Viruela: de la primera vacuna al nacimiento del primer movimiento antivacunas / Smallpox: from the first vaccine to the birth of the first anti-vaccine movement

El último caso de viruela, la peor plaga que ha enfrentado la humanidad, fue diagnosticado hace 45 años y con él la enfermedad fue erradicada del planeta. Una hazaña épica iniciada a finales del siglo XVIII por Edward Jenner, el hombre que inoculó a su propio hijo con el pus de las lesiones de una ordeñadora que sufría viruela bovina, una enfermedad benigna antigénicamente relacionada con la viruela y que le confería inmunidad. Pocos años más tarde, en 1803, partía de España la "Real expedición filantrópica de la vacuna", llevando la vacuna a América y Asia, transportándola de brazo en brazo. A pesar del éxito de la vacuna, Jenner y la sociedad victoriana sufrieron los primeros movimientos antivacunas que hoy, en el contexto de la pandemia del COVID-19, son catapultados por los sitios de noticias falsas que socaban el conocimiento científico.

The last case of smallpox, the worst plague that humanity has faced, was diagnosed 45 years ago, marking the end of this disease in our world. It is a fascinating story that started in the late 18th century with a man called Edward Jenner. He made a name for himself by inoculating his son with the secretion of pus from the hand of a milkmaid sick with cowpox, a benign disease antigenically related to smallpox, and his inoculum conferred immunity. A few years later, in 1803, the "Royal Philanthropic Vaccine Expedition" left Spain, carrying the vaccine to the Americas and the Orient and passing the inoculum from arm to arm. Despite the vaccine's success, Jenner and Victorian society found themselves up against the first anti-vaccine backlash. In today's COVID-19 pandemic, these movements are now being super-charged by fake news websites, undermining scientific knowledge.

[The value of dental imaging in the teaching and promotion of oral health]. / El valor de las imágenes odontológicas en docencia y promoción de la salud oral.

In the context of the great diversity of oral microflora, including over 600 species, we highlight the educational value of electron micrographs and images of dental plaque cultures in dental models made with culture media, showing the bacterial colonies in the anatomic sites of the teeth that were most abundantly colonized. Such images allow for an easy understanding of the magnitude of the oral microbiome for students of biomedical careers--especially dentistry--and for the general public. As such, these images can be used in teaching programs and oral health campaigns.

El valor de las imágenes odontológicas en docencia y promoción de la salud oral / The value of dental imaging in the teaching and promotion of oral health

En el contexto de la gran diversidad de la microflora oral, con más de 600 especies, se resalta el valor pedagógico de las micrografías electrónicas de placa alba y las imágenes de cultivos bacterianos, realizados en modelos dentales hechos con medios de cultivo, que muestran colonias bacterianas en los sitios anatómicos de los dientes colonizados más abundantemente. Este tipo de imágenes facilita la comprensión de la magnitud del microbioma oral, a estudiantes de carreras biomédicas, especialmente odontología y al público en general, por lo que el uso de estas imágenes pueden ser utilizadas en docencia como en campañas de salud oral.

In the context of the great diversity of oral microflora, including over 600 species, we highlight the educational value of electron micrographs and images of dental plaque cultures in dental models made with culture media, showing the bacterial colonies in the anatomic sites of the teeth that were most abundantly colonized. Such images allow for an easy understanding of the magnitude of the oral microbiome for students of biomedical careers -especially dentistry- and for the general public. As such, these images can be used in teaching programs and oral health campaigns.

Scanning electron microscopy of damage caused by Mesocyclops thermocyclopoides (Copepoda: Cyclopoidea) on larvae of the Dengue fever vector Aedes aegypti (Diptera: Culicidae)

Dengue fever is a mosquito-borne viral disease, whose main biological vector is Aedes aegypti. This mosquito colonizes tropical areas where the disease is endemic. The most obvious action against dengue is attacking its vector. Biological control appears to be an alternative approach, using natural enemies of the mosquitoes, such as predatory copepods. Thus, the morphological study of the damage caused by copepods is important to understand its predatory capacity. Twenty-five A. aegypti larvae were exposed to the copepod Mesocyclops thermocyclopoides and the damage caused by the copepods was evaluated using scanning electron microscopy. The larvae showed damage mainly at the anal segment, the siphon and the abdomen; only three attacks to the head were observed. The size of the siphon might be of importance in determining whether or not a copepod will attack a mosquito larva.

