A new WHO bottle bioassay method to assess the susceptibility of mosquito vectors to public health insecticides: results from a WHO-coordinated multi-centre study.

BACKGROUND: The continued spread of insecticide resistance in mosquito vectors of malaria and arboviral diseases may lead to operational failure of insecticide-based interventions if resistance is not monitored and managed efficiently. This study aimed to develop and validate a new WHO glass bottle bioassay method as an alternative to the WHO standard insecticide tube test to monitor mosquito susceptibility to new public health insecticides with particular modes of action, physical properties or both. METHODS: A multi-centre study involving 21 laboratories worldwide generated data on the susceptibility of seven mosquito species (Aedes aegypti, Aedes albopictus, Anopheles gambiae sensu stricto [An. gambiae s.s.], Anopheles funestus, Anopheles stephensi, Anopheles minimus and Anopheles albimanus) to seven public health insecticides in five classes, including pyrethroids (metofluthrin, prallethrin and transfluthrin), neonicotinoids (clothianidin), pyrroles (chlorfenapyr), juvenile hormone mimics (pyriproxyfen) and butenolides (flupyradifurone), in glass bottle assays. The data were analysed using a Bayesian binomial model to determine the concentration-response curves for each insecticide-species combination and to assess the within-bioassay variability in the susceptibility endpoints, namely the concentration that kills 50% and 99% of the test population (LC50 and LC99, respectively) and the concentration that inhibits oviposition of the test population by 50% and 99% (OI50 and OI99), to measure mortality and the sterilizing effect, respectively. RESULTS: Overall, about 200,000 mosquitoes were tested with the new bottle bioassay, and LC50/LC99 or OI50/OI99 values were determined for all insecticides. Variation was seen between laboratories in estimates for some mosquito species-insecticide combinations, while other test results were consistent. The variation was generally greater with transfluthrin and flupyradifurone than with the other compounds tested, especially against Anopheles species. Overall, the mean within-bioassay variability in mortality and oviposition inhibition were < 10% for most mosquito species-insecticide combinations. CONCLUSION: Our findings, based on the largest susceptibility dataset ever produced on mosquitoes, showed that the new WHO bottle bioassay is adequate for evaluating mosquito susceptibility to new and promising public health insecticides currently deployed for vector control. The datasets presented in this study have been used recently by the WHO to establish 17 new insecticide discriminating concentrations (DCs) for either Aedes spp. or Anopheles spp. The bottle bioassay and DCs can now be widely used to monitor baseline insecticide susceptibility of wild populations of vectors of malaria and Aedes-borne diseases worldwide

Determination of the role of Anopheles species as malaria vector in Meta department, Colombia

Con el fin de actualizar las especies del género Anopheles presentes en el departamento de Meta y establecer el papel de cada una de ellas en la transmisión de la malaria se realizó entre junio de 2007 y junio de 2009 la recolección de material entomológico en seis municipios del Meta. Para la confirmación taxonómica se utilizaron las series entomológicas y la secuencia de nucleótidos del espaciador transcrito intergénico dos (ITS2) del ADN ribosomal y del gen mitocondrial citocromo oxidasa I (COI). Para conocer aspectos de la biología se realizaron capturas con atrayente humano, búsqueda en sitios de cría y detección de infección con Plasmodium spp con la técnica de ELISA. Se identificaron An. argyritarsis, An. braziliensis, An. costai, An. darlingi, An. neomaculipalpus, An. nimbus, An. peryassui, An. pseudopunctipennis s.l. y An. rangeli. De los complejos de especies se confirmó An. marajoara, An. triannulatus s.s. y An. oswaldoi B. An. darlingi, fue la especie más abundante en las capturas con atrayente humano y en sitios de cría, presentó una amplia distribución en el departamento, estuvo presente todo el año y durante toda la noche en el intradomiclio y peridomicilio, exhibió una mayor actividad entre las 18:00 y 22:00 horas y se encontró infectada con P. falciparum. Se determinó la presencia de otras especies de Anopheles con antecedentes de infección con especies de Plasmodium o vectores reconocidos, sin embargo, solo se encontraron evidencias para confirmar a An. darlingi como vector de malaria en el Meta. / Abstract. This study was designed to update the taxonomic determination of the Anopheles species present in Meta Department and establish the role of each one of them in the malaria transmission. From July 2007 to June 2009, mosquitoes were collected by human-landing catches and breeding site collections in six municipalities. Specimens were firstly identified based on morphological characters, and later confirmed using DNA sequences of the mtDNA COI barcoding region and or the nuclear second internal transcribed spacer (ITS2). ELISA was used to identify positive mosquitoes of Plasmodium spp. CS protein. A total of 5.215 mosquitoes were determined using the integration of morphological characters from all life stages and molecular sequence data. This enabled the taxonomic verification of the following 12 taxa: An. argyritarsis, An. braziliensis, An. costai, An. darlingi, An. neomaculipalpus, An. nimbus, An. peryassui, An. pseudopunctipennis s.l., An. rangeli, An. marajoara, An. triannulatus s.s. y An. oswaldoi B. An. darlingi, was the most abundant species in human-landing catches and breeding sites, presented a wide distribution, was present all the year and during the all night in the indoors and outdoors, exhibited a major activity between 18:00 and 22:00 hours and was infected with P. falciparum. 12 Anopheles species were found, some considered as vectors elsewhere. However, only An. darlingi could be confirmed as a vector of malaria in Meta.Maestría en infecciones y salud en el trópicoMaestrí

