Host-specific effects of a generalist parasite of mosquitoes.

Microsporidians are obligate parasites of many animals, including mosquitoes. Some microsporidians have been proposed as potential agents for the biological control of mosquitoes and the diseases they transmit due to their detrimental impact on larval survival and adult lifespan. To get a more complete picture of their potential use as agents of biological control, we measured the impact of Vavraia culicis on several life-history traits of Aedes aegypti and Anopheles gambiae. We measured the infection dynamics and clearance rate for the two species, and we assessed sexual dimorphism in infection dynamics within each species. Our results show differences in infection dynamics, with Ae. aegypti life-history traits being more affected during its aquatic stage and exhibiting higher clearance of the infection as adults. In contrast, An. gambiae was unable to clear the infection. Additionally, we found evidence of sexual dimorphism in parasite infection in An. gambiae, with males having a higher average parasite load. These findings shed light and improve our knowledge of the infection dynamics of V. culicis, a microsporidian parasite previously recognized as a potential control agent of malaria.

Infectivity of Plasmodium parasites to Aedes aegypti and Anopheles stephensi mosquitoes maintained on blood-free meals of SkitoSnack.

BACKGROUND: Aedes and Anopheles mosquitoes are responsible for tremendous global health burdens from their transmission of pathogens causing malaria, lymphatic filariasis, dengue, and yellow fever. Innovative vector control strategies will help to reduce the prevalence of these diseases. Mass rearing of mosquitoes for research and support of these strategies presently depends on meals of vertebrate blood, which is subject to acquisition, handling, and storage issues. Various blood-free replacements have been formulated for these mosquitoes, but none of these replacements are in wide use, and little is known about their potential impact on competence of the mosquitoes for Plasmodium infection. METHODS: Colonies of Aedes aegypti and Anopheles stephensi were continuously maintained on a blood-free replacement (SkitoSnack; SS) or bovine blood (BB) and monitored for engorgement and hatch rates. Infections of Ae. aegypti and An. stephensi were assessed with Plasmodium gallinaceum and P. falciparum, respectively. RESULTS: Replicate colonies of mosquitoes were maintained on BB or SS for 10 generations of Ae. aegypti and more than 63 generations of An. stephensi. The odds of engorgement by SS- relative to BB-maintained mosquitoes were higher for both Ae. aegypti (OR = 2.6, 95% CI 1.3-5.2) and An. stephensi (OR 2.7, 95% CI 1.4-5.5), while lower odds of hatching were found for eggs from the SS-maintained mosquitoes of both species (Ae. aegypti OR = 0.40, 95% CI 0.26-0.62; An. stephensi OR = 0.59, 95% CI 0.36-0.96). Oocyst counts were similar for P. gallinaceum infections of Ae. aegypti mosquitoes maintained on SS or BB (mean ratio = [mean on SS]/[mean on BB] = 1.11, 95% CI 0.85-1.49). Similar oocyst counts were also observed from the P. falciparum infections of SS- or BB-maintained An. stephensi (mean ratio = 0.76, 95% CI 0.44-1.37). The average counts of sporozoites/mosquito showed no evidence of reductions in the SS-maintained relative to BB-maintained mosquitoes of both species. CONCLUSIONS: Aedes aegypti and An. stephensi can be reliably maintained on SS over multiple generations and are as competent for Plasmodium infection as mosquitoes maintained on BB. Use of SS alleviates the need to acquire and preserve blood for mosquito husbandry and may support new initiatives in fundamental and applied research, including novel manipulations of midgut microbiota and factors important to the mosquito life cycle and pathogen susceptibility.

A Mosquito Parasite Is Locally Adapted to Its Host but Not Temperature.

AbstractClimate change will alter interactions between parasites and their hosts. Warming may affect patterns of local adaptation, shifting the environment to favor the parasite or host and thus changing the prevalence of disease. We assessed local adaptation to hosts and temperature in the facultative ciliate parasite Lambornella clarki, which infects the western tree hole mosquito Aedes sierrensis. We conducted laboratory infection experiments with mosquito larvae and parasites collected from across a climate gradient, pairing sympatric or allopatric populations across three temperatures that were either matched or mismatched to the source environment. Lambornella clarki parasites were locally adapted to their hosts, with 2.6 times higher infection rates on sympatric populations compared with allopatric populations, but they were not locally adapted to temperature. Infection peaked at the intermediate temperature of 12.5°C, notably lower than the optimum temperature for free-living L. clarki growth, suggesting that the host's immune response can play a significant role in mediating the outcome of infection. Our results highlight the importance of host selective pressure on parasites, despite the impact of temperature on infection success.

Development of a novel rodent model for dog heartworm microfilaremia using the severe-combined immunodeficiency mouse.

Dirofilaria immitis is a mosquito-borne parasitic nematode that causes fatal heartworm disease in canids. The microfilariae are essential for research, including drug screening and mosquito-parasite interactions. However, no reliable methods for maintaining microfilaria long-term are currently available. Therefore, we used severe combined immunodeficiency (SCID) mice to develop a reliable method for maintaining D. immitis microfilaria. SCID mice were injected intravenously with microfilariae isolated from a D. immitis-infected dog. Microfilariae were detected in blood collected from the tail vein 218 days post-inoculation (dpi) and via cardiac puncture 296 dpi. Microfilariae maintained in and extracted from SCID mice showed infectivity and matured into third-stage larvae (L3s) in the vector mosquito Aedes aegypti. L3s can develop into the fourth stage larvae in vitro. Microfilariae from SCID mice respond normally to ivermectin in vitro. The microfilariae in SCID mice displayed periodicity in the peripheral circulation. The SCID mouse model aided in the separation of microfilariae from cryopreserved specimens. The use of SCID mice enabled the isolation and sustained cultivation of microfilariae from clinical samples. These findings highlight the usefulness of the SCID mouse model for studying D. immitis microfilaremia in canine heartworm research.

