RESUMO
Efforts directed at genetic modification of mosquitoes for population control or replacement are highly dependent on the initial mating success of transgenic male mosquitoes following their release into natural populations. Adult mosquito phenotypes are influenced by the environmental conditions experienced as larvae. Semifield studies conducted to date have not taken that under consideration when testing male mating fitness, and have compared mating success of males reared under identical environmental conditions. We performed pairwise mating challenges between males from a genetically modified laboratory strain (BF2) versus males from a recent Trinidad field isolate of Aedes aegypti (L.), a major vector of multiple arboviruses. We utilized larval density and nutrition to simulate environmental stress experienced by the Trinidad males and females. Our results indicated that environmental stress during larval development negatively influenced the competitiveness and reproductive success of males from the Trinidad population when paired with optimum reared BF2 males. Small (0.027 m3) and large (0.216 m3) trials were conducted wherein stressed or optimum Trinidad males competed with optimum BF2 males for mating with stressed Trinidad females. When competing with stress reared Trinidad males, optimum reared BF2 males were predominant in matings with stress reared Trinidad females, and large proportions of these females mated with males of both strains. When competing with optimum reared Trinidad males, no difference in mating success was observed between them and BF2 males, and frequencies of multiple matings were low. Our results indicate that future mating competition studies should incorporate appropriate environmental conditions when designing mating fitness trials of genetically modified males.
Assuntos
Aedes/fisiologia , Comportamento Sexual Animal , Animais , Animais Geneticamente Modificados/fisiologia , Comportamento Competitivo , Masculino , Trinidad e TobagoRESUMO
Surveillance for blood-fed female mosquitoes was performed between August 2015 and February 2016 at sites along the periphery of the Aripo Savannas Environmentally Reserve (ASSR) located in northeastern Trinidad, West Indies. We collected engorged female mosquitoes representing 13 species. DNA extractions from dissected abdomens were subjected to PCR amplification with three primer pairs targeting the mitochondrial cytochrome oxidase I and cytochrome b gene sequences. High-quality sequence information and host identification were obtained for 42 specimens representing eight mosquito species with at least one primer combination. A broad range of vertebrates including humans were identified, but the majority were nonhuman mammals, both domestic and wild. Domestic dogs were the most common host and may represent potential sentinel species for monitoring local enzootic arbovirus activity in Trinidad. Culex declarator Dyer and Knab and Culex nigripalpus Theobald were the most common blood-fed mosquito species comprising 79.1% of the total number identified. These species obtained blood meals from birds, nonhuman mammals, and human hosts, and therefore pose significant risks as potential bridge vectors for epizootic arbovirus transmission in the ASSR area as well as other sylvan areas in Trinidad. These data represent the first such results for Trinidad.
Assuntos
Culicidae/fisiologia , Cadeia Alimentar , Mosquitos Vetores/fisiologia , Animais , Arbovírus , Aves , Dieta , Comportamento Alimentar , Feminino , Humanos , Mamíferos , Trinidad e TobagoRESUMO
In this paper, we describe and illustrate a new species of parasitoid wasp as Brachymeria philornisae Delvare, sp. nov. The new species was reared from Philornis trinitensis Dodge & Aitken (Diptera: Muscidae) puparia that were found in the nests of the bird species Mimus gilvus (Vieillot) (Mimidae) and Tiaris bicolor (L.) (Thraupidae) in Tobago. The new species is of particular interest as it may be considered a potential biological control agent in locations where Philornis species are invasive, such as the Galapagos Islands. Closely related Brachymeria species had taxonomically ambiguous relationship in the past and are compared and reviewed. The species have been classified in the subgenus Pseudobrachymeria, but are here treated within the newly defined subconica species-group of Brachymeria as part of a sibling species complex designated as the subrugosa complex. Species assigned to the subconica species-group are listed and five, one unnamed, are assigned to the subrugosa complex and their females keyed. Species are separated by qualitative characters and morphometry using distance measurements. Trigonura annulipes Costa Lima is renamed as Brachymeria costalimai Delvare nom. nov. because of secondary homonymy.
