High prevalence of gastric intestinal metaplasia detected by confocal laser endomicroscopy in Zambian adults

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.

A Review of Helicobacter pylori Diagnostics in Africa : From the Bedside to the Laboratory

Helicobacter pylori (H. pylori) is endemic in Africa with a prevalence estimate of 79.1%. In addition, there is a significant community burden of dyspepsia in Africa, similar to other western countries. However, the majority of infected persons do not manifest the disease. In Africa, for instance, peptic ulcer disease is prevalent, whereas gastric cancer has reportedly low incidence. Therefore, it is important that testing is focused, targeting individuals most likely to benefit from treatment. In Africa, there are currently no guidelines for H. pylori testing and treatment. Empirical treatment is common due to variable access to diagnostics and health care. To assess the spectrum of H. pylori testing in Africa, we performed a literature search in PubMed over the past 10 years, 2013 to 2023. Histology was the most widely used modality in 16 out of 18 countries. Capacity for culture was shown in 11 studies, importantly across regions of Africa. H. pylori serology was demonstrated in 8 countries, although it has limited sensitivity in identifying active infection. H. pylori test-and-treat strategy has been shown to be cost-effective. Particularly in a region with high antibiotic resistance, adopting this strategy ensures that only confirmed positive patients are treated. Furthermore, test-of-cure ought to be mandatory to guide future therapies. Health authorities can leverage polymerase chain reaction facilities, left behind by the coronavirus disease 2019 pandemic, to make molecular susceptibility testing available in the near future. A systematic approach to testing incorporating indication for endoscopy and medication use is recommended.

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.

The Spontaneous Control of HIV Replication is Characterized by Decreased Pathological Changes in the Gut-associated Lymphoid Tissue

BACKGROUND

HIV infection induces alterations in the gut-associated lymphoid tissue (GALT) that constitutes the most important site for viral replication due to the extensive presence of effector memory T-cells. In the case of HIV-controllers, several studies have reported fewer peripheral alterations and conserved immune responses that correlate with viral control; however, the histopathological characterization of GALT in those patients is still missing. In this study, we evaluated pathological alterations in GALT, trying to associate them with clinical parameters of HIV infected patients with or without evidence of viral control.

METHODS

This study included eight HIV-controllers (antiretroviral treatment-naïve patients, with viral loads below 2.000 copies/mL for at least 1 year); 14 Noncontrollers (antiretroviral treatmentnaïve patients, with viral loads > 2.000 copies/mL and CD4+ T cells count > 250 cells/μL), and 12 uninfected donors. Biopsy fragments were obtained by rectosigmoidoscopy and stained with hematoxylin and eosin, silver methenamine, Ziehl Neelsen, and modified Ziehl Neelsen.

RESULTS

Histopathological findings in HIV-controllers were similar to those observed in the uninfected group. In contrast, noncontrollers exhibited several alterations including condyloma acuminate, squamous metaplasia and acute colitis. These alterations were associated with disease progression.

CONCLUSION

HIV-controllers exhibit lower pathological alterations in the gut tissue, associated with higher CD4 T cell count, and lower viral load.

Presence of blood in gastric juice: A sensitive marker for gastric cancer screening in a poor resource setting

BACKGROUND

Gastric cancer survival rates in Africa are low as many cases are diagnosed late. Currently, there are no inexpensive, non-invasive and simple techniques that can be employed in poor resource settings for early case detection. In this study, we explored the possibility using blood in gastric juice as a screening tool to identify patients requiring referral for endoscopy.

METHODS

The study was conducted at the University Teaching Hospital endoscopy unit in Lusaka, Zambia. During esophagogastroduodenoscopy, gastric juice was aspirated and the pH determined using pH paper test strips. The presence of blood was tested using urinalysis reagent strips.

RESULTS

We enrolled 276 patients; 147(53%) were female and median age was 49 years (IQR 40-64 years). The presence of blood was associated with mucosal lesions, [OR 2.1; 95% CI 1.2-3.7, P = 0.004]. It was also associated with gastric cancer, [OR 6.7; 95% CI 2-35, P = 0.0005], even at 1:10 and 1:100 dilutions, [OR 5.4; 95% CI 2.3-13.8, P<0.0001] and [OR 9.1; 95% CI 3.5-23, P<0.0001] respectively. The sensitivity for gastric cancer detection using blood in gastric juice was 91% and the specificity was 41%. Analysis using the intensity of blood in gastric juice yielded an area under the receiver operating characteristic curve of 0.78; 95% CI 0.71-0.86 with a sensitivity of 79% and a specificity of 77%.

CONCLUSIONS

The presence of blood in gastric juice is associated with gastric mucosal lesions. It has a high sensitivity but low specificity for gastric cancer detection.