Entomological assessment in 'hotspots' of four lymphatic filariasis endemic districts, Central Nepal during post-MDA surveillance.

BACKGROUND OBJECTIVES: Annual mass drug administration (MDA) is the main strategy to interrupt the transmission of lymphatic filariasis (LF) in the community. The main aim of monitoring the MDA program, for its effectiveness and interruption of LF is the post-MDA surveillance using antigen survey in children born after MDA. The latest technique of new research suggests that xenomonitoring is an effective tool for monitoring LF intervention. The objective of this study was to assess the W. bancrofti infection/or infectivity in vector mosquitoes by xenomonitoring during post-MDA surveillance. METHODS: A descriptive cross-sectional study was conducted in the hotspots of selected four districts of Central Nepal. A gravid trap technique was used for sampling mosquitoes. Infection/or infectivity was determined via the dissection of vector mosquitoes. Anopheles, Aedes, Armigerus and Culex species were collected from hotspots of four endemic districts, two from the hilly region (Lalitpur and Dhading) and two from Terai region (Bara and Mahottari) of Central Nepal. RESULTS: A total of 4450 mosquitoes belonging to four genera, Anopheles, Culex, Armigeres, and Aedes were collected from four hotspots. The distribution of Culex quinquefasciatus was found to be the highest, 88.9% (n=3955/4450) followed by Cx. vishnui (4.5%), Armigeres sp (5.8%), An. culicifascies (0.2%), Aedes spp (0.8%). The proportion of female mosquitoes trapped is significantly higher. A total of 3344 parous Cx. quinquefasciatus mosquitoes were dissected for any larval stage of W. bancrofti. We could not find any filarial infection in dissected mosquito samples. INTERPRETATION CONCLUSION: We conclude that the gravid trap is an efficient tool for the collection of gravid Cx. quinquefasciatus mosquitoes for xenomonitoring studies of filariasis endemic regions. Vector composition indicated a maximum number of vector mosquitoes of lymphatic filariasis were trapped compared with the other three species. Distribution and density of Cx. quinquefasciatus was found highest in four hotspots of endemic districts. None of the Cx. quinquefasciatus dissected were found to be infected by larval forms of filaria. Since the low levels of infection persistence in the human population in these hot spots, vector infection and infectivity can't be ignored. Microscopic xenomonitoring at a low level of infection persistent is less likely to be efficient so molecular xenomonitoring along with a large sample should be required in each of the hot spots of the districts. Additionally, area is receptive so further vector control intervention should be required to reduce the risk of resurgence of infection.

Avian Plasmodium in invasive and native mosquitoes from southern Spain.

BACKGROUND: The emergence of diseases of public health concern is enhanced by factors associated with global change, such as the introduction of invasive species. The Asian tiger mosquito (Aedes albopictus), considered a competent vector of different viruses and parasites, has been successfully introduced into Europe in recent decades. Molecular screening of parasites in mosquitoes (i.e. molecular xenomonitoring) is essential to understand the potential role of different native and invasive mosquito species in the local circulation of vector-borne parasites affecting both humans and wildlife. METHODS: The presence of avian Plasmodium parasites was molecularly tested in mosquitoes trapped in five localities with different environmental characteristics in southern Spain from May to November 2022. The species analyzed included the native Culex pipiens and Culiseta longiareolata and the invasive Ae. albopictus. RESULTS: Avian Plasmodium DNA was only found in Cx. pipiens with 31 positive out of 165 mosquito pools tested. None of the Ae. albopictus or Cs. longiareolata pools were positive for avian malaria parasites. Overall, eight Plasmodium lineages were identified, including a new lineage described here. No significant differences in parasite prevalence were found between localities or sampling sessions. CONCLUSIONS: Unlike the invasive Ae. albopictus, Cx. pipiens plays a key role in the transmission of avian Plasmodium in southern Spain. However, due to the recent establishment of Ae. albopictus in the area, further research on the role of this species in the local transmission of vector-borne pathogens with different reservoirs is required.

Aedes aegypti: ações de controle no Município de Pedra Branca/Ceará

Adaptación del mosquito Aedes aegypti a 2 550 m s.n.m. Cochabamba, Bolivia. Febrero 2016 / Adaptation of mosquito Aedes aegypti a 2 550 m s.n.m. Cochabamba, Bolivia. February 2016