Assuntos
Himenópteros , Parasitos , Animais , Equador , Feminino , Larva , Muscidae , Trinidad e TobagoRESUMO
Few laboratory and field studies have reported long survival periods for Ae. aegypti females and even fewer have designed experiments to characterize this important life history trait. This study was conducted under laboratory conditions to determine the number of blood meals taken by individual females, the number of eggs laid per individual female, the length of the gonotrophic cycle, and the duration of female survival. The results showed individual females oviposited between 670 and 1,500 eggs throughout their lifetimes, females undergoing large numbers of gonotrophic cycles and surviving up to 224 days. These results are discussed in the context of vector competence, unique alternating high and low oviposition patterns observed after week 14, and resource partitioning/allocation by older Ae. aegypti females after blood feeding.
Assuntos
Aedes , Longevidade , Animais , Feminino , Mosquitos Vetores , Oviposição , Trinidad e TobagoRESUMO
The 2014 enterovirus D68 (EV-D68) outbreak in the United States raised concerns about the introduction of the virus in the Caribbean region. The objective of this study was to provide rapid evidence of the introduction of EV-D68 strains in the Caribbean region during the 2014 outbreak in the United States, using a relatively simple phylogenetic approach. From October 2014 to May 2015, four EV-D68 cases from two countries (Bermuda and Dominica) were detected at the regional referral laboratory at the Caribbean Public Health Agency (Port of Spain, Trinidad and Tobago) based on molecular testing of respiratory specimens. All cases were children presenting to hospitals with moderate respiratory distress. No cases of acute flaccid paralysis were detected. Phylogenetic analysis of the Caribbean strains showed more than 99% similarity with the 2014 U.S.-outbreak strain, providing evidence of the introduction and circulation of the virus in the region.
Assuntos
Surtos de Doenças , Enterovirus Humano D , Infecções por Enterovirus/epidemiologia , Região do Caribe/epidemiologia , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Estudos Retrospectivos , Estados Unidos/epidemiologiaRESUMO
The 2014 enterovirus D68 (EV-D68) outbreak in the United States raised concerns about the introduction of the virus in the Caribbean region. The objective of this study was to provide rapid evidence of the introduction of EV-D68 strains in the Caribbean region during the 2014 outbreak in the United States, using a relatively simple phylogenetic approach. From October 2014 to May 2015, four EV-D68 cases from two countries (Bermuda and Dominica) were detected at the regional referral laboratory at the Caribbean Public Health Agency (Port of Spain, Trinidad and Tobago) based on molecular testing of respiratory specimens. All cases were children presenting to hospitals with moderate respiratory distress. No cases of acute flaccid paralysis were detected. Phylogenetic analysis of the Caribbean strains showed more than 99% similarity with the 2014 U.S.-outbreak strain, providing evidence of the introduction and circulation of the virus in the region.
El brote de enterovirus D68 (EV-D68) registrado en el 2014 en los Estados Unidos suscitó preocupación acerca de la introducción del virus en el Caribe. El objetivo de este estudio fue aportar pruebas rápidas, mediante la adopción de un enfoque filogénico relativamente sencillo, de que durante ese brote ingresaron en el Caribe cepas del EV-D68. Entre octubre del 2014 y mayo del 2015, el laboratorio regional de referencia ubicado en el Organismo de Salud Pública del Caribe (Puerto España, Trinidad y Tabago) detectó cuatro casos de EV-D68 provenientes de dos países (Bermudas y Dominica) mediante el análisis molecular de muestras respiratorias. Todos los casos correspondían a niños que acudieron al hospital con dificultad respiratoria moderada. No se detectó ningún caso de parálisis flácida aguda. El análisis filogénico de las cepas encontradas en el Caribe demostró una semejanza superior al 99 % con la cepa responsable del brote del 2014 en los Estados Unidos, lo que demuestra la introducción y la circulación del virus en la región.
