Economic analysis of an educational human security model in southwestern bateyes of the Dominican Republic / Análisis económico de un modelo educativo de seguridad humana en los bateyes del suroeste de la República Dominicana

Objetivos: realizar un análisis económico para evaluar los costos de una intervención educativa, utilizando los principios de un modelo de seguridad humana en Bateyes del suroeste de la República Dominicana. Métodos: se consideraron cuatro recursos de intervención, incluyendo la capacitación del personal, los incentivos mensuales, la supervisión de las actividades de campo y el costo total asociado al tratamiento anual de la diarrea aguda. El gasto se comparó entre el programa estándar de atención (Batey Control) y la intervención con el modelo de seguridad humana (Batey Caso). Resultados: el ahorro del costo total anual para el Ministerio de Salud de República Dominicana asociado con la reducción de la incidencia de episodios de diarrea aguda fue de US$252,399. Si se extrapolan a los 300 Bateyes de República Dominicana, se podría ahorrar aproximadamente US$75 millones en prevención de enfermedades infecciosas. Conclusiones: el modelo de seguridad humana luce ser un método eficaz para mejorar el conocimiento sobre la prevención de enfermedades y aumentar el empoderamiento de la comunidad para la movilización de recursos. Aplicada a otros entornos, la intervención podría tener una incidencia beneficiosa en las poblaciones de refugiados e indocumentados bajo el impacto de la violencia estructural.

Objectives: To conduct an economic analysis to evaluate the costs of an educational intervention, using the human security model, and potential sources of economic benefits, in Southwestern Bateyes in the Dominican Republic. Methods: Four intervention resources were considered, including staff training, monthly incentives, supervision of field activities, and total cost associated with annual treatment for acute diarrhea. The expenditure was compared between the standard program of care and the intervention using the human security model. Results: The total annual cost saving to the Dominican Republic Ministry of Health, associated with reducing the incidence of acute diarrhea episodes, was US$252,399. If this is extrapolated to the 300 Bateyes of the Dominican Republic, the Ministry of Health could save approximately US$75 million in infectious disease prevention by implementing this intervention model in these isolated rural communities. Conclusions: The educational intervention, which incorporated a human security approach, appeared to be an effective method to enhance knowledge about disease prevention and to increase empathy among community members for resource mobilization and local empowerment. Applied to other settings, the intervention could have a beneficial impact on refugee and undocumented populations under the

Immunopathological features developing in the mosquito midgut after feeding on anopheles gambiae mucin-1 / interleukin-12 cDNA immunized mice / Desarrollo de características inmunopatológicas en el intestino medio del mosquito después de alimentarse de ratones inmunizados con mucina-1 / interleucina-12 ADNc de anopheles gambiae

The mosquito midgut is the organ into which the blood meal passes and in which, within a peritrophic membrane secreted by the epithelium, the blood is retained during digestion and absorption. The mosquito midgut is lined with an actin filled microvilli that are exposed to the harsh environment of the gut lumen such as food particle abrasion, digestive hydrolases and attack by pathogens and parasites that are taken in by the blood meal. These microvilli are protected them these effects by the peritrophic matrix, the glycocalyx and the mucin proteins that line their epithelial surfaces. Immunization of BALB/c mice with AgMUC1/IL-12 cDNA has been shown to kill mosquitoes when fed on these mice. Mucin is one of the proteins produced in the mosquito midgut after a blood meal. The fine structure of the mosquito midgut epithelium interacting with immune factors such as antibodies or immune cells is of special significance for interpreting early events in the interaction between the mosquito midgut lining and the specific immune components present in the blood of AgMUC1/IL-12 cDNA immunized BALB/c mice. Following bright light microscopy, scanning electron and transmission electron microscopic observations of the features seen in mosquito midgut sections from An. gambiae mosquitoes fed on BALB/c mice immunized with AgMUC1/IL-12 cDNA, the most likely immune mechanisms responsible for mosquito killing could be cell mediated, most likely antibody dependent cellular cytotoxicity. Both necrotic and apoptotic processes that could be the cause of mosquito death were seen to take place in the cells lining the midgut epithelium.

