Estimation of vectorial capacity of Anopheles minimus Theobald & An. fluviatilis James (Diptera: Culicidae) in a malaria endemic area of Odisha State, India.

Background & objectives: Anopheles minimus and An. fluviatilis were incriminated as the major malaria vectors in Keonjhar district of Odisha State recently. This study was carried out to elucidate the potential role of these two vector species in transmission of malaria during different seasons, and vectorial capacity of these species was also estimated. Methods: Three hilly and forested villages of Keonjhar district were randomly selected. Vectorial capacity (C) was calculated using the Macdonald’s formula as modified by Garret-Jones. The human landing density of the vector species was obtained from all night human landing collections (bait protected by bed-net). Man feeding habit was estimated by multiplying the human blood index with feeding frequency, which was obtained on daily basis from the duration of gonotrophic cycle. The probability of survival through the extrinsic incubation cycle was calculated from the probability of survival through one day and duration of sporogonic cycle. Results: The estimated vectorial capacity of An. minimus varied between 0.014 and 1.09 for Plasmodium falciparum (Pf) and between 0.1 and 1.46 for P. vivax (Pv). The C of An. minimus for both Pf and Pv was higher during rainy season than the other two seasons. The estimated C of An. fluviatilis varied between 0.04 and 1.28 for Pf and between 0.20 and 1.54 for Pv. Interpretation & conclusions: Based on the estimated values of vectorial capacity of the two vector species, the area could be stratified and such stratification would reflect the difference in the intensity of transmission between different strata and accordingly the appropriate control strategy could be adopted for each stratum.

Phlebotomine fauna, natural infection rate and feeding habits of Lutzomyia cruzi in Jaciara, state of Mato Grosso, Brazil

Visceral leishmaniasis (VL) in Brazil is transmitted by the phlebotomine Lutzomyia longipalpis and in some midwestern regions by Lutzomyia cruzi. Studies of the phlebotomine fauna, feeding habits and natural infection rate by Leishmania contribute to increased understanding of the epidemiological chain of leishmaniases and their vectorial capacity. Collections were performed in Jaciara, state of Mato Grosso from 2010-2013, during which time 2,011 phlebotomines (23 species) were captured (68.70% Lu. cruzi and 20.52% Lutzomyia whitmani). Lu. cruzi females were identified by observing the shapes of the cibarium (a portion of the mouthpart) and spermatheca, from which samples were obtained for polymerase chain reaction to determine the rates of natural infection. Engorged phlebotomines were assessed to identify the blood-meal host by ELISA. A moderate correlation was discovered between the number of Lu. cruzi and the temperature and the minimum rate of infection was 6.10%. Twenty-two females were reactive to the antisera of bird (28%), dog (3.30%) and skunk (1.60%). We conclude that Lu. cruzi and Lu. whitmani have adapted to the urban environment in this region and that Lu. cruzi is the most likely vector of VL in Jaciara. Moreover, maintenance of Leishmania in the environment is likely aided by the presence of birds and domestic and synanthropic animals.

Enfrentamiento a eventos epidémicos de transmisión vectorial: paludismo y dengue / Facing epidemic events of vector transmission: malaria and dengue

El libro titulado Enfrentamiento a eventos epidémicos de transmisión vectorial: paludismo y dengue deviene un referente necesario cuando se aborde lo relacionado con fenómenos de ese tipo en cualquier momento y lugar.

The book entitled Facing epidemic events of vector transmission: malaria and dengue becomes a reference material necessary when approaching topics related to phenomena of this type at any moment and place.

