Corrigendum: Coronavirus Disease-2019 Survival in Mexico: A Cohort Study on the Interaction of the Associated Factors.

[This corrects the article DOI: 10.3389/fpubh.2021.660114.].

Coronavirus Disease-2019 Survival in Mexico: A Cohort Study on the Interaction of the Associated Factors.

The pandemic caused by the new coronavirus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is currently affecting more than 200 countries. The most lethal clinical presentation is respiratory insufficiency, requiring attention in intensive care units (ICU). The most susceptible people are over 60 years old with comorbidities. The health systems organization may represent a transcendental role in survival. Objective: To analyze the correlation of sociodemographic factors, comorbidities and health system organization variables with survival in cases infected by SARS-CoV-2 during the first 7 months of the pandemic in Mexico. Methods: The cohort study was performed in a health system public basis from March 1st to September 30th, 2020. The included subjects were positive for the SARS-CoV-2 test, and the target variable was mortality in 60 days. The risk variables studied were: age, sex, geographic distribution, comorbidities, health system, hospitalization, and access to ICU. Bivariate statistics (X2-test), calculation of fatality rates, survival analyses and adjustment of confusing variables with Cox proportional-hazards were performed. Results: A total of 753,090 subjects were analyzed, of which the 52% were men. There were 78,492 deaths (10.3% of general fatality and 43% inpatient). The variables associated with a higher risk of hospital mortality were age (from 60 years onwards), care in public sectors, geographic areas with higher numbers of infection and endotracheal intubation without management in the ICU. Conclusions: The variables associated with a lower survival in cases affected by SARS-CoV-2 were age, comorbidities, and respiratory insufficiency (with endotracheal intubation without care in the ICU). Additionally, an interaction was observed between the geographic location and health sector where they were treated.

International heterogeneity in coronavirus disease 2019 pediatric mortality rates.

Background: Severe coronavirus disease 2019 (COVID-19) is infrequent in children and shows a mortality rate of around 0.08%. This study aims to explore international differences in the pediatric mortality rate. Methods: We analyzed several countries with populations over 5 million that report disaggregated data of COVID-19 deaths by quinquennial or decennial age groups. Data were extracted from COVID-19 cases and deaths by age database, National Ministeries of Health, and the World Health Organization. Results: We included 23 countries in the analysis. Pediatric mortality varied from 0 to 12.1 deaths per million children of the corresponding age group, with the highest rate in Peru. In most countries, deaths were more frequent in the 0-4-year-old age group, except for Brazil. The pediatric/general COVID-19 mortality showed a great variation and ranged from 0% (Republic of Korea) to 10.4% (India). Pediatric and pediatric/general COVID mortality correlates strongly with 2018 neonatal mortality (r = 0.77, p < 0.001; and r = 0.88, p < 0.001, respectively), while shows a moderate or no correlation (r = 0.47, p = 0.02; and r = 0.19, p = 0.38, respectively) with COVID-19 mortality in the general population. Conclusions: International heterogeneity in pediatric COVID-19 mortality importantly parallels historical neonatal mortality. Neonatal mortality is a well-known index of the quality of a country's health system, which points to the importance of social determinants of health in pediatric COVID-19 mortality disparities. This issue should be further explored.

Introducción: La COVID-19 grave es poco frecuente en la infancia. El objetivo de este estudio fue explorar las diferencias en la tasa de mortalidad internacional por COVID-19 en la población pediátrica. Método: Se analizaron países con poblaciones superiores a 5 millones de habitantes que reporten muertes por COVID-19 con datos desglosados por grupos de edad quinquenales o decenales. Los datos se extrajeron de la base de datos COVerAge-DBs, de los ministerios nacionales de salud y de la Organización Mundial de la Salud. Resultados: Se incluyeron 23 países. La mortalidad pediátrica varió de 0 a 12.1 muertes por millón de personas del grupo de edad correspondiente, con la tasa más alta en Perú. En la mayoría de los países, las muertes fueron más frecuentes en el grupo de 0 a 4 años, excepto en Brasil. La mortalidad pediátrica/general por COVID-19 mostró una gran variación entre países y osciló entre el 0% (República de Corea) y el 10.4% (India). La mortalidad pediátrica y pediátrica/general por COVID-19 se correlaciona fuertemente con la mortalidad neonatal de 2018, mientras que tiene una moderada o nula correlación con la mortalidad por COVID-19 en la población general. Conclusiones: Existe una importante heterogeneidad internacional en la mortalidad pediátrica por COVID-19, que es paralela a la mortalidad neonatal histórica, la cual es un indicador de la calidad de los sistemas de salud y señala la importancia de los determinantes sociales de la salud en las disparidades de mortalidad pediátrica por COVID-19. Este tema debe explorarse a fondo.