El intestino medio es el órgano al cual pasa la sangre consumida por el mosquito y donde, mediante una membrana peritrófica secretada por el epitelio, esta sangre es mantenida durante la digestión y absorción. El intestino del mosquito está revestido por microvellosidades llenas de actina que son expuestas a las complejas condiciones en torno a la luz intestinal, tales como la abrasión producida por partículas de alimentos, hidrolasas digestivas y el ataque de patógenos y parásitos que son tomados en la sangre consumida. Estas microvellosidades se protegen de estos efectos mediante la matriz peritrófica, el glicocálix y las proteínas de mucina que revisten las superficies epiteliales. La inmunización con AgMUC1/IL-12 ADNc en ratones BALB/c ha demostrado ser útil para matar los mosquitos cuando se alimentan de estos ratones. La mucina es una de las proteínas producidas en el intestino medio del mosquito después de consumir sangre. La fina estructura del epitelio del intestino interactúa con factores inmunes tales como anticuerpos o células inmunes es de especial importancia para interpretar los eventos tempranos en la interacción entre el revestimiento del intestino medio y los componentes inmunológicos específicos presentes en la sangre de ratones BALB/c inmunizados con AgMUC1/IL-12 cDNA. Después de observar mediante microscopías de luz, electrónica de barrido y de transmisión las características de secciones del intestino medio del mosquito Anopheles gambiae alimentado de ratones BALB/c inmunizados con AgMUC1/IL-12 cDNA, mecanismos inmunes mediados por citotoxicidad celular dependiente de anticuerpos (ADCC) podrían ser los responsables de matar a los mosquitos. Los procesos necróticos y apoptóticos que pueden ser la causa de la muerte del mosquito tienen lugar en las células que recubren el epitelio del intestino medio.

Malaria transmission blocking immunity and sexual stage vaccines for interrupting malaria transmission in Latin America

Malaria is a vector-borne disease that is considered to be one of the most serious public health problems due to its high global mortality and morbidity rates. Although multiple strategies for controlling malaria have been used, many have had limited impact due to the appearance and rapid dissemination of mosquito resistance to insecticides, parasite resistance to multiple antimalarial drug, and the lack of sustainability. Individuals in endemic areas that have been permanently exposed to the parasite develop specific immune responses capable of diminishing parasite burden and the clinical manifestations of the disease, including blocking of parasite transmission to the mosquito vector. This is referred to as transmission blocking (TB) immunity (TBI) and is mediated by specific antibodies and other factors ingested during the blood meal that inhibit parasite development in the mosquito. These antibodies recognize proteins expressed on either gametocytes or parasite stages that develop in the mosquito midgut and are considered to be potential malaria vaccine candidates. Although these candidates, collectively called TB vaccines (TBV), would not directly stop malaria from infecting individuals, but would stop transmission from infected person to non-infected person. Here, we review the progress that has been achieved in TBI studies and the development of TBV and we highlight their potential usefulness in areas of low endemicity such as Latin America.

Urban mosquito species (Diptera: Culicidae) of dengue endemic communities in the Greater Puntarenas area, Costa Rica

Field studies were conducted to determine the mosquito species richness in the urban area of Greater Puntarenas in Costa Rica. Two cross-sectional entomological surveys were performed in seven localities of Puntarenas: one survey was performed during the wet season and the other during the dry season. The sections evaluated were determined by applying a stratified cluster sampling method using satellite imagery, and a sample of 26 cells (100x100m) was selected for the study. The number of cells per locality was proportional to the area of each locality. The presence of mosquito larvae and pupae in water-filled artificial and natural containers was determined in each cell. Infestation was expressed as a diversity index per type of container (Ii). Eight types of larvae were identified (Aedes aegypti, Culex quinquefasciatus, Culex interrogator, Culex nigripalpus, Culex corniger, Culex tarsalis, Limatus durhamii and Toxorhynchites theobaldi) and in two cases it was only possible to identify the genus (Culex sp. and Uranotaenia sp.). A. aegypti was the most common species followed by C. quinquefascitus. Diversity of wet environments can explain the co-occurrence of various culicid species in some localities. Although A. aegypti is the only documented disease vector in the area, C quinquefasciatus, C. nigripalpus, and the other species of Culex could be considered potential vectors of other pathogens. The presence and ecology of all mosquito species should be studied to optimize surveillance and prevention of dengue and to prevent the emergence of other mosquito-transmitted diseases. Rev. Biol. Trop. 57 (4): 1223-1234. Epub 2009 December 01.