Objetivo: proporcionar datos de la adaptación del Aedes aegypti en altitudes superiores a los de su hábitat natural en el departamento de Cochabamba. Métodos: la notificación así como la vigilancia entomológica, permitieron caracterizar taxonómicamente y geográficamente la infestación por Aedes aegypti, en municipios del eje metropolitano del departamento de Cochabamba y observar el cambio de escenario epidemiológico producido. La utilización de materiales de investigación entomológica, además del estudio integral permitió identificar factores predisponentes para la colonización del vector. Resultados: se encontró la presencia del vector en diferentes altitudes geográficas y en varios municipios del departamento de Cochabamba, en los que anteriormente no se encontraba. Se observó una variación de temperatura inusitada y lluvia en el mes de enero de 2016, que proporcionó climáticas favorables para la proliferación de Aedes aegypti y otros vectores. Se identificó una mayor infestación en la zona sur de la ciudad de Cochabamba, además de ser el área que ha presentado más factores de riesgo como son la presencia de criaderos artificiales comunes y no comunes, con presencia incalculable de desechos inservibles intradomiciliarios. Conclusiones: observar la presencia del vector en municipios grandes como Cercado, denota Riesgo de gran magnitud para la población por lo que representa un ESPII-ESPIN. El cambio climático como uno de los factores para la variación de los diversos nichos ecológicos, ha permitido que los Valles hayan brindado condiciones propicias para la colonización del Aedes aegypti y que este se adapte a altitudes mayores a 2 200 m s.n.m. La ciudad de Cochabamba es un punto importante de entrada para el ingreso de personas provenientes de áreas endémicas de trasmisión de Dengue, Zika y Chikungunya, tanto del exterior como del interior, lo que representa alto riesgo para la transmisión de estas enfermedades en las nuevas áreas de dispersión del vector. Hasta el momento julio 2016 solo se evidencio la presentación autóctona de un caso en la ciudad de Cochabamba. La dificultad en la provisión y almacenamiento de agua en las viviendas, son factores fundamentales para la proliferación de criaderos potenciales para Aedes aegypti.

Objetive: to provide data of the adaptation of Aedes aegypti at higher altitudes than its natural habitat in the department Cochabamba. Methods: notification as well as Entomological Surveillance allowed taxonomic and geographic characterization of Aedes aegypti infestation in municipalities of the metropolitan axis of Cochabamba department and to observe the change in the epidemiological scenario produced. The use of entomological research materials, besides the integral study allowed to identify predisposing factors for the colonization of the vector. Results: the presence of the vector was found at different geographic altitudes and in several municipalities in the department of Cochabamba, where it was previously not found. An unusual temperature variation and rainfall in January 2016 provided favorable climatic conditions for the proliferation of Aedes aegypti and other vectors. Greater infestation was identified in the southern area of the city of Cochabamba, besides being the area that has presented more risk factors such as the presence of common and non-common artificial breeding grounds, with an incalculable presence of intradomiciliary waste. Conclusions: observing the presence of the vector in large municipalities such as Cercado, denotes a high risk for the population, which represents an ESPII-ESPIN. Climate change as one of the factors for the variation of the various ecological niches has allowed the Valleys to provide conditions conducive to the colonization of Aedes aegypti and that it overcomes adaptation to altitudes higher than 2200 m s.n.m. The city of Cochabamba is an important entry point for the entry of people from endemic areas of Dengue, Zika and Chikungunya transmission, both from the outside and the interior, which represents a high risk for the transmission of these diseases in the new areas of vector dispersion. Until July 2016 only the autochthonous presentation of a case in the city of Cochabamba was evidenced. The difficulty in the provision and storage of water in the dwellings are fundamental factors for the proliferation of potential breeding sites for Aedes aegypti.

Modelo matemático para la dinámica de trasmisión del virus del Zika en Honduras / Mathematical model for the dynamic transmission of the Zika virus in Honduras

En términos históricos, las enfermedades infecciosas han constituido una amenaza grave para la sociedad Objetivo: Analizar e implementar un modelo matemático para pronosticar la dinámica de trasmisión del virus del Zika en la epidemia de 2015 − 2016 en Honduras. Métodos: Se utilizó el modelo Ross-Macdonald que aproxima el número de personas y vectores (Aedes Aegypti) infectados por el virus, mediante un sistema de dos ecuaciones diferenciales no lineales que retratan las interacciones entre perso-nas y vectores, analizando mediante enfo-que cuantitativo, alcance descriptivo y diseño no experimental trasversal; haciendo uso del software Matlab. Resultados: Se encontró la estabilidad y puntos críticos, además se hicieron pruebas de sensibilidad para conocer cuales son los aspectos que incrementen y disminuyen la epidemia. Con-clusiones: Al estudiar los puntos críticos se encontró el número de reproducción básica, el cual ayuda a conocer si un brote será endémico o no, también se conoció la esta-bilidad que tendrá la enfermedad; con las pruebas de sensibilidad se determinó que la población del vector juega un papel impor-tante. Asi mismo se encontró que controlar la densidad de población de vectores antes del brote es más efectiva que el control del vector y la obtención de inmunidad progresi-va, adicionalmente se aplicó el modelo en la epidemia ocurrida en 2015−2016. Se encon-tró que el modelo de Ross-Macdonald cumple su objetivo a pesar de sus limitantes, por otra parte se dedujo que es preferible utilizarlo en intervalos cortos de tiempo mientras la densidad del vector varia en las diferentes épocas del año...(AU)

Ensayos de sensibilidad de larvas de Aedes aegypti y Culex quinquefasciatus frente al nematodo Heterorhabditis bacteriophora en condiciones de laboratorio / Laboratory susceptibility tests of Aedes aegypti and Culex quinquefasciatus larvae to the entomopathogenic nematode Heterorhabditis bacteriophora