Assuntos
Enterovirus Humano D , Infecções por Enterovirus , Região do Caribe , Dominica , Bermudas , Enterovirus Humano D , Infecções por Enterovirus , Região do CaribeRESUMO
ABSTRACT The 2014 enterovirus D68 (EV-D68) outbreak in the United States raised concerns about the introduction of the virus in the Caribbean region. The objective of this study was to provide rapid evidence of the introduction of EV-D68 strains in the Caribbean region during the 2014 outbreak in the United States, using a relatively simple phylogenetic approach. From October 2014 to May 2015, four EV-D68 cases from two countries (Bermuda and Dominica) were detected at the regional referral laboratory at the Caribbean Public Health Agency (Port of Spain, Trinidad and Tobago) based on molecular testing of respiratory specimens. All cases were children presenting to hospitals with moderate respiratory distress. No cases of acute flaccid paralysis were detected. Phylogenetic analysis of the Caribbean strains showed more than 99% similarity with the 2014 U.S.-outbreak strain, providing evidence of the introduction and circulation of the virus in the region.(AU)
RESUMEN El brote de enterovirus D68 (EV-D68) registrado en el 2014 en los Estados Unidos suscitó preocupación acerca de la introducción del virus en el Caribe. El objetivo de este estudio fue aportar pruebas rápidas, mediante la adopción de un enfoque filogénico relativamente sencillo, de que durante ese brote ingresaron en el Caribe cepas del EV-D68. Entre octubre del 2014 y mayo del 2015, el laboratorio regional de referencia ubicado en el Organismo de Salud Pública del Caribe (Puerto España, Trinidad y Tabago) detectó cuatro casos de EV-D68 provenientes de dos países (Bermudas y Dominica) mediante el análisis molecular de muestras respiratorias. Todos los casos correspondían a niños que acudieron al hospital con dificultad respiratoria moderada. No se detectó ningún caso de parálisis flácida aguda. El análisis filogénico de las cepas encontradas en el Caribe demostró una semejanza superior al 99 % con la cepa responsable del brote del 2014 en los Estados Unidos, lo que demuestra la introducción y la circulación del virus en la región.(AU)
Assuntos
Humanos , Recém-Nascido , Lactente , Pré-Escolar , Infecções por Enterovirus/prevenção & controle , Infecções por Enterovirus/epidemiologia , Bermudas/epidemiologia , Região do Caribe/epidemiologia , Dominica/epidemiologia , Enterovirus Humano D/isolamento & purificaçãoRESUMO
BACKGROUND: The purpose of the study is to determine the epidemiology of road traffic collisions (RTCs) in Trinidad and Tobago by characterizing RTCs in terms of number of collisions, fatalities, victim profiles, and locations for the purpose of informing accident prevention programs. Previous studies of RTCs in Trinidad and Tobago were primarily concerned with patterns of drivers use of seat belts, road collisions as a cause of mortality in young men, and the economic burden of road collisions. Attempts were made to model road fatalities, but limited epidemiological data meant that it was difficult to determine trends or develop models. METHODS: This study determined the epidemiology of RTCs in Trinidad and Tobago over the period 2000-2011 using data collected by the Trinidad and Tobago Road Traffic Branch of the Police Service and secondary data from the Central Statistical Office. Data were analyzed using Excel, SPSS, and R statistical packages. RESULTS: Fatalities were greater among men (80%) than among women (20%) and were highest on two major freeways in Trinidad [the Churchill-Roosevelt Highway and the Sir Solomon Hochoy Highway]. Most collisions occurred during the night among individuals between the ages of 15 and 44 years. Fatalities among drivers steadily increased over the study period and overtook fatalities among pedestrians, who were the group most affected in 2000. Most fatalities occurred at weekends. CONCLUSIONS: These patterns can inform (i) education programs and (ii) road and traffic control measures.
RESUMO
The epidemiology of dengue fever is characterized by highly seasonal, multi-annual fluctuations, and the irregular circulation of its four serotypes. It is believed that this behaviour arises from the interplay between environmental drivers and serotype interactions. The exact mechanism, however, is uncertain. Constraining mathematical models to patterns characteristic to dengue epidemiology offers a means for detecting such mechanisms. Here, we used a pattern-oriented modelling (POM) strategy to fit and assess a range of dengue models, driven by combinations of temporary cross protective-immunity, cross-enhancement, and seasonal forcing, on their ability to capture the main characteristics of dengue dynamics. We show that all proposed models reproduce the observed dengue patterns across some part of the parameter space. Which model best supports the dengue dynamics is determined by the level of seasonal forcing. Further, when tertiary and quaternary infections are allowed, the inclusion of temporary cross-immunity alone is strongly supported, but the addition of cross-enhancement markedly reduces the parameter range at which dengue dynamics are produced, irrespective of the strength of seasonal forcing. The implication of these structural uncertainties on predicted vulnerability to control is also discussed. With ever expanding spread of dengue, greater understanding of dengue dynamics and control efforts (e.g. a near-future vaccine introduction) has become critically important. This study highlights the capacity of multi-level pattern-matching modelling approaches to offer an analytic tool for deeper insights into dengue epidemiology and control.