El dengue es una enfermedad viral transmitida por mosquitos, cuyo principal vector es Aedes aegypti. Este mosquito coloniza muchas áreas tropicales donde la enfermedad es endémica. La acción más obvia contra el dengue es el ataque a su vector. El control biológico parece una buena alternativa, empleando enemigos naturales de los mosquitos, como los copépodos. Por lo tanto, es importante el estudio morfológico del daño causado por los copépodos para comprender su capacidad depredadora. Veinticinco larvas de A. aegypti fueron expuestas a la actividad depredadora del copépodo Mesocyclops thermocyclopoides. Mediante microscopia electrónica de rastreo se evaluó el daño causado por los copépodos. Éstos atacaron principalmente el segmento anal, el sifón y el abdomen de las larvas; sólo vimos tres ataques a la cabeza. El tamaño del sifón podría ser de importancia para predecir si los copépodos pudiesen atacar larvas de determinado mosquito.

Scanning electron microscopy of the four larval instars of the Dengue fever vector Aedes aegypti (Diptera: Culicidae)

Aedes aegypti is the main insect vector of Dengue fever and dengue hemorrhagic fever/dengue shock syndrome and represents the only vulnerable element in the control of this disease. Therefore, the identification and quantification of this mosquito is an important task; however, the majority of taxonomic keys are based on the 4th larval instar. For that reason, this study describes the four larval instars ofA. aegypti using scanning electron microscopy. Morphological changes during larval development were observed at the pecten, comb scales and the ventral brush of the abdominal segment X; however, the 3rd and 4th instars showed similar structures with only a slight variation. The structures described in this study will be helpful in the identification of the four instars of A. aegypti, a fundamental task for comprehending the natural history of dengue mainly in new territories affected.

Aedes aegypti es el principal insecto vector de la fiebre del dengue y del dengue hemorrágico/síndrome del choque por dengue y es el único elemento atacable para el control de esta virosis. La identificación y cuantificación de éste es una tarea importante; no obstante, la mayoría de las llaves taxonómicas se basan en el cuarto estadio larval. Por esta razón, en este trabajo se describen los cuatro estadios larvales de A. aegypti los cuales fueron examinados mediante microscopia electrónica de rastreo. Los cambios morfológicos ocurridos durante el desarrollo larval fueron observados en el pecten, las escamas del peine, el cepillo ventral del décimo segmento. El 3ero y 4to estadios larvales mostraron estructuras similares con sólo ligeras variaciones. Las estructuras descritas en este artículo permiten identificar cualquiera de los cuatro estadios larvales de A. aegypti, lo cual representa una tarea importante en la comprensión de la historia natural del dengue en los nuevos territorios afectados.

Detección inmunoenzimática de la toxina de la bacteria Clostridium tetani: una alternativa a las pruebas biológicas con ratones / Immunoenzimatic detection of the Clostridium tetani bacterial toxin: an alternative to mice bioassays

Cell-free extracts from 20 strains of Clostridium tetani isolated from soil samples, were tested for tetanus toxin production using an enzyme immunoassay. All the extracts were classified as positive for the toxin presence, and eight of them showed absorbance values corresponding to tetanus toxin concentrations between 3.2 and 88 ng/ml; thus, they fell within the linear absorbance range (0.135-0.317). All dilutions of toxin used to obtain the calibration curve (0.0071 to 1.1 ng) were lethal for mice.

Scanning electron microscopy of damage caused by Mesocyclops thermocyclopoides (Copepoda: Cyclopoidea) on larvae of the Dengue fever vector Aedes aegypti (Diptera: Culicidae).