Resumen Introducción. Aedes aegypti es el vector de los virus del dengue, la fiebre amarilla, el Zika y el chikungunya, y Culex quinquefasciatus, de los virus de la encefalitis de Saint Louis y de la del Oeste del Nilo. Objetivo. Evaluar la capacidad infecciosa de Heterorhabditis bacteriophora N4 en larvas de C. quinquefasciatus y A. aegypti en el laboratorio. Materiales y métodos. Treinta larvas de segundo estadio de cada especie de mosquito se expusieron a diferentes dosis (0:1, 1:1, 5:1, 15:1, 100:1, 500:1, 750:1 y 1.500:1) de ejemplares juveniles infectivos del nematodo. Se hicieron cuatro réplicas por dosis. Resultados. El parasitismo varió entre 2,5 y 80 % en C. quinquefasciatus y entre 4,2 y 92,5 % en A. aegypti, con diferencias significativas entre las dosis (p<0,0001). Las DL50 fueron de 160,8 ejemplares juveniles infectivos por larva de C. quinquefasciatus y 113,6 por larva de A. aegypti; 4 a 6 % de los ejemplares juveniles infectivos llegaron a la fase adulta en C. quinquefasciatus, y 12 a 61 % en A. aegypti. Nuevos ejemplares juveniles infectivos aparecieron a partir de la dosis de 100:1. En A. aegypti aparecieron solo con dosis superiores a esta y, en C. quinquefasciatus, con una dosis de 1500:1. Se observó melanización de los ejemplares juveniles infectivos en las dos especies de mosquitos. Conclusión. Se estableció la sensibilidad de estas especies de mosquitos al parasitismo producido por un aislamiento autóctono de H. bacteriophora en condiciones de laboratorio y su potencial efecto como agente de control biológico.

Abstract Introduction: Aedes aegypti is the vector of dengue, yellow fever, Zika and Chikungunya viruses, and Culex quinquefasciatus is the vector of St. Louis and West Nile encephalitis viruses. Objective: To evaluate infectivity of Heterorhabditis bacteriophora N4 in C. quinquefasciatus and A. aegypti larvae under laboratory conditions. Materials and methods: Thirty second-instar larvae of the two mosquito species were exposed each to different doses (0:1, 1:1, 5:1, 15:1, 100:1, 500:1, 750:1 and 1,500:1) of nematode infective juveniles. Four replications per dose were performed. Results: Parasitism varied between 2.5 and 80 % in C. quinquefasciatus, and between 4.2 and 92.5 % in A. aegypti, with significant differences between doses (p<0.0001). DL50 were: 160.8 infective juveniles per larva for C. quinquefasciatus and 113.6 infective juveniles per larva for A. aegypti. In C. quinquefasciatus, 4 to 6 % of the infective juveniles developed to adults and in A. aegypti, 12- 61 %. In A. aegypti the emergence of new infective juveniles occurred with 100:1, 500:1, 750:1 and 1,500:1 infective juveniles per larva, and in C. quinquefasciatus, with 1,500:1 infective juveniles per larva. Melanization of infective juveniles was observed in both mosquito species. Conclusion: The susceptibility of these mosquito species to parasitism of an indigenous isolate of H. bacteriophora in the laboratory was demonstrated. Heterorhabditis bacteriophora N4 could be an efficient biological control agent.

Ascogregarina taiwanensis infection in Aedes aegypti and Aedes albopictus in Santa Catarina, South Brazil

Abstract INTRODUCTION This study registers Ascogregarina spp. infection in field populations of Aedes aegypti and Aedes albopictus in a subtropical region of Brazil. METHODS Mosquito larvae collected in tires placed in four municipalities of Santa Catarina were identified morphologically and assessed for Ascogregarina sp. infection using morphological and molecular methods. RESULTS Both mosquito species harbored Ascogregarina taiwanensis, whose genomic DNA was confirmed in both the Aedes species by PCR. DNA sequences were deposited in GenBank. Conclusion: Both Ae. albopictus e Ae. aegypti harbor Ascogregarina sp.

Trombose venosa profunda e vírus chicungunha / Deep venous thrombosis and chikungunya virus

Resumo Algumas infecções virais sistêmicas podem estar relacionadas ao desenvolvimento de trombose venosa profunda e/ou embolia pulmonar. Essa associação já está bem descrita em pacientes com infeções pelo vírus da imunodeficiência humana (HIV), hepatite C ou influenza. Recentemente introduzido no continente americano, o vírus chicungunha, agente etiológico da febre de chicungunha, ainda não tem essa relação bem sedimentada, mas com o aumento progressivo de sua incidência e pelo fato dessa infecção causar, muitas vezes, uma restrição severa da locomoção por poliartralgia e uma possível lesão endotelial direta, casos de tromboembolismo venoso podem começar a ser descritos. Neste relato de caso, descrevemos um paciente que desenvolveu trombose de veia poplítea direita durante internação para tratamento de febre por infecção por vírus chicungunha e poliartralgia severa.

Abstract Some systemic viral infections can be linked to development of deep venous thrombosis and/or pulmonary embolism. This association has already been well described in patients infected by human immunodeficiency virus (HIV), hepatitis C, and influenza. The chikungunya virus is the etiologic agent of chikungunya fever and it has recently been introduced to the American continent. As yet, there is no firm foundation for a relationship between chikungunya and thromboembolism, but the progressive increase in its incidence, the fact that this infection very often causes severe locomotion restrictions due to polyathralgia, and the possibility of direct endothelial injury suggest that cases of venous thromboembolism may begin to be described. In this case report, we describe a patient who developed thrombosis of the right popliteal vein after being admitted for treatment of severe polyathralgia and fever caused by chikungunya virus infection.