Comportamiento de picadura de Anopheles darlingi Root, 1926 (Diptera: Culicidae) y su asociación con la transmisión de malaria en Villavicencio (Colombia)

Introduction: Anopheles darlingi is the main malaria vector in the neotropics. This species is recognized by its anthropophilic behavior and its high variability in biting activity throughout its distribution range.Objective: To characterize the biting behavior of An. darlingi and to establish its association with malaria transmission in Villavicencio.Materials and methods: Between 2008 and 2009, a cross sectional and a longitudinal entomological study were carried out in 5 localities with malaria transmission in Villavicencio. Mosquito collections included breeding sites search and human landing catches in houses. Collected mosquitoes were analyzed for Plasmodium using the ELISA standard protocol.Results: A total of 2,772 mosquitoes were collected in the study. Anopheles darlingi was the mostabundant anopheline species. The most common breeding sites for this species were marshes, streams, lakes and fish ponds. Anopheles darlingi was found at all times during the year with monthly average human biting rates between 2.2 y 55.5 mosquitos/person/night. This species was collected throughout the night, indoors and outdoors, and 47 to 81% of An. darling captured during twelve hoursof observation (18:00 to 06:00) were collected between 18:00 and 22:00. Anopheles darlingi was found positive for P. falciparum with a 0.05% rate and the entomological inoculation rate was estimated at 2.9 infective bites/person per year.Conclusion: Anopheles darlingi was infected with P. falciparum, it was found all year long and itexhibited characteristics in biting behavior that favor human-vector contact, being a permanent risk formalaria transmission in Villavicencio. doi: http://dx.doi.org/10.7705/biomedica.v33i2.1492Introducción. Anopheles darlingi es el principal vector de la malaria, o paludismo, en el neotrópico. Esta especie es reconocida por presentar un comportamiento antropofílico y variabilidad en sus hábitos de picadura a lo largo de su rango de distribución.Objetivo. Caracterizar el comportamiento de picadura de An. darlingi y establecer su relación con latransmisión de la malaria en Villavicencio.Materiales y métodos. Entre 2008 y 2009 se llevaron a cabo un estudio de tipo transversal y uno longitudinal, en cinco localidades de Villavicencio con transmisión de malaria. Estos incluyeron recolección de ejemplares inmaduros y de adultos en las viviendas. Se utilizó la prueba ELISA para la detección de infección con Plasmodium spp.Resultados. Se recolectaron 2.772 mosquitos. Anopheles darlingi fue la especie predominante enlas capturas con atrayente humano. Los criaderos identificados para esta especie fueron pantanos, caños, lagunas y estanques piscícolas. Anopheles darlingi estuvo presente durante todo el año, con densidades mensuales promedio entre 2,2 y 55,5 mosquitos por persona por noche. Presentó actividad hematofágica durante toda la noche en el intradomicilio y en el peridomicilio. De las 18:00 a las 22:00, se registraron entre el 47 % y el 81 % de los mosquitos capturados en 12 horas de observación. Se encontró una tasa de infección con Plasmodium falciparum de 0,05 % y se estimó una tasa entomológica de inoculación de 2,9 picaduras infecciosas por persona al año.Conclusión. Anopheles darlingi se encontró infectado con P. falciparum, estuvo presente durante todo el año y exhibió características en su comportamiento de picadura que favorecen el contacto entre humano y vector, lo cual es un riesgo permanente para la transmisión de la malaria en Villavicencio. doi: http://dx.doi.org/10.7705/biomedica.v33i2.1492

Preliminary evaluation of the Culicoides biting nuisance (Diptera: Ceratopogonidae) in the province of Boyacá, Colombia