Dengue fever is a mosquito-borne viral disease, whose main biological vector is Aedes aegypti. This mosquito colonizes tropical areas where the disease is endemic. The most obvious action against dengue is attacking its vector. Biological control appears to be an alternative approach, using natural enemies of the mosquitoes, such as predatory copepods. Thus, the morphological study of the damage caused by copepods is important to understand its predatory capacity. Twenty-five A. aegypti larvae were exposed to the copepod Mesocyclops thermocyclopoides and the damage caused by the copepods was evaluated using scanning electron microscopy. The larvae showed damage mainly at the anal segment, the siphon and the abdomen; only three attacks to the head were observed. The size of the siphon might be of importance in determining whether or not a copepod will attack a mosquito larva.

Scanning electron microscopy of the four larval instars of the Dengue fever vector Aedes aegypti (Diptera: Culicidae).

Aedes aegypti is the main insect vector of Dengue fever and dengue hemorrhagic fever/dengue shock syndrome and represents the only vulnerable element in the control of this disease. Therefore, the identification and quantification of this mosquito is an important task; however, the majority of taxonomic keys are based on the 4th larval instar. For that reason, this study describes the four larval instars ofA. aegypti using scanning electron microscopy. Morphological changes during larval development were observed at the pecten, comb scales and the ventral brush of the abdominal segment X; however, the 3rd and 4th instars showed similar structures with only a slight variation. The structures described in this study will be helpful in the identification of the four instars of A. aegypti, a fundamental task for comprehending the natural history of dengue mainly in new territories affected.

[Immunoenzimatic detection of the Clostridium tetani bacterial toxin: an alternative to mice bioassays]. / Detección inmunoenzimática de la toxina de la bacteria Clostridium tetani: una alternativa a las pruebas biológicas con ratones.

Cell-free extracts from 20 strains of Clostridium tetani isolated from soil samples, were tested for tetanus toxin production using an enzyme immunoassay. All the extracts were classified as positive for the toxin presence, and eight of them showed absorbance values corresponding to tetanus toxin concentrations between 3.2 and 88 ng/ml; thus, they fell within the linear absorbance range (0.135-0.317). All dilutions of toxin used to obtain the calibration curve (0.0071 to 1.1 ng) were lethal for mice.

Parásitos intestinales en una comunidad Amerindia, Costa Rica / Intestinal parasites in an Amerindian community

In Costa Rica there were three national surveys of intestinal parasitism (1966, 1982, and 1996) that showed dramatic reduction of the prevalence of Trichuris, Ascaris, and Necator/Ancylostoma (hookworms); however, these nematodes persist with high prevalence in low socio-economically groups, as the squatter settlements around the cities; however, it is possible that pour Amerindian communities with substandard housing condition also suffer the burden of intestinal parasites. For this reason, the present study was planted in a rural disperse Amerindian community from the South of Costa Rica. 45 fecal samples were collected from children under 15 years old, and were processed according a modification of the Baermann method, which also permits the observation of other parasites beyond Strongyloides. 38 (84 percent) of the analyzed samples were positive for at least one parasite. The prevalence for nematodes was Ascaris (36 percent), hookworms (22 percent) Enterobius (4 percent), and Trichuris (2 percent). For protozoa was Endolimax nana (33 percent), Entamoeba coli (27 percent), and Entamoeba histolytica/dispar (11 percent). These data are the reflect of the inadequate sanitation conditions of this community.

In Costa Rica there were three national surveys of intestinal parasitism (1966, 1982, and 1996) that showed dramatic reduction of the prevalence of Trichuris, Ascaris, and Necator/Ancylostoma (hookworms); however, these nematodes persist with high prevalence in low socio-economically groups, as the squatter settlements around the cities; however, it is possible that pour Amerindian communities with substandard housing condition also suffer the burden of intestinal parasites. For this reason, the present study was planted in a rural disperse Amerindian community from the South of Costa Rica. 45 fecal samples were collected from children under 15 years old, and were processed according a modification of the Baermann method, which also permits the observation of other parasites beyond Strongyloides. 38 (84%) of the analyzed samples were positive for at least one parasite. The prevalence for nematodes was Ascaris (36%), hookworms (22%) Enterobius (4%), and Trichuris (2%). For protozoa was Endolimax nana (33%), Entamoeba coli (27%), and Entamoeba histolytica/dispar (11%). These data are the reflect of the inadequate sanitation conditions of this community.