Assuntos
Vírus da Dengue/classificação , Dengue/epidemiologia , Dengue/prevenção & controle , Modelos Biológicos , Reconhecimento Automatizado de Padrão , Estações do Ano , Simulação por Computador , Dengue/imunologia , Humanos , Sorogrupo , Trinidad e Tobago/epidemiologiaRESUMO
BACKGROUND: Dengue is an acute arboviral disease responsible for most of the illness and death in tropical and subtropical regions. Over the last 25 years there has been increase epidemic activity of the disease in the Caribbean, with the co-circulation of multiple serotypes. An understanding of the space and time dynamics of dengue could provide health agencies with important clues for reducing its impact. METHODS: Dengue Haemorrhagic Fever (DHF) cases observed for the period 1998-2004 were georeferenced using Geographic Information System software. Spatial clustering was calculated for individual years and for the entire study period using the Nearest Neighbor Index. Space and time interaction between DHF cases was determined using the Knox Test while the Nearest Neighbor Hierarchical method was used to extract DHF hot spots. All space and time distances calculated were validated using the Pearson r significance test. RESULTS: Results shows that (1) a decrease in mean distance between DHF cases correlates with activity leading up to an outbreak, (2) a decrease in temporal distance between DHF cases leads to increased geographic spread of the disease, with an outbreak occurrence about every 2 years, and (3) a general pattern in the movement of dengue incidents from more rural to urban settings leading up to an outbreak with hotspot areas associated with transportation hubs in Trinidad. CONCLUSION: Considering only the spatial dimension of the disease, results suggest that DHF cases become more concentrated leading up to an outbreak. However, with the additional consideration of time, results suggest that when an outbreak occurs incidents occur more rapidly in time leading to a parallel increase in the rate of distribution of the disease across space. The results of this study can be used by public health officers to help visualize and understand the spatial and temporal patterns of dengue, and to prepare warnings for the public. Dengue space-time patterns and hotspot detection will provide useful information to support public health officers in their efforts to control and predict dengue spread over critical hotspots allowing better allocation of resources.
Assuntos
Dengue/epidemiologia , Viagem , Análise por Conglomerados , Dengue/transmissão , Humanos , Incidência , Estudos Retrospectivos , Fatores de Tempo , Trinidad e Tobago/epidemiologiaRESUMO
The diel copulation periodicity of domestic Aedes aegypti in the field in Trinidad, West Indies was monitored weekly at indoor and outdoor sites over a 16 month period. At indoor sites two significant (P<0.02) peaks in copulation occurred between 06.00 and 08.00 (25% of copulation events) and between 16.00 and 18.00 (24%): at outdoor sites the copulation periodicity was similar to that observed indoors with an early morning peak in copulation at 06.00-08.00 (30%) and a late evening peak at 16.00-18.00 h (25%). Laboratory studies showed similar copulation patterns to those observed at indoor and outdoor sites. Copulation occurred at two different locations: at outdoor sites copulation was primarily in close proximity to breeding sites while at indoor sites copulation was observed in close proximity to human bait or members of the household. The parity rate of copulating females collected indoors was 59% in contrast to only 15% collected outdoors, which suggests that females found indoors were older. The diel copulation periodicity, location where copulation occurs, parous rates and insemination rates are discussed in the context of sterile insect technique or genetic control modalities.