Infectivity of Chordodes nobilii larvae (Gordiida: Nematomorpha) / Infectividad de las larvas de Chordodes nobilii (Gordiida: Nematomorpha)

AbstractThe gordiids are freshwater representatives of the parasite phylum Nematomorpha that function as a link between aquatic and terrestrial ecosystems. In recent years, different ecotoxicologic studies have been made with the South-American gordiid species, Chordodes nobilii, that have demonstrated the capacity of this group to act as a bioindicator of contamination. Despite the Gordiida's ecologic relevance, further studies are still needed to elucidate different aspects of the biology of the class, and among those, the infective capacity, a parameter that can be evaluated by the infection index mean abundance (IIMA). A knowledge of the intrinsic variability in the infective capacity of C. nobilii would warrant priority in order to establish, the range of acceptable responses for normal or standard conditions in the laboratory, and, to compare the criteria among different assays. The objective of this study was to establish a baseline value for the infective capacity for C. nobilii larvae, under controlled laboratory conditions, by employing the IIMA as the evaluation parameter. To that end, we analyzed the infective capacity of C. nobilii larvae that had hatched from different strings of eggs laid in the laboratory by a total of 12 females. The C. nobilii adults were collected from streams within the Argentina Sauce Grande basin, between 2006 and 2009. Once in the laboratory, after mating, the females were placed in individual containers for oviposition. The egg strings obtained from each female were cut in 3 mm long segments; and when free larvae were observed, the segments (N= 90) were placed together with 30 Aedes aegypti larvae for evaluation of the gordiids' infective capacity. After 72 h, the mosquito larvae were observed by microscopy in order to quantify the C. nobilii larvae in body cavities. The IIMAs were calculated as the total number of C. nobilii larvae present divided by total number of A. aegypti larvae examined. For analysis of the IIMAs obtained, the data were grouped according to the female who made the original ovoposition. Our results enabled the corroboration of an ample range of responses in the infective capacity of this species, a characteristic that would normally be linked to the progenitors originating the hatch. Because this relationship prevents the establishment of a baseline for making comparisons among assays with gordiids, through the IIMA as a response parameter, we recommend expressing the IIMA values in each assay relative to their respective controls. These findings also provide evidence for the greater success in infections by certain members of the progeny over others. Finally, on the basis of the results obtained from this study, we stress the relevance of the use of the IIMA as a decisive aspect to be considered in different studies on the biology of Gordiida. Rev. Biol. Trop. 65 (1): 1-8. Epub 2017 March 01.

ResumenLos gordiidos son representantes dulceacuícolas del Phylum parásito Nematomorpha que actúan como un enlace entre ecosistemas acuáticos y terrestres. En años recientes, diferentes estudios ecotoxicológicos se han desarrollado con una especie sudamericana de gordiido, C. nobilii, que ha demostrado la capacidad de este grupo de actuar como bioindicador de contaminación. A pesar de su evidente importancia ecológica, aún se necesitan realizar estudios para dilucidar distintos aspectos de su biología, entre estos, la capacidad infectiva, un parámetro que puede evaluarse utilizando el Índice de Infección Abundancia Media (IIMA). El conocimiento de la variabilidad intrínseca en la capacidad infectiva de C. nobilii merece prioridad con el objeto de establecer el ámbito de respuesta aceptable para condiciones normales o estándar en el laboratorio, y que permita comparar los resultados entre distintos ensayos. El objetivo de este estudio es establecer la línea de base de la capacidad infectiva del gordiido C. nobilii en condiciones controladas de laboratorio, empleando el IIMA como parámetro de evaluación. Con este fin, se analizó la capacidad infectiva de larvas de C. nobilii que eclosionaron de diferentes cordones de huevos depositados por un total de 12 hembras, mantenidas en laboratorio. Los adultos de C. nobilii fueron recolectados de arroyos de la cuenca argentina Sauce Grande, entre 2006 y 2009. Una vez en el laboratorio, después de la cópula, las hembras se ubicaron en recipientes individuales a la espera de la oviposición. Los cordones de huevos obtenidos de cada hembra se cortaron en segmentos de 3 mm de longitud; y cuando las larvas libres fueron observadas al microscopio, los segmentos (N= 90) fueron ubicados junto con 30 larvas de Aedes aegypti para evaluar la capacidad infectiva del gordiido. Después de 72 h, las larvas del mosquito fueron observadas al microscopio para contabilizar las larvas de C. nobilii en las cavidades corporales. El IIMA fue calculado como el número total de larvas de C. nobilii presentes dividido entre el número total de larvas de A. aegypti examinadas. Para el análisis de los IIMAs obtenidos, los datos fueron agrupados de acuerdo a la hembra que hizo la oviposición. Nuestros resultados permiten corroborar un amplio rango de respuesta en la capacidad infectiva de esta especie, que estaría vinculada al origen de la camada. Debido a que no se pudo establecer una línea de base para realizar comparaciones entre estudios en los gordiidos utilizando el IIMA como parámetro de respuesta, se aconseja relativizar los valores de los IIMAs a sus respectivos controles. Estos resultados también pusieron en evidencia la ventaja en el éxito de infección de algunas progenies sobre las restantes. Finalmente, con base en los resultados obtenidos a partir de este estudio se plantea la importancia del uso del IIMA como punto final a considerar en distintos estudios sobre la biología de los gordiida.

A competência vetorial do Aedes aegyptiassociada à genética populacional na cidade de Belo Horizonte, Minas Gerais

A Dengue é uma doença emergente, causada por quatro sorotipos do DENV (DENV-1, DENV-2, DENV-3 e DENV-4) pertencentes ao gênero Flavivirus e à família Flaviviridae. O vírus é transmitido pela picada de mosquitos fêmeas do gênero Aedes, sendo o Aedes aegypti o vetor primário. Estima-se 390 milhões de infecções anuais e 22.000 mortes, principalmente em crianças no mundo (WHO, 2016). A presença e a alta densidade dos vetores intensifica a necessidade de ações de controle. No entanto, um importante fato precisa ser considerado: as populações de mosquitos variam na sua permissividade para o desenvolvimento do flavivírus. A cidade de Belo Horizonte, alvo desse estudo, passou por 6 epidemias da doença nos últimos 20 anos (PBH, 2016). Os ovos dos Ae. aegypti de cada regional administrativa foram coletados pela Secretaria Municipal de Saúde separadamente e colonizados no insetário do LEM. Os adultos foram submetidos à extração de DNA, o qual foi amplificado para a sequência total de ITS. As análises filogenéticas foram realizadas com o software MEGA6. Em nosso estudo filogenético com as populações de Ae. aegypti de Belo Horizonte, observamos clusters melhores definidos e valores mais altos de bootstrap para três regionais: Oeste (O), Leste (L) e Nordeste (ND)