Fusarium sp como agente etiológico de onicomicosis: informe de tres casos y revisión de la literatura / Fusarium sp like etiologico agent of onicomicosis: report of three cases and revision of literature

Usualmente las onicomicosis se asocian con dermatofitos o Candida; no obstante, otros hongos diferentes a estos se han asociado a esta condición clínica, entre ellos Fusarium, un hongo que muchas veces se considera contaminante de laboratorio; por lo que es importante correlacionar el examen directo con el cultivo. Se describen tres casos de onicomicosis asociados a Fusarium sp., en uno de ellos el hallazgo más relevante y raro fue la intensa coloración verdosa de la uña. En los tres casos se aisló repetidamente el agente en cuestión. Se discute la importancia de identificar otros agentes diferentes de los usuales en onicomicosis, pues esos no responden a los tratamientos convencionales.

Dermatophytes and Candida spp. are the most common agents associated with onychomycosis. However, other fungi that are considered laboratory contaminants, such as Fusarium spp. have been isolated from this clinical condition as etiological agents. In the present communication, three cases of onychomycosis caused by Fusarium are described. The nail of one of the patients exhibited an intense dark green color, which is a rare finding in this pathology. In all cases the fungus was repeatedly isolated. The importance of identifying the etiological agent is emphasized since conventional treatment for onychomycosis is ineffective against Fusarium.

The windows, scales, and bristles of the tropical moth Rothschildia lebeau (Lepidoptera: Saturniidae)

The common Spanish name of the moth Rothschildia lebeau (Saturniidae)is cuatro ventanas (four ‘windows ’),because it exhibits a transparent oval path in each wing.The scales of the colored areas and the bristles from the "window "were analyzed.We developed a simple device to measure transmittance across the "windows "with an spectrophotometer.A square section of "window "was mounted onto a flat black card and placed onto a clamp that hung in the path of the light -beam of the spectrophotometer.Absorbance was measured at 350 and 550 nm,with the "window "positioned perpendicular to the light beam (incidence of 90 °);then the measurements were repeated with the "window "moved at an angle of 45 °.Each measurement was replicated 5 times.Wing color spots were analyzed with a light dissection microscope (stereoscope)and with scanning electron microscopy.The scales have a minimum of 4 morphological types,3 of them showed the typical appearance of unspecialized scales described for other butterflies; whereas the fourth has features particular to this species. On the "window "the scales are transformed in hair-like bristles that do not interfere with light, conferring the transparency that characterizes the "windows ".However,if the wing is illuminated at an almost grazing-incidence,they reflect the light as a mirror.Two hypothetical functional explanation for the windows are mimicry and interspecies communication

El nombre común de la mariposa nocturna Rothschildia lebeau (Saturniidae)es "cuatro ventanas ",porque exhibe una zona transparente en cada ala.Las escamas de las áreas coloreadas y las cerdas de las "ventanas "fueron analizadas al estereoscopio y al microscopio electrónico de rastreo. Al menos se identificaron cuatro tipos morfológicos de escamas similares a las escamas no especializadas de otras mariposas.En la "ventana "las escamas han sido sustituidas por cerdas que no interfieren el paso de la luz,confiriéndoles la transparencia que las caracteriza.No obstante,si el ala es iluminada en ángulo rasante refleja la luz como un espejo.Dos hipótesis para explicar la evolución de estas "ventanas "son el mimetismo y la comunicación

Strongyloides stercoralis en pacientes psiquiátricos / Strongyloides stercoralis in psychiatric patients

