Studying the Humoral Response against SARS-CoV-2 in Cuban COVID-19 Recovered Patients.

Understanding the immune response generated by SARS-CoV-2 is critical for assessing efficient therapeutic protocols and gaining insights into the durability of protective immunity. The current work was aimed at studying the specific humoral responses against SARS-CoV-2 in Cuban COVID-19 convalescents. We developed suitable tools and methods based on ELISA methodology, for supporting this evaluation. Here, we describe the development of an ELISA for the quantification of anti-RBD IgG titers in a large number of samples and a similar test in the presence of NH4SCN as chaotropic agent for estimating the RBD specific antibody avidity. Additionally, a simple and rapid ELISA based on antibody-mediated blockage of the binding RBD-ACE2 was implemented for detecting, as a surrogate of conventional test, the levels of anti-RBD inhibitory antibodies in convalescent sera. In a cohort of 273 unvaccinated convalescents, we identified higher anti-RBD IgG titer (1 : 1,330, p < 0.0001) and higher levels of inhibitory antibodies blocking RBD-ACE2 binding (1 : 216, p < 0.05) among those who had recovered from severe illness. Our results suggest that disease severity, and not demographic features such as age, sex, and skin color, is the main determinant of the magnitude and neutralizing ability of the anti-RBD antibody response. An additional paired longitudinal assessment in 14 symptomatic convalescents revealed a decline in the antiviral antibody response and the persistence of neutralizing antibodies for at least 4 months after the onset of symptoms. Overall, SARS-CoV-2 infection elicits different levels of antibody response according to disease severity that declines over time and can be monitored using our homemade serological assays.

Dementia and other chronic diseases in older adults in Havana and Matanzas: the 10/66 study in Cuba.

INTRODUCTION: Chronic non-communicable diseases are the leading cause of death worldwide, except in Sub-Saharan Africa. Nonetheless, one of these conditions, dementia, is the major contributor to disability-adjusted life years in people aged ≥60 years. Few epidemiological studies exist of the prevalence and impact of dementia and selected chronic diseases in older adults in Latin America. OBJECTIVE: Describe prevalence of dementia, other chronic vascular diseases and cardiovascular risk factors, as well as resulting disabilities and care needs generated in adults aged ≥65 years in Havana City and Matanzas provinces, Cuba. METHODS: The 10/66 study is a prospective longitudinal study involving a cohort of 3015 adults aged ≥65 years in municipalities of Havana City and Matanzas provinces, divided into two phases: a cross-sectional door-to-door study conducted in 2003-2006, and a follow-up and assessment phase in 2007-2010. This article reports findings from the first phase. Hypertension diagnosis was based on criteria from the International Society for Hypertension; diabetes mellitus on American Diabetes Association criteria; stroke according to WHO definitions; and dementia according to criteria of the American Psychiatric Society's Diagnostic and Statistical Manual of Mental Disorders DSM-IV and the 10/66 International Dementia Research Group. Ischemic heart disease was defined by self-report of previous physician diagnosis. Study variables included age, sex, educational level, substance use (alcohol, tobacco) and dietary habits. A structured physical and neurological exam, including blood pressure measurement, was performed on all participants. Laboratory tests included complete blood count, fasting blood glucose, total cholesterol and lipoprotein fractions, triglycerides and apolipoprotein E genotype. Prevalence and standardized morbidity ratios (crude and adjusted) were calculated for chronic diseases studied with 95% confidence intervals, using a Poisson regression model and indirect standardization. RESULTS: The study assessed 2944 older adults (response rate 97.6%) and found high prevalence of vascular risk factors and of chronic non-communicable diseases: hypertension 73.0% (95% CI 71.4-74.7), diabetes mellitus 24.8% (95% CI 22.9-26.5), ischemic heart disease 14.1% (95% CI 12.9-15.4), dementia 10.8% (95% CI 9.7-12.0) and stroke 7.8% (95% CI 6.9-8.8). The majority of participants (85%) had more than one cardiovascular risk factor. The main cause of disability and dependency in the study population was dementia. CONCLUSION: The high prevalence of chronic diseases observed in the elderly--with the consequent morbidity, disability and dependency--highlights the need for prevention, early diagnosis and risk factor control, particularly given the demographic and epidemiologic transition faced by Cuba and other developing countries.

Prevalence of stroke and associated risk factors in older adults in Havana City and Matanzas Provinces, Cuba (10/66 population-based study).