Essas foram selecionadas para as demais análises. Mosquitos fêmeas dessas regionais foram infectadas experimentalmente com DENV-2 e o vírus foi detectado através da RT-qPCR nas amostras dissecadas dos corpos e cabeças contendo as glândulas salivares. As análises das regionais ND, L e O revelou, em 7dpi taxas de infecção de 70, 80 e 70%, respectivamente. Em 14 dpi, as taxas foram de 80% para a regional ND e de 90% para as regionais L e O. A competência vetorial das três populações em estudo variou de 50 à 70%. Não observamos diferenças estatísticas entre nenhum os grupos Realizamos a análise do ITS dos indivíduos submetidos à infecção experimental. Não observamos o padrão de clusters encontrado anteriormente. No entanto, foi possível observar dois indivíduos negativos agrupados, ambos provenientes da regional nordeste, o que pode ser um fraco indicativo (devido ao número de amostras) de fenótipo característico para as amostras negativas

Caracterización de la infestación de viviendas por Aedes aegypti en el área metropolitana de Cochabamba, Bolivia: nuevos registros altitudinales / Characterization of dwellings' infestation by Aedes aegypti in the metropolitan area of Cochabamba, Bolivia: new altitudinal records

La rápida proliferación del vector en áreas de clima cálido y baja altitud, como el oriente y la amazonia boliviana, generó la necesidad de analizar la adaptabilidad del A. aegypti en zonas templadas, tal es el caso de los valles mesotérmicos de la ciudad metropolitana de Cochabamba. La evaluación entomológica se realizó en una muestra de 264 viviendas seleccionadas al azar en Abril del 2016. El área de estudio abarca zonas urbanas de seis municipios (Cercado, Sacaba, Colcapirhua, Tiquipaya, Quillacollo y Vinto) del departamento de Cochabamba. El diseño para el estudio fue epidemiológico, transversal de diagnóstico comunitario. De la muestra referida, 100 viviendas se encontraron larvas de A. aegypti , que corresponde a un 38% de infestación larvaria y un Índice Breteau de 1,0. Las llantas, turriles y recipientes desechables son un factor de riesgo para la propagación y adaptación del vector en nuestra región. Los hallazgos confirman la dispersión del A. aegypti con algunas regiones con mayor prevalencia (zona sud de cercado urbano, Colcapirhua y Quillacollo en el valle bajo). También se evidenció por primera vez que la dispersión y colonización de larvas de A. aegypti en el área de estudio alcanzó una altura mínima de 2 538 m/s/n/m. y una altura máxima de 2 623 m.s.n.m. La prevención y el control de A. aegypti , en la metrópoli de Cochabamba va a requerir un trabajo mancomunado integral e intersectorial enfocados en una estrategia de intervención de gestión socioambiental de corresponsabilidad y participación comunitaria, generando como resultado un Manejo Integrado del Vector.

The fast proliferation of the vector at warm weather and low altitude over the sea level, such as the Bolivian valleys (as Cochabamba city), generates the need to analyze the adaptability of A. aegypti . This study of comunitary diagnosis, was developed at the metropolitan area of Cochabamba city, it confirms an spread A. aegypti , shown by georeferences of identified focus of high prevalence (sud of the city, Colcapirhua and Quillacollo as a low valley). For the first time this vector spread, reached between 2 538 to 2 623 meters over sea level. From 264 inspected houses over the city, 100 cases were found positive for A. aegypti (38%) (Breteau Index: 1,0). According to the study, tires, barrels and small containers are a risk factor for the spread and adaptation of the vector in our region. Prevention and control of A. aegypti in the metropolis of Cochabamba will require an integrated and intersectoral joint work, focused on a strategy of intervention socio-environmental and community participation, generating results in an Integrated Vector Management.

Xenomonitoramento de populações de Aedes aegypti e Aedes albopictus para o Dengue virus em Belo Horizonte, uma cidade de alto risco para a incidência de epidemias

Dengue é considerada a mais relevante arbovirose que afeta seres humanos, e constitui grave problema de saúde pública. A detecção de Dengue virus (DENV) por RT-PCR em Tempo Real, em mosquitos vetores do gênero Aedes, tem se mostrado importante ferramenta na vigilância epidemiológica. A presente pesquisa verificou a presença de DENV em mosquitos fêmeas de Ae. aegypti e Ae. albopictus nos Distritos Sanitários (DS) Pampulha, Norte e Leste, de Belo Horizonte, Minas Gerais. Foram utilizadas armadilhas BG-Sentinel Full Version®, em capturas semanais de mosquitos, realizadas em quatro períodos: primeiro (dezembro de 2010 a maio de 2011), segundo (outubro de 2011 a maio de 2012), terceiro (outubro de 2012 a maio de 2013) e quarto (outubro de 2013 a maio de 2014). Foi instalado um total de 60 armadilhas (20 por DS). Após a identificação, as fêmeas de Ae. aegypti foram separadas em pools formados por um até 10 exemplares, e as fêmeas de Ae. albopictus foram separadas de forma individual. Procedeu-se com extração de RNA viral e RT-PCR em Tempo Real para a pesquisa de DENV. Foram coletadas 10.662 fêmeas de Ae. aegypti sendo 1.504 (14,10%), 2.516 (23,59%), 3.728 (34,98%) e 2.914 (27,33%) no primeiro, segundo, terceiro e quarto períodos respectivamente. Estas fêmeas foram agrupadas em 6.056 pools, dos quais 343 (5,66%) foram positivos para o DENV. Em relação ao Ae. albopictus foram coletadas 511 fêmeas, sendo 117 (22,89%), 44 (8,61%), 199 (38,96%) e 151 (29,54%) no primeiro, segundo, terceiro e quarto períodos respectivamente. Destas, 79 (15,45%) foram positivas para o vírus. Houve elevada ocorrência de fêmeas deAe. aegypti e Ae. albopictus nas áreas pesquisadas, positivas para o DENV. Isso mostra a importância da adoção de medidas de controle no sentido de reduzir as notificações da infecção em seres humanos.