Strongyloides stercoralis es un parásito intestinal, cuya prevalencia es usualmente subestimada en Costa Rica, porque se emplea sólo el examen directo de las muestras de heces; mientras que, para S. stercoralis es necesario emplear métodos más sensibles, como el Baermann o el cultivo en agar. En otros países se ha considerado a los pacientes psiquiátricos como un grupo de riesgo para esta parasitosis; por lo que estudiamos un grupo de pacientes (n=108)y del personal (n=71) del Hospital Nacional Psiquiátrico, analizado mediante una modificación del método de Baermann y el examen directo estándar. Los parásitos más frecuentes fueron Endolimax nana (20 por ciento), Entamoeba coli (16 por ciento), Giardia duodenalis (4 por ciento) y dos casos de S. stercoralis, uno del grupo de pacientes y el otro del personal. Este informe corrobora la importancia del método de Baermann, porque los dos casos de S. stercoralis spp., encontrados, además de dos de Trichuris spp. y otros dos de uncinarias solo fueron detectados por el método de Baermann. Adicionalmente, la prevalencia global de parásitos intestinales encontrada fue un 10 por ciento superior a la prevalencia informada para el país en la encuestra nacional de 1996. Los datos presentados corroboran un grupo de alto riesgo para los parásitos intestinales y cualquier otro agente transmitido por contaminación fecal.

Strongyloides stercoralis is an intestinal parasite, which prevalence is usually underestimated in Costa Rica, because the stool samples are analyzed only by direct fecal smears; where as, for S. stercoralis analysis is necessary to use more sensible methods; such as the Baermann or agar culture methods. In other countries the psychiatric patients are considered as a risk group for this parasite. For this reason, a group of patients (n=108) and personal (n=71) from the National Hospital of Psychiatric were studied using a modification of the Baermann method and the standard direct fecal analysis. The most frequent parasites found were Endolimax nana (20%), Entamoeba coli (16%), Giardia duodenalis (4%), and two cases of S. stercoralis were diagnosed, one from the patients and the other in the staff. This report stresses the importance of the use of Baermann method, because the two cases of S. stercoralis found and other two cases of Trichuris and another two of hookworms were diagnosed only with this method. The global prevalence of intestinal parasites of the psychiatric patients was 30%, a 10% higher than the prevalence described for the country, according to the national survey from 1996. Our data corroborate that the psychiatric patients represent a high-risk group for intestinal parasites and also to any other agent transmitted by fecal contamination.

Nanobacterias y la epidemiología de las litiasis renales / Nanobacteria and the epidemiology of the renal litiasis

Nanovesículas o nanoestructuras que semejan pequeñas bacterias de menos de 0.5 um de diámetro han sido encontradas como contaminantes de sueros comerciales provenientes de fetos bovinos y fueron responsables de efectos citotóxicos en monocapas celulares cultivadas in vitro. Posteriormente el agente fue cultivado y clasificado como Nanobacterium sanguineum, el cual se ha relacionado con la formación de cálculos renales y más recientemente con otras patologías asociadas a calcificación de tejidos. Por otra parte, otros científicios no aceptan la existencia de tal bacteria. Se quiere más investigación para determimar si estas nanoestructuras son realmente bacterias

The "windows", scales, and bristles of the tropical moth Rothschildia lebeau (Lepidoptera: Saturniidae).

The common Spanish name of the moth Rothschildia lebeau (Saturniidae) is cuatro ventanas (four 'windows'), because it exhibits a transparent oval path in each wing. The scales of the colored areas and the bristles from the "window" were analyzed. We developed a simple device to measure transmittance across the "windows" with an spectrophotometer. A square section of "window" was mounted onto a flat black card and placed onto a clamp that hung in the path of the light - beam of the spectrophotometer. Absorbance was measured at 350 and 550 nm, with the "window" positioned perpendicular to the light beam (incidence of 90 degrees); then the measurements were repeated with the "window" moved at an angle of 45 degrees. Each measurement was replicated 5 times. Wing color spots were analyzed with a light dissection microscope (stereoscope) and with scanning electron microscopy. The scales have a minimum of 4 morphological types, 3 of them showed the typical appearance of unspecialized scales described for other butterflies; whereas the fourth has features particular to this species. On the "window" the scales are transformed in hair-like bristles that do not interfere with light, conferring the transparency that characterizes the "windows". However, if the wing is illuminated at an almost grazing-incidence, they reflect the light as a mirror. Two hypothetical functional explanation for the windows are mimicry and interspecies communication.