INTRODUCTION: Cerebrovascular disease (CVD) is the third cause of death and second cause of disability and dementia in adults aged>or=65 years worldwide. The few epidemiological studies of stroke in Latin America generally report lower prevalence and different patterns than developed countries. OBJECTIVE: Estimate the prevalence of stroke and associated risk factors in adults aged>or=65 years in Havana City and Matanzas provinces, Cuba. METHODS: Single phase, cross-sectional, door-to-door study of 3015 adults aged>or=65 years in selected municipalities of Havana City and Matanzas provinces. Variables studied were age, sex, educational level, and self-report and description of chronic disease (stroke, heart attack, angina, and diabetes mellitus), substance use (alcohol, tobacco), and dietary habits. Respondents were given a structured physical and neurological exam, and blood pressure was measured. Laboratory tests comprised complete blood count, fasting glucose, total cholesterol and fractions, triglycerides, and apolipoprotein E (APOE) genotype. Diagnosis of stroke was based on the World Health Organization's definition. Stroke prevalence ratios (crude and adjusted), with 95% confidence intervals (CI), were calculated for the variables studied using a Poisson regression model. Risk association was analyzed using multiple logistic regression for dichotomous responses. RESULTS: Assessments were made of 2944 older adults (97.6% response rate). Prevalence of stroke was 7.8% (95% CI 6.9-8.8), and was higher in men. The risk profile for this population group included history of hypertension (OR 2.8; 95% CI 2.0-4.0), low HDL cholesterol (OR 2.6; 95% CI 1.7-3.9), male sex (OR 1.7; 95% CI 1.2-2.5), anemia (OR 1.6; 95% CI 1.1-2.5), history of ischemic heart disease (OR 1.5; 95% CI 1.0-2.3), carrier of one or two apolipoprotein E4 genotype (APOE E4) alleles (OR 1.4; 95% CI 1.0-2.0), and advanced age (OR 1.3; 95% CI 1.1-1.9). CONCLUSIONS: Stroke prevalence in this study is similar to that reported for Europe and North America, and higher than that observed in other Latin American countries. The risk profile identified includes classic risk factors plus anemia and APOE E genotype.

Asymptomatic dengue infection in a Cuban population confirms the protective role of the RR variant of the FcgammaRIIa polymorphism.

The role of human Fcgamma receptors (FcgammaR) has been recognized considerably over the last years. These receptors vary in their affinity for IgG subclasses and the intracellular signals elicited by them. Allelic variants of FcgammaR genes may influence the biological phagocyte activity, accounting for an inherited pre-disposition to disease. The specific FcgammaRIIa (CD32) contains a polymorphic variant (H/R131) that has been associated to a reduced risk for developing dengue hemorrhagic fever (DHF). Here, we investigated the role of this polymorphism in a very well-characterized group of Cuban individuals with antecedents of DHF, dengue fever (DF), or subclinical dengue infection. The HH131 genotype was significantly associated with dengue disease, either DF (*P = 0.016; odds ratio = 4.425; 95% confidence interval = 1.10-20.52) or DHF (P = 0.00018; odds ratio = 10.56; 95% confidence interval = 2.33-54.64) with respect to the subclinical infection.

Cuba's National Medical Genetics Program.

Since first emerging in the late 1970s, the field of human genetics has advanced with extraordinary speed. In just thirteen years (1990 to 2003), the human genome project deciphered the code of life. Today, by detecting genetic predisposition to certain diseases, we can anticipate their appearance even before the onset of symptoms, and progress is being made toward creating so-called "personalized drugs" designed to fit an individual's genetic profile. Yet, these developments are far beyond the reach of the vast majority of people. Few countries have transformed the giant steps in human genetics into national policies, programs and services accessible to the general population.

Prevalence of Dementia and Alzheimer's Disease in a Havana Municipality: A Community-Based Study among Elderly Residents.

Introduction Approximately 24.2 million persons throughout the world suffer dementia with 4.6 million new cases reported annually. Only 10% of dementia and Alzheimer's disease studies are conducted in developing countries where 66% of sufferers live. Cuba, a developing country, exhibits health indicators similar to those of developed nations. Its population of 11.6 million is aging rapidly: by the year 2020 it is estimated that persons aged ≥65 years will comprise 25% of the population, making Cuban society the "oldest" in Latin America. Objectives Ascertain and characterize behavior of dementia, its etiologies and risk factors in persons aged ≥65 years in the Havana City municipality of Playa. Methods A two-phase, cross-sectional, door-to-door study was conducted in the municipality targeting all persons aged ≥65 years, achieving a 96.4% response rate (n=18,351). Folstein Mini Mental State Examination (MMSE), Hughes Clinical Dementia Rating (CDR) and a structured interview on risk factors were applied. DSM-IV, NINCDS-ADRDA and NINDS-AIREN criteria were used to determine dementia diagnosis, as well as other criteria for diagnosing Alzheimer's and other specific forms of dementia. Results Dementia prevalence was 8.2% of adults aged ≥65 years, with a slight predominance in males. The most frequent cause of dementia was Alzheimer's disease, followed by mixed dementias. Dementia-associated risk factors were: history of stroke, hypertension, depression, skull-brain trauma, family history of dementia, low educational level and advanced age. Conclusions This study corroborates that dementia and Alzheimer's disease constitute an important and growing health problem for our country due to the accelerated aging of the Cuban population. It also underlines the importance of early diagnosis and proper treatment of hypertension and other vascular risk factors, as well as the need for a national public health program for the prevention and early diagnosis of dementia and Alzheimer's disease, targeting elderly and at-risk populations.