High SARS-CoV-2 Seroprevalence in Rural Peru, 2021: a Cross-Sectional Population-Based Study.

Latin America has been severely affected by the COVID-19 pandemic. The COVID-19 burden in rural settings in Latin America is unclear. We performed a cross-sectional, population-based, random-selection SARS-CoV-2 serologic study during March 2021 in the rural population of San Martin region, northern Peru. In total, 563 persons from 288 houses across 10 provinces were enrolled, reaching 0.2% of the total rural population of San Martin. Screening for SARS-CoV-2 IgG antibodies was done using a chemiluminescence immunoassay (CLIA), and reactive sera were confirmed using a SARS-CoV-2 surrogate virus neutralization test (sVNT). Validation of the testing algorithm using prepandemic sera from two regions of Peru showed false-positive results in the CLIA (23/84 sera; 27%) but not in the sVNT, highlighting the pitfalls of SARS-CoV-2 antibody testing in tropical regions and the high specificity of the two-step algorithm used in this study. An overall 59.0% seroprevalence (95% confidence interval [CI], 55 to 63%) corroborated intense SARS-CoV-2 spread in San Martin. Seroprevalence rates between the 10 provinces varied from 41.3 to 74.0% (95% CI, 30 to 84%). Higher seroprevalence was not associated with population size, population density, surface area, mean altitude, or poverty index in Spearman correlations. Seroprevalence and reported incidence diverged substantially between provinces, suggesting regional biases of COVID-19 surveillance data. Potentially, limited health care access due to environmental, economic, and cultural factors might lead to undetected infections in rural populations. Additionally, test avoidance to evade mandatory quarantine might affect rural regions more than urban regions. Serologic diagnostics should be pursued in resource-limited settings to inform country-level surveillance and vaccination strategies and to support control measures for COVID-19. IMPORTANCE Latin America is a global hot spot of the COVID-19 pandemic. Serologic studies in Latin America have been mostly performed in urban settings. Rural populations comprise 20% of the total Latin American population. Nevertheless, information on COVID-19 spread in rural settings is scarce. Using a representative population-based seroprevalence study, we detected a high seroprevalence in rural populations in San Martin, northern Peru, in 2021, reaching 41 to 74%. However, seroprevalence and reported incidence diverged substantially between regions, potentially due to limited health care access or test avoidance due to mandatory quarantine. Our results suggest that rural populations are highly affected by SARS-CoV-2 even though they are sociodemographically distinct from urban populations and that highly specific serological diagnostics should be performed in resource-limited settings to support public health strategies of COVID-19 control.

Efectividad de las vitaminas C y E como tratamiento adyuvante a la terapia triple estándar para Helicobacter pylori en una cohorte de la Amazonía peruana / Effectiveness of vitamins C and E adjuvant to standard triple therapy for Helicobacter pylori in a cohort from the Peruvian Amazon

Resumen Introducción y objetivos: la terapia con vitaminas C y E ha sido propuesta como adyuvante a la terapia triple estándar (TTE) con el fin de incrementar la tasa de erradicación del Helicobacter pylori (H. pylori). En este estudio probamos esta hipótesis en una cohorte de pacientes de la Amazonía peruana. Materiales y métodos: retrospectivamente, evaluamos una cohorte de 50 pacientes infectados con H. pylori del Hospital de Tarapoto en el período comprendido entre julio-diciembre de 2016; de estos, 25 fueron tratados con TTE (amoxicilina 1 g, claritromicina 500 mg y omeprazol 20 mg, dos veces al día por 14 días) en adyuvancia con las vitaminas C y E, y 25 fueron tomados al azar (1:1), quienes solo recibieron TTE. Se estimó y comparó la efectividad de ambos tratamientos utilizando un modelo regresión general lineal con familia Poisson y link log, teniendo como desenlace de interés la erradicación del H. pylori confirmada por histopatología. Resultados: al comparar la cohorte de expuestos y con los no expuestos, no se encontraron diferencias significativas en sus características basales, incluyendo edad (38 ± 11 frente a 36 ± 10 años), género masculino (65 % frente a 63 %), síntomas y diagnóstico histopatológico. Al comparar la efectividad de ambos tratamientos, se encontró un incrementó no significativo en las tasas de erradicación del 9,5 % (91 % frente a 82 %, razón de tasas de incidencia = 1,11; intervalo de confianza [IC] 95 %: 0,92 a 1,36). Conclusiones: la terapia adyuvante con vitaminas C y E podría ayudar a incrementar la efectividad de la TTE para H. pylori en pacientes de la Amazonía peruana, aunque se requiere confirmar esta hipótesis en un ensayo clínico.

Abstract Introduction and Objectives: Adjuvant therapy with vitamins C and E has been proposed to increase standard triple therapy's Helicobacter pylori eradication rate. This study tested this hypothesis in a cohort of patients from the Peruvian Amazon. Material and Methods: We retrospectively evaluated a cohort of 50 patients at Tarapoto Hospital who were treated for H. pylori infections from July to December 2016. Of these, 25 were randomly selected to receive standard triple therapy of 1 g amoxicillin, 500mg clarithromycin and 20mg omeprazole twice a day for 14 days plus adjuvant vitamins C and E. The other 25 only received standard triple therapy. The effectiveness of both treatments was estimated and compared using a general linear regression model using the Poisson family of distributions and log link with H. pylori eradication confirmed by histopathology as the outcome of interest. Results: A comparison of the two groups found no significant differences in their baseline symptoms, histopathological diagnoses, ages (38 ± 11 years vs. 36 ± 10 years) or genders (65% male vs. 63% male). A comparison of the effectiveness both treatments found a non-significant increase in eradication rates of 9.5% (91% vs. 82%, incidence rate ratio = 1.11; 95% confidence interval: 0.92 to 1.36). Conclusions: Adjuvant therapy with vitamins C and E may help increase the effectiveness of standard triple therapy for H. pylori in patients in the Peruvian Amazon, although this hypothesis needs to be confirmed in a clinical trial.