La riqueza de especies de mosquitos urbanos de la Gran Puntarenas (Puntarenas, Costa Rica) fue evaluada por medio de análisis larvales. Dos encuestas entomológicas fueron realizadas en siete localidades de la Gran Puntarenas durante un año. Una de las encuestas fue realizada en la estación seca y la otra se llevó a cabo en la estación lluviosa. Las áreas evaluadas fueron determinadas aplicando un muestreo por conglomerados usando imágenes satelitales. Veintiséis celdas (100x100m) fueron seleccionadas en las comunidades elegidas y en éstas fueron realizadas las evaluaciones entomológicas. El número de celdas por localidad fue proporcional al área de cada localidad. La presencia de larvas o pupas fue determinada en contenedores con agua (naturales y artificiales). La infestación se expresó por medio índices de diversidad por tipo de contenedor (Ii). La asociación entre contenedores positivos por especies particulares y localidades fue evaluada mediante pruebas de Chi-cuadrado (α=0.05). Ocho de los tipos de larvas encontrados fueron identificados a nivel de especie (Aedes aegypti, Culex quinquefasciatus, C. interrogator, C. nigripalpus, C. corniger, C. tarsalis, Limatus durhamii, Toxorhynchites theobaldi) y dos se identificaron a nivel de género (Culex sp., y Uranotaenia sp). A aegypti fue la especie más frecuente en la Gran Puntarenas. C. quinquefasciatus fue la segunda en frecuencia. Algunas localidades como Carrizal mostraron una importante diversidad de ambientes acuáticos que promovieron la ocurrencia de diferentes especies de culícidos. La distribución de los contenedores positivos por localidad en función de las especies encontradas no mostró homogeneidad (p>0.05). Aunque A. aegypti es el único vector documentado en la zona, otros mosquitos como C. quinquefasciatus y otras especies de Culex podrían ser potenciales vectores de otros agentes etiológicos (virus del Nilo occidental, virus de la encefalitis de San Luis, virus de la encefalitis equina del este). Los resultados obtenidos indican la necesidad considerar la presencia y la ecología de todas las especies de mosquitos en las campañas preventivas por dengue en el área, y en la vigilancia epidemiológica por otras enfermedades transmitidas por mosquitos.

Influence of biological and physicochemical characteristics of larval habitats on the body size of Anopheles gambiae mosquitoes (Diptera: Culicidae) along the Kenyan coast.

BACKGROUND & OBJECTIVES: The number and productivity of larval habitats ultimately determine the density of adult mosquitoes. The biological and physicochemical conditions at the larval habitat affect larval development hence affecting the adult body size. The influence of biological and physicochemical characteristics on the body size of Anopheles gambiae was assessed in Jaribuni village, Kilifi district along the Kenyan Coast. METHODS: Ten cages measuring 1 x 1 x 1 m (1 m3) with a netting material were placed in 10 different aquatic habitats, which were positive for anopheline mosquito larvae. Emergent mosquitoes were collected daily by aspiration and the wing lengths were determined by microscopy. In the habitats, physicochemical parameters were assessed: pH, surface debris, algae and emergent plants, turbidity, substrate, nitrate, ammonia, phosphate and chlorophyll a content. RESULTS: A total of 685 anopheline and culicine mosquitoes were collected from the emergent cages. Only female mosquitoes were considered in this study. Among the Anopheles spp, 202 were An. gambiae s.s., eight An. arabiensis, two An. funestus, whereas the Culex spp was composed of 214 Cx. quinquefasciatus, 10 Cx. tigripes, eight Cx. annulioris and one Cx. cumminsii. The mean wing length of the female An. gambiae s.s. mosquitoes was 3.02 mm (n=157), while that of An. arabiensis was 3.09 mm (n=9). There were no associations between the wing lengths and the environmental and chemical parameters, except for a positive correlation between wing length of An. gambiae and chlorophyll a content (r = 0.622). The day on which the mosquitoes emerged was not significant for the anopheline (p = 0.324) or culicine mosquitoes (p = 0.374), because the mosquito emerged from the cages on a daily basis. INTERPRETATION & CONCLUSION: In conclusion, there was variability in production of emergent mosquitoes from different habitats, which means that there should be targeted control on these habitats based on productivity.

Spatial distribution and habitat characterisation of Anopheles larvae along the Kenyan coast.