Assuntos
Aedes/fisiologia , Animais , Copulação , Periodicidade , Trinidad e TobagoRESUMO
Studies on the diel sugar feeding periodicity of male and female Aedes aegypti were conducted under laboratory conditions and monitored in single cages using the polyphagometer device and examined every 2h. Males mosquitoes displayed two peaks in sugar feeding, a small morning peak at 06.00-08.00 h (16% of sugar feeding) and a significant evening peak at 16.00-18.00 h (40% of sugar feeding). A similar pattern was observed among females: a small early morning peak (18% of sugar feeding) and a significant peak in the evening 16.00-18.00 h (42% of sugar feeding). Studies on the effects of sugar feeding on the excitation of males showed 100% erect antennal fibrillae after 36 h. In contrast, only 15% of the water-fed males responded. Laboratory studies on the effects of sugar feeding on the insemination rates of A. aegypti females showed similar inseminations rates among sugar and water fed males but after 4 days all water fed males died while the sugar fed males continued to survive and inseminate females. The synchronization of the male and female diel sugar feeding periodicity is discussed in the context of sterile insect techniques or genetic control methods.
Assuntos
Aedes/fisiologia , Comportamento Alimentar , Comportamento Sexual Animal , Animais , Animais de Laboratório , Carboidratos , Feminino , Humanos , Masculino , Trinidad e TobagoRESUMO
BACKGROUND: Historically, Aedes aegypti (L.) mosquitoes were controlled/eradicated by fumigation, residual spraying and the elimination of breeding sites. However, the underlying mechanisms of how these vector populations were managed have never been evaluated. Most studies report that these programs failed due to the emergence of DDT resistance in the 1950s and early 1960s. Therefore, behavioural and physiological factors have never been examined to determine program success or failure. METHODS: A ten- week study collecting resting and flying mosquitoes from every room in houses using small hand nets and Propokock aspirators in St. Augustine, Trinidad, West Indies was conducted during the rainy season months of October to December 2010. During this period a laboratory study was also conducted to determine how soon after egg laying individual females took a blood-meal. RESULTS: The field study showed the major resting sites of Ae. aegypti were bed rooms (81.9%), living rooms (8.7%) and kitchen (6.9%). The laboratory study showed only 10% of females accepted a blood meal immediately after oviposition but the majority, 70% accepted a blood meal 12 hours post oviposition. CONCLUSIONS: The results provide evidence for the efficacy of indoor residual spraying (IRS) and recommend its re-introduction by targeting the major resting sites of these mosquitoes, especially during dengue fever outbreaks.
Assuntos
Aedes/fisiologia , Comportamento Animal , Dengue/prevenção & controle , Vetores de Doenças , Controle de Mosquitos/métodos , Animais , Comportamento Alimentar , Feminino , Habitação , Humanos , Masculino , Trinidad e TobagoRESUMO
We report here the development of 65 novel microsatellite loci and construction of a composite genetic linkage map for Culex pipiens complex mosquitoes. Microsatellites were identified by in silico screening of the Culex quinquefasciatus genome assembly. Cross-species utility of 73 microsatellites for population studies in C. pipiens sensu stricto and C. quinquefasciatus was evaluated by genotyping a subset of samples collected in Indiana, United States, and Point Fortin, Trinidad. Allele frequencies of 67 microsatellites were within Hardy-Weinberg expectations in both population subsets. A composite linkage map was constructed based on restriction fragment length polymorphism and microsatellite polymorphisms in 12 independent F1 intercross mapping populations. The composite map consists of 61 marker loci totaling 183.9 cM distributed across the 3 linkage groups. These loci cover 29.5, 88.8, and 65.6 cM on chromosomes I-III, respectively, and allow for assignment of 10.4% of the genome assembly and 13.5% of the protein coding genes to chromosome position. Our results suggest that these microsatellites will be useful for mapping and population studies of 2 pervasive species in the C. pipiens complex. Moreover, the composite map presented here will serve as a basis for the construction of high-resolution genetic and physical maps, as well as detection of quantitative trait loci to aid in the investigation of complex genetic traits influencing phenotypes of interest.