Competencia vectorial: consideraciones entomológicas y suinfluencia sobre la epidemiología del dengue / Vector competence: entomological considerations and its implications on the epidemiology of dengue

Las enfermedades transmitidas por vectores constituyen un complejo problema de salud en el ámbito mundial, especialmente en áreas tropicales y subtropicales, que por sus condiciones ambientales favorecen la supervivencia del vector. El dengue es la principal enfermedad transmitida por vectores en el mundo, cuyo agente etiológico es el Virus Dengue, el cual es transmitido por la picadura de mosquitos hematófagos de la especie Aedes aegypti. La interacción virus-vector es esencial para una transmisión efectiva y depende de factores tanto virales como vectoriales. Entre los factores relacionados con el vector, la competencia vectorial es considerada de gran importancia, pues se refiere a la capacidad intrínseca del vector para infectarse con el virus, permitir su replicación y posteriormente su transmisión a un huésped susceptible. A su vez, la habilidad para ser un buen vector depende principalmente de barreras naturales a la infección, barreras inmunológicas y presencia de receptores específicos para el virus. Todas estas características, sumadas a las características propias del virus, favorecerán o no la transmisión del mismo. Un estudio integral dela relación virus-vector permitirá comprender sus implicaciones en la epidemiología de la enfermedad. Estos temas han sido revisados en el presente documento, discutiendo su importancia dentro del contexto entomológico y epidemiológico.

Vector-borne diseases are a serious problem in public health, especially in tropical and subtropical areas where environmental conditions favor the survival and expansion of vectors into new habitats. Dengue fever is one of the most important vector-borne diseases transmitted by arthropods (arbovirosis) worldwide. The etiologic agent of the disease is the dengue virus, which is transmitted by the bite of bloodsucking Aedes aegypti mosquitoes. The virus-vector interaction is essential for the efficient transmission of the disease, and depends on both, viral factors and vector competence or intrinsic vector capacity to be infected with the virus. Vector competence allows virus replication and subsequent transmission to susceptible hosts. Factors that influence vector capacity include: natural barriers to infection, immunological defenses as well as the presence of receptors for the virus. All these factors inaddition to the viral characteristics will determine the degree of transmission. There is a need for a better understanding of the virus-vector relationship and its epidemiological implications. These issues are addressed in this article.

Informações sobre a biologia do conorhinus megitus Burm / Information on the biology of conorhinus megitus Burm

Revisões históricas aos avanços científicos para o controle da doença, o Simpósio Internacional Comemorativo do Centenário da Descoberta da Doença de Chagas (1909-2009).

Incidência de moscas vetores de patógenos em imediações de universidade, em Santo André, SP e o risco de contaminação alimentar para o corpo discente / Effect of fly vectors of pathogens in the vicinity of the university, in Santo André, SP, and the risk of food contamination for the student

O presente trabalho aborda um levantamento sobre as espécies de moscas e possíveis patógenos por elas carreados, junto a áreas de comércio ambulante de alimentos. Durante uma semana foram montadas armadilhas nos arredores do Centro Universitário de Santo André (UniA), para verificar a diversidade de moscas vetores de microrganismos patogênicos e o risco de incidência de cistos de protozoários aderidos ao corpo ou endogenamente junto aos estabelecimentos de veda e manipulação de alimentos. Foram capturadas moscas comuns e moscas pertencentes à família Calliphoridae (popularmente conhecidas como varejeiras), extremamente implicadas com a transmissão de doenças. Em todo o período de coleta (75 minutos), encontramos uma variedade de moscas semelhantes (em espécies) a outros trabalhos efetuados. Não foram encontrados cistos de protozoários, porém a presença desses animais mostra um problema relevante com as condições higiênico-sanitárias locais e conseqüentemente, um risco de contaminação dos alimentos servidos à população.

Isolation and characterization of a chitinase gene from entomopathogenic fungus Verticillium lecanii / Isolamento e caracterização de um gene de quitinase do fungo entomopatogênico Verticillium lecanii

Entomopathogenic fungus Verticillium lecanii is a promising whitefly and aphid control agent. Chitinases secreted by this insect pathogen have considerable importance in the biological control of some insect pests. An endochitinase gene Vlchit1 from the fungus was cloned and overexpressed in Escherichia coli. The Vlchit1 gene not only contains an open reading frame (ORF) which encodes a protein of 423 amino acids (aa), but also is interrupted by three short introns. A homology modelling of Vlchit1 protein showed that the chitinase Vlchit1 has a (α/β)8 TIM barrel structure. Overexpression test and Enzymatic activity assay indicated that the Vlchit1 is a functional enzyme that can hydrolyze the chitin substrate, so the Vlchit1 gene can service as a useful gene source for genetic manipulation leading to strain improvement of entomopathogenic fungi or constructing new transgenic plants with resistance to various fungal and insects pests.