Microwave irradiation for shortening the processing time of samples of flagellated bacteria for scanning electron microscopy.

Microwave irradiation (MWI) has been applied to the development of rapid methods to process biological samples for scanning electron microscopy (SEM). In this paper we propose two simple and quick techniques for processing bacteria (Proteus mirabilis and Vibrio mimicus) for SEM using MWI. In the simplest methodology, the bacteria were placed on a cover-glass, air-dried, and submitted to conductivity stain. The reagent used for the conductivity stain was the mordant of a light microscopy staining method (10 ml of 5% carbolic acid solution, 2 g of tannic acid, and 10 ml of saturated aluminum sulfate 12-H2O). In the second method the samples were double fixed (glutaraldehyde and then osmium), submitted to conductivity stain, dehydrated through a series of ethanol solutions of increasing concentration, treated with hexamethyldisilazine (HMDS), and dried at 35 degrees C for 5 minutes. In both methods the steps from fixation to treatment with HMDS were done under MWI for 2 minutes in an ice-water bath, in order to dissipate the heat generated by the MWI. Although both techniques preserve bacterial morphology adequately, the latter, technique showed the best preservation, including the appearance of flagella, and that process was completed in less than 2 hours at temperatures of MWI between 4 to 5 degrees C.

Historia natural de la infección por Helicobacter Pylori, su tratamiento antimicrobiano y el empleo de plantas medicinales / Natural history of the infection by Helicobacter Pylori, its antimicrobial treatment and the use of medicinal plants

Los miembros del género Helicobacter, descrito en 1989, colonizan el estómago e intestino de humanos y algunas especies animales. El número de especies en este género se ha expandido desde 1983, cuando se describió H. pylori, la especie tipo; actualmente el género incluye más de 20 especies. En humanos, descrita en 1983, es reconocida como la principal causa de gastritis crónica, úlceras gástricas y duodenales y algunos tipos de cáncer gástrico. También, algunas especies relacionadas se han asociado ocasionalmente con septicemias en pacientes con SIDA. Helicobacter spp. son bacilos Gram negativos, catalasa, oxidasa y ureasa positivos, miden de 2,5 a 3,5 mm de largo por 0,5 a 1 mm de diámetro, son microaerofílicos, curvados o espirales con uno o varios flagelos envainados polares, localizados en uno de los extremos de la bacteria y al menos tres especies tienen fibras periplásmaticas. Los estudios epidemiológicos revelan que la infección con H. pylori es más común en países en desarrollo que en los desarrollados, debido a muchos factores del ambiente como hacinamiento, disponibilidad de agua potable, nivel económico, contaminación fetal y otros factores de hospedero y de agente como la edad y el tipo de cepa, respectivamente. Aunque este agente es sensible a muchos antimicrobianos in vitor, es difícil de erradicar del estómago, debido a su nicho ácido y su localización extracelular, pues reside en la cepa de mucho del estoómago y desarrolla resistencia a los antibióticos que usualmente se utilizan en su tratamiento, especialmente el metronidazol. Las monoterapias o las terapias duales muestran niveles inaceptablemente bajos de curación; por esta razón, se han propuesto varios esquemas triples o cuádruples de terapia; los primeros utilizan uno o dos antibióticos (metronidazol, amoxicilina, claritromicina, tetraciclina), una droga supresora de la secreción ácida y compuesto de bismuto (Pepto Bismol o citrato de bismuto). Las terapias cuádruples incorporan adicionalmente un inhibidor de la bomba protónica. Comúnmente, la tasa de erradicación de los diferentes esquemas oscila entre un 70 y 90 por ciento. El alto costo del tratamiento, especialmente de los esquemas cuádruples, su baja tolerabilidad, su abandono y la emergencia de cepas de H. pylori resistentes a los antibióticos, son responsables de la talla en un 10 a 30 por ciento de los casos...