Assuntos
Mapeamento Cromossômico , Culex/genética , Marcadores Genéticos/genética , Animais , Frequência do Gene , Ligação Genética , Genoma , Genótipo , Repetições de Microssatélites/genética , Polimorfismo de Fragmento de Restrição/genética , Trinidad e Tobago , Estados UnidosRESUMO
BACKGROUND: Effective malaria control relies on accurate identification of those Anopheles mosquitoes responsible for the transmission of Plasmodium parasites. Anopheles oswaldoi s.l. has been incriminated as a malaria vector in Colombia and some localities in Brazil, but not ubiquitously throughout its Neotropical range. This evidence together with variable morphological characters and genetic differences supports that An. oswaldoi s.l. compromises a species complex. The recent fully integrated redescription of An. oswaldoi s.s. provides a solid taxonomic foundation from which to molecularly determine other members of the complex. METHODS: DNA sequences of the Second Internal Transcribed Spacer (ITS2 - rDNA) (n = 192) and the barcoding region of the Cytochrome Oxidase I gene (COI - mtDNA) (n = 110) were generated from 255 specimens of An. oswaldoi s.l. from 33 localities: Brazil (8 localities, including the lectotype series of An. oswaldoi), Ecuador (4), Colombia (17), Trinidad and Tobago (1), and Peru (3). COI sequences were analyzed employing the Kimura-two-parameter model (K2P), Bayesian analysis (MrBayes), Mixed Yule-Coalescent model (MYC, for delimitation of clusters) and TCS genealogies. RESULTS: Separate and combined analysis of the COI and ITS2 data sets unequivocally supported four separate species: two previously determined (An. oswaldoi s.s. and An. oswaldoi B) and two newly designated species in the Oswaldoi Complex (An. oswaldoi A and An. sp. nr. konderi). The COI intra- and inter-specific genetic distances for the four taxa were non-overlapping, averaging 0.012 (0.007 to 0.020) and 0.052 (0.038 to 0.064), respectively. The concurring four clusters delineated by MrBayes and MYC, and four independent TCS networks, strongly confirmed their separate species status. In addition, An. konderi of Sallum should be regarded as unique with respect to the above. Despite initially being included as an outgroup taxon, this species falls well within the examined taxa, suggesting a combined analysis of these taxa would be most appropriate. CONCLUSIONS: Through novel data and retrospective comparison of available COI and ITS2 DNA sequences, evidence is shown to support the separate species status of An. oswaldoi s.s., An. oswaldoi A and An. oswaldoi B, and at least two species in the closely related An. konderi complex (An. sp. nr. konderi, An. konderi of Sallum). Although An. oswaldoi s.s. has never been implicated in malaria transmission, An. oswaldoi B is a confirmed vector and the new species An. oswaldoi A and An. sp. nr. konderi are circumstantially implicated, most likely acting as secondary vectors.
Assuntos
Anopheles/classificação , Animais , Anopheles/genética , Análise por Conglomerados , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA , América do SulRESUMO
Seroprevalence rates of selected arboviruses in animal populations in Trinidad were determined using serum samples collected between 2006 and 2009 from horses (n=506), cattle (n=163), sheep (n=198), goats (n=82), pigs (n=184), birds (n=140), rodents (n=116), and other vertebrates (n=23). The sera were screened for antibodies to West Nile virus (WNV), St. Louis encephalitis virus (SLEV), Ilheus virus (ILHV), Bussuquara virus (BSQV), Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV), using hemagglutination inhibition assay (HIA) and epitope-blocking enzyme-linked immunosorbent assays (ELISA). Antibodies to SLEV were detected in a total of 49 (9.7%) horses, 8 (4.9%) cattle, 1 (1.2%) goat, 2 (1.4%) wild birds, and 3 (2.2%) wild rodents by both methods. In contrast, antibodies to EEEV, VEEV, and WNV were detected only in horses, at rates of 4.3%, 0.8%, and 17.2%, respectively, by ELISA, and IgM capture ELISA was WNV-positive in 3 (0.6%) of these sera. Among locally bred unvaccinated horses that had never left Trinidad, seroprevalence rates against WNV were 12.1% and 17.2% by ELISA and HIA, respectively. The presence of WNV- and SLEV-specific antibodies in a representative sample of horse sera that were both ELISA- and HIA-seropositive was confirmed by plaque reduction neutralization testing (PRNT). Antibodies to ILHV and BSQV were not detected in any of the serum samples tested (i.e., sera from horses, other livestock, and wild birds in the case of ILHV, and wild mammals in the case of BSQV). The data indicate the presence of WNV in Trinidad, and continuing low-level circulation of SLEV, EEEV, and VEEV.