Xenomonitoring of Different Filarial Nematodes Using Single and Multiplex PCR in Mosquitoes from Assiut Governorate, Egypt

Wuchereria bancrofti, Dirofilaria immitis, and Dirofilaria repens are filarial nematodes transmitted by mosquitoes belonging to Culex, Aedes, and Anopheles genera. Screening by vector dissection is a tiresome technique. We aimed to screen filarial parasites in their vectors by single and multiplex PCR and evaluate the usefulness of multiplex PCR as a rapid xenomonitoring and simultaneous differentiation tool, in area where 3 filarial parasites are coexisting. Female mosquitoes were collected from 7 localities in Assiut Governorate, were microscopically identified and divided into pools according to their species and collection site. Detection of W. bancrofti, D. immitis, and D. repens using single PCR was reached followed by multiplex PCR. Usefulness of multiplex PCR was evaluated by testing mosquito pools to know which genera and species are used by filarial parasites as a vector. An overall estimated rate of infection (ERI) in mosquitoes was 0.6%; the highest was Culex spp. (0.47%). W. bancrofti, D. immitis, and D. repens could be simultaneously and differentially detected in infected vectors by using multiplex PCR. Out of 100 mosquito pools, 8 were positive for W. bancrofti (ERI of 0.33%) and 3 pools each were positive for D. immitis and D. repens (ERI 0.12%). The technique showed 100% sensitivity and 98% specificity. El-Nikhila, El-Matiaa villages, and Sahel Seleem district in Assiut Governorate, Egypt are still endemic foci for filarial parasites. Multiplex PCR offers a reliable procedure for molecular xenomonitoring of filariasis within their respective vectors in endemic areas. Therefore, it is recommended for evaluation of mosquito infection after lymphatic filariasis eradication programs.

Xenomonitoring of Different Filarial Nematodes Using Single and Multiplex PCR in Mosquitoes from Assiut Governorate, Egypt

Wuchereria bancrofti, Dirofilaria immitis, and Dirofilaria repens are filarial nematodes transmitted by mosquitoes belonging to Culex, Aedes, and Anopheles genera. Screening by vector dissection is a tiresome technique. We aimed to screen filarial parasites in their vectors by single and multiplex PCR and evaluate the usefulness of multiplex PCR as a rapid xenomonitoring and simultaneous differentiation tool, in area where 3 filarial parasites are coexisting. Female mosquitoes were collected from 7 localities in Assiut Governorate, were microscopically identified and divided into pools according to their species and collection site. Detection of W. bancrofti, D. immitis, and D. repens using single PCR was reached followed by multiplex PCR. Usefulness of multiplex PCR was evaluated by testing mosquito pools to know which genera and species are used by filarial parasites as a vector. An overall estimated rate of infection (ERI) in mosquitoes was 0.6%; the highest was Culex spp. (0.47%). W. bancrofti, D. immitis, and D. repens could be simultaneously and differentially detected in infected vectors by using multiplex PCR. Out of 100 mosquito pools, 8 were positive for W. bancrofti (ERI of 0.33%) and 3 pools each were positive for D. immitis and D. repens (ERI 0.12%). The technique showed 100% sensitivity and 98% specificity. El-Nikhila, El-Matiaa villages, and Sahel Seleem district in Assiut Governorate, Egypt are still endemic foci for filarial parasites. Multiplex PCR offers a reliable procedure for molecular xenomonitoring of filariasis within their respective vectors in endemic areas. Therefore, it is recommended for evaluation of mosquito infection after lymphatic filariasis eradication programs.

Avaliação da influência da Wolbachia na infecção e transmissão vertical do vírus dengue em mosquitos Aedes aegypti

A dengue é um problema médico crescente em países subtropicais e tropicais. A dengue é uma infecção viral que apresentem quatro sorotipos distintos, DENV-1 a -4, sendo recentemente relatado o quinto sorotipo, DENV-5, na Malásia. Estes são transmitidos pela picada de mosquitos infectados do gênero Aedes, sendo o Aedes aegypti o principal vetor. Atualmente, a prevenção e controle da dengue dependem exclusivamente de medidas de combate ao vetor, e estas apresentam-se ineficientes, principalmente em países em desenvolvimento. Nesse contexto, há a necessidade da busca de novas estratégias que possam ser utilizadas concomitantemente com as formas de controle já existentes. A Wolbachia é uma bactéria intracelular, amplamente conhecida por promover o fenótipo de bloqueio do vírus dengue em mosquitos A. aegypti. Apesar disto, não se conhece se a Wolbachia é capaz de interferir na infecção da progênie de mosquitos infectados com o vírus dengue, fenômeno conhecido como transmissão vertical. A transmissão vertical pode estar associada com a manutenção do vírus em períodos inter-epidêmicos ou em locais nos quais a transmissão ativa está diminuída.