Microorganismos presentes en el reverso de las uñas de trabajadores de la salud, Hospital Max Peralta, Cartago, Costa Rica / Present microorganis in reverse of the nails of workers of the health, Hospital Max Peralta, Cartago, Costa Rica

El lavado de las manos constituye el método más efectivo y económico para prevenir la transmisión de infecciones nosocomiales; no obstante, a veces es una práctica realizada con negligencia lo que provoca el establecimiento de agentes potencialmente patógenos en las áreas subungales, las que podrían actuar como reservorios de esos agentes. Por esta razón, el objetivo de este estudio fue determinar la presencia de microorganismos en la zona subungal de un grupo muestreado de trabajadores de la salud de un hospital en Costa Rica. Se realizaron cultivos de material obtenido del área bajo las uñas de 46 trabajadores de la salud, el cual fue inoculado en agar sangre. Del 48 por ciento de esas personas se aisló al menos un microorganismo. Los agentes aislados más frecuentemente fueron Staphylococcus (12 por ciento S. aureus 24 por ciento, S. epidermidis y 22 por ciento S. warneri), que corresponde al 75 por ciento del total de aislamientos; también, se cultivaron tres cepas de Candida (C. tropicalis, C.guillermondi y C. parapsilopsis). Estos datos confirman la importancia de hacer un lavado concienzudo de las manos para como medida de prevención de las infecciones nosocomiales.

Una vision de la biologia tropical a traves del microscopio electronico / A view of the biology by electron microscope

The first electron microscope in Costa Rica was a donation from the government of Japan through its International Cooperation Agency (JICA) in 1974. This donation made possible the consolidation of what was to become the University of Costa Rica's Electron Microscope Unit (UME). Within three years the first scientific papers were published, dealing with ultrastructural aspects of "Corn's rayado fino virus" and rotavirus, viral agent of human diarrhea. Subsequent papers out of the UME were published for the most part in the Journal of Tropical Biology, totaling at least 50 in that journal alone by the year 2000. With the recent acquisition of Energy Dispersive Spectrometer to coupled in transmission electron microscope and scanning electron microscope to X ray analysis, the data acquisition of the UME has been greatly enhanced, making possible to analyze both structure and elemental chemical composition in a specimen. Other applications of this new technology include studies of environmental pollution with heavy metals, such as comparative analysis of residues on leaves from urban areas and those on leaves from primary forest

Epidemiología del dengue en el Cantón de Esparza, Puntarenas, Costa Rica 1997-2002 / Epidemiology of dengue in the Cantón de Esparza, Puntarenas, Costa Rica 1997-2002

Dengue es la infección por flavivirus más prevalente en humanos transmitida por mosquitos. El dengue etiológico es el virus Dengue y su principal vector es el mosquito Aedes aegypti, que se ha adaptado al ambiente humano. Esta enfermedad re-emergió en Costa Rica en 1993 y ahora es endémica en la costa pacífica, principalmente en el poblado de Puntarenas. El objetivo de esta investigación es describir algunos aspectos del dengue en el cantón de Esparza, Puntarenas, Costa Rica, durante los últimos cinco años. El pico epidémico más importante ocurrió en 1997, ese año se presentaron 1347 casos, que iniciaron en junio y terminaron en diciembre. Ese patrón, caracterizado por la ausencia de casos durante los primeros cinco o seis meses fue estable hasta el 2001. Este año hubo casos durante todos los meses del año, cuya frecuencia fue en aumento hasta alcanzar un pico epidémico entre enero y febrero de 2002 con 90 y 77 casos, respectivamente. Es importante evaluar algunos de los posibles determinantes epidemiológicos involucrados en esta población; uno de los posibles factores fue el pobre suministro de agua potable que obligó a muchas familias a guardar agua en contenedores y a perforar pozos. Palabras clave: Dengue, Aedes aegypti, flavivirus.