Assuntos
Infecções por Alphavirus/veterinária , Alphavirus/imunologia , Anticorpos Antivirais/sangue , Infecções por Flavivirus/veterinária , Flavivirus/imunologia , Alphavirus/isolamento & purificação , Infecções por Alphavirus/epidemiologia , Infecções por Alphavirus/virologia , Animais , Animais Selvagens , Aves , Bovinos , Ensaio de Imunoadsorção Enzimática , Flavivirus/isolamento & purificação , Infecções por Flavivirus/epidemiologia , Infecções por Flavivirus/virologia , Cabras , Testes de Inibição da Hemaglutinação , Cavalos , Gado , Roedores , Estudos Soroepidemiológicos , Ovinos , Suínos , Trinidad e Tobago/epidemiologia , Febre do Nilo Ocidental/imunologia , Febre do Nilo Ocidental/veterinária , Febre do Nilo Ocidental/virologia , Vírus do Nilo Ocidental/imunologia , Vírus do Nilo Ocidental/isolamento & purificaçãoRESUMO
OBJECTIVE: To examine the effects of increasing larval rearing temperatures on the resistance status of Trinidadian populations of Aedes aegypti to organophosphate (OP) insecticides. METHODS: In 2007-2008, bioassays and biochemical assays were conducted on A. aegypti larvae collected in 2006 from eight geographically distinct areas in Trinidad (Trinidad and Tobago). Larval populations were reared at four temperatures (28 ± 2ºC, 32ºC, 34ºC, and 36ºC) prior to bioassays with OP insecticides (fenthion, malathion, and temephos) and biochemical assays for esterase enzymes. RESULTS: Most larval populations reared at 28 ± 2ºC were susceptible to fenthion (>98% mortality) but resistant to malathion and temephos (< 80% mortality). A positive association was found between resistance to OP insecticides and increased activities of α- and ß-esterases in larval populations reared at 28 ± 2ºC. Although larval populations reared at higher temperatures showed variations in resistance to OPs, there was a general increase in susceptibility. However, increases or decreases in activity levels of enzymes did not always correspond with an increase or decrease in the proportion of resistant individuals reared at higher temperatures. CONCLUSIONS: Although global warming may cause an increase in dengue transmission, based on the current results, the use of insecticides for dengue prevention and control may yet be effective if temperatures increase as projected.
Assuntos
Aedes/efeitos dos fármacos , Fention/farmacologia , Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Malation/farmacologia , Temefós/farmacologia , Temperatura , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Animais , Dengue/prevenção & controle , Esterases/análise , Esterases/fisiologia , Aquecimento Global , Temperatura Alta , Proteínas de Insetos/análise , Proteínas de Insetos/fisiologia , Insetos Vetores/enzimologia , Insetos Vetores/crescimento & desenvolvimento , Resistência a Inseticidas/fisiologia , Larva/efeitos dos fármacos , Larva/enzimologia , Especificidade da Espécie , Trinidad e TobagoRESUMO
OBJECTIVE: To examine the effects of increasing larval rearing temperatures on the resistance status of Trinidadian populations of Aedes aegypti to organophosphate (OP) insecticides. METHODS: In 2007-2008, bioassays and biochemical assays were conducted on A. aegypti larvae collected in 2006 from eight geographically distinct areas in Trinidad (Trinidad and Tobago). Larval populations were reared at four temperatures (28 ± 2ºC, 32ºC, 34ºC, and 36ºC) prior to bioassays with OP insecticides (fenthion, malathion, and temephos) and biochemical assays for esterase enzymes. RESULTS: Most larval populations reared at 28 ± 2ºC were susceptible to fenthion (>98% mortality) but resistant to malathion and temephos (< 80% mortality). A positive association was found between resistance to OP insecticides and increased activities of α- and β-esterases in larval populations reared at 28 ± 2ºC. Although larval populations reared at higher temperatures showed variations in resistance to OPs, there was a general increase in susceptibility. However, increases or decreases in activity levels of enzymes did not always correspond with an increase or decrease in the proportion of resistant individuals reared at higher temperatures. CONCLUSIONS: Although global warming may cause an increase in dengue transmission, based on the current results, the use of insecticides for dengue prevention and control may yet be effective if temperatures increase as projected.