International heterogeneity in coronavirus disease 2019 pediatric mortality rates / Heterogeneidad internacional en las tasas de mortalidad pediátrica por COVID-19

Abstract Background: Severe coronavirus disease 2019 (COVID-19) is infrequent in children and shows a mortality rate of around 0.08%. This study aims to explore international differences in the pediatric mortality rate. Methods: We analyzed several countries with populations over 5 million that report disaggregated data of COVID-19 deaths by quinquennial or decennial age groups. Data were extracted from COVID-19 cases and deaths by age database, National Ministeries of Health, and the World Health Organization. Results: We included 23 countries in the analysis. Pediatric mortality varied from 0 to 12.1 deaths per million children of the corresponding age group, with the highest rate in Peru. In most countries, deaths were more frequent in the 0-4-year-old age group, except for Brazil. The pediatric/general COVID-19 mortality showed a great variation and ranged from 0% (Republic of Korea) to 10.4% (India). Pediatric and pediatric/general COVID mortality correlates strongly with 2018 neonatal mortality (r = 0.77, p < 0.001; and r = 0.88, p < 0.001, respectively), while shows a moderate or no correlation (r = 0.47, p = 0.02; and r = 0.19, p = 0.38, respectively) with COVID-19 mortality in the general population. Conclusions: International heterogeneity in pediatric COVID-19 mortality importantly parallels historical neonatal mortality. Neonatal mortality is a well-known index of the quality of a country's health system, which points to the importance of social determinants of health in pediatric COVID-19 mortality disparities. This issue should be further explored.

Resumen Introducción: La COVID-19 grave es poco frecuente en la infancia. El objetivo de este estudio fue explorar las diferencias en la tasa de mortalidad internacional por COVID-19 en la población pediátrica. Método: Se analizaron países con poblaciones superiores a 5 millones de habitantes que reporten muertes por COVID-19 con datos desglosados por grupos de edad quinquenales o decenales. Los datos se extrajeron de la base de datos COVerAge-DBs, de los ministerios nacionales de salud y de la Organización Mundial de la Salud. Resultados: Se incluyeron 23 países. La mortalidad pediátrica varió de 0 a 12.1 muertes por millón de personas del grupo de edad correspondiente, con la tasa más alta en Perú. En la mayoría de los países, las muertes fueron más frecuentes en el grupo de 0 a 4 años, excepto en Brasil. La mortalidad pediátrica/general por COVID-19 mostró una gran variación entre países y osciló entre el 0% (República de Corea) y el 10.4% (India). La mortalidad pediátrica y pediátrica/general por COVID-19 se correlaciona fuertemente con la mortalidad neonatal de 2018, mientras que tiene una moderada o nula correlación con la mortalidad por COVID-19 en la población general. Conclusiones: Existe una importante heterogeneidad internacional en la mortalidad pediátrica por COVID-19, que es paralela a la mortalidad neonatal histórica, la cual es un indicador de la calidad de los sistemas de salud y señala la importancia de los determinantes sociales de la salud en las disparidades de mortalidad pediátrica por COVID-19. Este tema debe explorarse a fondo.

COVID-19 pandemic: challenges ahead.