BACKGROUND & OBJECTIVES: A study was conducted to characterise larval habitats and to determine spatial heterogeneity of the Anopheles mosquito larvae. The study was conducted from May to June 1999 in nine villages along the Kenyan coast. METHODS: Aquatic habitats were sampled by use of standard dipping technique. The habitats were characterised based on size, pH, distance to the nearest house, coverage of canopy, surface debris, algae and emergent plants, turbidity, substrate, and habitat type. RESULTS: A total of 110 aquatic habitats like stream pools (n=10); puddles (n=65); tire tracks (n=5); ponds (n=5) and swamps (n=25) were sampled in nine villages located in three districts of the Kenyan coast. A total of 7,263 Anopheles mosquito larvae were collected, 63.9% were early instars and 36.1% were late instars. Morphological identification of the III and IV instar larvae by use of microscopy yielded 90.66% (n=2377) Anopheles gambiae Complex, 0.88% (n=23) An. funestus, An. coustani 7.63% (n=200), An. rivulorum 0.42% (n=11), An. pharoensis 0.19% (n=5), An. swahilicus 0.08% (n=2), An. wilsoni 0.04% (n=1) and 0.11% (n=3) were unidentified. A subset of the An. gambiae Complex larvae identified morphologically, was further analysed using rDNA-PCR technique resulting in 68.22% (n=1290) An. gambiae s.s., 7.93% (n=150) An. arabiensis and 23.85% (n=451) An. merus. Multiple logistic regression model showed that emergent plants (p = 0.019), and floating debris (p = 0.038) were the best predictors of An. gambiae larval abundance in these habitats. Interpretation & conclusion: Habitat type, floating debris and emergent plants were found to be the key factors determining the presence of Anopheles larvae in the habitats. For effective larval control, the type of habitat should be considered and most productive habitat type be given a priority in the mosquito abatement programme.

Dengue in Costa Rica: the gap in local scientific research

El dengue es una enfermedad de gran importancia a escala mundial. Los esfuerzos para su control en la mayoría de las regiones del mundo no han logrado detener el aumento en su incidencia, y se fomenta la investigación científica para contribuir a desarrollar nuevos enfoques de control basados en la evidencia científica o a mejorar los existentes. Enfermedad recientemente reemergente en Costa Rica, el dengue se ha convertido en un grave problema de salud en ese país. A pesar de esta crítica situación, se dispone de pocas publicaciones científicas sobre dengue en Costa Rica. En una búsqueda realizada en la base de datos PubMed se encontraron solo 11 artículos, mientras que en varias bases de datos bibliográficas centradas en Costa Rica y otros países de América Latina se hallaron 19 artículos más. Además, se encontraron 10 tesis relacionadas con el dengue realizadas en universidades costarricenses. Por lo tanto, son pocos los artículos científicos originales publicados sobre este tema en revistas científicas arbitradas, especialmente en aspectos vinculados con la epidemiología, la salud pública y la idoneidad y eficacia de las intervenciones en marcha. Esta brecha en las investigaciones puede deberse a diversos factores, como el contexto histórico y político, insuficientes recursos financieros y humanos, deficiencias en la colaboración entre las instituciones y dificultades para disponer de los datos. Costa Rica puede aprender de la experiencia de otros países de la Región de las Américas (como Cuba y Trinidad y Tobago), donde se ha investigado mucho más sobre dengue. Las investigaciones de esos dos países han aportado evidencias cruciales para el desarrollo de estrategias locales y generales dirigidas al control y la prevención del dengue. En dependencia del contexto local, algunos métodos de control pueden ser más eficaces que otros, por lo que las acciones basadas en la evidencia deben adaptarse para las diferentes regiones del mundo,...

Relationship between malaria and filariasis transmission indices in an endemic area along the Kenyan Coast.

BACKGROUND AND OBJECTIVES: An entomological survey was conducted to determine the relationship between malaria and lymphatic filariasis transmission by Anopheles gambiae s.l. and An. funestus in two inland villages along the Kenyan coast. METHODS: Mosquitoes were sampled inside houses by pyrethrum spray sheet collection (PSC). In the laboratory, the mosquitoes were sorted to species, dissected for examination of filarial infection and the anophelines later tested for Plasmodium falciparum circumsporozoite proteins by an enzyme-linked immunosorbent assay (ELISA). RESULTS: From a total of 2,032 female mosquitoes collected indoors, An. gambiae s.l constituted 94.4% while the remaining 5.6% comprised of An. funestus and Culex quinquefasciatus. None of the Cx. quinquefasciatus was positive for filarial worms. P. falciparum sporozoite rate for An. gambiae s.l. from both villages was significantly higher than Wuchereria bancrofti infectivity rate. Similarly, the entomological inoculation rate for An. gambiae s.l. was significantly higher than the corresponding W. bancrofti infective biting rate and transmission potential for both the villages. Mass treatment of people with filaricidal drugs in Shakahola in the ongoing global elimination of lymphatic filariasis campaign seemed to have reduced the indices of filariasis transmission but had no effect on malaria transmission. INTERPRETATION AND CONCLUSION: These results indicate the intensity of malaria transmission by anophelines to be much higher than that of lymphatic filariasis in areas where both diseases co-exist and re-emphasise the need to integrate the control of the two diseases in such areas.