Introduction: Inhabitants in the western border of Boyacá province have reported high nuisance levels and dermatologic problems caused by the intensely irritating bites of the very small flies of the genus Culicoides. Objective. A survey was carried out to locate the affected area, identify the anthropophylic Culicoides species and estimate its abundance in Boyacá. Materials and methods: Nuisance reports and clinical records of dermatologic cases associated with Culicoides bites were requested from health authorities in counties where nuisance reports had been received or which had geographical features apparently favorable for Culicoides infestations. An outdoors entomological survey using human landing catches was undertaken in areas reporting a pest problem. Results: Culicoides infestations were confirmed as a serious nuisance problem in the rural areas of nine counties located in the western foothills of the Eastern Range of the Colombian Andes. Although available epidemiological records were fragmented, it was established that in six counties 11.4% of the dermatitis cases (total=2,472 cases) reported between 2003 and 2005 were attributed to the Culicoides bites. The entomological survey identified Culicoides pachymerus as the dominant species, 99.3% of 3,389 caught females. Biting rates in the most intensely affected areas reach a geometric mean of 52 females/person per 5 minutes. Multivariate analysis indicated that abundance of C. pachymerus had a negative relationship with altitude. Conclusions: Based on its dominance and high biting rates, C. pachymerus is probably the species responsible for the high nuisance levels caused by Culicoides bites and the associated dermatological pathology, within the study area

Malaria risk stratification in Colombia 2010 to 2019.

BackgroundHeterogeneity and focalization are the most common epidemiological characteristics of endemic countries in the Americas, where malaria transmission is moderate and low. During malaria elimination, the first step is to perform a risk stratification exercise to prioritize interventions. This study aimed to identify malaria risk strata in the ecoepidemiological regions of Colombia.MethodsThis was a descriptive and retrospective study using cumulative malaria cases in 1,122 municipalities of Colombia from 2010 to 2019. To identify the strata, the criteria proposed by PAHO were adapted. To classify the receptive areas (strata 2, 3, and 4) and nonreceptive areas (stratum 1), 1,600 m above sea level, ecotypes, main malaria vector presence, Plasmodium species prevalence and occurrence of malaria cases were used. The area occupied by the receptive municipalities, the cumulative burden, and the at-risk population in the regions were calculated.ResultsNinety-one percent of the Colombian territory is receptive to the transmission of malaria and includes 749 municipalities with 9,734,271 (9,514,243-9,954,299) million at-risk inhabitants. Stratum 4 accounted for 96.7% of the malaria burden, and cases were concentrated primarily in the Pacific and Uraba-Bajo Cauca-Sinu-San Jorge regions. Plasmodium vivax predominates in most of the receptive municipalities, except in the municipalities of the Pacific region, where P. falciparum predominates. Anopheles albimanus, An. nuneztovari s.l., and An. darlingi were the main vectors in receptive areas.ConclusionsIn Colombia, 91.2% of the territory is receptive to the transmission of malaria and is characterized by being both heterogeneous and focused. Stratum 4 contains the greatest burden of disease, with a relatively greater proportion of municipalities with a predominance of P. vivax. However, there is a low proportion of municipalities with P. falciparum mainly in the Pacific region. These findings suggest that the latter be prioritized within the malaria elimination plan in Colombia

A new WHO bottle bioassay method to assess the susceptibility of mosquito vectors to public health insecticides: results from a WHO-coordinated multi-centre study

Abstract Background The continued spread of insecticide resistance in mosquito vectors of malaria and arboviral diseases may lead to operational failure of insecticide-based interventions if resistance is not monitored and managed efficiently. This study aimed to develop and validate a new WHO glass bottle bioassay method as an alternative to the WHO standard insecticide tube test to monitor mosquito susceptibility to new public health insecticides with particular modes of action, physical properties or both. Methods A multi-centre study involving 21 laboratories worldwide generated data on the susceptibility of seven mosquito species (Aedes aegypti, Aedes albopictus, Anopheles gambiae sensu stricto [An. gambiae s.s.], Anopheles funestus, Anopheles stephensi, Anopheles minimus and Anopheles albimanus) to seven public health insecticides in five classes, including pyrethroids (metofluthrin, prallethrin and transfluthrin), neonicotinoids (clothianidin), pyrroles (chlorfenapyr), juvenile hormone mimics (pyriproxyfen) and butenolides (flupyradifurone), in glass bottle assays. The data were analysed using a Bayesian binomial model to determine the concentration–response curves for each insecticide–species combination and to assess the within-bioassay variability in the susceptibility endpoints, namely the concentration that kills 50% and 99% of the test population (LC50 and LC99, respectively) and the concentration that inhibits oviposition of the test population by 50% and 99% (OI50 and OI99), to measure mortality and the sterilizing effect, respectively. Results Overall, about 200,000 mosquitoes were tested with the new bottle bioassay, and LC50/LC99 or OI50/OI99 values were determined for all insecticides. Variation was seen between laboratories in estimates for some mosquito species–insecticide combinations, while other test results were consistent. The variation was generally greater with transfluthrin and flupyradifurone than with the other compounds tested, especially against Anopheles species. Overall, the mean within-bioassay variability in mortality and oviposition inhibition were < 10% for most mosquito species-insecticide combinations. Conclusion Our findings, based on the largest susceptibility dataset ever produced on mosquitoes, showed that the new WHO bottle bioassay is adequate for evaluating mosquito susceptibility to new and promising public health insecticides currently deployed for vector control. The datasets presented in this study have been used recently by the WHO to establish 17 new insecticide discriminating concentrations (DCs) for either Aedes spp. or Anopheles spp. The bottle bioassay and DCs can now be widely used to monitor baseline insecticide susceptibility of wild populations of vectors of malaria and Aedes-borne diseases worldwide. Graphical abstrac