Since December 2019, health systems worldwide have faced the pandemic caused by the new severe acute respiratory syndrome coronavirus 2. The pandemic began in China and has spread throughout the world. This new coronavirus has a high transmission capacity and elevated lethality in people over 60 years old and in those with risk factors (obesity, diabetes, and systemic arterial hypertension); those characteristics have a different proportion in each country. At present, there is no specific, effective, and safe treatment to treat this virus. In this review, an analysis is made on the differences in epidemiological aspects of the disease and its presentation in pediatric patients; the poorly-based recommendation for using an empirical combination of antimalarials plus antimicrobials as antiviral treatment; the indication of intravenous steroids; and the possible influence of antihypertensive drugs on the course of the disease.

A partir de diciembre de 2019, los sistemas de salud de todos los países se han enfrentado a la pandemia causada por un nuevo coronavirus (SARS-CoV-2), el cual fue notificado por primera vez en China y se ha esparcido por todo el mundo. Este nuevo coronavirus posee una alta capacidad para transmitirse. A escala mundial la letalidad ha sido más alta en la población mayor de 60 años y en aquellos que tienen factores de riesgo (obesidad, diabetes e hipertensión arterial sistémica). Sin embargo, estas características varían en proporción en cada país. Hasta el momento no hay un tratamiento específico, eficaz y seguro para combatir este virus. En este artículo se realiza un análisis sobre las diferencias globales en los aspectos ­epidemiológicos y con relación a su presentación en pacientes pediátricos, así como de la recomendación, con pobre fundamento, del uso de la combinación de antimaláricos y antimicrobianos empíricos como antivirales. También se analizan la indicación de esteroides intravenosos y la posible influencia de los fármacos antihipertensivos en el curso de la enfermedad.

COVID-19 pandemic: challenges ahead / Pandemia de COVID-19: retos por enfrentar

Abstract Since December 2019, health systems worldwide have faced the pandemic caused by the new severe acute respiratory syndrome coronavirus 2. The pandemic began in China and has spread throughout the world. This new coronavirus has a high transmission capacity and elevated lethality in people over 60 years old and in those with risk factors (obesity, diabetes, and systemic arterial hypertension); those characteristics have a different proportion in each country. At present, there is no specific, effective, and safe treatment to treat this virus. In this review, an analysis is made on the differences in epidemiological aspects of the disease and its presentation in pediatric patients; the poorly-based recommendation for using an empirical combination of antimalarials plus antimicrobials as antiviral treatment; the indication of intravenous steroids; and the possible influence of antihypertensive drugs on the course of the disease.

Resumen A partir de diciembre de 2019, los sistemas de salud de todos los países se han enfrentado a la pandemia causada por un nuevo coronavirus (SARS-CoV-2), el cual fue notificado por primera vez en China y se ha esparcido por todo el mundo. Este nuevo coronavirus posee una alta capacidad para transmitirse. A escala mundial la letalidad ha sido más alta en la población mayor de 60 años y en aquellos que tienen factores de riesgo (obesidad, diabetes e hipertensión arterial sistémica). Sin embargo, estas características varían en proporción en cada país. Hasta el momento no hay un tratamiento específico, eficaz y seguro para combatir este virus. En este artículo se realiza un análisis sobre las diferencias globales en los aspectos epidemiológicos y con relación a su presentación en pacientes pediátricos, así como de la recomendación, con pobre fundamento, del uso de la combinación de antimaláricos y antimicrobianos empíricos como antivirales. También se analizan la indicación de esteroides intravenosos y la posible influencia de los fármacos antihipertensivos en el curso de la enfermedad.

Feasibility Study of an Optical Caustic Plasmonic Light Scattering Sensor for Human Serum Anti-Dengue Protein E Antibody Detection.

Antibody detection and accurate diagnosis of tropical diseases is essential to help prevent the spread of disease. However, most detection methods lack cost-effectiveness and field portability, which are essential features for achieving diagnosis in a timely manner. To address this, 3D-printed oblate spheroid sample chambers were fabricated to measure green light scattering of gold nanoparticles using an optical caustic focus to detect antibodies. Scattering signals of 20-200 nm gold nanoparticles using a green laser were compared to green light emitting diode (LED) light source signals and to Mie theory. The change in signal from 60 to 120 nm decreased in the order of Mie Theory > optical caustic scattering > 90° scattering. These results suggested that conjugating 60 nm gold nanoparticles and using an optical caustic system to detect plasmonic light scattering, would result in a sensitive test for detecting human antibodies in serum. Therefore, we studied the light scattering response of conjugated gold nanoparticles exposed to different concentrations of anti-protein E antibody, and a feasibility study of 10 human serum samples using dot blot and a handheld optical caustic-based sensor device. The overall agreement between detection methods suggests that the new sensor concept shows promise to detect gold nanoparticle aggregation in a homogeneous assay. Further testing and protocol optimization is needed to draw conclusions on the positive and negative predictive values for this new testing system.

