Impact of layered non-pharmacological interventions on COVID-19 transmission dynamics in Yucatan, Mexico.

Background: The pandemic propagation of SARS-CoV-2 led to the adoption of a myriad of non-pharmacological interventions (NPIs, e.g., social distancing, mobility restrictions, gathering restrictions) in the Americas. Using national epidemiological data, here we report the impact of the layered adoption of multiple NPIs aimed at curving SARS-CoV-2 transmission in Yucatan State, Mexico. Methods: Data from suspected and laboratory confirmed COVID-19 cases during 2020 were analyzed by age groups and sex, clinical signs, and symptoms as well as outcome. The impact of NPIs was quantified using time-varying reproduction numbers (R t) estimated as a time-series and by sectors of the city. Findings: A total of 69,602 suspected cases were reported, 39.3% were laboratory-confirmed. Men were hospitalized (60.2%), more severely ill (3% vs 1.9%) and more likely to die (62%) than women. Early in the outbreak, all sectors in Merida had R t estimates above unity. Once all NPÍs were in place, R t values were dramatically reduced below one, and in the last interval transmission estimates of R t remained below one in all sectors. Interpretation: In the absence of a COVID-19 vaccination program, the combination and wide adherence of NPÍs led to a low and stable trend in SARS-CoV-2 transmission that did not overwhelm the health sector. Our study reflects that a controlled and planned ease of restrictions to balance health, social and economic recovery resulted in a single wave of transmission that prolonged at low and stable levels. Funding: GVP received funding from Emory University via the MP3 Initiative.

Short communication: impact of climate variability on the incidence of dengue in Mexico.

We evaluated the impact of weather variables and climatic indicators associated with the incidence of dengue in two municipalities of the state of Veracruz, Mexico, from 1995 to 2003. A retrospective ecological study was conducted, using time-series analysis in which we compiled the weekly reported cases of dengue and the weather and climatic parameters: temperature, rainfall and sea-surface temperature (SST), the latter as an El Niño Southern Oscillation indicator. We statistically evaluated the data with autogressive models. The models' predictive abilities were evaluated using data collected from 1995 to 2002 and were validated with those observed for 2003. Each degree Centigrade increase in SST was followed by an increase in the number of dengue cases: 46% in San Andrés Tuxtla (P = 0.001) 16 weeks later and 42% in Veracruz 20 weeks later (P = 0.002). Increases in weekly minimum temperature and rainfall were also significant factors in the increase in the reported cases of dengue. We recommend future studies using the same method, involving larger populations with different geographic location, climate and weather. We also recommend strengthening environmental, health and entomological surveillance systems to improve preparedness and emergency responses.

Field evaluation of Mesocyclops longisetus (Copepoda: Cyclopoidea) for the control of larval Aedes aegypti (Diptera Culicidae) in northeastern Mexico.

Field trials of the predacious copepod Mesocyclops longisetus Thiubaud were conducted in northeastern Mexico to determine the effectiveness of this species to control larval Aedes aegypti (L.) populations and to survive and reproduce in nature. Groups of 200, 50, and 50 ovigerous M. longisetus females were inoculated into 200-liter metal drums, discarded tires, and cemetery flower vases, respectively, which are 3 of the more important Aedes breeding sites in this area. Larvae were sampled at 15-d intervals, and total surviving cyclops were collected at the end of the study, 120 d later. Community participation was solicited through a simple training program on copepod rescue before drum cleaning and facilitated by the addition of a drum marker to remind residents of copepod presence. Results showed good cooperation and after 4 mo all peridomestic drums, still supported variable numbers of cyclopoids. Average of larvae reduction was 37.5% for drums, 67.5% for flower vases, and 40.9% for tires. This study shows difficulties of using cyclopoids for tires and vases in areas where prolonged dry seasons desiccated these habitats and reduced copepod survival.

Malaria and social movements in Mexico: the last 60 years.

The Mexican Ministry of Health's anti-malaria campaigns of the last sixty years have overlapped and interacted with both the World Health Organization's Global Eradication Program and a series of major political, social, and demographic movements in Mexico, including economic transformation, migration, urbanization, tourism, rural development, and the building of social and sanitary services. The authors argue that three decades of successful environmentally-oriented malaria work that integrated social and economic development was followed by the Global Campaign's insecticide-based approach that failed in both its economic and public health objectives, ultimately serving to block development efforts, particularly in poorer and southern states.

[Incorporating molecular tests into the practice of public health]. / La incorporación de las pruebas moleculares en la práctica de la salud pública.

Public Health has evolved in accordance with basic scientific and technologic advances. Molecular biology has provided sophisticated laboratory techniques and fine diagnostic tools that are being exploited in the area of Public Health in order to deepen our knowledge of the natural history of diseases, identify populations at risk, diagnose infectious process and different pathologies in the early stages of the illness and limit the damage produced by a late diagnosis. The modern molecular techniques provide a promising insight into the identification and measurement of molecular structures linked to the pathological process, the genotypic identification of infectious agents, the level of exposure and the susceptibility at individual as well as population levels. This paper describes its applications in the area of Public Health and highlights its limits and potential risks.

