HIV related hypochlorhydria does not appear to respond to anti-retroviral therapy in Zambian adults: a case control study

Nationwide survey of Helicobacter pylori seropositivity and gastric atrophy in Zambia

BACKGROUND

Helicobacter pylori (H. pylori) is a common bacterial infection which predominately drives upper gastrointestinal pathology. We carried out a nationwide serological survey in response to the deficiency of robust African data on H. pylori prevalence, age of acquisition, socio-geographic determinants, and impact on gastric physiology.

MATERIALS AND METHODS

This was a cross-sectional study of archival plasma samples collected during the Zambia Population-based HIV impact Assessment (ZAMPHIA) 2016 survey. ZAMPHIA used a two-stage door-to-door stratified cluster sample approach to collect samples from adults and children from age 0 to 59 years (n = 24,266). We randomly retrieved one fifth of these samples from each of Zambia's 10 provinces and used ELISA to test for H. pylori IgG antibodies, pepsinogen 1 and 2 and gastrin-17. A pepsinogen 1:2 ratio of <3 was used to define gastric atrophy.

RESULTS

The analysis of 4050 plasma samples (30% <16 years, 53% females) revealed an overall H. pylori seroprevalence of 79%. By the age of 10 years, more than 75% of the children had H. pylori. Urban residence was associated with increased odds (OR 1.8, 95% CI 1.5-2.2, p < 0.001) and HIV infection was associated with reduced odds (OR 0.7, 95% CI 0.5-0.9, p = 0.02) of H. pylori seropositivity. Gastric atrophy was detected in 6% of H. pylori seropositive adults below 45 years of age and 9% in those between 45 and 59 years.

CONCLUSIONS

We have confirmed a high prevalence of H. pylori seropositivity in Zambia, predominantly in urban settings. The prevalence of gastric atrophy is broadly consistent with other populations around the globe, but our sample did not include adults over 60 years.

Endoscopic diagnosis of gastric and oesophageal cancer in Lusaka, Zambia: a retrospective analysis

INTRODUCTION

There are uncertainties surrounding the spectrum of upper gastrointestinal (UGI) diseases in sub-Saharan Africa. This is mainly due to the limitations of data collection and recording. We previously reported an audit of UGI endoscopic diagnoses in Zambia spanning from 1977 to 2014. We now have extended this analysis to include subsequent years, in order to provide a more comprehensive picture of how the diagnoses have evolved over 4 decades.

METHODS

We combined data collected from the endoscopy unit at the University Teaching Hospital (UTH) in Lusaka during a previous review with that collected from the beginning of 2015 to the end of 2021. Since 2015, an electronic data base of endoscopy reports at the UTH was kept. The electronic data base was composed of drop-down menus that allowed for standardised reporting of findings. Collected data were coded by two experienced endoscopists and analysed.

RESULTS

In total, the analysis included 25,849 endoscopic records covering 43 years. The number of endoscopic procedures performed per year increased drastically in 2010. With the exception of the last 2 years, the proportion of normal endoscopies also increased during the time under review. In total, the number of gastric cancer (GC) cases was 658 (3%) while that of oesophageal cancer (OC) was 1168 (5%). The number of GC and OC diagnoses increased significantly over the period under review, (p < 0.001 for both). For OC the increase remained significant when analysed as a percentage of all procedures performed (p < 0.001). Gastric ulcers (GU) were diagnosed in 2095 (8%) cases, duodenal ulcers (DU) in 2276 (9%) cases and 239 (1%) had both ulcer types. DU diagnosis showed a significantly decreasing trend over each decade (p < 0.001) while GU followed an increasing trend (p < 0.001).

CONCLUSIONS

UGI endoscopic findings in Lusaka, Zambia, have evolved over the past four decades with a significant increase of OC and GU diagnoses. Reasons for these observations are yet to be established.

Introducing the Sanguis-Filum for Detection of Gastric Mucosal Lesions Prior to Endoscopy: A Study Protocol

Early diagnosis of gastric cancer (GC) is compromised by a lack of specific signs to enable identification of affected individuals. We designed the Sanguis-filum (S-filum) as a simple bedside tool that could be used to detect the presence of gastric mucosal lesions prior to endoscopy. We previously published evidence that at a sensitivity of 91%, the presence of free blood in the stomach was associated with mucosal lesions. The S-filum is made of an inert but absorbent string coiled up in a gelatin capsule (Capsuline, FL, USA), which can be swallowed and the string retrieved to test for free blood. Preliminary testing of the S-filum was successfully conducted on healthy volunteers. We now intend to test it on actual patients, comparing the results to oesophagogastroduodenoscopy (OGD) findings. This will enable us to determine the diagnostic accuracy of the S-filum at detecting GC and other mucosal lesions. The S-filum as a bedside tool has the potential to assist healthcare providers to identify individuals likely to have early gastric mucosal lesions and requiring OGD examination. The S-filum could, in the long run, facilitate population-wide screening for early GC prior to endoscopy.

Helicobacter pylori infection and hypochlorhydria in Zambian adults and children: A secondary data analysis

Background

Hypochlorhydria (gastric pH >4) increases susceptibility to diarrhoea, iron deficiency, and gastric cancer. We sought to clarify the prevalence of this condition and its predisposing factors in Zambia by pooling data from previous studies conducted in hospital and community settings.