Assim, o objetivo deste trabalho foi avaliar se a Wolbachia introduzida na linhagem brasileira de A. aegypti influencia a transmissão vertical da dengue. Duas metodologias de infecção foram utilizadas: infecção oral e nanoinjeção intratorácica, onde utilizou-se o DENV-4 e DENV-1,-3 e -4, respectivamente. Para estes experimentos, foram comparados mosquitos com Wolbachia (Mel) e uma linhagem de mosquitos tratada com antibiótico e portanto, livre da bactéria (Tet). Os ovos dos mosquitos infectados foram coletados em um período de 20 e 11 dias após a infecção, oral e injeções, respectivamente. A fecundidade e fertilidade, de forma geral, foram diminuídas na co-infecção da Wolbachia com o vírus dengue. Em todos os mosquitos infectados, não se observou diferenças na suscetibilidade ao vírus, porém a carga viral foi diminuída pela Wolbachia no DENV-4, em ambas as formas de infecção.

Foi possível a detecção de pools positivos independente da forma de infecção, demonstrando que a transmissão vertical do vírus dengue ocorreu, porém a proporção de pools positivos entre os grupos Mel e Tet não foi alterada. Entretanto, pudemos observar uma diminuição da carga viral nos pools positivos Mel. Os ovários na infecção oral, interessantemente, tiveram uma forte diminuição da suscetibilidade conferida pela Wolbachia. A carga viral dos ovários foi diminuída em DENV-1 e DENV-4, em ambas as formas de infecção. Os dados obtidos nestes experimentos apontam que a transmissão vertical do vírus dengue ocorreu em pequenas taxas. Independente da forma de infecção utilizada, as taxas não variaram, mostrando que os mecanismos que regulam a ocorrência da transmissão vertical precisam ser explorados. Concluímos que, a Wolbachia pode potencialmente ser responsável pela redução da transmissão vertical em campo. Isto é considerado um grande avanço no controle da dengue, se realmente for comprovada que a transmissão vertical é a responsável pela manutenção do vírus em períodos inter-epidêmicos.

Avaliação da influência da Wolbachia na infecção e transmissão vertical do vírus dengue em mosquitos Aedes aegypti / Evaluation of the influence of the Wolbachia infection and vertical transmission of dengue virus in Aedes aegypti mosquitoes

A dengue é um problema médico crescente em países subtropicais e tropicais. A dengue é uma infecção viral que apresentem quatro sorotipos distintos, DENV-1 a -4, sendo recentemente relatado o quinto sorotipo, DENV-5, na Malásia. Estes são transmitidos pela picada de mosquitos infectados do gênero Aedes, sendo o Aedes aegypti o principal vetor. Atualmente, a prevenção e controle da dengue dependem exclusivamente de medidas de combate ao vetor, e estas apresentam-se ineficientes, principalmente em países em desenvolvimento. Nesse contexto, há a necessidade da busca de novas estratégias que possam ser utilizadas concomitantemente com as formas de controle já existentes. A Wolbachia é uma bactéria intracelular, amplamente conhecida por promover o fenótipo de bloqueio do vírus dengue em mosquitos A. aegypti. Apesar disto, não se conhece se a Wolbachia é capaz de interferir na infecção da progênie de mosquitos infectados com o vírus dengue, fenômeno conhecido como transmissão vertical. A transmissão vertical pode estar associada com a manutenção do vírus em períodos inter-epidêmicos ou em locais nos quais a transmissão ativa está diminuída.

Assim, o objetivo deste trabalho foi avaliar se a Wolbachia introduzida na linhagem brasileira de A. aegypti influencia a transmissão vertical da dengue. Duas metodologias de infecção foram utilizadas: infecção oral e nanoinjeção intratorácica, onde utilizou-se o DENV-4 e DENV-1,-3 e -4, respectivamente. Para estes experimentos, foram comparados mosquitos com Wolbachia (Mel) e uma linhagem de mosquitos tratada com antibiótico e portanto, livre da bactéria (Tet). Os ovos dos mosquitos infectados foram coletados em um período de 20 e 11 dias após a infecção, oral e injeções, respectivamente. A fecundidade e fertilidade, de forma geral, foram diminuídas na co-infecção da Wolbachia com o vírus dengue. Em todos os mosquitos infectados, não se observou diferenças na suscetibilidade ao vírus, porém a carga viral foi diminuída pela Wolbachia no DENV-4, em ambas as formas de infecção.

Foi possível a detecção de pools positivos independente da forma de infecção, demonstrando que a transmissão vertical do vírus dengue ocorreu, porém a proporção de pools positivos entre os grupos Mel e Tet não foi alterada. Entretanto, pudemos observar uma diminuição da carga viral nos pools positivos Mel. Os ovários na infecção oral, interessantemente, tiveram uma forte diminuição da suscetibilidade conferida pela Wolbachia. A carga viral dos ovários foi diminuída em DENV-1 e DENV-4, em ambas as formas de infecção. Os dados obtidos nestes experimentos apontam que a transmissão vertical do vírus dengue ocorreu em pequenas taxas. Independente da forma de infecção utilizada, as taxas não variaram, mostrando que os mecanismos que regulam a ocorrência da transmissão vertical precisam ser explorados. Concluímos que, a Wolbachia pode potencialmente ser responsável pela redução da transmissão vertical em campo. Isto é considerado um grande avanço no controle da dengue, se realmente for comprovada que a transmissão vertical é a responsável pela manutenção do vírus em períodos inter-epidêmicos.