O fungo entomopatogênico Verticillium lecanii é um agente promissor no controle da mosca-branca e do pulgão. As quitinases secretadas por esse patógeno de insetos têm uma grande importância no controle biológico de doenças causadas por insetos. Um gene de endoquitinase Vlchit1 desse fungo foi clonado e expresso em Escherichia coli. O gene Vlchit contém não apenas um ORF que codifica uma proteína de 423 aminoácidos, mas também é interrompido por três pequenos introns. A modelagem de homologia da proteína Vlchit1indicou que a quitinase Vlchit1 tem uma estrutura (α/β) 8 TIM barrel. Testes de expressão e de atividade enzimática indicaram que Vlchit1 é uma enzima funcional que hidroliza quitina, portanto o gene Vlchit pode ser um gene útil para manipulação genética para melhoramento de cepas de fungos entomopatogênicos ou para a construção de novas plantas transgênicas com resistência a várias doenças causadas por fungos e insetos.

Spread, establishment & prevalence of dengue vector Aedes aegypti (L.) in Konkan region, Maharashtra, India.

BACKGROUND & OBJECTIVE: Aedes aegypti (L.) (Diptera: Culicidae) was surveyed in the residential biotopes of Sindhudurg, Ratnagiri and Raigadh districts, Maharashtra State during dry (January-May & November- December) and wet (June-October) months in 2002 to update information on its distribution, to analyse post invasion establishment, and to study its prevalence. METHODS: The survey was designed to unfold Ae. aegypti distributions at landscape, habitat and micro-habitat levels. Risks of distribution and establishment due to differences amongst settlements, households and habitat attributes were analysed by univariate and multivariate methods. Demographic/transport changes were surveyed for its breeding refugia during dry months and prevalence during the wet seasons. Chi square tests for difference and relative risks of container types were applied to assess container habitats preferences for Ae. aegypti breeding, thus contributing to the risk of establishment and prevalence through seasons. RESULTS: Ae. aegypti was present in 16 out of total 28 settlements in dry season and 22 of 25 in wet season; the Breteau index (BI) varied from 1.25 to 57.33 and the container index (CI) was 0.6 to 25.81 in the dry season and BI from 1.25 to 110-00 and CI - 0.2 to 11.37 in the wet season, respectively. At macro-level, rural settlements and ports showed higher odds ratios (OR>1) for presence of Ae. aegypti. At meso-level, OR were 65.8, 24.8 and 4.9 for Ae. aegypti breeding in compact houses, clustered housing and in houses with tap water source respectively. At micro-level the plastic drums and small plastic containers were the important key habitats of its breeding. In the non-residential areas Ae. aegypti breeding was noted in one port during dry season; 10-road transport tyre dumps and scrap, 5 of 7 seaports and none of the two railway station areas during wet season. INTERPRETATION & CONCLUSION: At macro-geographic level Ae. aegypti distribution increased in 3 settlements, new establishment was seen in 7, new records in ten settlements and two were negative in past and present surveys. Logistic regression analyses indicated that the distribution was found to be more associated with ports and rural areas. At meso-geographic level the house aggregations and household drinking water supplies were of risk even at lower urbanization and rural levels. At micro-level, the site and potability were confounders; outdoor non potable water storage containers posed significant breeding risk, the potable water storage was significant but it contributed little to Ae. aegypti breeding. Further, Ae. aegypti breeding showed high preference to the plastic drums and other plastic miscellany. The results signified an expansion in the risk area of diseases borne by it in the context of urbanization, transport development and changing habitats.