Naturaleza urbana. Plataforma de experiencias

Naturaleza Urbana presenta experiencias autogestionadas que, con el tiempo, se han posicionado como ejercicios alternativos de identificación, monitoreo y recuperación de la biodiversidad urbana. En otros casos, el modelo comunidad-gobierno ha permitido desarrollar diagnósticos y propuestas de gestión corresponsables y sistémicas, entendiendo por esto último iniciativas que nacen desde los valores mismos que cada comunidad le atribuye a su biodiversidad. Del mismo modo, se presentan esfuerzos gubernamentales que han enriquecido la visión ambiental de los principales instrumentos de planificación urbana, por ejemplo, integrando la condición propiamente urbana como oportunidad para aumentar la oferta ambiental de la ciudad, fortaleciendo las funciones y procesos de la biodiversidad y revitalizando, con ello, la calidad de vida del entorno urbano. Por su parte, las universidades y los centros de investigación se han sumado a la ola emergente de generación de conocimiento en biodiversidad urbana (fenómeno nacional e internacional), han brindado evidencia científica de su valor para el bienestar humano y han propuesto reflexiones y lineamientos cualitativos de biodiversidad, con miras a hacer del ordenamiento un ejercicio más coherente con cada contexto territorial en particular.Bogotá, D. C., ColombiaInstituto de Investigación de Recursos Biológicos Alexander von Humbold

Urban Nature

Preservation, restoration, monitoring of biodiversity and promotion of native species, in their strict and classical sense, could be unviable strategies in the cities. Management systems such as the protected areas acquire profoundly different connotations and objectives from the traditional ones when thought of in the context of a city. Similarly, although ecological restoration seeks to return to a baseline ecosystem, there is little that we know about the vegetation present on the urban borders of the main Colombian cities prior to the 20th century. Finally, the models for potential distribution of species could produce unreliable results, because their methodological bases were not conceived based on urban dynamics. In this context, to de ne urban biodiversity and what strategy must be applied for its conservation implies a challenge that, beyond being scienti c, is necessarily social and cultural and involves planning and design. Innovation is inevitable.Bogotá, D. C

International Nosocomial Infection Control Consortiu (INICC) report, data summary of 43 countries for 2007-2012. Device-associated module

We report the results of an International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2007-December 2012 in 503 intensive care units (ICUs) in Latin America, Asia, Africa, and Europe. During the 6-year study using the Centers for Disease Control and Prevention's (CDC) U.S. National Healthcare Safety Network (NHSN) definitions for device-associated health care–associated infection (DA-HAI), we collected prospective data from 605,310 patients hospitalized in the INICC's ICUs for an aggregate of 3,338,396 days. Although device utilization in the INICC's ICUs was similar to that reported from ICUs in the U.S. in the CDC's NHSN, rates of device-associated nosocomial infection were higher in the ICUs of the INICC hospitals: the pooled rate of central line–associated bloodstream infection in the INICC's ICUs, 4.9 per 1,000 central line days, is nearly 5-fold higher than the 0.9 per 1,000 central line days reported from comparable U.S. ICUs. The overall rate of ventilator-associated pneumonia was also higher (16.8 vs 1.1 per 1,000 ventilator days) as was the rate of catheter-associated urinary tract infection (5.5 vs 1.3 per 1,000 catheter days). Frequencies of resistance of Pseudomonas isolates to amikacin (42.8% vs 10%) and imipenem (42.4% vs 26.1%) and Klebsiella pneumoniae isolates to ceftazidime (71.2% vs 28.8%) and imipenem (19.6% vs 12.8%) were also higher in the INICC's ICUs compared with the ICUs of the CDC's NHSN