[Dengue in the Americas. A problem of regional health]. / El dengue en las Américas. Un problema de salud regional.

The Aedes aegypti was almost eradicate from The Americas in the early sixties but reinfested the Region a few years later, and dengue transmission has become a major health problem. The Americas have been affected by dengue epidemics since the 1970s and hemorrhagic fever is becoming a threat for millions of people living in the tropical and subtropical areas of the continent. Resources to cope with the increasing transmission of different serotypes in the Region are scarce. Therefore a regional effort to prevent the dissemination of dengue hemorrhagic fever (DHF) is necessary. Public awareness and community participation must be promoted and enhanced in order to decrease the risk of DHF.

[Dengue in Mexico: a priority problem of public health]. / El dengue en México: un problema prioritario de salud pública.

Dengue fever is a viral disease transmitted by Aedes aegypti. It has been recently incorporated to the agenda of priorities in many countries in the Americas. The emergence of dengue hemorrhagic fever cases is becoming a public health threat and requires the implementation of intensive surveillance and control strategies. The epidemiological panorama of dengue in Mexico provides the opportunity to analyze a regional health problem and the risk factors involved in the genesis of hemorrhagic cases under a situation that has not reached epidemic proportions yet.

[Vectors of dengue in Mexico: a critical review)]. / Los vectores del dengue en México: una revisión crítica.

The mosquito Aedes (Stegomyia) aegypti (Linneaus, 1762) is the vector of dengue viruses in America. Recently, another related species, Aedes albopictus (Skuse, 1894) was first introduced to America in 1986 in Texas, USA and later on in Sao Paulo, Brazil. Since then, this mosquito has rapidly colonized new areas along the northern border states of Mexico. The importance of this species as a vector of dengue virus is not clear. This work presents a revision of some characteristics of the two species in Mexico, with special emphasis in the documented vector, A. aegypti. Additionally, it includes a critical analysis of the methods for vector surveillance and its importance for a better application of control strategies, as well as some ideas about research needs and priorities in Mexico.

[The risk of dengue transmission: a space for stratification]. / El riesgo de transmisión del dengue: un espacio para la estratificación.

The emergence of dengue fever as a public health problem in the Americas is increasing. Its rapid spread in the region and the geographical dissemination of dengue infection has not been followed by a corresponding input of financial, human and technical resources necessary to control dengue fever epidemics. This situation compelled to the analysis of dengue transmission in Mexico with the objective of designing a strategy of dengue fever surveillance based on the stratification of transmission risks taking into account geographical variables like climate, rain precipitation, mean annual temperature and altitude, as well as socio-demographical variables like population density and socio-economic level. This strategy will permit the efficient use of the scant resources available for control, although the impact of dengue transmission is yet to be evaluated.

[Use of health services by a population of 60-year olds and older in Mexico]. / Uso de los servicios de salud por la población de 60 años y más en México.

OBJECTIVE: To describe the sociodemographic characteristics and determinants of health services utilization by the Mexican population of 60 years of age or more. MATERIAL AND METHODS: Information obtained from the National Health Survey II (ENSA-II) allowed analysis of 4,628 elderly people. Prevalence of chronic diseases was analyzed and the determinants of individuals who had used the health services in the two weeks prior to the interview. RESULTS: The chronic diseases most frequently reported were: hypertension, diabetes and heart disease. The utilization and hospitalization rates of that age group were 11.4 and 5.5%, respectively. The services most frequently used were: the private physician, social security (IMSS, ISSSTE) welfare services (Ministry of Health--SSA- and IMSS-Solidaridad). Interestingly, 25 to 45% of social security insurance holders did not use the services, instead they consulted a private physician. The most important explanatory variables for health services utilization were: the perceived illness, not having worked for the previous week and being a social security insurance holder. Gender, area of residence and level of education were not significant in the explanation of health services utilization. CONCLUSIONS: This study demonstrates the need to strengthen preventive and support programs for the elderly population, since they only demand health services when they feel sick.

[The diagnosis of dengue in Mexico: an update and outlook]. / El diagnóstico del dengue en México: actualidad y perspectivas.

Few diseases have unique clinical findings sufficient to identify them. Dengue fever is not one of them, being necessary the clinical and laboratory support to confirm its diagnosis. Since dengue virus was first isolated, there has been a worldwide effort to develop cheaper and more accurate serologic diagnostic tests. Dengue hemorrhagic fever deserves closer attention because of its devastating clinical effects and lethal outcomes. In addition to the wide circulation of serotypes 1, 2 and 4 for over a decade in the Americas, the presence of Den-3 was detected again in 1994 since its last appearance in 1963 and 1977. Given the high rates of vectorial infestation and the presence of a susceptible population, the probability of circulation of this serotype in our continent is high. The present work defines the wide range of diagnostic methods available today, their advantages and disadvantages, and their importance in the epidemiological surveillance of dengue fever in Mexico.

