Forty Years of Helicobacter pylori: The African Perspective

BACKGROUND

Helicobacter pylori colonises 50% of the world population and is a causative agent of gastritis, peptic ulcer disease, mucosa associate lymphoid tissue lymphoma and gastric cancer.

SUMMARY

In Africa, the prevalence rate has been found to be the highest in comparison to other parts of the world. Despite its high prevalence there are low rates of gastric cancer recorded in Africa. This African perspective gives an insight into the history of H. pylori in Africa and also examines the issue of the so-called "African Enigma," it's diagnosis and treatment and where we are now.

KEY MESSAGES

Our vision is to have an African community that is free from H. pylori infections and complications. To this end, the African Helicobacter and Microbiota Study Group was initiated in 2021 and launched on the June 27, 2022 in Lagos, Nigeria (https://ahmsg-africa.org/). The African perspective includes the need for more detailed information on actual community and hospital prevalence, resistance data, and standardizing processes and algorithms to enable comparative diagnosis and therapy of H. pylori infections using a multi-pronged approach with international support.

Infections with Helicobacter pylori and challenges encountered in Africa

Helicobacter pylori (H. pylori) is the causative agent of gastritis, peptic ulcer disease, mucosa associated lymphoid tissue lymphoma and gastric cancer (GC). While this bacterium infects 50% of the world’s population, in Africa its prevalence reach as high as 80% as the infection is acquired during childhood. Risk factors for H. pylori acquisition have been reported to be mainly due to overcrowding, to have infected siblings or parent and to unsafe water sources. Despite this high H. pylori prevalence there still does not exist an African guideline, equivalent to the Maastricht V/Florence Consensus Report of the European Helicobacter and Microbiota Study Group for the management of this infection. In this continent, although there is a paucity of epidemiologic data, a contrast between the high prevalence of H. pylori infection and the low incidence of GC has been reported. This phenomenon is the so-called “African Enigma” and it has been hypothesized that it could be explained by environmental, dietary and genetic factors. A heterogeneity of data both on diagnosis and on therapy have been published. In this context, it is evident that in several African countries the increasing rate of bacterial resistance, mainly to metronidazole and clarithromycin, requires continental guidelines to recommend the appropriate management of H. pylori. The aim of this manuscript is to review current literature on H. pylori infection in Africa, in terms of prevalence, risk factors, impact on human health, treatment and challenges encountered so as to proffer possible solutions to reduce H. pylori transmission in this continent.

Allergies, Helicobacter pylori and the continental enigmas

Helicobacter pylori, a gastric pathogen, is known to be associated with gastric and duodenal ulcers, and is also a strong risk factor for the development of gastric cancer and lymphoma of the mucosal-associated lymphoid tissue. Ordinarily, this should make a strong case for its eradication at par with any other infectious disease. However, the unique biology of H. pylori and the complexity of its interactions with humans, its only known natural host, do not permit the recommendation of unambiguous preventive and therapeutic measures. Moreover, this organism has co-evolved with humans as a practically universal member of the natural gastric microbiota over at least 100,000 years. H. pylori persists for a lifetime in mostly asymptomatic hosts, and causes clinical disease only in a minority of infections. Therefore, its potential contribution to the maintenance of human immune homeostasis, as is the case with the better-studied members of the intestinal microbiota, is certainly worthy of serious investigation. In this paper, we summarize some interesting and often anecdotal data drawn from recent studies, and examine their significance in the context of the hygiene hypothesis. We also examine whether the lower incidence of gastric cancer over large parts of the world in spite of a high prevalence of infection (the Asian and African enigmas) may be re-interpreted in terms of the hygiene hypothesis. Finally, it is suggested that an evolutionary-ecological approach to the study of H. pylori infection may help in the formulation of strategies for the management of this infection. This may well be an infectious disease wherein medical interventions may have to be personalized to ensure optimal outcomes.

[Epidemiology of infection Helicobacter pylori in Yaoundé: specificity of the African enigma]

Introduction

L'infection à Hélicobacter pylori concerne la moitié de la population mondiale, principalement dans les pays en voie de développement où l'infection atteint 80% de la population. Le but de notre étude était de déterminer la prévalence de l'infection à Hélicobacter pylori et de mettre en évidence les déterminants de l'infection ainsi que les maladies associées au Cameroun.

Méthodes

L’étude concernait 171 sujets symptomatiques référés pour une fibroscopie œsogastroduodénale au Centre Hospitalier et Universitaire de Yaoundé et au Centre Médical la Cathédrale. L'infection à H.pylori était objectivée par un test rapide à l'uréase kit commercial Pronto Dry^® (Medical Instruments Corporation, Solothurn, Switzerland).

Résultats

La prévalence globale de l'infection à Hélicobacter pylori était de 72,5% (124/171) (Intervalle de Confiance (IC) à 95% 65,2-79,1%) et dans chaque groupe d’âge (moins de 40ans, 40-50ans, plus de 50ans) de 83,1%(64/77), 67,4%(29/43) et 60,8%(31/51) respectivement. En analyse univariée, le risque de l'infection était significativement élevé dans le groupe de moins de 40ans comparé au groupe de 40-50ans (Risque Relatif (RR) 0,42 IC 95% 0,16-1,1, p = 0,04 pour le groupe 40-50ans) et comparé au groupe de plus de 50ans (RR 0,73; 0,57-0,93, p = 0,004 pour le groupe de plus de 50ans). La prévalence de l'infection à H.pylori était de 63,0% (17/27) pour l'ulcère duodénal, 50%(4/8) pour l'ulcère gastrique et 100%(2/2) pour le cancer gastrique.

Conclusion

A prévalence de l'infection à H.pylori au Cameroun est très élevée et significativement liée à l’âge de moins de 40 ans.

Histopathological profile of gastritis in adult patients seen at a referral hospital in Kenya

AIM: To conduct a detailed histological study of gastritis in adult patients attending an endoscopy clinic at a Kenyan teaching and referral hospital.

METHODS: Biopsy specimens from consecutive patients were examined and graded according to the Updated Sydney System for H pylori infection, chronic inflammation, neutrophil activity, glandular atrophy and intestinal metaplasia. Also documented were gastric tissue eosinophil counts and presence of lymphoid follicles.

RESULTS: The rate of the graded variables, in the antrum and corpus respectively, were as follows: H pylori infection (91%, 86%), chronic inflammation (98%, 93%), neutrophil activity (91%, 86%), glandular atrophy (57%, 15%) and intestinal metaplasia (11%, 2%). Lymphoid follicles were noted in 11% of cases. Duodenal and gastric ulcers were documented in 32% and 2% respectively. The mean eosinophil count was 5.9 ± 0.74 eosinophils/HPF and 9.58 ± 0.93 eosinophils/HPF in the corpus and antrum respectively. Significant association was found between the degree of H pylori colonisation with chronic inflammation, neutrophil activity and antral glandular atrophy. Biopsies from the antrum and corpus showed significant histopathological discordance for all the graded variables. H pylori negative cases were associated with recent antibiotic use.

CONCLUSION: The study reaffirms that H pylori is the chief cause of gastritis in this environment. The majority of patients show a moderate to high degree of inflammation but a low degree of glandular atrophy and intestinal metaplasia. The study shows that inter-relationships between the histological variables in this African population are similar to those found in other populations worldwide including non-African populations.