Oncocercosis: ¿la próxima enfermedad eliminable en México? / Onchocerciasis: the next eliminable disease in México?

La oncocercosis es la segunda causa de ceguera a escala mundial, después del tracoma, según la Organización Mundial de la Salud. Fue descubierta en América por Rodolfo Robles en Guatemala, en 1915 (enfermedad de Robles); en 1923 en Chiapas y en 1926 en Oaxaca, México. En 1930 se estableció el programa para su control; es el más antiguo del país y ha realizado trabajos ininterrumpidamente hasta la fecha. Se pueden describir tres grandes etapas del programa para el control de la oncocercosis: a) de 1930-1946 se llevó a cabo la lucha antilarvaria con creolina, la eliminación de larvas de las corrientes de agua y la extirpación de nódulos; b) la administración de la dietilcarbamazina en 1947, la extirpación de nódulos y la aplicación de DDT en 1952; y c) en 1993 la eliminación de la enfermedad con el tratamiento con ivermectina y la extirpación de nódulos. Hasta 1980 se observaba una notificación promedio de 20 mil casos anuales pero, a partir de 1993, al iniciar la administración de ivermectina en dos rondas anuales, se redujo a menos de 100 casos nuevos por año para finales del año 2000 y se eliminó la transmisión en dos focos (en el norte de Oaxaca y en Chamula, en Chiapas), aunque todavía permanece en uno (en Soconusco, Chiapas). En el presente artículo nos referimos a la lucha, durante los últimos 17 años, en contra de la oncocercosis y qué nos permite suponer que, en breve, podrá ser erradicada del país.

According to the World Health Organization, onchocerciasis is the second cause of global blindness after trachoma. It was first discovered in America by Rodolfo Robles in Guatemala in 1915 (Robles's disease); in Chiapas, Mexico in 1923; and in Oaxaca in 1926. In 1930, the first control program was established in Mexico that, to date, has worked uninterruptedly. Three stages of the program can be described: a) from 1930-1946 the antilarvae campaign with creolin was carried out along with the elimination of larvae from water and the removal of nodules; (b) administration of diethylcarbamazine in 1947, removal of nodules and application of DDT in 1952; and c) in 1993 the elimination of the disease with ivermectin treatment and the removal of nodules. Until 1980, an average of 20,000 cases have been reported each year. Since 1993, with the initiation of the administration of ivermectin in two annual doses, the incidence was reduced to <100 new cases per year by the end of 2000 and the transmission in two foci (northern Oaxaca and in Chamula in Chiapas) has been deleted, with one remaining in Soconusco, Chiapas. In this article, we report on the campaign against river blindness during the past 17 years and why we assume that, in brief, this disease can be eliminated in Mexico.

Best practices in dengue surveillance: a report from the Asia-Pacific and Americas Dengue Prevention Boards.