[Chronic diseases in persons of 60-69 years of age]. / Las enfermedades crónicas en las personas de 60-69 años.

OBJECTIVE: The results of the National Survey of Chronic Diseases (Mexico, 1993) regarding the prevalence of hypertension, diabetes mellitus and obesity in the 60 to 69 years old group are presented on a national and regional level. MATERIAL AND METHODS: Measurements taken included weight, height, blood pressure, visual acuity, glycosylated hemoglobin, cholesterol, lipoproteins, insulin, triglycerides and albumin. Data analysis were performed using the statistical package SPSS to carry out Mantel-Haenszel and chi square tests. RESULTS: Analysis of data for 1239 individuals showed that 38% of the aging population have hypertension. 25% are obese and 21% have diabetes. Findings showed that 28% of the individuals with hypertension and 18% of those with diabetes were detected through the survey. Obesity was strongly associated with hypertension and 33% of cases were not under treatment. Differences on the regional level are presented and results are discussed by sex and risk factors. The risk of diabetes was higher in those with other family members with diabetes, while microalbuminuria and hypercholesterolemia were associated with diabetes in this population. CONCLUSIONS: The results of the study support the need to improve early detection programs and intensify those interventions that prevent early mortality due to these particular diseases.

[Lactation and weaning patterns in Mexico. 1986 National Health Survey]. / Patrones de lactancia y ablactación en México. Encuesta nacional de salud 1986.

In the process of nutrition, breastfeeding is fundamentally important, due to the nutritional and immunological value of the mother's milk. Within its beneficial effects, it is found that it improves weight and size in children. Another stage in the child's feeding that should be considered during the first year of life is the weaning that complements, at certain age of the breastfeeder, the nutrition given by breastmilk. The decrease or abandonment of breastfeeding is alarming in the developing countries, where this natural product is more available, economical and nutritious. There is evidence that within the health institutions, artificial feeding is encouraged. The National Health Survey collected basic information on sociodemographic variables risk factors, demand and use of health services. It also included questions on breastfeeding and weaning for the population under one year of age. It was found that 19.9 percent was never breastfed. Another important fact is that 42.4 percent of children received breastmilk for just three months or less. This view suggests that breastfeeding in our country is changing, due to various factors, among which we can mention the differences in life styles, education and economical development among states. The results of this study show interesting data that oblige us to consider more detailed and specific analyses in the future.

[Use of hospital services by the aged population of Mexico City]. / Utilización de servicios hospitalarios por la población anciana de la Ciudad de México.

OBJECTIVE: The purpose of this study was to determine the characteristics of hospital utilization by the elderly in three hospitals in Mexico City during 1992 and 1993. Main reason for admission, average length of stay and type of treatment received were some of the variables studied. MATERIAL AND METHODS: A random sample of 820 clinical files were selected, 308 from the Instituto Nacional de la Nutrición Salvador Zubirán (INNSZ), 189 from the Hospital General Manuel Gea González (HGMGG) and 323 from the Hospital Regional Adolfo López Mateos (HRALM). The principal reasons for admission, average days spent in the hospital and type of treatment received were identified for patients 60 years and older. Univariate and bivariate analysis was performed with hypothesis test for differences between sexes. RESULTS: Diabetes mellitus and hypertension were the principal reasons for admission length of stay varied considerably and was the longest at the INNSZ (median: 12 days) and the shortest at the HRALM (median: 8 days). Most of the patients were admitted through the emergency service, except in the INNSZ where most came for ambulatory visit.

Determinants and predictors of dengue infection in Mexico.

A national serosurvey was conducted in Mexico from March to October 1986 to identify predictors of dengue transmission and target areas at high risk of severe annual epidemics. A total of 3,408 households in 70 localities with populations less than 50,000 were randomly sampled, and serology was obtained from one subject under age 25 years in each household. When comparing exposure and infection frequencies across the 70 communities, the authors found that median temperature during the rainy season was the strongest predictor of dengue infection, with an adjusted fourfold risk in the comparison of 30 degrees C with 17 degrees C. High temperatures increase vector efficiency by reducing the period of viral replication in mosquitoes. The proportion of houses in a community with larva on the premises was significantly associated with the community proportion infected (odds ratio (OR)adj = 1.9; 95% confidence interval (CI) 1.4-2.5), as was the proportion of households with uncovered water containers present (ORadj = 1.9; 95% CI 1.4-2.7). Because these factors have effects beyond the individual household and subjects infected from them create a risk for other subjects, both analyses of effects and organization of control efforts must be at the community level. A predictive model was constructed using the community level risk factors to classify communities as being at high, medium, or low risk of experiencing an epidemic; 57% of these communities were correctly classified using this model.