Distribuição das espécies do gênero Anopheles (Diptera, Culicidae) no Estado do Maranhão, Brasil / Distribution of species from genus Anopheles (Diptera, Culicidae) in the State of Maranhão, Brazil

Estudou-se a distribuição e diversidade de espécies de Anopheles em 123 municípios do Estado do Maranhão, Brasil. O método básico foi a captura de fêmeas dentro e nos arredores das habitações humanas, em intervalos compreendidos entre 18h e 6h, no período de janeiro de 1992 a dezembro de 2001. Foram capturados 84.467 exemplares distribuídos em 24 espécies, com o predomínio de A. triannulatus sensu lato (20.788), A. darlingi (19.083), A. nuneztovari (16.884), A. albitarsis s.l. (14.352), A. aquasalis (8.202) e A. evansae (2.885). As outras 18 espécies juntas representaram apenas 2,7 por cento. As espécies encontradas no maior número de municípios foram: A. albitarsis s.l. (109 municípios), A. triannulatus s.l. (106), A. nuneztovari (93), A. darlingi (87) e A. evansae (64). A riqueza e a ampla distribuição das espécies de anofelinos no Maranhão concordam com a posição geográfica do estado, entre as macrorregiões que caracterizam o Brasil, resultando em uma fauna mista, com elementos representativos dessas regiões.

We studied the distribution and diversity of Anopheles species in 123 counties (municipalities) in the State of Maranhão, Brazil. The basic method consisted of capturing female specimens inside and around human dwellings between 6 PM and 6 AM from January 1992 to December 2001. A total of 84,467 specimens belonging to 24 species were captured, with a predominance of A. triannulatus sensu lato (20,788), A. darlingi (19,083), A. nuneztovari (16,884), A. albitarsis s.l. (14,352), A. aquasalis (8.202), and A. evansae (2,885). The other 18 species together accounted for only 2.7 percent of the total. The species found in the most counties were A. albitarsis s.l. (109 counties), A. triannulatus s.l. (106), A. nuneztovari (93), A. darlingi (87), and A. evansae (64). The richness and wide distribution of anopheline species in Maranhão agree with the State's geographic position among Brazil's macro-regions, resulting in a mixed fauna with representative elements from these regions.

Índice de defecación y éxito reproductivo de Triatoma maculata (Hemiptera: Reduviidae)en condiciones de laboratorio / Defecation index and reproductive success of Triatoma maculata (Hemiptera: Reduviidae) under laboratory conditions

Se estudió el comportamiento reproductivo y de defecación de Triatoma maculata (Erichson 1848)alimentando artificialmente con sangre humana.Los estadios II y III mostraron mayor frecuencia de defecaciones (ID=0.6 n=40),el estadio V no alcanzó la diferenciación sexual, la fertilidad fue 55%(n=865),fecundidad 8 huevos/hembra/semana (n=26),22 días de desarrollo embrionario (n=477),longevidad de hembras 51 días (n=26),el tiempo intermuda aumenta progresivamente desde 35 días en el estadio I hasta 46 días en el estadio IV,el porcentaje de muda varió desde 0%en el estadio V hasta 63%en el estadio III,la mortalidad varió desde 8%en el estadio III hasta 100%en el estadio V (n=40).Los resultados del presente trabajo aportan evidencias que explican la menor capacidad vectorial y la baja densidad de T.maculata en el domicilio humano

The reproductive and defecating behavior of Triatoma maculata (Erichson 1848)was studied on animals from an university culture in Venezuela.This species does not reach the importance of Rhodnius prolixus Stal 1859 as Chagas disease vector in Venezuela.This study addressed the role of defecating frequency,an index of how dangerous the animals are for the human population,and its relationship with why T.maculata is a less important vector than R.prolixus .Human blood was fed to the insects through an artificial feeding device.The 2nd and 3rd instar nymphs defecated more frequently (Id=0.6,n=40),and our Vth instar nymphs did not complete sexual differentiation.Fertility was 55%(n=865)and fecundity 8 eggs/female/week (n=26). Egg incubation lasted 22 days (n=477).Female longevity was 51 days (n=26).Intermould time grew progressively from 35 days for 1st to 40 days for 4th instar nymphs (n=40).Mould percentage varied from 0% for Vth to 63%for 3rd instar nymphs.Mortality varied from 8% for 3rd to 100% for Vth instar nymphs.These results support evidences explaining the lesser vectorial capacity and low density of T.maculata in human domiciles, including reduced reproduction and defecation when the animal feeds on human blood