BACKGROUND: Dengue fever is a virus infection that is spread by the Aedes aegypti mosquito and can cause severe disease especially in children. Dengue fever is a major problem in tropical and sub-tropical regions of the world. METHODOLOGY/PRINCIPAL FINDINGS: We invited dengue experts from around the world to attend meetings to discuss dengue surveillance. We reviewed literature, heard detailed reports on surveillance programs, and shared expert opinions. RESULTS: Presentations by 22 countries were heard during the 2.5 day meetings. We describe the best methods of surveillance in general, the stakeholders in dengue surveillance, and the steps from mosquito bite to reporting of a dengue case to explore how best to carry out dengue surveillance. We also provide details and a comparison of the dengue surveillance programs by the presenting countries. CONCLUSIONS/SIGNIFICANCE: The experts provided recommendations for achieving the best possible data from dengue surveillance accepting the realities of the real world (e.g., limited funding and staff). Their recommendations included: (1) Every dengue endemic country should make reporting of dengue cases to the government mandatory; (2) electronic reporting systems should be developed and used; (3) at minimum dengue surveillance data should include incidence, hospitalization rates, deaths by age group; (4) additional studies should be completed to check the sensitivity of the system; (5) laboratories should share expertise and data; (6) tests that identify dengue virus should be used in patients with fever for four days or less and antibody tests should be used after day 4 to diagnose dengue; and (7) early detection and prediction of dengue outbreaks should be goals for national surveillance systems.

The growing burden of dengue in Latin America.

The re-emergence and subsequent failure to control dengue in Latin America provides a compelling illustration of the clinical, political and socio-economic challenges to eradicating dengue across the world. Insufficient political commitment, inadequate financial resources and increased urbanisation have contributed to the re-emergence and dramatic increase in dengue fever and dengue haemorrhagic fever in all 19 Latin American countries previously certified as free of Aedes aegypti. Difficulties with diagnosis, asymptomatic infection and the lack of effective surveillance systems account for the discrepancies between antibody prevalence against dengue and reported cases. Accurate incidence data and appreciation of the economic impact of dengue at regional, national and international levels are essential to securing political and economic commitment for dengue control efforts as well as increased scientific and social awareness. Environmental control efforts require an integrated and systematic approach at both the national and community level, while successful introduction of a dengue vaccine will require an educational programme that clearly communicates the cost-effectiveness and desirability of this interventional measure. In addition, countries must anticipate their national regulatory requirements, and vaccination strategies should be optimised according to the dengue epidemiology of each country. A broad scope is required to finance vaccination programmes to ensure individual countries' monetary shortcomings are addressed.

The participation of secondary clinical episodes in the epidemiology of vivax malaria during pre- and post-implementation of focal control in the state of Oaxaca, Mexico.

The participation of vivax malaria secondary clinical was researched in a retrospective cohort of 33,414 confirmed cases occurring between 1994 and 2005 in the state of Oaxaca, Mexico. Secondary episodes occurred in 23.4% of all primary cases. An increase in secondary episodes was associated with primary cases occurring during the dry seasons (risk ratio [RR] = 1.68, 95% CI: 1.45-1.96). The incidence of secondary episodes peaked at an older age, occurred similarly in men and women mostly during low mosquito abundance, and had a uniform distribution among localities. A reduction in secondary episodes was associated with the administration of an increased dose and early administration of primaquine (RR = 0.32, 95% CI: 0.26-0.38). However, limitations to distinguish relapses from re-infections impede assessment of the new treatment effect on relapses and its contribution to malaria control in the area. These findings highlight the need for new therapeutic schemes to radical cure of P. vivax infections and operational research aimed at parasite pool elimination.

Individual risk factors for Plasmodium vivax infection in the residual malaria transmission focus of Oaxaca, Mexico

