidazole has been reported in up to 80%, and resistance to clarithromycin in 2-10% of strains cultured. Resistance to either one of the antibiotics has been reported to result in a drop in efficacy of up to 50%. Emergence of resistance to both metronidazole and clarithromycin following failed therapy is a cause for concern; this underlines the need to use the best available first-line therapy. To avoid the emergence of resistance to both key antibiotics, the combination of metronidazole and clarithromycin should be avoided where possible. For failed treatment, several strategies can be employed. These include ensuring better compliance with repeat therapy, and maximizing the efficacy of repeat treatment by increasing dosage and duration of treatment, as well as altering the choice of drugs. Quadruple therapy incorporating a bismuth compound with a PPI, tetracycline and metronidazole has been a popular choice as a "rescue" therapy. Ranitidine bismuth citrate has been shown to be able to overcome metronidazole and clarithromycin resistance; it may be a useful compound drug to use in place of a PPI in "rescue" therapies. In the case of persistent treatment failures, it is useful to consider repeating gastroscopy and obtaining tissue for culture, and then prescribe antibiotics according to bacterial susceptibility patterns. It is also important in refractory cases to review the original indication for treatment and determine the importance of the indication.
The aim of the present study was to determine the risk factors for Helicobacter pylori in a dyspeptic Malaysian population. A cross-sectional survey of 1060 consecutive patients presenting with dyspepsia at the Endoscopic Unit, University Hospital, Kuala Lumpur, Malaysia from January 1994 to July 1995 was undertaken. All patients answered a detailed questionnaire and underwent endoscopy, with two antral biopsies taken for diagnosis of H. pylori using a rapid urease test. An overall H. pylori prevalence of 49.0% was recorded. Helicobacter pylori prevalence in relation to the major endoscopic diagnoses were as follows: non-ulcer dyspepsia (NUD) 31.2%; duodenal ulcer (DU) 91.4%; and gastric ulcer (GU) 74.1%. The prevalence among the races were as follows: Malay 16.4%; Chinese 48.5%; and Indians 61.8%. Multiple logistic regression analysis identified the following as independent risk factors: > 45 years old 1.5 (1.1,2.0); male gender 1.6 (1.2,2.1); ethnic group: Chinese 2.5 (1.7,3.7); Indians 4.9 (3.2,7.5); level of education: low 2.3 (1.5,3.5); middle 1.7 (1.1,2.6); and smoking 1.6 (1.2,2.3). Analysis was also performed on DU, GU and non-UD patients separately; in both DU and GU patients, H. pylori prevalence was high regardless of age, sex, race or level of education. However, in DU patients, Indian race had an independent risk factor (Odds ratio = 7.8 (1.2,48.4)). The findings in the NUD group reflected the findings in the ¿all patients' group; > 45 years old, male gender, Indian and Chinese race, and low level of education were also significant, independent risk factors. The overall differences in H. pylori prevalence between the different subgroups were mainly due to differences in the NUD group. The increased risk of H. pylori infection in Chinese and Indians points to either an inherent ethnic genetic predisposition or to socio-cultural practices peculiar to the particular race which may be responsible for transmission of the infection.
The link between Helicobacter. pylori and peptic ulcer disease in 1997 is an irrefutable one. The association between infection and ulcerogenesis has been shown to be biologically plausible with induction of epithelial inflammation and cell damage and its effect on gastrin/acid homeostasis. The association of H. pylori infection and peptic ulcer disease is a close and consistent one. There is ample evidence indicating that H. pylori eradication results in virtual abolition of ulcer relapse. Several studies have demonstrated that eradication of H. pylori results in ulcer healing and there is evidence showing a temporal relationship between infection and development of peptic ulcer disease.
257 cases of acute hepatitis B were reported between January 1977 and June 1979. This constituted about one-third of all reported acute viral hepatitis cases in Singapore. The mean annual morbidity and mortality rates per 100,000 was 4.4 and 0.12 respectively. The case-fatality rate was 2.7%. The age-specific morbidity rates were high in the 15-24 and 25-34 years age groups, while the ethnic specific morbidity rate was highest in Indians. The male to female ratio was 4.6: 1. Cases were concentrated in urban and suburban areas with high population density. Three outbreaks, one traced to contaminated needles and syringes, one to contaminated tattoo neeedles, and amongst close contacts, were described. Although parenteral procedures were associated with hepatitis B infection (p < 0.005), non-parenteral or inapparent parenteral mode of transmission probably contributes to a significant extent in the transmission of hepatitis B in Singapore. Studies to determine the role of perinatal transmission, and of vectors, in maintaining the endemicity of the disease, were suggested.