OBJETIVO: Examinar los efectos del aumento de las temperaturas de desarrollo larvario sobre el estado de resistencia a los insecticidas organofosforados de las poblaciones de Aedes aegypti en Trinidad. MÉTODOS: En 2007 y 2008 se llevaron a cabo ensayos biológicos y bioquímicos en larvas de A. aegypti recogidas en el 2006 de ocho áreas geográficamente separadas en Trinidad (Trinidad y Tabago). Las poblaciones larvarias se desarrollaron en cuatro temperaturas (28 ± 2 ºC, 32 ºC, 34 ºC y 36 ºC) antes de los ensayos biológicos con insecticidas organofosforados (fentión, malatión y temefós) y los análisis bioquímicos para las enzimas de esterasa. RESULTADOS: La mayoría de las poblaciones larvarias que se desarrollaron a 28 ± 2 ºC fueron susceptibles al fentión (mortalidad > 98%) pero resistentes al malatión y al temefós (mortalidad < 80%). Se encontró una asociación positiva entre la resistencia a los insecticidas organofosforados y la mayor actividad de αy β-esterasas en las poblaciones larvarias que se desarrollaron a 28 ± 2 ºC. Aunque las poblaciones larvarias que se desarrollaron a temperaturas mayores mostraron variaciones en la resistencia a los organofosforados, hubo un aumento general de la sensibilidad. Sin embargo, los aumentos o las disminuciones en los niveles de actividad de las enzimas no siempre se correspondieron con un aumento o disminución en la proporción de individuos resistentes desarrollados a las temperaturas más altas. CONCLUSIONES: Aunque el recalentamiento del planeta puede causar un aumento de la transmisión del dengue, según los resultados de este estudio el uso de insecticidas para la prevención y el control del dengue todavía puede ser eficaz si las temperaturas aumentan según lo proyectado.
Assuntos
Animais , Aedes/efeitos dos fármacos , Fention/farmacologia , Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Malation/farmacologia , Temefós/farmacologia , Temperatura , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Dengue/prevenção & controle , Esterases/análise , Esterases/fisiologia , Aquecimento Global , Temperatura Alta , Proteínas de Insetos/análise , Proteínas de Insetos/fisiologia , Insetos Vetores/enzimologia , Insetos Vetores/crescimento & desenvolvimento , Resistência a Inseticidas/fisiologia , Larva/efeitos dos fármacos , Larva/enzimologia , Especificidade da Espécie , Trinidad e TobagoAssuntos
Culicidae , Aedes , Controle de Mosquitos , Resistência a Inseticidas , Inseticidas Organofosforados , Temperatura , Controle de Mosquitos , Resistência a Inseticidas , Inseticidas Organofosforados , Temperatura , Trinidad e Tobago , Fention , Resistência a Inseticidas , Inseticidas , Malation , Temefós , Temperatura , Dengue , Esterases , Aquecimento Global , Temperatura Alta , Proteínas de Insetos , Larva , Trinidad e Tobago , Trinidad e Tobago , Insetos Vetores , Especificidade da EspécieRESUMO
Like other countries around the globe where conditions existed for the parasites causing hookworm disease to thrive, this disease was a serious problem to settlers in countries of the Commonwealth Caribbean, i.e. those countries that were formerly part of the British Empire. Early in the 20th century, the Rockefeller Foundation (RF) assisted the southern United States in controlling this disease. Soon other countries requested assistance and the Rockefeller Foundation responded by creating their International Health Commission to target the problem. Guyana (then British Guiana) was the first country where work was started. Through a system of chemotherapy, sanitation with the provision of latrines and health education the RF assisted the Commonwealth Caribbean countries during the period 1914-1925 in controlling the disease. Most countries continued the programmes started by the Rockefeller Foundation and this paper provides evidence through a series of surveys to show that hookworm disease is no longer a public health problem.