OBJECTIVE: To identify individual risk factors for malaria infection of inhabitants in the residual transmission focus on the Pacific coast of Oaxaca, Mexico. MATERIALS AND METHODS: A population-based, matched case-control study was conducted from January 2002 to July 2003 comparing the frequency of exposure to individual risk factors in subjects presenting clinical malaria and uninfected controls. A malaria case was defined as an individual living in the study area presenting malaria symptoms and a Plasmodium vivax-positive thick blood smear; controls were individuals negative to P. vivax parasites and antibodies of the same gender and with ± five years as the case. A standardized questionnaire was used to record information about the individual risk factors associated with malaria episodes in cases and two controls for each case. RESULTS: In a multiple conditional logistic regression model analysis of data from 119 cases and 238 controls, 18 out of 99 variables were significantly associated (p< 0.05) with increased risk of malaria, including: being born in another locality (RM 3.16, 95 percent IC 1.16-6.13); speaking only an autochthonous language (RM= 2.48, 95 percent IC 1.19-3.77); having poor knowledge about malaria (RM= 2.26 95 percent IC 1.10-4.66 P< 0.02); the amount of vegetation around the house (RM= 20.43, 95 percent IC 5.98-70.87, P< 0.000; RM= 3.78, 95 percent IC 1.21-11.80, for 60-100 percent and 30-59 percent, respectively); living in houses constructed with perishable materials (RM= 2.85, 95 percent IC 1.62-5.01); living on the periphery of the town (RM= 6.23, 95 percent IC 3.50-11.0); sleeping on a dirt floor (RM= 2.98, 95 percent IC 1.78-5.01) or with two or more people in the same bed (RM= 1.85, 95 percent CI 1.09-3.14); not using bed nets (RM= 2.39, 95 percent IC 1.18-4.83, P< 0.003) or using bed nets with holes (RM= 13.93, 95 IC 2.48-78.01); traveling outside of the village (RM= 9.16, 95 percent IC 1.98-42.2); y..

OBJETIVO: Identificar los factores de riesgo individuales determinantes para contraer paludismo en habitantes del foco residual de transmisión de paludismo localizado en la costa del Pacífico de Oaxaca. MATERIAL Y MÉTODOS: Se realizó un estudio pareado de casos y controles, con base poblacional de enero de 2002 a julio de 2003, comparando la frecuencia de exposición a diversos factores de riesgo individuales en sujetos que presentaron un cuadro clínico de paludismo y controles no infectados. Un caso de paludismo fue definido como un individuo que vive en el área de estudio que presentó síntomas de paludismo y diagnosticado positivo a P. vivax en examen de gota gruesa de sangre, los controles fueron individuos negativos a parásitos y anticuerpos anti-P. vivax del mismo sexo y ± cinco años la edad del caso. Se usó un cuestionario estandarizado para registrar información de factores de riesgo individuales asociados a episodios de paludismo en casos y dos controles por caso. RESULTADOS: El análisis en un modelo de regresión logística condicional múltiple, 18 de 99 variables fueron significativamente asociadas (p< 0.05) con el incremento en el riesgo de paludismo, incluyendo: nacer fuera de la localidad (RM 3.16, 95 por ciento IC 1.16-6.13); hablar sólo un idioma autóctono (RM= 2.48, 95 por ciento IC 1.19-3.77); pobre conocimiento de cómo se transmite y trata el paludismo (RM= 2.26 95 por ciento IC 1.10-4.66 P< 0.02); cobertura de vegetación alrededor de la casa (RM= 20.43, 95 por ciento IC 5.98-70.87, P< 0.000; RM= 3.78, 95 por ciento IC 1.21-11.80, para 60-100 por ciento y 30-59 por ciento, respectivamente); casas construidas con materiales perecederos (RM= 2.85, 95 por ciento IC 1.62-5.01); localización de la casa en la periferia de la localidad (RM= 6.23, 95 por ciento IC 3.50-11.0); dormir en el suelo (RM= 2.98, 95 por ciento IC 1.78-5.01); dormir con dos o más personas en la misma cama (RM= 1.85, 95 por ciento CI 1.09-3.14); not...

Individual risk factors for Plasmodium vivax infection in the residual malaria transmission focus of Oaxaca, Mexico.