Methods

Gastric pH was measured in participants from five separate studies by collecting gastric aspirate from fasted adults and children under 3 years of age undergoing gastroscopy. Gastric pH was correlated with serological testing for Human Immunodeficiency Virus (HIV) and Helicobacter pylori (H. pylori) infections.

Results

We studied 597 individuals (487 adults and 110 children). Hypochlorhydria was present in 53% of adults and 31% of children. HIV infection was detected in 41% of adults and 11% of children. H. pylori serology was available for 366 individuals: 93% of adults and 6% of children were seropositive. In univariate analysis, hypochlorhydria was significantly associated with HIV seropositivity (OR 1.7; 95% CI 1.2–2.4; p = 0.004) and H. pylori antibody seropositivity (OR 4.9; 95% CI 2.8–8.6; p<0.0001), and with advancing age in HIV negative individuals (p = 0.0001). In multivariable analysis, only H. pylori was associated with hypochlorhydria (OR 4.0; 95% CI 2.2–7.2; p<0.0001) while excluding possible exposure to proton pump inhibitors.

Conclusions

Hypochlorhydria is common in our population, with H. pylori being the dominant factor. Only young HIV seronegative individuals had a low prevalence of hypochlorhydria. This may have implications for the risk of other health conditions including gastric cancer.

Molecular profiling of gastric cancer in a population with high HIV prevalence reveals a shift to MLH1 loss but not the EBV subtype

The human immunodeficiency virus (HIV) pandemic heavily affects sub-Saharan Africa. It is associated with persistently active Epstein-Barr virus (EBV) infection. To determine if this translates into increased frequency of EBV-associated gastric cancer (EBVaGC), we evaluated molecular profiles of gastric cancer (GC) in Zambia. Patients with GC or premalignant gastric lesions were enrolled in Lusaka, Zambia. We used patients without any of these lesions as a control group. Chromogenic in situ hybridization (CISH) on tumor tissue was used to identify EBVaGC. To identify the microsatellite unstable subtype, immunofluorescence staining for MutL homolog 1 (MLH1) was used. Exposure to EBV and HIV was assessed serologically. We enrolled 369 patients (median age 52 years [IQR 41-65]; 198 (54%) female). Of these, 72 (20%) had GC and 35 (9%) had gastric premalignant lesions (PL). CISH identified EBVaGC in 5/44 (11%) of those with adequate tissue, while MLH1 loss was identified in 29/45 (64%). Both GC and PL were associated with the highest titers of antibodies to Early antigen-diffuse (OR 2.5, 95% CI 1.0-6.1, P = .048 and OR 3.9, 95% CI 1.1-12.9, P = .03, respectively) at high concentrations. Human immunodeficiency virus infection was associated with a range of antibodies to EBV, but not with any cancer subtype. Despite the association of HIV with persistent EBV, the proportion of EBVaGC in Zambia is similar to populations with a low prevalence of HIV infection. The proportion of microsatellite unstable tumors may be higher than other populations.

HIV Research Training Partnership of the University of Zambia and Vanderbilt University: Features and Early Outcomes

Background

Despite the burden of HIV being highest in sub-Saharan Africa (SSA), research expertise and capacity to address scientific questions regarding complications of HIV and ART, especially chronic non-communicable conditions, is limited in the region. The comorbidities prevalent in persons with HIV are mediated through diverse mechanisms, many of which can be context or region-specific and are yet to be elucidated. The phenotype, risk factors, and effective interventions for these conditions may differ between populations and settings, and therefore there is an urgent need for research to help understand these processes and how to best address them in SSA. Here, we report the research capacity building activities in SSA conducted by the University of Zambia (UNZA)-Vanderbilt Training Partnership for HIV-Nutrition-Metabolic Research (UVP), drawing lessons and challenges for a wide global health audience.

Methods

We reviewed program data and conducted interviews with program leaders and participants to understand and document the progress and outcomes of the partnership. We report the program's early achievements, highlighting drivers and challenges.

Results

Between 2015 and 2019, UVP made substantial progress on its goals of training new UNZA PhD scientists to investigate complex nutritional and metabolic factors related to long-term HIV complications and comorbidities. The program has supported 11 UNZA PhD students with dual UNZA-Vanderbilt mentorship; three have graduated, and other candidates are progressing in their PhD studies. The project also supported institutional capacity through UNZA faculty participation in Vanderbilt grant writing workshops, with strong success in obtaining grants among those who participated. UVP also supported development of greater structure to UNZA's PhD program and a mentorship curriculum, both now adopted by UNZA. The major drivers for success included UVP's alignment of goals between UNZA and Vanderbilt, and local institutional ownership. The longstanding history of collaborations between the two institutions contributed substantially to alignment and mutual support of UVP's goals. Several challenges were noted, including limits on direct research funding for students and a relatively small pool of funded investigators at UNZA.

Conclusions

Despite some challenges, UVP has achieved positive outcomes over its first four years. Longstanding partnerships and local institutional ownership were the main drivers. We expect the challenges to mitigated as the project continues and produces more UNZA researchers and teams and more funded projects, collectively building the local research community. With continued resources and clear focus, we expect that UNZA's investigators and partners will attract research funding and generate high-impact research outputs across a broad range of studies in HIV as well as newer threats from non-communicable conditions experienced by long-term survivors of HIV and by the general population.