Malaria transmission

No Brasil, a malária está restrita à regiäo amazônica, onde ocorre mais de 95 por cento dos casos registrados no país. Somente as fêmeas de mosquitos do gênero Anopheles säo capazes de transmitir os parasitos da malária humana. Treze espécies de anofelinos do Brasil foram encontradas naturalmente infectadas com Plasmodium, mas somente poucas estäo envolvidas na transmissäo. Anopheles darlingi é o principal vetor de malária nas ecorregiões de savana e floresta plana enquanto que o A. aquasalis é responsável pela transmissäo desta infecçäo na área costeira. Todavia, A. deaneorum, A. oswaldoi e A. marajoara tem sido incriminados como vetores locais de malária. Controlar a transmissäo de malária na regisäo Amazônica é uma tarefa muito difícil por causa de suas características ecológicas, ambientais, sociais e econômicas. Nos últimos 10 anos, os assentamentos desordenados (invasões) têm sido uma das principais causas de disseminaçäo de malária humana nos grandes centros urbanos, como é o caso da cidade de Manaus e Belém.

El papel del vector Aedes aegypti en la epidemiología del dengue en México / The role of Aedes aegypti in the epidemiology of dengue fever in Mexico

Se discute el papel del Aedes aegypti (Lineo) en la epidemiología del dengue en México usando como referencia el modelo de la capacidad vectorial. Se presentan comentarios sobre las ventajas y desventajas de cada uno de los componentes de este modelo al momento de su determinación en campo. Se enfatiza cómo la suma de errores metodológicos y de muestreo, afecta finalmente el resultado de la capacidad vectorial. Se subraya la necesidad de incrementar el conocimiento en la biología del Aedes aegypti, como una respuesta a las necesidades de la epidemiología en su tarea de predecir y explicar brotes de dengue, y se comenta sobre variables potenciales de importancia epidemiológica de origen entomológico que del modelo cuantitativo no considera. Finalmente, se menciona la introducción del Aedes albopictus (Skuse) en México y cómo esto viene a complicar más la comprensión de la transmisión del dengue

The role of Aedes aegypti (Lineo) in the epidemiology of dengue fever in Mexico is herein discussed based on the vectorial capacity model. Comments on the advantages and disadvantages of each model component at the time of field determinations are also presented. Emphasis is made on the impact of sampling and method bias on the results of vectorial capacity studies. The paper also addresses the need to increase vector biology knowledge as an input for epidemiological work to explain and predict dengue fever outbreaks. Comments on potential entomological variables not considered by the quantitative model are included. Finally, we elaborate on the introduction of Aedes albopictus (Skuse) in Mexico as a new risk factor and on its implications for the understanding of dengue fever transmission in Mexico.

Infecciones bacterianas cutáneas superficiales o impétigos: aspectos clínicos y terapéuticos / Superficial bacterial skin infections or impetigo: clinical and therapeutic aspects

Impétigo es una infección bacteriana, cutánea, superficial causada sobre todo por estafilococo dorado por estreptococo o por ambos. Es el padecimiento cutáneo infecto-contagioso más frecuente. Predomina en niños de estrato socioeconómicocultural bajo, en regiones húmedas y cálidas. Las lesiones son vesículas frágiles que se transforman en costras, preferentemente vecinas a los orificios naturales de la cara. El tratamiento consiste en antimicrobianos tópicos y/o sistémicos. La prevención consiste en el aseo y antisepsia de todo traumatismo que cause pérdida de la continuidad de la piel