OBJECTIVE: To identify individual risk factors for malaria infection of inhabitants in the residual transmission focus on the Pacific coast of Oaxaca, Mexico. MATERIALS AND METHODS: A population-based, matched case-control study was conducted from January 2002 to July 2003 comparing the frequency of exposure to individual risk factors in subjects presenting clinical malaria and uninfected controls. A malaria case was defined as an individual living in the study area presenting malaria symptoms and a Plasmodium vivax-positive thick blood smear; controls were individuals negative to P. vivax parasites and antibodies of the same gender and with +/- five years as the case. A standardized questionnaire was used to record information about the individual risk factors associated with malaria episodes in cases and two controls for each case. RESULTS: In a multiple conditional logistic regression model analysis of data from 119 cases and 238 controls, 18 out of 99 variables were significantly associated (p< 0.05) with increased risk of malaria, including: being born in another locality (RM 3.16, 95% IC 1.16-6.13); speaking only an autochthonous language (RM= 2.48, 95% IC 1.19-3.77); having poor knowledge about malaria (RM= 2.26 95% IC 1.10-4.66 P< 0.02); the amount of vegetation around the house (RM= 20.43, 95% IC 5.98-70.87, P< 0.000; RM= 3.78, 95% IC 1.21-11.80, for 60-100% and 30-59%, respectively); living in houses constructed with perishable materials (RM= 2.85, 95% IC 1.62-5.01); living on the periphery of the town (RM= 6.23, 95% IC 3.50-11.0); sleeping on a dirt floor (RM= 2.98, 95% IC 1.78-5.01) or with two or more people in the same bed (RM= 1.85, 95% CI 1.09-3.14); not using bed nets (RM= 2.39, 95% IC 1.18-4.83, P< 0.003) or using bed nets with holes (RM= 13.93, 95 IC 2.48-78.01); traveling outside of the village (RM= 9.16, 95% IC 1.98-42.2); and previous malaria cases in the house (RM= 5.84, 95% IC 3.33-10.22). CONCLUSIONS: Risk of malaria infection was associated with socio-cultural and environmental factors exposing individuals to mosquito bites. A higher risk of malaria infection occurred outside the locality and by intradomiciliar transmission probably as a result of relapsing asymptomatic relatives.

Determinant factors for malaria transmission on the coast of Oaxaca State, the main residual transmission focus in Mexico.

OBJECTIVE: The purpose of this study was to investigate the influence of demographic, socioeconomic and ecological factors in malaria transmission in the most important residual transmission focus in Mexico, located in the state of Oaxaca. MATERIAL AND METHODS: The extension of the focus was determined by a spatial and time analysis of the distribution of malaria cases in the state between 1998 and 1999 using a Geographical Information System. A malaria transmission intensity index (MTII) was constructed based on the total number of cases during the study period and the duration and frequency of transmission outbreaks within the villages. The relationship between local determinants and malaria transmission intensity was investigated using multinomial and ordered logistic models. RESULTS: The distribution of villages according to their MTII was: 325 high, 341 medium, 142 low and 717 with no transmission. Localities of high MTII were associated with areas having a tropical climate with summer rains and low water evaporation. Most high MTII villages were located in elevations between 200 and 500 m above sea level, in the area around Pochutla City. The amount of temporary streams in the neighborhood of localities had a highly significant positive association with the MTII. Distance to roads was only significant in the high malaria MTII stratum. CONCLUSIONS: The main factors determining malaria transmission in the focus are related to good conditions for the breeding of mosquito vectors. The existence of short-range population movements around Pochutla, the main economically active city in the area, indicates the necessity to implement a system of epidemiological surveillance to halt the dispersion of new outbreaks.

Determinant factors for malaria transmission on the coast of Oaxaca State, the main residual transmission focus in Mexico / Factores determinantes de la transmisión de paludismo en la costa del estado de Oaxaca, el principal foco residual de transmisión en México

OBJECTIVE: The purpose of this study was to investigate the influence of demographic, socioeconomic and ecological factors in malaria transmission in the most important residual transmission focus in Mexico, located in the state of Oaxaca. MATERIAL AND METHODS: The extension of the focus was determined by a spatial and time analysis of the distribution of malaria cases in the state between 1998 and 1999 using a Geographical Information System. A malaria transmission intensity index (MTII) was constructed based on the total number of cases during the study period and the duration and frequency of transmission outbreaks within the villages. The relationship between local determinants and malaria transmission intensity was investigated using multinomial and ordered logistic models. RESULTS: The distribution of villages according to their MTII was: 325 high, 341 medium, 142 low and 717 with no transmission. Localities of high MTII were associated with areas having a tropical climate with summer rains and low water evaporation. Most high MTII villages were located in elevations between 200 and 500 m above sea level, in the area around Pochutla City. The amount of temporary streams in the neighborhood of localities had a highly significant positive association with the MTII. Distance to roads was only significant in the high malaria MTII stratum. CONCLUSIONS: The main factors determining malaria transmission in the focus are related to good conditions for the breeding of mosquito vectors. The existence of short-range population movements around Pochutla, the main economically active city in the area, indicates the necessity to implement a system of epidemiological surveillance to halt the dispersion of new outbreaks.

OBJETIVO: Investigar la participación de factores demográficos, socio-económicos y ecológicos en la transmisión de la malaria en el foco de transmisión residual más importante en México, localizado en el estado de Oaxaca. MATERIAL Y MÉTODOS: La extensión del foco se determinó por medio de un análisis espacio-temporal de la distribución de casos de malaria en el estado entre 1998 y 1999, usando un Sistema de Información Geográfico. Un índice de intensidad de transmisión de malaria (MTII, por sus siglas en inglés) se construyó basado en el número total de casos durante el periodo del estudio y la duración y frecuencia de brotes de transmisión dentro de las localidades. La relación de determinantes locales con el MTII se investigó por medio de modelos multinomiales logísticos. RESULTADOS: La distribución de localidades según su MTII fue de 325 alto, 341 medio, 142 bajo y 717 sin transmisión. Localidades con MTII alto estuvieron asociadas a las áreas de clima tropical con lluvias en verano y evaporación baja. La mayoría de las localidades con MTII alto se localizaron a elevaciones entre 200 y 500 msnm, en el área alrededor de la ciudad de Pochutla. La cantidad de arroyos temporales en la vecindad de localidades tuvo una asociación positiva significativa con el MTII. La cercanía a carreteras de localidades con MTII alto fue significativa. CONCLUSIONES: Los factores principales que determinan la transmisión de la malaria en el foco están relacionados con las condiciones favorables para la cría de mosquitos vectores. La participación de movimientos de población de rango cortos alrededor de Pochutla, la principal ciudad económicamente activa en el área, indica la necesidad de implementar un sistema de vigilancia epidemiológica para detener la dispersión de nuevos brotes.

Antibodies to West Nile virus in asymptomatic mammals, birds, and reptiles in the Yucatan Peninsula of Mexico.

Surveillance for evidence of West Nile virus (WNV) infection in taxonomically diverse vertebrates was conducted in the Yucatan Peninsula of Mexico in 2003 and 2004. Sera from 144 horses on Cozumel Island, Quintana Roo State, 415 vertebrates (257 birds, 52 mammals, and 106 reptiles) belonging to 61 species from the Merida Zoo, Yucatan State, and 7 farmed crocodiles in Ciudad del Carmen, Campeche State were assayed for antibodies to flaviviruses. Ninety (62%) horses on Cozumel Island had epitope-blocking enzyme-linked immunosorbent assay (ELISA) antibodies to flaviviruses, of which 75 (52%) were seropositive for WNV by plaque reduction neutralization test (PRNT). Blocking ELISA antibodies to flaviviruses also were detected in 13 (3%) animals in the Merida Zoo, including 7 birds and 2 mammals (a jaguar and coyote) seropositive for WNV by PRNT. Six (86%) crocodiles in Campeche State had PRNT-confirmed WNV infections. All animals were healthy at the time of serum collections and none had a history of WNV-like illness.

Cooperative actions to achieve malaria control without the use of DDT.

The success of regional networks to provide incentives and mechanisms for sharing information is illustrated through the North American Regional Action Plan on DDT (NARAP). This NARAP was designed to reduce human and environmental exposure to DDT and its metabolites in North America through cooperative efforts. The increasing role of environmental concerns in the planning and design of Mexico's DDT phase-out program motivated the Mexican Ministry of Health to undertake an alternative program for malaria control maximizing community participation without negatively affecting human and ecosystem health. This program relies on: 1) elimination of parasites in people, 2) improvement of personal and household hygiene, and 3) use of environmental management practices to eliminate mosquito breeding sites. This new strategy resulted in the elimination of DDT for malaria control in Mexico in the year 2000. While malaria and its corresponding vectors show considerable variability within a single country and certainly around the globe, the case example of Mexico provides a methodology for developing alternatives to DDT.